// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;

import "./v2-solidity-utils/contracts/helpers/InputHelpers.sol";
import "./v2-solidity-utils/contracts/math/FixedPoint.sol";
import "./v2-solidity-utils/contracts/math/Math.sol";

// These functions start with an underscore, as if they were part of a contract and not a library. At some point this
// should be fixed.
// solhint-disable private-vars-leading-underscore

library WeightedMath {
    using FixedPoint for uint256;
    // A minimum normalized weight imposes a maximum weight ratio. We need this due to limitations in the
    // implementation of the power function, as these ratios are often exponents.
    uint256 internal constant _MIN_WEIGHT = 0.01e18;
    // Having a minimum normalized weight imposes a limit on the maximum number of tokens;
    // i.e., the largest possible pool is one where all tokens have exactly the minimum weight.
    uint256 internal constant _MAX_WEIGHTED_TOKENS = 100;

    // Pool limits that arise from limitations in the fixed point power function (and the imposed 1:100 maximum weight
    // ratio).

    // Swap limits: amounts swapped may not be larger than this percentage of total balance.
    uint256 internal constant _MAX_IN_RATIO = 0.3e18;
    uint256 internal constant _MAX_OUT_RATIO = 0.3e18;

    // Invariant growth limit: non-proportional joins cannot cause the invariant to increase by more than this ratio.
    uint256 internal constant _MAX_INVARIANT_RATIO = 3e18;
    // Invariant shrink limit: non-proportional exits cannot cause the invariant to decrease by less than this ratio.
    uint256 internal constant _MIN_INVARIANT_RATIO = 0.7e18;

    // About swap fees on joins and exits:
    // Any join or exit that is not perfectly balanced (e.g. all single token joins or exits) is mathematically
    // equivalent to a perfectly balanced join or exit followed by a series of swaps. Since these swaps would charge
    // swap fees, it follows that (some) joins and exits should as well.
    // On these operations, we split the token amounts in 'taxable' and 'non-taxable' portions, where the 'taxable' part
    // is the one to which swap fees are applied.

    // Invariant is used to collect protocol swap fees by comparing its value between two times.
    // So we can round always to the same direction. It is also used to initiate the BPT amount
    // and, because there is a minimum BPT, we round down the invariant.
    function _calculateInvariant(
        uint256[] memory normalizedWeights,
        uint256[] memory balances
    ) internal pure returns (uint256 invariant) {
        /**********************************************************************************************
        // invariant               _____                                                             //
        // wi = weight index i      | |      wi                                                      //
        // bi = balance index i     | |  bi ^   = i                                                  //
        // i = invariant                                                                             //
        **********************************************************************************************/

        invariant = FixedPoint.ONE;
        for (uint256 i = 0; i < normalizedWeights.length; i++) {
            invariant = invariant.mulDown(
                balances[i].powDown(normalizedWeights[i])
            );
        }

        _require(invariant > 0, Errors.ZERO_INVARIANT);
    }

    // Computes how many tokens can be taken out of a pool if `amountIn` are sent, given the
    // current balances and weights.
    function _calcOutGivenIn(
        uint256 balanceIn,
        uint256 weightIn,
        uint256 balanceOut,
        uint256 weightOut,
        uint256 amountIn
    ) internal pure returns (uint256) {
        /**********************************************************************************************
        // outGivenIn                                                                                //
        // aO = amountOut                                                                            //
        // bO = balanceOut                                                                           //
        // bI = balanceIn              /      /            bI             \    (wI / wO) \           //
        // aI = amountIn    aO = bO * |  1 - | --------------------------  | ^            |          //
        // wI = weightIn               \      \       ( bI + aI )         /              /           //
        // wO = weightOut                                                                            //
        **********************************************************************************************/

        // Amount out, so we round down overall.

        // The multiplication rounds down, and the subtrahend (power) rounds up (so the base rounds up too).
        // Because bI / (bI + aI) <= 1, the exponent rounds down.

        // Cannot exceed maximum in ratio
        _require(
            amountIn <= balanceIn.mulDown(_MAX_IN_RATIO),
            Errors.MAX_IN_RATIO
        );

        uint256 denominator = balanceIn.add(amountIn);
        uint256 base = balanceIn.divUp(denominator);
        uint256 exponent = weightIn.divDown(weightOut);
        uint256 power = base.powUp(exponent);

        return balanceOut.mulDown(power.complement());
    }

    // Computes how many tokens must be sent to a pool in order to take `amountOut`, given the
    // current balances and weights.
    function _calcInGivenOut(
        uint256 balanceIn,
        uint256 weightIn,
        uint256 balanceOut,
        uint256 weightOut,
        uint256 amountOut
    ) internal pure returns (uint256) {
        /**********************************************************************************************
        // inGivenOut                                                                                //
        // aO = amountOut                                                                            //
        // bO = balanceOut                                                                           //
        // bI = balanceIn              /  /            bO             \    (wO / wI)      \          //
        // aI = amountIn    aI = bI * |  | --------------------------  | ^            - 1  |         //
        // wI = weightIn               \  \       ( bO - aO )         /                   /          //
        // wO = weightOut                                                                            //
        **********************************************************************************************/

        // Amount in, so we round up overall.

        // The multiplication rounds up, and the power rounds up (so the base rounds up too).
        // Because b0 / (b0 - a0) >= 1, the exponent rounds up.

        // Cannot exceed maximum out ratio
        _require(
            amountOut <= balanceOut.mulDown(_MAX_OUT_RATIO),
            Errors.MAX_OUT_RATIO
        );

        uint256 base = balanceOut.divUp(balanceOut.sub(amountOut));
        uint256 exponent = weightOut.divUp(weightIn);
        uint256 power = base.powUp(exponent);

        // Because the base is larger than one (and the power rounds up), the power should always be larger than one, so
        // the following subtraction should never revert.
        uint256 ratio = power.sub(FixedPoint.ONE);

        return balanceIn.mulUp(ratio);
    }

    function _calcBptOutGivenExactTokensIn(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory amountsIn,
        uint256 bptTotalSupply,
        uint256 swapFeePercentage
    ) internal pure returns (uint256) {
        // BPT out, so we round down overall.

        uint256[] memory balanceRatiosWithFee = new uint256[](amountsIn.length);

        uint256 invariantRatioWithFees = 0;
        for (uint256 i = 0; i < balances.length; i++) {
            balanceRatiosWithFee[i] = balances[i].add(amountsIn[i]).divDown(
                balances[i]
            );
            invariantRatioWithFees = invariantRatioWithFees.add(
                balanceRatiosWithFee[i].mulDown(normalizedWeights[i])
            );
        }

        uint256 invariantRatio = _computeJoinExactTokensInInvariantRatio(
            balances,
            normalizedWeights,
            amountsIn,
            balanceRatiosWithFee,
            invariantRatioWithFees,
            swapFeePercentage
        );

        uint256 bptOut = (invariantRatio > FixedPoint.ONE)
            ? bptTotalSupply.mulDown(invariantRatio.sub(FixedPoint.ONE))
            : 0;
        return bptOut;
    }

    /**
     * @dev Intermediate function to avoid stack-too-deep errors.
     */
    function _computeJoinExactTokensInInvariantRatio(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory amountsIn,
        uint256[] memory balanceRatiosWithFee,
        uint256 invariantRatioWithFees,
        uint256 swapFeePercentage
    ) private pure returns (uint256 invariantRatio) {
        // Swap fees are charged on all tokens that are being added in a larger proportion than the overall invariant
        // increase.
        invariantRatio = FixedPoint.ONE;

        for (uint256 i = 0; i < balances.length; i++) {
            uint256 amountInWithoutFee;

            if (balanceRatiosWithFee[i] > invariantRatioWithFees) {
                uint256 nonTaxableAmount = balances[i].mulDown(
                    invariantRatioWithFees.sub(FixedPoint.ONE)
                );
                uint256 taxableAmount = amountsIn[i].sub(nonTaxableAmount);
                uint256 swapFee = taxableAmount.mulUp(swapFeePercentage);

                amountInWithoutFee = nonTaxableAmount.add(
                    taxableAmount.sub(swapFee)
                );
            } else {
                amountInWithoutFee = amountsIn[i];
            }

            uint256 balanceRatio = balances[i].add(amountInWithoutFee).divDown(
                balances[i]
            );

            invariantRatio = invariantRatio.mulDown(
                balanceRatio.powDown(normalizedWeights[i])
            );
        }
    }

    function _calcTokenInGivenExactBptOut(
        uint256 balance,
        uint256 normalizedWeight,
        uint256 bptAmountOut,
        uint256 bptTotalSupply,
        uint256 swapFeePercentage
    ) internal pure returns (uint256) {
        /******************************************************************************************
        // tokenInForExactBPTOut                                                                 //
        // a = amountIn                                                                          //
        // b = balance                      /  /    totalBPT + bptOut      \    (1 / w)       \  //
        // bptOut = bptAmountOut   a = b * |  | --------------------------  | ^          - 1  |  //
        // bpt = totalBPT                   \  \       totalBPT            /                  /  //
        // w = weight                                                                            //
        ******************************************************************************************/

        // Token in, so we round up overall.

        // Calculate the factor by which the invariant will increase after minting BPTAmountOut
        uint256 invariantRatio = bptTotalSupply.add(bptAmountOut).divUp(
            bptTotalSupply
        );
        _require(
            invariantRatio <= _MAX_INVARIANT_RATIO,
            Errors.MAX_OUT_BPT_FOR_TOKEN_IN
        );

        // Calculate by how much the token balance has to increase to match the invariantRatio
        uint256 balanceRatio = invariantRatio.powUp(
            FixedPoint.ONE.divUp(normalizedWeight)
        );

        uint256 amountInWithoutFee = balance.mulUp(
            balanceRatio.sub(FixedPoint.ONE)
        );

        // We can now compute how much extra balance is being deposited and used in virtual swaps, and charge swap fees
        // accordingly.
        uint256 taxableAmount = amountInWithoutFee.mulUp(
            normalizedWeight.complement()
        );
        uint256 nonTaxableAmount = amountInWithoutFee.sub(taxableAmount);

        uint256 taxableAmountPlusFees = taxableAmount.divUp(
            swapFeePercentage.complement()
        );

        return nonTaxableAmount.add(taxableAmountPlusFees);
    }

    function _calcAllTokensInGivenExactBptOut(
        uint256[] memory balances,
        uint256 bptAmountOut,
        uint256 totalBPT
    ) internal pure returns (uint256[] memory) {
        /************************************************************************************
        // tokensInForExactBptOut                                                          //
        // (per token)                                                                     //
        // aI = amountIn                   /   bptOut   \                                  //
        // b = balance           aI = b * | ------------ |                                 //
        // bptOut = bptAmountOut           \  totalBPT  /                                  //
        // bpt = totalBPT                                                                  //
        ************************************************************************************/

        // Tokens in, so we round up overall.
        uint256 bptRatio = bptAmountOut.divUp(totalBPT);

        uint256[] memory amountsIn = new uint256[](balances.length);
        for (uint256 i = 0; i < balances.length; i++) {
            amountsIn[i] = balances[i].mulUp(bptRatio);
        }

        return amountsIn;
    }

    function _calcBptInGivenExactTokensOut(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory amountsOut,
        uint256 bptTotalSupply,
        uint256 swapFeePercentage
    ) internal pure returns (uint256) {
        // BPT in, so we round up overall.

        uint256[] memory balanceRatiosWithoutFee = new uint256[](
            amountsOut.length
        );
        uint256 invariantRatioWithoutFees = 0;
        for (uint256 i = 0; i < balances.length; i++) {
            balanceRatiosWithoutFee[i] = balances[i].sub(amountsOut[i]).divUp(
                balances[i]
            );
            invariantRatioWithoutFees = invariantRatioWithoutFees.add(
                balanceRatiosWithoutFee[i].mulUp(normalizedWeights[i])
            );
        }

        uint256 invariantRatio = _computeExitExactTokensOutInvariantRatio(
            balances,
            normalizedWeights,
            amountsOut,
            balanceRatiosWithoutFee,
            invariantRatioWithoutFees,
            swapFeePercentage
        );

        return bptTotalSupply.mulUp(invariantRatio.complement());
    }

    /**
     * @dev Intermediate function to avoid stack-too-deep errors.
     */
    function _computeExitExactTokensOutInvariantRatio(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory amountsOut,
        uint256[] memory balanceRatiosWithoutFee,
        uint256 invariantRatioWithoutFees,
        uint256 swapFeePercentage
    ) private pure returns (uint256 invariantRatio) {
        invariantRatio = FixedPoint.ONE;

        for (uint256 i = 0; i < balances.length; i++) {
            // Swap fees are typically charged on 'token in', but there is no 'token in' here, so we apply it to
            // 'token out'. This results in slightly larger price impact.

            uint256 amountOutWithFee;
            if (invariantRatioWithoutFees > balanceRatiosWithoutFee[i]) {
                uint256 nonTaxableAmount = balances[i].mulDown(
                    invariantRatioWithoutFees.complement()
                );
                uint256 taxableAmount = amountsOut[i].sub(nonTaxableAmount);
                uint256 taxableAmountPlusFees = taxableAmount.divUp(
                    swapFeePercentage.complement()
                );

                amountOutWithFee = nonTaxableAmount.add(taxableAmountPlusFees);
            } else {
                amountOutWithFee = amountsOut[i];
            }

            uint256 balanceRatio = balances[i].sub(amountOutWithFee).divDown(
                balances[i]
            );

            invariantRatio = invariantRatio.mulDown(
                balanceRatio.powDown(normalizedWeights[i])
            );
        }
    }

    function _calcTokenOutGivenExactBptIn(
        uint256 balance,
        uint256 normalizedWeight,
        uint256 bptAmountIn,
        uint256 bptTotalSupply,
        uint256 swapFeePercentage
    ) internal pure returns (uint256) {
        /*****************************************************************************************
        // exactBPTInForTokenOut                                                                //
        // a = amountOut                                                                        //
        // b = balance                     /      /    totalBPT - bptIn       \    (1 / w)  \   //
        // bptIn = bptAmountIn    a = b * |  1 - | --------------------------  | ^           |  //
        // bpt = totalBPT                  \      \       totalBPT            /             /   //
        // w = weight                                                                           //
        *****************************************************************************************/

        // Token out, so we round down overall. The multiplication rounds down, but the power rounds up (so the base
        // rounds up). Because (totalBPT - bptIn) / totalBPT <= 1, the exponent rounds down.

        // Calculate the factor by which the invariant will decrease after burning BPTAmountIn
        uint256 invariantRatio = bptTotalSupply.sub(bptAmountIn).divUp(
            bptTotalSupply
        );
        _require(
            invariantRatio >= _MIN_INVARIANT_RATIO,
            Errors.MIN_BPT_IN_FOR_TOKEN_OUT
        );

        // Calculate by how much the token balance has to decrease to match invariantRatio
        uint256 balanceRatio = invariantRatio.powUp(
            FixedPoint.ONE.divDown(normalizedWeight)
        );

        // Because of rounding up, balanceRatio can be greater than one. Using complement prevents reverts.
        uint256 amountOutWithoutFee = balance.mulDown(
            balanceRatio.complement()
        );

        // We can now compute how much excess balance is being withdrawn as a result of the virtual swaps, which result
        // in swap fees.

        // Swap fees are typically charged on 'token in', but there is no 'token in' here, so we apply it
        // to 'token out'. This results in slightly larger price impact. Fees are rounded up.
        uint256 taxableAmount = amountOutWithoutFee.mulUp(
            normalizedWeight.complement()
        );
        uint256 nonTaxableAmount = amountOutWithoutFee.sub(taxableAmount);
        uint256 taxableAmountMinusFees = taxableAmount.mulUp(
            swapFeePercentage.complement()
        );

        return nonTaxableAmount.add(taxableAmountMinusFees);
    }

    function _calcTokensOutGivenExactBptIn(
        uint256[] memory balances,
        uint256 bptAmountIn,
        uint256 totalBPT
    ) internal pure returns (uint256[] memory) {
        /**********************************************************************************************
        // exactBPTInForTokensOut                                                                    //
        // (per token)                                                                               //
        // aO = amountOut                  /        bptIn         \                                  //
        // b = balance           a0 = b * | ---------------------  |                                 //
        // bptIn = bptAmountIn             \       totalBPT       /                                  //
        // bpt = totalBPT                                                                            //
        **********************************************************************************************/

        // Since we're computing an amount out, we round down overall. This means rounding down on both the
        // multiplication and division.

        uint256 bptRatio = bptAmountIn.divDown(totalBPT);

        uint256[] memory amountsOut = new uint256[](balances.length);
        for (uint256 i = 0; i < balances.length; i++) {
            amountsOut[i] = balances[i].mulDown(bptRatio);
        }

        return amountsOut;
    }

    /**
     * @dev Calculate the amount of BPT which should be minted when adding a new token to the Pool.
     *
     * Note that normalizedWeight is set that it corresponds to the desired weight of this token *after* adding it.
     * i.e. For a two token 50:50 pool which we want to turn into a 33:33:33 pool, we use a normalized weight of 33%
     * @param totalSupply - the total supply of the Pool's BPT.
     * @param normalizedWeight - the normalized weight of the token to be added (normalized relative to final weights)
     */
    function _calcBptOutAddToken(
        uint256 totalSupply,
        uint256 normalizedWeight
    ) internal pure returns (uint256) {
        // The amount of BPT which is equivalent to the token being added may be calculated by the growth in the
        // sum of the token weights, i.e. if we add a token which will make up 50% of the pool then we should receive
        // 50% of the new supply of BPT.
        //
        // The growth in the total weight of the pool can be easily calculated by:
        //
        // weightSumRatio = totalWeight / (totalWeight - newTokenWeight)
        //
        // As we're working with normalized weights `totalWeight` is equal to 1.

        uint256 weightSumRatio = FixedPoint.ONE.divDown(
            FixedPoint.ONE.sub(normalizedWeight)
        );

        // The amount of BPT to mint is then simply:
        //
        // toMint = totalSupply * (weightSumRatio - 1)

        return totalSupply.mulDown(weightSumRatio.sub(FixedPoint.ONE));
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./BaseWeightedPool.sol";
import "./WeightedPoolProtocolFees.sol";

/**
 * @dev Basic Weighted Pool with immutable weights.
 */
contract WeightedPool is BaseWeightedPool, WeightedPoolProtocolFees {
    using FixedPoint for uint256;

    uint256 private constant _MAX_TOKENS = 8;

    uint256 private immutable _totalTokens;
    string private _version;

    IERC20 internal immutable _token0;
    IERC20 internal immutable _token1;
    IERC20 internal immutable _token2;
    IERC20 internal immutable _token3;
    IERC20 internal immutable _token4;
    IERC20 internal immutable _token5;
    IERC20 internal immutable _token6;
    IERC20 internal immutable _token7;

    // All token balances are normalized to behave as if the token had 18 decimals. We assume a token's decimals will
    // not change throughout its lifetime, and store the corresponding scaling factor for each at construction time.
    // These factors are always greater than or equal to one: tokens with more than 18 decimals are not supported.

    uint256 internal immutable _scalingFactor0;
    uint256 internal immutable _scalingFactor1;
    uint256 internal immutable _scalingFactor2;
    uint256 internal immutable _scalingFactor3;
    uint256 internal immutable _scalingFactor4;
    uint256 internal immutable _scalingFactor5;
    uint256 internal immutable _scalingFactor6;
    uint256 internal immutable _scalingFactor7;

    uint256 internal immutable _normalizedWeight0;
    uint256 internal immutable _normalizedWeight1;
    uint256 internal immutable _normalizedWeight2;
    uint256 internal immutable _normalizedWeight3;
    uint256 internal immutable _normalizedWeight4;
    uint256 internal immutable _normalizedWeight5;
    uint256 internal immutable _normalizedWeight6;
    uint256 internal immutable _normalizedWeight7;

    struct NewPoolParams {
        string name;
        string symbol;
        IERC20[] tokens;
        uint256[] normalizedWeights;
        IRateProvider[] rateProviders;
        address[] assetManagers;
        uint256 swapFeePercentage;
    }

    constructor(
        NewPoolParams memory params,
        IVault vault,
        IProtocolFeePercentagesProvider protocolFeeProvider,
        uint256 pauseWindowDuration,
        uint256 bufferPeriodDuration,
        address owner,
        string memory version
    )
        BaseWeightedPool(
            vault,
            params.name,
            params.symbol,
            params.tokens,
            params.assetManagers,
            params.swapFeePercentage,
            pauseWindowDuration,
            bufferPeriodDuration,
            owner,
            false
        )
        ProtocolFeeCache(protocolFeeProvider, ProtocolFeeCache.DELEGATE_PROTOCOL_SWAP_FEES_SENTINEL)
        WeightedPoolProtocolFees(params.tokens.length, params.rateProviders)
    {
        uint256 numTokens = params.tokens.length;
        InputHelpers.ensureInputLengthMatch(numTokens, params.normalizedWeights.length);

        _totalTokens = numTokens;
        _version = version;

        // Ensure each normalized weight is above the minimum
        uint256 normalizedSum = 0;
        for (uint8 i = 0; i < numTokens; i++) {
            uint256 normalizedWeight = params.normalizedWeights[i];

            _require(normalizedWeight >= WeightedMath._MIN_WEIGHT, Errors.MIN_WEIGHT);
            normalizedSum = normalizedSum.add(normalizedWeight);
        }
        // Ensure that the normalized weights sum to ONE
        _require(normalizedSum == FixedPoint.ONE, Errors.NORMALIZED_WEIGHT_INVARIANT);

        // Immutable variables cannot be initialized inside an if statement, so we must do conditional assignments
        _token0 = params.tokens[0];
        _token1 = params.tokens[1];
        _token2 = numTokens > 2 ? params.tokens[2] : IERC20(0);
        _token3 = numTokens > 3 ? params.tokens[3] : IERC20(0);
        _token4 = numTokens > 4 ? params.tokens[4] : IERC20(0);
        _token5 = numTokens > 5 ? params.tokens[5] : IERC20(0);
        _token6 = numTokens > 6 ? params.tokens[6] : IERC20(0);
        _token7 = numTokens > 7 ? params.tokens[7] : IERC20(0);

        _scalingFactor0 = _computeScalingFactor(params.tokens[0]);
        _scalingFactor1 = _computeScalingFactor(params.tokens[1]);
        _scalingFactor2 = numTokens > 2 ? _computeScalingFactor(params.tokens[2]) : 0;
        _scalingFactor3 = numTokens > 3 ? _computeScalingFactor(params.tokens[3]) : 0;
        _scalingFactor4 = numTokens > 4 ? _computeScalingFactor(params.tokens[4]) : 0;
        _scalingFactor5 = numTokens > 5 ? _computeScalingFactor(params.tokens[5]) : 0;
        _scalingFactor6 = numTokens > 6 ? _computeScalingFactor(params.tokens[6]) : 0;
        _scalingFactor7 = numTokens > 7 ? _computeScalingFactor(params.tokens[7]) : 0;

        _normalizedWeight0 = params.normalizedWeights[0];
        _normalizedWeight1 = params.normalizedWeights[1];
        _normalizedWeight2 = numTokens > 2 ? params.normalizedWeights[2] : 0;
        _normalizedWeight3 = numTokens > 3 ? params.normalizedWeights[3] : 0;
        _normalizedWeight4 = numTokens > 4 ? params.normalizedWeights[4] : 0;
        _normalizedWeight5 = numTokens > 5 ? params.normalizedWeights[5] : 0;
        _normalizedWeight6 = numTokens > 6 ? params.normalizedWeights[6] : 0;
        _normalizedWeight7 = numTokens > 7 ? params.normalizedWeights[7] : 0;
    }

    /**
     * @dev Ensure we are not in a Vault context when this function is called, by attempting a no-op internal
     * balance operation. If we are already in a Vault transaction (e.g., a swap, join, or exit), the Vault's
     * reentrancy protection will cause this function to revert.
     *
     * The exact function call doesn't really matter: we're just trying to trigger the Vault reentrancy check
     * (and not hurt anything in case it works). An empty operation array with no specific operation at all works
     * for that purpose, and is also the least expensive in terms of gas and bytecode size.
     *
     * Use this modifier with any function that can cause a state change in a pool and is either public itself,
     * or called by a public function *outside* a Vault operation (e.g., join, exit, or swap).
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    modifier whenNotInVaultContext() {
        _ensureNotInVaultContext();
        _;
    }

    /**
     * @dev Reverts if called in the middle of a Vault operation; has no effect otherwise.
     */
    function _ensureNotInVaultContext() private {
        IVault.UserBalanceOp[] memory noop = new IVault.UserBalanceOp[](0);
        getVault().manageUserBalance(noop);
    }

    function _getNormalizedWeight(IERC20 token) internal view virtual override returns (uint256) {
        // prettier-ignore
        if (token == _token0) { return _normalizedWeight0; }
        else if (token == _token1) { return _normalizedWeight1; }
        else if (token == _token2) { return _normalizedWeight2; }
        else if (token == _token3) { return _normalizedWeight3; }
        else if (token == _token4) { return _normalizedWeight4; }
        else if (token == _token5) { return _normalizedWeight5; }
        else if (token == _token6) { return _normalizedWeight6; }
        else if (token == _token7) { return _normalizedWeight7; }
        else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    function _getNormalizedWeights() internal view virtual override returns (uint256[] memory) {
        uint256 totalTokens = _getTotalTokens();
        uint256[] memory normalizedWeights = new uint256[](totalTokens);

        // prettier-ignore
        {
            normalizedWeights[0] = _normalizedWeight0;
            normalizedWeights[1] = _normalizedWeight1;
            if (totalTokens > 2) { normalizedWeights[2] = _normalizedWeight2; } else { return normalizedWeights; }
            if (totalTokens > 3) { normalizedWeights[3] = _normalizedWeight3; } else { return normalizedWeights; }
            if (totalTokens > 4) { normalizedWeights[4] = _normalizedWeight4; } else { return normalizedWeights; }
            if (totalTokens > 5) { normalizedWeights[5] = _normalizedWeight5; } else { return normalizedWeights; }
            if (totalTokens > 6) { normalizedWeights[6] = _normalizedWeight6; } else { return normalizedWeights; }
            if (totalTokens > 7) { normalizedWeights[7] = _normalizedWeight7; } else { return normalizedWeights; }
        }

        return normalizedWeights;
    }

    function _getMaxTokens() internal pure virtual override returns (uint256) {
        return _MAX_TOKENS;
    }

    function _getTotalTokens() internal view virtual override returns (uint256) {
        return _totalTokens;
    }

    /**
     * @notice Returns a JSON representation of the contract version containing name, version number and task ID.
     */
    function version() external view returns (string memory) {
        return _version;
    }

    /**
     * @dev Returns the scaling factor for one of the Pool's tokens. Reverts if `token` is not a token registered by the
     * Pool.
     */
    function _scalingFactor(IERC20 token) internal view virtual override returns (uint256) {
        // prettier-ignore
        if (token == _token0) { return _getScalingFactor0(); }
        else if (token == _token1) { return _getScalingFactor1(); }
        else if (token == _token2) { return _getScalingFactor2(); }
        else if (token == _token3) { return _getScalingFactor3(); }
        else if (token == _token4) { return _getScalingFactor4(); }
        else if (token == _token5) { return _getScalingFactor5(); }
        else if (token == _token6) { return _getScalingFactor6(); }
        else if (token == _token7) { return _getScalingFactor7(); }
        else {
            _revert(Errors.INVALID_TOKEN);
        }
    }

    function _scalingFactors() internal view virtual override returns (uint256[] memory) {
        uint256 totalTokens = _getTotalTokens();
        uint256[] memory scalingFactors = new uint256[](totalTokens);

        // prettier-ignore
        {
            scalingFactors[0] = _getScalingFactor0();
            scalingFactors[1] = _getScalingFactor1();
            if (totalTokens > 2) { scalingFactors[2] = _getScalingFactor2(); } else { return scalingFactors; }
            if (totalTokens > 3) { scalingFactors[3] = _getScalingFactor3(); } else { return scalingFactors; }
            if (totalTokens > 4) { scalingFactors[4] = _getScalingFactor4(); } else { return scalingFactors; }
            if (totalTokens > 5) { scalingFactors[5] = _getScalingFactor5(); } else { return scalingFactors; }
            if (totalTokens > 6) { scalingFactors[6] = _getScalingFactor6(); } else { return scalingFactors; }
            if (totalTokens > 7) { scalingFactors[7] = _getScalingFactor7(); } else { return scalingFactors; }
        }

        return scalingFactors;
    }

    // Initialize

    function _onInitializePool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual override returns (uint256, uint256[] memory) {
        // Initialize `_athRateProduct` if the Pool will pay protocol fees on yield.
        // Not initializing this here properly will cause all joins/exits to revert.
        if (!_isExemptFromYieldProtocolFees()) _updateATHRateProduct(_getRateProduct(_getNormalizedWeights()));

        return super._onInitializePool(poolId, sender, recipient, scalingFactors, userData);
    }

    // WeightedPoolProtocolFees functions

    function _beforeJoinExit(uint256[] memory preBalances, uint256[] memory normalizedWeights)
        internal
        virtual
        override
        returns (uint256, uint256)
    {
        uint256 supplyBeforeFeeCollection = totalSupply();
        uint256 invariant = WeightedMath._calculateInvariant(normalizedWeights, preBalances);
        (uint256 protocolFeesToBeMinted, uint256 athRateProduct) = _getPreJoinExitProtocolFees(
            invariant,
            normalizedWeights,
            supplyBeforeFeeCollection
        );

        // We then update the recorded value of `athRateProduct` to ensure we only collect fees on yield once.
        // A zero value for `athRateProduct` represents that it is unchanged so we can skip updating it.
        if (athRateProduct > 0) {
            _updateATHRateProduct(athRateProduct);
        }

        if (protocolFeesToBeMinted > 0) {
            _payProtocolFees(protocolFeesToBeMinted);
        }
        return (supplyBeforeFeeCollection.add(protocolFeesToBeMinted), invariant);
    }

    function _afterJoinExit(
        uint256 preJoinExitInvariant,
        uint256[] memory preBalances,
        uint256[] memory balanceDeltas,
        uint256[] memory normalizedWeights,
        uint256 preJoinExitSupply,
        uint256 postJoinExitSupply
    ) internal virtual override {
        uint256 protocolFeesToBeMinted = _getPostJoinExitProtocolFees(
            preJoinExitInvariant,
            preBalances,
            balanceDeltas,
            normalizedWeights,
            preJoinExitSupply,
            postJoinExitSupply
        );

        if (protocolFeesToBeMinted > 0) {
            _payProtocolFees(protocolFeesToBeMinted);
        }
    }

    function _updatePostJoinExit(uint256 postJoinExitInvariant)
        internal
        virtual
        override(BaseWeightedPool, WeightedPoolProtocolFees)
    {
        WeightedPoolProtocolFees._updatePostJoinExit(postJoinExitInvariant);
    }

    /**
     * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
     * an exit, because the state of the pool could be out of sync with the state of the Vault. The modifier
     * `whenNotInVaultContext` prevents calling this function (and in turn, the external
     * `updateProtocolFeePercentageCache`) in such a context.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function _beforeProtocolFeeCacheUpdate() internal override whenNotInVaultContext {
        // The `getRate()` function depends on the actual supply, which in turn depends on the cached protocol fee
        // percentages. Changing these would therefore result in the rate changing, which is not acceptable as this is a
        // sensitive value.
        // Because of this, we pay any due protocol fees *before* updating the cache, making it so that the new
        // percentages only affect future operation of the Pool, and not past fees. As a result, `getRate()` is
        // unaffected by the cached protocol fee percentages changing.

        // Given that this operation is state-changing and relatively complex, we only allow it as long as the Pool is
        // not paused.
        _ensureNotPaused();

        uint256 invariant = getInvariant();

        (uint256 protocolFeesToBeMinted, uint256 athRateProduct) = _getPreJoinExitProtocolFees(
            invariant,
            _getNormalizedWeights(),
            totalSupply()
        );

        if (protocolFeesToBeMinted > 0) {
            _payProtocolFees(protocolFeesToBeMinted);
        }

        // With the fees paid, we now store the current invariant and update the ATH rate product (if necessary),
        // marking the Pool as free of protocol debt.

        _updatePostJoinExit(invariant);
        if (athRateProduct > 0) {
            _updateATHRateProduct(athRateProduct);
        }
    }

    /**
     * @notice Returns the effective BPT supply.
     *
     * @dev This would be the same as `totalSupply` however the Pool owes debt to the Protocol in the form of unminted
     * BPT, which will be minted immediately before the next join or exit. We need to take these into account since,
     * even if they don't yet exist, they will effectively be included in any Pool operation that involves BPT.
     *
     * In the vast majority of cases, this function should be used instead of `totalSupply()`.
     *
     * **IMPORTANT NOTE**: calling this function within a Vault context (i.e. in the middle of a join or an exit) is
     * potentially unsafe, since the returned value is manipulable. It is up to the caller to ensure safety.
     *
     * This is because this function calculates the invariant, which requires the state of the pool to be in sync
     * with the state of the Vault. That condition may not be true in the middle of a join or an exit.
     *
     * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
     * function before calling `getActualSupply`. That will make the transaction revert in an unsafe context.
     * (See `whenNotInVaultContext` in `WeightedPool`).
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function getActualSupply() external view returns (uint256) {
        uint256 supply = totalSupply();

        (uint256 protocolFeesToBeMinted, ) = _getPreJoinExitProtocolFees(
            getInvariant(),
            _getNormalizedWeights(),
            supply
        );

        return supply.add(protocolFeesToBeMinted);
    }

    /**
     * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
     *
     * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
     * an exit, because the state of the pool could be out of sync with the state of the Vault.
     *
     * The modifier `whenNotInVaultContext` prevents calling this function (and in turn, the external
     * `disableRecoveryMode`) in such a context.
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function _onDisableRecoveryMode() internal override whenNotInVaultContext {
        // Update the postJoinExitInvariant to the value of the currentInvariant, zeroing out any protocol swap fees.
        _updatePostJoinExit(getInvariant());

        // If the Pool has any protocol yield fees accrued then we update the athRateProduct to zero these out.
        // If the current rate product is less than the athRateProduct then we do not perform this update.
        // This prevents the Pool from paying protocol fees on the same yield twice if the rate product were to drop.
        if (!_isExemptFromYieldProtocolFees()) {
            uint256 athRateProduct = getATHRateProduct();
            uint256 rateProduct = _getRateProduct(_getNormalizedWeights());

            if (rateProduct > athRateProduct) {
                _updateATHRateProduct(rateProduct);
            }
        }
    }

    function _getScalingFactor0() internal view returns (uint256) {
        return _scalingFactor0;
    }

    function _getScalingFactor1() internal view returns (uint256) {
        return _scalingFactor1;
    }

    function _getScalingFactor2() internal view returns (uint256) {
        return _scalingFactor2;
    }

    function _getScalingFactor3() internal view returns (uint256) {
        return _scalingFactor3;
    }

    function _getScalingFactor4() internal view returns (uint256) {
        return _scalingFactor4;
    }

    function _getScalingFactor5() internal view returns (uint256) {
        return _scalingFactor5;
    }

    function _getScalingFactor6() internal view returns (uint256) {
        return _scalingFactor6;
    }

    function _getScalingFactor7() internal view returns (uint256) {
        return _scalingFactor7;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./v2-interfaces/contracts/pool-weighted/WeightedPoolUserData.sol";

import "./v2-solidity-utils/contracts/math/FixedPoint.sol";
import "./v2-solidity-utils/contracts/helpers/InputHelpers.sol";

import "./v2-pool-utils/contracts/BaseMinimalSwapInfoPool.sol";

import "./WeightedMath.sol";

/**
 * @dev Base class for WeightedPools containing swap, join and exit logic, but leaving storage and management of
 * the weights to subclasses. Derived contracts can choose to make weights immutable, mutable, or even dynamic
 *  based on local or external logic.
 */
abstract contract BaseWeightedPool is BaseMinimalSwapInfoPool {
    using FixedPoint for uint256;
    using WeightedPoolUserData for bytes;

    constructor(
        IVault vault,
        string memory name,
        string memory symbol,
        IERC20[] memory tokens,
        address[] memory assetManagers,
        uint256 swapFeePercentage,
        uint256 pauseWindowDuration,
        uint256 bufferPeriodDuration,
        address owner,
        bool mutableTokens
    )
        BasePool(
            vault,
            // Given BaseMinimalSwapInfoPool supports both of these specializations, and this Pool never registers
            // or deregisters any tokens after construction, picking Two Token when the Pool only has two tokens is free
            // gas savings.
            // If the pool is expected to be able register new tokens in future, we must choose MINIMAL_SWAP_INFO
            // as clearly the TWO_TOKEN specification doesn't support adding extra tokens in future.
            tokens.length == 2 && !mutableTokens
                ? IVault.PoolSpecialization.TWO_TOKEN
                : IVault.PoolSpecialization.MINIMAL_SWAP_INFO,
            name,
            symbol,
            tokens,
            assetManagers,
            swapFeePercentage,
            pauseWindowDuration,
            bufferPeriodDuration,
            owner
        )
    {
        // solhint-disable-previous-line no-empty-blocks
    }

    // Virtual functions

    /**
     * @dev Returns the normalized weight of `token`. Weights are fixed point numbers that sum to FixedPoint.ONE.
     */
    function _getNormalizedWeight(
        IERC20 token
    ) internal view virtual returns (uint256);

    /**
     * @dev Returns all normalized weights, in the same order as the Pool's tokens.
     */
    function _getNormalizedWeights()
        internal
        view
        virtual
        returns (uint256[] memory);

    /**
     * @dev Returns the current value of the invariant.
     *
     * **IMPORTANT NOTE**: calling this function within a Vault context (i.e. in the middle of a join or an exit) is
     * potentially unsafe, since the returned value is manipulable. It is up to the caller to ensure safety.
     *
     * Calculating the invariant requires the state of the pool to be in sync with the state of the Vault.
     * That condition may not be true in the middle of a join or an exit.
     *
     * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
     * function before calling `getInvariant`. That will make the transaction revert in an unsafe context.
     * (See `whenNotInVaultContext` in `WeightedPool`).
     *
     * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
     */
    function getInvariant() public view returns (uint256) {
        (, uint256[] memory balances, ) = getVault().getPoolTokens(getPoolId());

        // Since the Pool hooks always work with upscaled balances, we manually
        // upscale here for consistency
        _upscaleArray(balances, _scalingFactors());

        uint256[] memory normalizedWeights = _getNormalizedWeights();
        return WeightedMath._calculateInvariant(normalizedWeights, balances);
    }

    function getNormalizedWeights() external view returns (uint256[] memory) {
        return _getNormalizedWeights();
    }

    // Base Pool handlers

    // Swap

    function _onSwapGivenIn(
        SwapRequest memory swapRequest,
        uint256 currentBalanceTokenIn,
        uint256 currentBalanceTokenOut
    ) internal virtual override returns (uint256) {
        return
            WeightedMath._calcOutGivenIn(
                currentBalanceTokenIn,
                _getNormalizedWeight(swapRequest.tokenIn),
                currentBalanceTokenOut,
                _getNormalizedWeight(swapRequest.tokenOut),
                swapRequest.amount
            );
    }

    function _onSwapGivenOut(
        SwapRequest memory swapRequest,
        uint256 currentBalanceTokenIn,
        uint256 currentBalanceTokenOut
    ) internal virtual override returns (uint256) {
        return
            WeightedMath._calcInGivenOut(
                currentBalanceTokenIn,
                _getNormalizedWeight(swapRequest.tokenIn),
                currentBalanceTokenOut,
                _getNormalizedWeight(swapRequest.tokenOut),
                swapRequest.amount
            );
    }

    /**
     * @dev Called before any join or exit operation. Returns the Pool's total supply by default, but derived contracts
     * may choose to add custom behavior at these steps. This often has to do with protocol fee processing.
     */
    function _beforeJoinExit(
        uint256[] memory preBalances,
        uint256[] memory normalizedWeights
    ) internal virtual returns (uint256, uint256) {
        return (
            totalSupply(),
            WeightedMath._calculateInvariant(normalizedWeights, preBalances)
        );
    }

    /**
     * @dev Called after any regular join or exit operation. Empty by default, but derived contracts
     * may choose to add custom behavior at these steps. This often has to do with protocol fee processing.
     *
     * If performing a join operation, balanceDeltas are the amounts in: otherwise they are the amounts out.
     *
     * This function is free to mutate the `preBalances` array.
     */
    function _afterJoinExit(
        uint256 preJoinExitInvariant,
        uint256[] memory preBalances,
        uint256[] memory balanceDeltas,
        uint256[] memory normalizedWeights,
        uint256 preJoinExitSupply,
        uint256 postJoinExitSupply
    ) internal virtual {
        // solhint-disable-previous-line no-empty-blocks
    }

    // Derived contracts may call this to update state after a join or exit.
    function _updatePostJoinExit(
        uint256 postJoinExitInvariant
    ) internal virtual {
        // solhint-disable-previous-line no-empty-blocks
    }

    // Initialize

    function _onInitializePool(
        bytes32,
        address,
        address,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual override returns (uint256, uint256[] memory) {
        WeightedPoolUserData.JoinKind kind = userData.joinKind();
        _require(
            kind == WeightedPoolUserData.JoinKind.INIT,
            Errors.UNINITIALIZED
        );

        uint256[] memory amountsIn = userData.initialAmountsIn();
        InputHelpers.ensureInputLengthMatch(
            amountsIn.length,
            scalingFactors.length
        );
        _upscaleArray(amountsIn, scalingFactors);

        uint256[] memory normalizedWeights = _getNormalizedWeights();
        uint256 invariantAfterJoin = WeightedMath._calculateInvariant(
            normalizedWeights,
            amountsIn
        );

        // Set the initial BPT to the value of the invariant times the number of tokens. This makes BPT supply more
        // consistent in Pools with similar compositions but different number of tokens.
        uint256 bptAmountOut = Math.mul(invariantAfterJoin, amountsIn.length);

        // Initialization is still a join, so we need to do post-join work. Since we are not paying protocol fees,
        // and all we need to do is update the invariant, call `_updatePostJoinExit` here instead of `_afterJoinExit`.
        _updatePostJoinExit(invariantAfterJoin);

        return (bptAmountOut, amountsIn);
    }

    // Join

    function _onJoinPool(
        bytes32,
        address sender,
        address,
        uint256[] memory balances,
        uint256,
        uint256,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual override returns (uint256, uint256[] memory) {
        uint256[] memory normalizedWeights = _getNormalizedWeights();

        (
            uint256 preJoinExitSupply,
            uint256 preJoinExitInvariant
        ) = _beforeJoinExit(balances, normalizedWeights);

        (uint256 bptAmountOut, uint256[] memory amountsIn) = _doJoin(
            sender,
            balances,
            normalizedWeights,
            scalingFactors,
            preJoinExitSupply,
            userData
        );

        _afterJoinExit(
            preJoinExitInvariant,
            balances,
            amountsIn,
            normalizedWeights,
            preJoinExitSupply,
            preJoinExitSupply.add(bptAmountOut)
        );

        return (bptAmountOut, amountsIn);
    }

    /**
     * @dev Dispatch code which decodes the provided userdata to perform the specified join type.
     * Inheriting contracts may override this function to add additional join types or extra conditions to allow
     * or disallow joins under certain circumstances.
     */
    function _doJoin(
        address,
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory scalingFactors,
        uint256 totalSupply,
        bytes memory userData
    ) internal view virtual returns (uint256, uint256[] memory) {
        WeightedPoolUserData.JoinKind kind = userData.joinKind();

        if (kind == WeightedPoolUserData.JoinKind.EXACT_TOKENS_IN_FOR_BPT_OUT) {
            return
                _joinExactTokensInForBPTOut(
                    balances,
                    normalizedWeights,
                    scalingFactors,
                    totalSupply,
                    userData
                );
        } else if (
            kind == WeightedPoolUserData.JoinKind.TOKEN_IN_FOR_EXACT_BPT_OUT
        ) {
            return
                _joinTokenInForExactBPTOut(
                    balances,
                    normalizedWeights,
                    totalSupply,
                    userData
                );
        } else if (
            kind ==
            WeightedPoolUserData.JoinKind.ALL_TOKENS_IN_FOR_EXACT_BPT_OUT
        ) {
            return
                _joinAllTokensInForExactBPTOut(balances, totalSupply, userData);
        } else {
            _revert(Errors.UNHANDLED_JOIN_KIND);
        }
    }

    function _joinExactTokensInForBPTOut(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory scalingFactors,
        uint256 totalSupply,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256[] memory amountsIn, uint256 minBPTAmountOut) = userData
            .exactTokensInForBptOut();
        InputHelpers.ensureInputLengthMatch(balances.length, amountsIn.length);

        _upscaleArray(amountsIn, scalingFactors);

        uint256 bptAmountOut = WeightedMath._calcBptOutGivenExactTokensIn(
            balances,
            normalizedWeights,
            amountsIn,
            totalSupply,
            getSwapFeePercentage()
        );

        _require(bptAmountOut >= minBPTAmountOut, Errors.BPT_OUT_MIN_AMOUNT);

        return (bptAmountOut, amountsIn);
    }

    function _joinTokenInForExactBPTOut(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256 totalSupply,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256 bptAmountOut, uint256 tokenIndex) = userData
            .tokenInForExactBptOut();
        // Note that there is no maximum amountIn parameter: this is handled by `IVault.joinPool`.

        _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);

        uint256 amountIn = WeightedMath._calcTokenInGivenExactBptOut(
            balances[tokenIndex],
            normalizedWeights[tokenIndex],
            bptAmountOut,
            totalSupply,
            getSwapFeePercentage()
        );

        // We join in a single token, so we initialize amountsIn with zeros
        uint256[] memory amountsIn = new uint256[](balances.length);
        // And then assign the result to the selected token
        amountsIn[tokenIndex] = amountIn;

        return (bptAmountOut, amountsIn);
    }

    function _joinAllTokensInForExactBPTOut(
        uint256[] memory balances,
        uint256 totalSupply,
        bytes memory userData
    ) private pure returns (uint256, uint256[] memory) {
        uint256 bptAmountOut = userData.allTokensInForExactBptOut();
        // Note that there is no maximum amountsIn parameter: this is handled by `IVault.joinPool`.

        uint256[] memory amountsIn = WeightedMath
            ._calcAllTokensInGivenExactBptOut(
                balances,
                bptAmountOut,
                totalSupply
            );

        return (bptAmountOut, amountsIn);
    }

    // Exit

    function _onExitPool(
        bytes32,
        address sender,
        address,
        uint256[] memory balances,
        uint256,
        uint256,
        uint256[] memory scalingFactors,
        bytes memory userData
    ) internal virtual override returns (uint256, uint256[] memory) {
        uint256[] memory normalizedWeights = _getNormalizedWeights();

        (
            uint256 preJoinExitSupply,
            uint256 preJoinExitInvariant
        ) = _beforeJoinExit(balances, normalizedWeights);

        (uint256 bptAmountIn, uint256[] memory amountsOut) = _doExit(
            sender,
            balances,
            normalizedWeights,
            scalingFactors,
            preJoinExitSupply,
            userData
        );

        _afterJoinExit(
            preJoinExitInvariant,
            balances,
            amountsOut,
            normalizedWeights,
            preJoinExitSupply,
            preJoinExitSupply.sub(bptAmountIn)
        );

        return (bptAmountIn, amountsOut);
    }

    /**
     * @dev Dispatch code which decodes the provided userdata to perform the specified exit type.
     * Inheriting contracts may override this function to add additional exit types or extra conditions to allow
     * or disallow exit under certain circumstances.
     */
    function _doExit(
        address,
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory scalingFactors,
        uint256 totalSupply,
        bytes memory userData
    ) internal view virtual returns (uint256, uint256[] memory) {
        WeightedPoolUserData.ExitKind kind = userData.exitKind();

        if (
            kind == WeightedPoolUserData.ExitKind.EXACT_BPT_IN_FOR_ONE_TOKEN_OUT
        ) {
            return
                _exitExactBPTInForTokenOut(
                    balances,
                    normalizedWeights,
                    totalSupply,
                    userData
                );
        } else if (
            kind == WeightedPoolUserData.ExitKind.EXACT_BPT_IN_FOR_TOKENS_OUT
        ) {
            return _exitExactBPTInForTokensOut(balances, totalSupply, userData);
        } else if (
            kind == WeightedPoolUserData.ExitKind.BPT_IN_FOR_EXACT_TOKENS_OUT
        ) {
            return
                _exitBPTInForExactTokensOut(
                    balances,
                    normalizedWeights,
                    scalingFactors,
                    totalSupply,
                    userData
                );
        } else {
            _revert(Errors.UNHANDLED_EXIT_KIND);
        }
    }

    function _exitExactBPTInForTokenOut(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256 totalSupply,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256 bptAmountIn, uint256 tokenIndex) = userData
            .exactBptInForTokenOut();
        // Note that there is no minimum amountOut parameter: this is handled by `IVault.exitPool`.

        _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);

        uint256 amountOut = WeightedMath._calcTokenOutGivenExactBptIn(
            balances[tokenIndex],
            normalizedWeights[tokenIndex],
            bptAmountIn,
            totalSupply,
            getSwapFeePercentage()
        );

        // This is an exceptional situation in which the fee is charged on a token out instead of a token in.
        // We exit in a single token, so we initialize amountsOut with zeros
        uint256[] memory amountsOut = new uint256[](balances.length);
        // And then assign the result to the selected token
        amountsOut[tokenIndex] = amountOut;

        return (bptAmountIn, amountsOut);
    }

    function _exitExactBPTInForTokensOut(
        uint256[] memory balances,
        uint256 totalSupply,
        bytes memory userData
    ) private pure returns (uint256, uint256[] memory) {
        uint256 bptAmountIn = userData.exactBptInForTokensOut();
        // Note that there is no minimum amountOut parameter: this is handled by `IVault.exitPool`.

        uint256[] memory amountsOut = WeightedMath
            ._calcTokensOutGivenExactBptIn(balances, bptAmountIn, totalSupply);
        return (bptAmountIn, amountsOut);
    }

    function _exitBPTInForExactTokensOut(
        uint256[] memory balances,
        uint256[] memory normalizedWeights,
        uint256[] memory scalingFactors,
        uint256 totalSupply,
        bytes memory userData
    ) private view returns (uint256, uint256[] memory) {
        (uint256[] memory amountsOut, uint256 maxBPTAmountIn) = userData
            .bptInForExactTokensOut();
        InputHelpers.ensureInputLengthMatch(amountsOut.length, balances.length);
        _upscaleArray(amountsOut, scalingFactors);

        // This is an exceptional situation in which the fee is charged on a token out instead of a token in.
        uint256 bptAmountIn = WeightedMath._calcBptInGivenExactTokensOut(
            balances,
            normalizedWeights,
            amountsOut,
            totalSupply,
            getSwapFeePercentage()
        );
        _require(bptAmountIn <= maxBPTAmountIn, Errors.BPT_IN_MAX_AMOUNT);

        return (bptAmountIn, amountsOut);
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./v2-interfaces/contracts/vault/IVault.sol";

import "./v2-pool-utils/contracts/factories/BasePoolFactory.sol";
import "./v2-pool-utils/contracts/factories/FactoryWidePauseWindow.sol";

import "./WeightedPool.sol";

contract WeightedPoolFactory is BasePoolFactory, FactoryWidePauseWindow {
    string private _factoryVersion;
    string private _poolVersion;

    constructor(
        IVault vault,
        IProtocolFeePercentagesProvider protocolFeeProvider,
        string memory factoryVersion,
        string memory poolVersion
    )
        BasePoolFactory(
            vault,
            protocolFeeProvider,
            type(WeightedPool).creationCode
        )
    {
        _factoryVersion = factoryVersion;
        _poolVersion = poolVersion;
    }

    /**
     * @notice Returns a JSON representation of the contract version containing name, version number and task ID.
     */
    function version() external view returns (string memory) {
        return _factoryVersion;
    }

    /**
     * @notice Returns a JSON representation of the deployed pool version containing name, version number and task ID.
     *
     * @dev This is typically only useful in complex Pool deployment schemes, where multiple subsystems need to know
     * about each other. Note that this value will only be updated at factory creation time.
     */
    function getPoolVersion() public view returns (string memory) {
        return _poolVersion;
    }

    /**
     * @dev Deploys a new `WeightedPool`.
     */
    function create(
        string memory name,
        string memory symbol,
        IERC20[] memory tokens,
        uint256[] memory normalizedWeights,
        IRateProvider[] memory rateProviders,
        uint256 swapFeePercentage,
        address owner,
        bytes32 salt
    ) external returns (address) {
        (
            uint256 pauseWindowDuration,
            uint256 bufferPeriodDuration
        ) = getPauseConfiguration();

        return
            _create(
                abi.encode(
                    WeightedPool.NewPoolParams({
                        name: name,
                        symbol: symbol,
                        tokens: tokens,
                        normalizedWeights: normalizedWeights,
                        rateProviders: rateProviders,
                        assetManagers: new address[](tokens.length), // Don't allow asset managers,
                        swapFeePercentage: swapFeePercentage
                    }),
                    getVault(),
                    getProtocolFeePercentagesProvider(),
                    pauseWindowDuration,
                    bufferPeriodDuration,
                    owner,
                    getPoolVersion()
                ),
                salt
            );
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "./v2-interfaces/contracts/pool-utils/IRateProvider.sol";
import "./v2-pool-utils/contracts/protocol-fees/ProtocolFeeCache.sol";
import "./v2-pool-utils/contracts/protocol-fees/InvariantGrowthProtocolSwapFees.sol";

import "./BaseWeightedPool.sol";

abstract contract WeightedPoolProtocolFees is
    BaseWeightedPool,
    ProtocolFeeCache
{
    using FixedPoint for uint256;
    using WordCodec for bytes32;

    // Rate providers are used only for computing yield fees; they do not inform swap/join/exit.
    IRateProvider internal immutable _rateProvider0;
    IRateProvider internal immutable _rateProvider1;
    IRateProvider internal immutable _rateProvider2;
    IRateProvider internal immutable _rateProvider3;
    IRateProvider internal immutable _rateProvider4;
    IRateProvider internal immutable _rateProvider5;
    IRateProvider internal immutable _rateProvider6;
    IRateProvider internal immutable _rateProvider7;

    bool internal immutable _exemptFromYieldFees;

    // All-time high value of the weighted product of the pool's token rates. Comparing such weighted products across
    // time provides a measure of the pool's growth resulting from rate changes. The pool also grows due to swap fees,
    // but that growth is captured in the invariant; rate growth is not.
    uint256 private _athRateProduct;

    // This Pool pays protocol fees by measuring the growth of the invariant between joins and exits. Since weights are
    // immutable, the invariant only changes due to accumulated swap fees, which saves gas by freeing the Pool
    // from performing any computation or accounting associated with protocol fees during swaps.
    // This mechanism requires keeping track of the invariant after the last join or exit.
    //
    // The maximum value of the invariant is the maximum allowable balance in the Vault (2**112) multiplied by the
    // largest possible scaling factor (10**18 for a zero decimals token). The largest invariant is then
    // 2**112 * 10**18 ~= 2**172, which means that to save gas we can place this in BasePool's `_miscData`.
    uint256 private constant _LAST_POST_JOINEXIT_INVARIANT_OFFSET = 0;
    uint256 private constant _LAST_POST_JOINEXIT_INVARIANT_BIT_LENGTH = 192;

    constructor(uint256 numTokens, IRateProvider[] memory rateProviders) {
        _require(numTokens <= 8, Errors.MAX_TOKENS);
        InputHelpers.ensureInputLengthMatch(numTokens, rateProviders.length);

        _exemptFromYieldFees = _getYieldFeeExemption(rateProviders);

        _rateProvider0 = rateProviders[0];
        _rateProvider1 = rateProviders[1];
        _rateProvider2 = numTokens > 2 ? rateProviders[2] : IRateProvider(0);
        _rateProvider3 = numTokens > 3 ? rateProviders[3] : IRateProvider(0);
        _rateProvider4 = numTokens > 4 ? rateProviders[4] : IRateProvider(0);
        _rateProvider5 = numTokens > 5 ? rateProviders[5] : IRateProvider(0);
        _rateProvider6 = numTokens > 6 ? rateProviders[6] : IRateProvider(0);
        _rateProvider7 = numTokens > 7 ? rateProviders[7] : IRateProvider(0);
    }

    function _getYieldFeeExemption(
        IRateProvider[] memory rateProviders
    ) internal pure returns (bool) {
        // If we know that no rate providers are set then we can skip yield fees logic.
        // If any tokens have rate providers, then set `_exemptFromYieldFees` to false, otherwise leave it true.
        for (uint256 i = 0; i < rateProviders.length; i++) {
            if (rateProviders[i] != IRateProvider(0)) {
                return false;
            }
        }
        return true;
    }

    /**
     * @dev Returns whether the pool is exempt from protocol fees on yield.
     */
    function _isExemptFromYieldProtocolFees() internal view returns (bool) {
        return _exemptFromYieldFees;
    }

    /**
     * @notice Returns the value of the invariant after the last join or exit operation.
     */
    function getLastPostJoinExitInvariant() public view returns (uint256) {
        return
            _getMiscData().decodeUint(
                _LAST_POST_JOINEXIT_INVARIANT_OFFSET,
                _LAST_POST_JOINEXIT_INVARIANT_BIT_LENGTH
            );
    }

    /**
     * @notice Returns the all time high value for the weighted product of the Pool's tokens' rates.
     * @dev Yield protocol fees are only charged when this value is exceeded.
     */
    function getATHRateProduct() public view returns (uint256) {
        return _athRateProduct;
    }

    /**
     * @dev Returns the rate providers configured for each token (in the same order as registered).
     */
    function getRateProviders() external view returns (IRateProvider[] memory) {
        uint256 totalTokens = _getTotalTokens();
        IRateProvider[] memory providers = new IRateProvider[](totalTokens);

        // prettier-ignore
        {
            providers[0] = _rateProvider0;
            providers[1] = _rateProvider1;
            if (totalTokens > 2) { providers[2] = _rateProvider2; } else { return providers; }
            if (totalTokens > 3) { providers[3] = _rateProvider3; } else { return providers; }
            if (totalTokens > 4) { providers[4] = _rateProvider4; } else { return providers; }
            if (totalTokens > 5) { providers[5] = _rateProvider5; } else { return providers; }
            if (totalTokens > 6) { providers[6] = _rateProvider6; } else { return providers; }
            if (totalTokens > 7) { providers[7] = _rateProvider7; } else { return providers; }
        }

        return providers;
    }

    // Protocol Fees

    /**
     * @dev Returns the percentage of the Pool's supply which corresponds to protocol fees on swaps accrued by the Pool.
     * @param preJoinExitInvariant - The Pool's invariant prior to the join/exit *before* minting protocol fees.
     * @param protocolSwapFeePercentage - The percentage of swap fees which are paid to the protocol.
     * @return swapProtocolFeesPercentage - The percentage of the Pool which corresponds to protocol fees on swaps.
     */
    function _getSwapProtocolFeesPoolPercentage(
        uint256 preJoinExitInvariant,
        uint256 protocolSwapFeePercentage
    ) internal view returns (uint256) {
        // Before joins and exits, we measure the growth of the invariant compared to the invariant after the last join
        // or exit, which will have been caused by swap fees, and use it to mint BPT as protocol fees. This dilutes all
        // LPs, which means that new LPs will join the pool debt-free, and exiting LPs will pay any amounts due
        // before leaving.

        return
            InvariantGrowthProtocolSwapFees.getProtocolOwnershipPercentage(
                preJoinExitInvariant.divDown(getLastPostJoinExitInvariant()),
                FixedPoint.ONE, // Supply has not changed so supplyGrowthRatio = 1
                protocolSwapFeePercentage
            );
    }

    /**
     * @dev Returns the percentage of the Pool's supply which corresponds to protocol fees on yield accrued by the Pool.
     * @param normalizedWeights - The Pool's normalized token weights.
     * @return yieldProtocolFeesPercentage - The percentage of the Pool which corresponds to protocol fees on yield.
     * @return athRateProduct - The new all-time-high rate product if it has increased, otherwise zero.
     */
    function _getYieldProtocolFeesPoolPercentage(
        uint256[] memory normalizedWeights
    ) internal view returns (uint256, uint256) {
        if (_isExemptFromYieldProtocolFees()) return (0, 0);

        // Yield manifests in the Pool by individual tokens becoming more valuable, we convert this into comparable
        // units by applying a rate to get the equivalent balance of non-yield-bearing tokens
        //
        // non-yield-bearing balance = rate * yield-bearing balance
        //                       x'i = ri * xi
        //
        // To measure the amount of fees to pay due to yield, we take advantage of the fact that scaling the
        // Pool's balances results in a scaling factor being applied to the original invariant.
        //
        // I(r1 * x1, r2 * x2) = (r1 * x1)^w1 * (r2 * x2)^w2
        //                     = (r1)^w1 * (r2)^w2 * (x1)^w1 * (x2)^w2
        //                     = I(r1, r2) * I(x1, x2)
        //
        // We then only need to measure the growth of this scaling factor to measure how the value of the BPT token
        // increases due to yield; we can ignore the invariant calculated from the Pool's balances as these cancel.
        // We then have the result:
        //
        // invariantGrowthRatio = I(r1_new, r2_new) / I(r1_old, r2_old) = rateProduct / athRateProduct

        uint256 athRateProduct = _athRateProduct;
        uint256 rateProduct = _getRateProduct(normalizedWeights);

        // Only charge yield fees if we've exceeded the all time high of Pool value generated through yield.
        // i.e. if the Pool makes a loss through the yield strategies then it shouldn't charge fees until it's
        // been recovered.
        if (rateProduct <= athRateProduct) return (0, 0);

        return (
            InvariantGrowthProtocolSwapFees.getProtocolOwnershipPercentage(
                rateProduct.divDown(athRateProduct),
                FixedPoint.ONE, // Supply has not changed so supplyGrowthRatio = 1
                getProtocolFeePercentageCache(ProtocolFeeType.YIELD)
            ),
            rateProduct
        );
    }

    function _updateATHRateProduct(uint256 rateProduct) internal {
        _athRateProduct = rateProduct;
    }

    /**
     * @dev Returns the amount of BPT to be minted as protocol fees prior to processing a join/exit.
     * Note that this isn't a view function. This function automatically updates `_athRateProduct`  to ensure that
     * proper accounting is performed to prevent charging duplicate protocol fees.
     * @param preJoinExitInvariant - The Pool's invariant prior to the join/exit.
     * @param normalizedWeights - The Pool's normalized token weights.
     * @param preJoinExitSupply - The Pool's total supply prior to the join/exit *before* minting protocol fees.
     * @return protocolFeesToBeMinted -  The amount of BPT to be minted as protocol fees.
     * @return athRateProduct - The new all-time-high rate product if it has increased, otherwise zero.
     */
    function _getPreJoinExitProtocolFees(
        uint256 preJoinExitInvariant,
        uint256[] memory normalizedWeights,
        uint256 preJoinExitSupply
    ) internal view returns (uint256, uint256) {
        uint256 protocolSwapFeesPoolPercentage = _getSwapProtocolFeesPoolPercentage(
                preJoinExitInvariant,
                getProtocolFeePercentageCache(ProtocolFeeType.SWAP)
            );
        (
            uint256 protocolYieldFeesPoolPercentage,
            uint256 athRateProduct
        ) = _getYieldProtocolFeesPoolPercentage(normalizedWeights);

        return (
            ProtocolFees.bptForPoolOwnershipPercentage(
                preJoinExitSupply,
                protocolSwapFeesPoolPercentage + protocolYieldFeesPoolPercentage
            ),
            athRateProduct
        );
    }

    /**
     * @dev Returns the amount of BPT to be minted to pay protocol fees on swap fees accrued during a join/exit.
     * Note that this isn't a view function. This function automatically updates `_lastPostJoinExitInvariant` to
     * ensure that proper accounting is performed to prevent charging duplicate protocol fees.
     * @param preJoinExitInvariant - The Pool's invariant prior to the join/exit.
     * @param preBalances - The Pool's balances prior to the join/exit.
     * @param balanceDeltas - The changes to the Pool's balances due to the join/exit.
     * @param normalizedWeights - The Pool's normalized token weights.
     * @param preJoinExitSupply - The Pool's total supply prior to the join/exit *after* minting protocol fees.
     * @param postJoinExitSupply - The Pool's total supply after the join/exit.
     */
    function _getPostJoinExitProtocolFees(
        uint256 preJoinExitInvariant,
        uint256[] memory preBalances,
        uint256[] memory balanceDeltas,
        uint256[] memory normalizedWeights,
        uint256 preJoinExitSupply,
        uint256 postJoinExitSupply
    ) internal returns (uint256) {
        bool isJoin = postJoinExitSupply >= preJoinExitSupply;

        // Compute the post balances by adding or removing the deltas.
        for (uint256 i = 0; i < preBalances.length; ++i) {
            preBalances[i] = isJoin
                ? SafeMath.add(preBalances[i], balanceDeltas[i])
                : SafeMath.sub(preBalances[i], balanceDeltas[i]);
        }

        // preBalances have now been mutated to reflect the postJoinExit balances.
        uint256 postJoinExitInvariant = WeightedMath._calculateInvariant(
            normalizedWeights,
            preBalances
        );
        uint256 protocolSwapFeePercentage = getProtocolFeePercentageCache(
            ProtocolFeeType.SWAP
        );

        _updatePostJoinExit(postJoinExitInvariant);
        // We return immediately if the fee percentage is zero to avoid unnecessary computation.
        if (protocolSwapFeePercentage == 0) return 0;

        uint256 protocolFeeAmount = InvariantGrowthProtocolSwapFees
            .calcDueProtocolFees(
                postJoinExitInvariant.divDown(preJoinExitInvariant),
                preJoinExitSupply,
                postJoinExitSupply,
                protocolSwapFeePercentage
            );

        return protocolFeeAmount;
    }

    function _updatePostJoinExit(
        uint256 postJoinExitInvariant
    ) internal virtual override {
        // After all joins and exits we store the post join/exit invariant in order to compute growth due to swap fees
        // in the next one.
        _setMiscData(
            _getMiscData().insertUint(
                postJoinExitInvariant,
                _LAST_POST_JOINEXIT_INVARIANT_OFFSET,
                _LAST_POST_JOINEXIT_INVARIANT_BIT_LENGTH
            )
        );
    }

    // Helper functions

    /**
     * @notice Returns the contribution to the total rate product from a token with the given weight and rate provider.
     */
    function _getRateFactor(
        uint256 normalizedWeight,
        IRateProvider provider
    ) internal view returns (uint256) {
        return
            provider == IRateProvider(0)
                ? FixedPoint.ONE
                : provider.getRate().powDown(normalizedWeight);
    }

    /**
     * @dev Returns the weighted product of all the token rates.
     */
    function _getRateProduct(
        uint256[] memory normalizedWeights
    ) internal view returns (uint256) {
        uint256 totalTokens = normalizedWeights.length;

        uint256 rateProduct = FixedPoint.mulDown(
            _getRateFactor(normalizedWeights[0], _rateProvider0),
            _getRateFactor(normalizedWeights[1], _rateProvider1)
        );

        if (totalTokens > 2) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[2], _rateProvider2)
            );
        } else {
            return rateProduct;
        }
        if (totalTokens > 3) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[3], _rateProvider3)
            );
        } else {
            return rateProduct;
        }
        if (totalTokens > 4) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[4], _rateProvider4)
            );
        } else {
            return rateProduct;
        }
        if (totalTokens > 5) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[5], _rateProvider5)
            );
        } else {
            return rateProduct;
        }
        if (totalTokens > 6) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[6], _rateProvider6)
            );
        } else {
            return rateProduct;
        }
        if (totalTokens > 7) {
            rateProduct = rateProduct.mulDown(
                _getRateFactor(normalizedWeights[7], _rateProvider7)
            );
        }

        return rateProduct;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.7.0;
pragma experimental ABIEncoderV2;

import "../../v2-interfaces/contracts/pool-utils/IAssetManager.sol";
import "../../v2-interfaces/contracts/pool-utils/IControlledPool.sol";
import "../../v2-interfaces/contracts/vault/IVault.sol";
import "../../v2-interfaces/contracts/vault/IBasePool.sol";

import "../../v2-solidity-utils/contracts/helpers/InputHelpers.sol";
import "../../v2-solidity-utils/contracts/helpers/WordCodec.sol";
import "../../v2-solidity-utils/contracts/helpers/TemporarilyPausable.sol";
import "../../v2-solidity-utils/contracts/openzeppelin/ERC20.sol";
import "../../v2-solidity-utils/contracts/math/FixedPoint.sol";
import "../../v2-solidity-utils/contracts/math/Math.sol";

import "./BalancerPoolToken.sol";
import "./BasePoolAuthorization.sol";
import "./RecoveryMode.sol";

// solhint-disable max-states-count

/**
 * @notice Reference implementation for the base layer of a Pool contract.
 * @dev Reference implementation for the base layer of a Pool contract that manages a single Pool with optional
 * Asset Managers, an admin-controlled swap fee percentage, and an emergency pause mechanism.
 *
 * This Pool pays protocol fees by minting BPT directly to the ProtocolFeeCollector instead of using the
 * `dueProtocolFees` return value. This results in the underlying tokens continuing to provide liquidity
 * for traders, while still keeping gas usage to a minimum since only a single token (the BPT) is transferred.
 *
 * Note that neither swap fees nor the pause mechanism are used by this contract. They are passed through so that
 * derived contracts can use them via the `_addSwapFeeAmount` and `_subtractSwapFeeAmount` functions, and the
 * `whenNotPaused` modifier.
 *
 * No admin permissions are checked here: instead, this contract delegates that to the Vault's own Authorizer.
 *
 * Because this contract doesn't implement the swap hooks, derived contracts should generally inherit from
 * BaseGeneralPool or BaseMinimalSwapInfoPool. Otherwise, subclasses must inherit from the corresponding interfaces
 * and implement the swap callbacks themselves.
 */
abstract contract BasePool is
    IBasePool,
    IControlledPool,
    BasePoolAuthorization,
    BalancerPoolToken,
    TemporarilyPausable,
    RecoveryMode
{
    using WordCodec for bytes32;
    using FixedPoint for uint256;
    using BasePoolUserData for bytes;

    uint256 private constant _MIN_TOKENS = 2;

    uint256 private constant _DEFAULT_MINIMUM_BPT = 1e6;

    // 1e18 corresponds to 1.0, or a 100% fee
    uint256 private constant _MIN_SWAP_FEE_PERCENTAGE = 1e12; // 0.0001%
    uint256 private constant _MAX_SWAP_FEE_PERCENTAGE = 1e17; // 10% - this fits in 64 bits

    // `_miscData` is a storage slot that can be used to store unrelated pieces of information. All pools store the
    // recovery mode flag and swap fee percentage, but `miscData` can be extended to store more pieces of information.
    // The most signficant bit is reserved for the recovery mode flag, and the swap fee percentage is stored in
    // the next most significant 63 bits, leaving the remaining 192 bits free to store any other information derived
    // pools might need.
    //
    // This slot is preferred for gas-sensitive operations as it is read in all joins, swaps and exits,
    // and therefore warm.

    // [ recovery | swap  fee | available ]
    // [   1 bit  |  63 bits  |  192 bits ]
    // [ MSB                          LSB ]
    bytes32 private _miscData;

    uint256 private constant _SWAP_FEE_PERCENTAGE_OFFSET = 192;
    uint256 private constant _RECOVERY_MODE_BIT_OFFSET = 255;

    // A fee can never be larger than FixedPoint.ONE, which fits in 60 bits, so 63 is more than enough.
    uint256 private constant _SWAP_FEE_PERCENTAGE_BIT_LENGTH = 63;

    bytes32 private immutable _poolId;

    // Note that this value is immutable in the Vault, so we can make it immutable here and save gas
    IProtocolFeesCollector private immutable _protocolFeesCollector;

    event SwapFeePercentageChanged(uint256 swapFeePercentage);

    constructor(
        IVault vault,
        IVault.PoolSpecialization specialization,
        string memory name,
        string memory symbol,
        IERC20[] memory tokens,
        address[] memory assetManagers,
        uint256 swapFeePercentage,
        uint256 pauseWindowDuration,
        uint256 bufferPeriodDuration,
        address owner
    )
        // Base Pools are expected to be deployed using factories. By using the factory address as the action
        // disambiguator, we make all Pools deployed by the same factory share action identifiers. This allows for
        // simpler management of permissions (such as being able to manage granting the 'set fee percentage' action in
        // any Pool created by the same factory), while still making action identifiers unique among different factories
        // if the selectors match, preventing accidental errors.
        Authentication(bytes32(uint256(msg.sender)))
        BalancerPoolToken(name, symbol, vault)
        BasePoolAuthorization(owner)
        TemporarilyPausable(pauseWindowDuration, bufferPeriodDuration)
    {
        _require(tokens.length >= _MIN_TOKENS, Errors.MIN_TOKENS);
        _require(tokens.length <= _getMaxTokens(), Errors.MAX_TOKENS);

        // The Vault only requires the token list to be ordered for the Two Token Pools specialization. However,
        // to make the developer experience consistent, we are requiring this condition for all the native pools.
        // Also, since these Pools will register tokens only once, we can ensure the Pool tokens will follow the same
        // order. We rely on this property to make Pools simpler to write, as it lets us assume that the
        // order of token-specific parameters (such as token weights) will not change.
        InputHelpers.ensureArrayIsSorted(tokens);

        _setSwapFeePercentage(swapFeePercentage);

        bytes32 poolId = vault.registerPool(specialization);

        vault.registerTokens(poolId, tokens, assetManagers);

        // Set immutable state variables - these cannot be read from during construction
        _poolId = poolId;
        _protocolFeesCollector = vault.getProtocolFeesCollector();
    }

    // Getters / Setters

    /**
     * @notice Return the pool id.
     */
    function getPoolId() public view override returns (bytes32) {
        return _poolId;
    }

    function _getTotalTokens() internal view virtual returns (uint256);

    function _getMaxTokens() internal pure virtual returns (uint256);

    /**
     * @dev Returns the minimum BPT supply. This amount is minted to the zero address during initialization, effectively
     * locking it.
     *
     * This is useful to make sure Pool initialization happens only once, but derived Pools can change this value (even
     * to zero) by overriding this function.
     */
    function _getMinimumBpt() internal pure virtual returns (uint256) {
        return _DEFAULT_MINIMUM_BPT;
    }

    /**
     * @notice Return the current value of the swap fee percentage.
     * @dev This is stored in `_miscData`.
     */
    function getSwapFeePercentage()
        public
        view
        virtual
        override
        returns (uint256)
    {
        return
            _miscData.decodeUint(
                _SWAP_FEE_PERCENTAGE_OFFSET,
                _SWAP_FEE_PERCENTAGE_BIT_LENGTH
            );
    }

    /**
     * @notice Return the ProtocolFeesCollector contract.
     * @dev This is immutable, and retrieved from the Vault on construction. (It is also immutable in the Vault.)
     */
    function getProtocolFeesCollector()
        public
        view
        returns (IProtocolFeesCollector)
    {
        return _protocolFeesCollector;
    }

    /**
     * @notice Set the swap fee percentage.
     * @dev This is a permissioned function, and disabled if the pool is paused. The swap fee must be within the
     * bounds set by MIN_SWAP_FEE_PERCENTAGE/MAX_SWAP_FEE_PERCENTAGE. Emits the SwapFeePercentageChanged event.
     */
    function setSwapFeePercentage(
        uint256 swapFeePercentage
    ) public virtual override authenticate whenNotPaused {
        _setSwapFeePercentage(swapFeePercentage);
    }

    function _setSwapFeePercentage(uint256 swapFeePercentage) internal virtual {
        _require(
            swapFeePercentage >= _getMinSwapFeePercentage(),
            Errors.MIN_SWAP_FEE_PERCENTAGE
        );
        _require(
            swapFeePercentage <= _getMaxSwapFeePercentage(),
            Errors.MAX_SWAP_FEE_PERCENTAGE
        );

        _miscData = _miscData.insertUint(
            swapFeePercentage,
            _SWAP_FEE_PERCENTAGE_OFFSET,
            _SWAP_FEE_PERCENTAGE_BIT_LENGTH
        );

        emit SwapFeePercentageChanged(swapFeePercentage);
    }

    function _getMinSwapFeePercentage()
        internal
        pure
        virtual
        returns (uint256)
    {
        return _MIN_SWAP_FEE_PERCENTAGE;
    }

    function _getMaxSwapFeePercentage()
        internal
        pure
        virtual
        returns (uint256)
    {
        return _MAX_SWAP_FEE_PERCENTAGE;
    }

    /**
     * @notice Returns whether the pool is in Recovery Mode.
     */
    function inRecoveryMode() public view override returns (bool) {
        return _miscData.decodeBool(_RECOVERY_MODE_BIT_OFFSET);
    }

    /**
     * @dev Sets the recoveryMode state, and emits the corresponding event.
     */
    function _setRecoveryMode(bool enabled) internal virtual override {
        _miscData = _miscData.insertBool(enabled, _RECOVERY_MODE_BIT_OFFSET);

        emit RecoveryModeStateChanged(enabled);

        // Some pools need to update their state when leaving recovery mode to ensure proper functioning of the Pool.
        // We do not allow an `_onEnableRecoveryMode()` hook as this may jeopardize the ability to enable Recovery mode.
        if (!enabled) _onDisableRecoveryMode();
    }

    /**
     * @dev Performs any necessary actions on the disabling of Recovery Mode.
     * This is usually to reset any fee collection mechanisms to ensure that they operate correctly going forward.
     */
    function _onDisableRecoveryMode() internal virtual {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @notice Set the asset manager parameters for the given token.
     * @dev This is a permissioned function, unavailable when the pool is paused.
     * The details of the configuration data are set by each Asset Manager. (For an example, see
     * `RewardsAssetManager`.)
     */
    function setAssetManagerPoolConfig(
        IERC20 token,
        bytes memory poolConfig
    ) public virtual override authenticate whenNotPaused {
        _setAssetManagerPoolConfig(token, poolConfig);
    }

    function _setAssetManagerPoolConfig(
        IERC20 token,
        bytes memory poolConfig
    ) private {
        bytes32 poolId = getPoolId();
        (, , , address assetManager) = getVault().getPoolTokenInfo(
            poolId,
            token
        );

        IAssetManager(assetManager).setConfig(poolId, poolConfig);
    }

    /**
     * @notice Pause the pool: an emergency action which disables all pool functions.
     * @dev This is a permissioned function that will only work during the Pause Window set during pool factory
     * deployment (see `TemporarilyPausable`).
     */
    function pause() external authenticate {
        _setPaused(true);
    }

    /**
     * @notice Reverse a `pause` operation, and restore a pool to normal functionality.
     * @dev This is a permissioned function that will only work on a paused pool within the Buffer Period set during
     * pool factory deployment (see `TemporarilyPausable`). Note that any paused pools will automatically unpause
     * after the Buffer Period expires.
     */
    function unpause() external authenticate {
        _setPaused(false);
    }

    function _isOwnerOnlyAction(
        bytes32 actionId
    ) internal view virtual override returns (bool) {
        return
            (actionId == getActionId(this.setSwapFeePercentage.selector)) ||
            (actionId == getActionId(this.setAssetManagerPoolConfig.selector));
    }

    function _getMiscData() internal view returns (bytes32) {
        return _miscData;
    }

    /**
     * @dev Inserts data into the least-significant 192 bits of the misc data storage slot.
     * Note that the remaining 64 bits are used for the swap fee percentage and cannot be overloaded.
     */
    function _setMiscData(bytes32 newData) internal {
        _miscData = _miscData.insertBits192(newData, 0);
    }

    // Join / Exit Hooks

    modifier onlyVault(bytes32 poolId) {
        _require(msg.sender == address(getVault()), Errors.CALLER_NOT_VAULT);
        _require(poolId == getPoolId(), Errors.INVALID_POOL_ID);
        _;
    }

    /**
     * @notice Vault hook for adding liquidity to a pool (including the first time, "initializing" the pool).
     * @dev This function can only be called from the Vault, from `joinPool`.
     */
    function onJoinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    )
        external
        override
        onlyVault(poolId)
        returns (uint256[] memory, uint256[] memory)
    {
        _beforeSwapJoinExit();

        uint256[] memory scalingFactors = _scalingFactors();

        if (totalSupply() == 0) {
            (
                uint256 bptAmountOut,
                uint256[] memory amountsIn
            ) = _onInitializePool(
                    poolId,
                    sender,
                    recipient,
                    scalingFactors,
                    userData
                );

            // On initialization, we lock _getMinimumBpt() by minting it for the zero address. This BPT acts as a
            // minimum as it will never be burned, which reduces potential issues with rounding, and also prevents the
            // Pool from ever being fully drained.
            _require(bptAmountOut >= _getMinimumBpt(), Errors.MINIMUM_BPT);
            _mintPoolTokens(address(0), _getMinimumBpt());
            _mintPoolTokens(recipient, bptAmountOut - _getMinimumBpt());

            // amountsIn are amounts entering the Pool, so we round up.
            _downscaleUpArray(amountsIn, scalingFactors);

            return (amountsIn, new uint256[](balances.length));
        } else {
            _upscaleArray(balances, scalingFactors);
            (uint256 bptAmountOut, uint256[] memory amountsIn) = _onJoinPool(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                scalingFactors,
                userData
            );

            // Note we no longer use `balances` after calling `_onJoinPool`, which may mutate it.

            _mintPoolTokens(recipient, bptAmountOut);

            // amountsIn are amounts entering the Pool, so we round up.
            _downscaleUpArray(amountsIn, scalingFactors);

            // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
            return (amountsIn, new uint256[](balances.length));
        }
    }

    /**
     * @notice Vault hook for removing liquidity from a pool.
     * @dev This function can only be called from the Vault, from `exitPool`.
     */
    function onExitPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    )
        external
        override
        onlyVault(poolId)
        returns (uint256[] memory, uint256[] memory)
    {
        uint256[] memory amountsOut;
        uint256 bptAmountIn;

        // When a user calls `exitPool`, this is the first point of entry from the Vault.
        // We first check whether this is a Recovery Mode exit - if so, we proceed using this special lightweight exit
        // mechanism which avoids computing any complex values, interacting with external contracts, etc., and generally
        // should always work, even if the Pool's mathematics or a dependency break down.
        if (userData.isRecoveryModeExitKind()) {
            // This exit kind is only available in Recovery Mode.
            _ensureInRecoveryMode();

            // Note that we don't upscale balances nor downscale amountsOut - we don't care about scaling factors during
            // a recovery mode exit.
            (bptAmountIn, amountsOut) = _doRecoveryModeExit(
                balances,
                totalSupply(),
                userData
            );
        } else {
            // Note that we only call this if we're not in a recovery mode exit.
            _beforeSwapJoinExit();

            uint256[] memory scalingFactors = _scalingFactors();
            _upscaleArray(balances, scalingFactors);

            (bptAmountIn, amountsOut) = _onExitPool(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                scalingFactors,
                userData
            );

            // amountsOut are amounts exiting the Pool, so we round down.
            _downscaleDownArray(amountsOut, scalingFactors);
        }

        // Note we no longer use `balances` after calling `_onExitPool`, which may mutate it.

        _burnPoolTokens(sender, bptAmountIn);

        // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
        return (amountsOut, new uint256[](balances.length));
    }

    // Query functions

    /**
     * @notice "Dry run" `onJoinPool`.
     * @dev Returns the amount of BPT that would be granted to `recipient` if the `onJoinPool` hook were called by the
     * Vault with the same arguments, along with the number of tokens `sender` would have to supply.
     *
     * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
     * data, such as the protocol swap fee percentage and Pool balances.
     *
     * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
     * explicitly use eth_call instead of eth_sendTransaction.
     */
    function queryJoin(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override returns (uint256 bptOut, uint256[] memory amountsIn) {
        InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());

        _queryAction(
            poolId,
            sender,
            recipient,
            balances,
            lastChangeBlock,
            protocolSwapFeePercentage,
            userData,
            _onJoinPool,
            _downscaleUpArray
        );

        // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
        // and we don't need to return anything here - it just silences compiler warnings.
        return (bptOut, amountsIn);
    }

    /**
     * @notice "Dry run" `onExitPool`.
     * @dev Returns the amount of BPT that would be burned from `sender` if the `onExitPool` hook were called by the
     * Vault with the same arguments, along with the number of tokens `recipient` would receive.
     *
     * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
     * data, such as the protocol swap fee percentage and Pool balances.
     *
     * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
     * explicitly use eth_call instead of eth_sendTransaction.
     */
    function queryExit(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData
    ) external override returns (uint256 bptIn, uint256[] memory amountsOut) {
        InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());

        _queryAction(
            poolId,
            sender,
            recipient,
            balances,
            lastChangeBlock,
            protocolSwapFeePercentage,
            userData,
            _onExitPool,
            _downscaleDownArray
        );

        // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
        // and we don't need to return anything here - it just silences compiler warnings.
        return (bptIn, amountsOut);
    }

    // Internal hooks to be overridden by derived contracts - all token amounts (except BPT) in these interfaces are
    // upscaled.

    /**
     * @dev Called when the Pool is joined for the first time; that is, when the BPT total supply is zero.
     *
     * Returns the amount of BPT to mint, and the token amounts the Pool will receive in return.
     *
     * Minted BPT will be sent to `recipient`, except for _getMinimumBpt(), which will be deducted from this amount and
     * sent to the zero address instead. This will cause that BPT to remain forever locked there, preventing total BTP
     * from ever dropping below that value, and ensuring `_onInitializePool` can only be called once in the entire
     * Pool's lifetime.
     *
     * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
     * be downscaled (rounding up) before being returned to the Vault.
     */
    function _onInitializePool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory scalingFactors,
        bytes memory userData
    )
        internal
        virtual
        returns (uint256 bptAmountOut, uint256[] memory amountsIn);

    /**
     * @dev Called whenever the Pool is joined after the first initialization join (see `_onInitializePool`).
     *
     * Returns the amount of BPT to mint, the token amounts that the Pool will receive in return, and the number of
     * tokens to pay in protocol swap fees.
     *
     * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
     * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
     *
     * Minted BPT will be sent to `recipient`.
     *
     * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
     * be downscaled (rounding up) before being returned to the Vault.
     *
     * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onJoinPool`). These
     * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
     */
    function _onJoinPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        uint256[] memory scalingFactors,
        bytes memory userData
    )
        internal
        virtual
        returns (uint256 bptAmountOut, uint256[] memory amountsIn);

    /**
     * @dev Called whenever the Pool is exited.
     *
     * Returns the amount of BPT to burn, the token amounts for each Pool token that the Pool will grant in return, and
     * the number of tokens to pay in protocol swap fees.
     *
     * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
     * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
     *
     * BPT will be burnt from `sender`.
     *
     * The Pool will grant tokens to `recipient`. These amounts are considered upscaled and will be downscaled
     * (rounding down) before being returned to the Vault.
     *
     * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onExitPool`). These
     * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
     */
    function _onExitPool(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        uint256[] memory scalingFactors,
        bytes memory userData
    )
        internal
        virtual
        returns (uint256 bptAmountIn, uint256[] memory amountsOut);

    /**
     * @dev Called at the very beginning of swaps, joins and exits, even before the scaling factors are read. Derived
     * contracts can extend this implementation to perform any state-changing operations they might need (including e.g.
     * updating the scaling factors),
     *
     * The only scenario in which this function is not called is during a recovery mode exit. This makes it safe to
     * perform non-trivial computations or interact with external dependencies here, as recovery mode will not be
     * affected.
     *
     * Since this contract does not implement swaps, derived contracts must also make sure this function is called on
     * swap handlers.
     */
    function _beforeSwapJoinExit() internal virtual {
        // All joins, exits and swaps are disabled (except recovery mode exits).
        _ensureNotPaused();
    }

    // Internal functions

    /**
     * @dev Pays protocol fees by minting `bptAmount` to the Protocol Fee Collector.
     */
    function _payProtocolFees(uint256 bptAmount) internal {
        _mintPoolTokens(address(getProtocolFeesCollector()), bptAmount);
    }

    /**
     * @dev Adds swap fee amount to `amount`, returning a higher value.
     */
    function _addSwapFeeAmount(uint256 amount) internal view returns (uint256) {
        // This returns amount + fee amount, so we round up (favoring a higher fee amount).
        return amount.divUp(getSwapFeePercentage().complement());
    }

    /**
     * @dev Subtracts swap fee amount from `amount`, returning a lower value.
     */
    function _subtractSwapFeeAmount(
        uint256 amount
    ) internal view returns (uint256) {
        // This returns amount - fee amount, so we round up (favoring a higher fee amount).
        uint256 feeAmount = amount.mulUp(getSwapFeePercentage());
        return amount.sub(feeAmount);
    }

    // Scaling

    /**
     * @dev Returns a scaling factor that, when multiplied to a token amount for `token`, normalizes its balance as if
     * it had 18 decimals.
     */
    function _computeScalingFactor(
        IERC20 token
    ) internal view returns (uint256) {
        if (address(token) == address(this)) {
            return FixedPoint.ONE;
        }

        // Tokens that don't implement the `decimals` method are not supported.
        uint256 tokenDecimals = ERC20(address(token)).decimals();

        // Tokens with more than 18 decimals are not supported.
        uint256 decimalsDifference = Math.sub(18, tokenDecimals);
        return FixedPoint.ONE * 10 ** decimalsDifference;
    }

    /**
     * @dev Returns the scaling factor for one of the Pool's tokens. Reverts if `token` is not a token registered by the
     * Pool.
     *
     * All scaling factors are fixed-point values with 18 decimals, to allow for this function to be overridden by
     * derived contracts that need to apply further scaling, making these factors potentially non-integer.
     *
     * The largest 'base' scaling factor (i.e. in tokens with less than 18 decimals) is 10**18, which in fixed-point is
     * 10**36. This value can be multiplied with a 112 bit Vault balance with no overflow by a factor of ~1e7, making
     * even relatively 'large' factors safe to use.
     *
     * The 1e7 figure is the result of 2**256 / (1e18 * 1e18 * 2**112).
     */
    function _scalingFactor(
        IERC20 token
    ) internal view virtual returns (uint256);

    /**
     * @dev Same as `_scalingFactor()`, except for all registered tokens (in the same order as registered). The Vault
     * will always pass balances in this order when calling any of the Pool hooks.
     */
    function _scalingFactors() internal view virtual returns (uint256[] memory);

    function getScalingFactors()
        external
        view
        override
        returns (uint256[] memory)
    {
        return _scalingFactors();
    }

    /**
     * @dev Applies `scalingFactor` to `amount`, resulting in a larger or equal value depending on whether it needed
     * scaling or not.
     */
    function _upscale(
        uint256 amount,
        uint256 scalingFactor
    ) internal pure returns (uint256) {
        // Upscale rounding wouldn't necessarily always go in the same direction: in a swap for example the balance of
        // token in should be rounded up, and that of token out rounded down. This is the only place where we round in
        // the same direction for all amounts, as the impact of this rounding is expected to be minimal (and there's no
        // rounding error unless `_scalingFactor()` is overriden).
        return FixedPoint.mulDown(amount, scalingFactor);
    }

    /**
     * @dev Same as `_upscale`, but for an entire array. This function does not return anything, but instead *mutates*
     * the `amounts` array.
     */
    function _upscaleArray(
        uint256[] memory amounts,
        uint256[] memory scalingFactors
    ) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.mulDown(amounts[i], scalingFactors[i]);
        }
    }

    /**
     * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
     * whether it needed scaling or not. The result is rounded down.
     */
    function _downscaleDown(
        uint256 amount,
        uint256 scalingFactor
    ) internal pure returns (uint256) {
        return FixedPoint.divDown(amount, scalingFactor);
    }

    /**
     * @dev Same as `_downscaleDown`, but for an entire array. This function does not return anything, but instead
     * *mutates* the `amounts` array.
     */
    function _downscaleDownArray(
        uint256[] memory amounts,
        uint256[] memory scalingFactors
    ) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.divDown(amounts[i], scalingFactors[i]);
        }
    }

    /**
     * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
     * whether it needed scaling or not. The result is rounded up.
     */
    function _downscaleUp(
        uint256 amount,
        uint256 scalingFactor
    ) internal pure returns (uint256) {
        return FixedPoint.divUp(amount, scalingFactor);
    }

    /**
     * @dev Same as `_downscaleUp`, but for an entire array. This function does not return anything, but instead
     * *mutates* the `amounts` array.
     */
    function _downscaleUpArray(
        uint256[] memory amounts,
        uint256[] memory scalingFactors
    ) internal pure {
        uint256 length = amounts.length;
        InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);

        for (uint256 i = 0; i < length; ++i) {
            amounts[i] = FixedPoint.divUp(amounts[i], scalingFactors[i]);
        }
    }

    function _getAuthorizer() internal view override returns (IAuthorizer) {
        // Access control management is delegated to the Vault's Authorizer. This lets Balancer Governance manage which
        // accounts can call permissioned functions: for example, to perform emergency pauses.
        // If the owner is delegated, then *all* permissioned functions, including `setSwapFeePercentage`, will be under
        // Governance control.
        return getVault().getAuthorizer();
    }

    function _queryAction(
        bytes32 poolId,
        address sender,
        address recipient,
        uint256[] memory balances,
        uint256 lastChangeBlock,
        uint256 protocolSwapFeePercentage,
        bytes memory userData,
        function(
            bytes32,
            address,
            address,
            uint256[] memory,
            uint256,
            uint256,
            uint256[] memory,
            bytes memory
        ) internal returns (uint256, uint256[] memory) _action,
        function(uint256[] memory, uint256[] memory)
            internal
            view _downscaleArray
    ) private {
        // This uses the same technique used by the Vault in queryBatchSwap. Refer to that function for a detailed
        // explanation.

        if (msg.sender != address(this)) {
            // We perform an external call to ourselves, forwarding the same calldata. In this call, the else clause of
            // the preceding if statement will be executed instead.

            // solhint-disable-next-line avoid-low-level-calls
            (bool success, ) = address(this).call(msg.data);

            // solhint-disable-next-line no-inline-assembly
            assembly {
                // This call should always revert to decode the bpt and token amounts from the revert reason
                switch success
                case 0 {
                    // Note we are manually writing the memory slot 0. We can safely overwrite whatever is
                    // stored there as we take full control of the execution and then immediately return.

                    // We copy the first 4 bytes to check if it matches with the expected signature, otherwise
                    // there was another revert reason and we should forward it.
                    returndatacopy(0, 0, 0x04)
                    let error := and(
                        mload(0),
                        0xffffffff00000000000000000000000000000000000000000000000000000000
                    )

                    // If the first 4 bytes don't match with the expected signature, we forward the revert reason.
                    if eq(
                        eq(
                            error,
                            0x43adbafb00000000000000000000000000000000000000000000000000000000
                        ),
                        0
                    ) {
                        returndatacopy(0, 0, returndatasize())
                        revert(0, returndatasize())
                    }

                    // The returndata contains the signature, followed by the raw memory representation of the
                    // `bptAmount` and `tokenAmounts` (array: length + data). We need to return an ABI-encoded
                    // representation of these.
                    // An ABI-encoded response will include one additional field to indicate the starting offset of
                    // the `tokenAmounts` array. The `bptAmount` will be laid out in the first word of the
                    // returndata.
                    //
                    // In returndata:
                    // [ signature ][ bptAmount ][ tokenAmounts length ][ tokenAmounts values ]
                    // [  4 bytes  ][  32 bytes ][       32 bytes      ][ (32 * length) bytes ]
                    //
                    // We now need to return (ABI-encoded values):
                    // [ bptAmount ][ tokeAmounts offset ][ tokenAmounts length ][ tokenAmounts values ]
                    // [  32 bytes ][       32 bytes     ][       32 bytes      ][ (32 * length) bytes ]

                    // We copy 32 bytes for the `bptAmount` from returndata into memory.
                    // Note that we skip the first 4 bytes for the error signature
                    returndatacopy(0, 0x04, 32)

                    // The offsets are 32-bytes long, so the array of `tokenAmounts` will start after
                    // the initial 64 bytes.
                    mstore(0x20, 64)

                    // We now copy the raw memory array for the `tokenAmounts` from returndata into memory.
                    // Since bpt amount and offset take up 64 bytes, we start copying at address 0x40. We also
                    // skip the first 36 bytes from returndata, which correspond to the signature plus bpt amount.
                    returndatacopy(0x40, 0x24, sub(returndatasize(), 36))

                    // We finally return the ABI-encoded uint256 and the array, which has a total length equal to
                    // the size of returndata, plus the 32 bytes of the offset but without the 4 bytes of the
                    // error signature.
                    return(0, add(returndatasize(), 28))
                }
                default {
                    // This call should always revert, but we fail nonetheless if that didn't happen
                    invalid()
                }
            }
        } else {
            // This imitates the relevant parts of the bodies of onJoin and onExit. Since they're not virtual, we know
            // that their implementations will match this regardless of what derived contracts might do.

            _beforeSwapJoinExit();

            uint256[] memory scalingFactors = _scalingFactors();
            _upscaleArray(balances, scalingFactors);

            (uint256 bptAmount, uint256[] memory tokenAmounts) = _action(
                poolId,
                sender,
                recipient,
                balances,
                lastChangeBlock,
                protocolSwapFeePercentage,
                scalingFactors,
                userData
            );

            _downscaleArray(tokenAmounts, scalingFactors);

            // solhint-disable-next-line no-inline-assembly
            assembly {
                // We will return a raw representation of `bptAmount` and `tokenAmounts` in memory, which is composed of
                // a 32-byte uint256, followed by a 32-byte for the array length, and finally the 32-byte uint256 values
                // Because revert expects a size in bytes, we multiply the array length (stored at `tokenAmounts`) by 32
                let size := mul(mload(tokenAmounts), 32)

                // We store the `bptAmount` in the previous slot to the `tokenAmounts` array. We can make sure there
                // will be at least one available slot due to how the memory scratch space works.
                // We can safely overwrite whatever is stored in this slot as we will revert immediately after that.
                let start := sub(tokenAmounts, 0x20)
                mstore(start, bptAmount)

                // We send one extra value for the error signature "QueryError(uint256,uint256[])" which is 0x43adbafb
                // We use the previous slot to `bptAmount`.
                mstore(
                    sub(start, 0x20),
                    0x0000000000000000000000000000000000000000000000000000000043adbafb
                )
                start := sub(start, 0x04)

                // When copying from `tokenAmounts` into returndata, we copy the additional 68 bytes to also return
                // the `bptAmount`, the array 's length, and the error signature.
                revert(start, add(size, 68))
            }
        }
    }
}