// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.21;

import { Math } from "src/utils/Math.sol";
import { SafeTransferLib } from "@solmate/utils/SafeTransferLib.sol";
import { ERC20 } from "@solmate/tokens/ERC20.sol";
import { ReentrancyGuard } from "@solmate/utils/ReentrancyGuard.sol";
import { IAtomicSolver } from "./IAtomicSolver.sol";

/**
 * @title AtomicQueue
 * @notice Allows users to create `AtomicRequests` that specify an ERC20 asset to `offer`
 *         and an ERC20 asset to `want` in return.
 * @notice Making atomic requests where the exchange rate between offer and want is not
 *         relatively stable is effectively the same as placing a limit order between
 *         those assets, so requests can be filled at a rate worse than the current market rate.
 * @notice It is possible for a user to make multiple requests that use the same offer asset.
 *         If this is done it is important that the user has approved the queue to spend the
 *         total amount of assets aggregated from all their requests, and to also have enough
 *         `offer` asset to cover the aggregate total request of `offerAmount`.
 * @author crispymangoes
 */
contract AtomicQueue is ReentrancyGuard {
    using SafeTransferLib for ERC20;
    using Math for uint256;

    // ========================================= STRUCTS =========================================

    /**
     * @notice Stores request information needed to fulfill a users atomic request.
     * @param deadline unix timestamp for when request is no longer valid
     * @param atomicPrice the price in terms of `want` asset the user wants their `offer` assets "sold" at
     * @dev atomicPrice MUST be in terms of `want` asset decimals.
     * @param offerAmount the amount of `offer` asset the user wants converted to `want` asset
     * @param inSolve bool used during solves to prevent duplicate users, and to prevent redoing multiple checks
     */
    struct AtomicRequest {
        uint64 deadline; // deadline to fulfill request
        uint88 atomicPrice; // In terms of want asset decimals
        uint96 offerAmount; // The amount of offer asset the user wants to sell.
        bool inSolve; // Indicates whether this user is currently having their request fulfilled.
    }

    /**
     * @notice Used in `viewSolveMetaData` helper function to return data in a clean struct.
     * @param user the address of the user
     * @param flags 8 bits indicating the state of the user only the first 4 bits are used XXXX0000
     *              Either all flags are false(user is solvable) or only 1 is true(an error occurred).
     *              From right to left
     *              - 0: indicates user deadline has passed.
     *              - 1: indicates user request has zero offer amount.
     *              - 2: indicates user does not have enough offer asset in wallet.
     *              - 3: indicates user has not given AtomicQueue approval.
     * @param assetsToOffer the amount of offer asset to solve
     * @param assetsForWant the amount of assets users want for their offer assets
     */
    struct SolveMetaData {
        address user;
        uint8 flags;
        uint256 assetsToOffer;
        uint256 assetsForWant;
    }

    // ========================================= GLOBAL STATE =========================================

    /**
     * @notice Maps user address to offer asset to want asset to a AtomicRequest struct.
     */
    mapping(address => mapping(ERC20 => mapping(ERC20 => AtomicRequest))) public userAtomicRequest;

    //============================== ERRORS ===============================

    error AtomicQueue__UserRepeated(address user);
    error AtomicQueue__RequestDeadlineExceeded(address user);
    error AtomicQueue__UserNotInSolve(address user);
    error AtomicQueue__ZeroOfferAmount(address user);

    //============================== EVENTS ===============================

    /**
     * @notice Emitted when `updateAtomicRequest` is called.
     */
    event AtomicRequestUpdated(
        address user,
        address offerToken,
        address wantToken,
        uint256 amount,
        uint256 deadline,
        uint256 minPrice,
        uint256 timestamp
    );

    /**
     * @notice Emitted when `solve` exchanges a users offer asset for their want asset.
     */
    event AtomicRequestFulfilled(
        address user,
        address offerToken,
        address wantToken,
        uint256 offerAmountSpent,
        uint256 wantAmountReceived,
        uint256 timestamp
    );

    //============================== USER FUNCTIONS ===============================

    /**
     * @notice Get a users Atomic Request.
     * @param user the address of the user to get the request for
     * @param offer the ERC0 token they want to exchange for the want
     * @param want the ERC20 token they want in exchange for the offer
     */
    function getUserAtomicRequest(address user, ERC20 offer, ERC20 want) external view returns (AtomicRequest memory) {
        return userAtomicRequest[user][offer][want];
    }

    /**
     * @notice Helper function that returns either
     *         true: Withdraw request is valid.
     *         false: Withdraw request is not valid.
     * @dev It is possible for a withdraw request to return false from this function, but using the
     *      request in `updateAtomicRequest` will succeed, but solvers will not be able to include
     *      the user in `solve` unless some other state is changed.
     * @param offer the ERC0 token they want to exchange for the want
     * @param user the address of the user making the request
     * @param userRequest the request struct to validate
     */
    function isAtomicRequestValid(
        ERC20 offer,
        address user,
        AtomicRequest calldata userRequest
    ) external view returns (bool) {
        // Validate amount.
        if (userRequest.offerAmount > offer.balanceOf(user)) return false;
        // Validate deadline.
        if (block.timestamp > userRequest.deadline) return false;
        // Validate approval.
        if (offer.allowance(user, address(this)) < userRequest.offerAmount) return false;
        // Validate offerAmount is nonzero.
        if (userRequest.offerAmount == 0) return false;
        // Validate atomicPrice is nonzero.
        if (userRequest.atomicPrice == 0) return false;

        return true;
    }

    /**
     * @notice Allows user to add/update their withdraw request.
     * @notice It is possible for a withdraw request with a zero atomicPrice to be made, and solved.
     *         If this happens, users will be selling their shares for no assets in return.
     *         To determine a safe atomicPrice, share.previewRedeem should be used to get
     *         a good share price, then the user can lower it from there to make their request fill faster.
     * @param offer the ERC20 token the user is offering in exchange for the want
     * @param want the ERC20 token the user wants in exchange for offer
     * @param userRequest the users request
     */
    function updateAtomicRequest(ERC20 offer, ERC20 want, AtomicRequest calldata userRequest) external nonReentrant {
        AtomicRequest storage request = userAtomicRequest[msg.sender][offer][want];

        request.deadline = userRequest.deadline;
        request.atomicPrice = userRequest.atomicPrice;
        request.offerAmount = userRequest.offerAmount;

        // Emit full amount user has.
        emit AtomicRequestUpdated(
            msg.sender,
            address(offer),
            address(want),
            userRequest.offerAmount,
            userRequest.deadline,
            userRequest.atomicPrice,
            block.timestamp
        );
    }

    //============================== SOLVER FUNCTIONS ===============================

    /**
     * @notice Called by solvers in order to exchange offer asset for want asset.
     * @notice Solvers are optimistically transferred the offer asset, then are required to
     *         approve this contract to spend enough of want assets to cover all requests.
     * @dev It is very likely `solve` TXs will be front run if broadcasted to public mem pools,
     *      so solvers should use private mem pools.
     * @param offer the ERC20 offer token to solve for
     * @param want the ERC20 want token to solve for
     * @param users an array of user addresses to solve for
     * @param runData extra data that is passed back to solver when `finishSolve` is called
     * @param solver the address to make `finishSolve` callback to
     */
    function solve(
        ERC20 offer,
        ERC20 want,
        address[] calldata users,
        bytes calldata runData,
        address solver
    ) external nonReentrant {
        // Save offer asset decimals.
        uint8 offerDecimals = offer.decimals();

        uint256 assetsToOffer;
        uint256 assetsForWant;
        for (uint256 i; i < users.length; ++i) {
            AtomicRequest storage request = userAtomicRequest[users[i]][offer][want];

            if (request.inSolve) revert AtomicQueue__UserRepeated(users[i]);
            if (block.timestamp > request.deadline) revert AtomicQueue__RequestDeadlineExceeded(users[i]);
            if (request.offerAmount == 0) revert AtomicQueue__ZeroOfferAmount(users[i]);

            // User gets whatever their atomic price * offerAmount is.
            assetsForWant += _calculateAssetAmount(request.offerAmount, request.atomicPrice, offerDecimals);

            // If all checks above passed, the users request is valid and should be fulfilled.
            assetsToOffer += request.offerAmount;
            request.inSolve = true;
            // Transfer shares from user to solver.
            offer.safeTransferFrom(users[i], solver, request.offerAmount);
        }

        IAtomicSolver(solver).finishSolve(runData, msg.sender, offer, want, assetsToOffer, assetsForWant);

        for (uint256 i; i < users.length; ++i) {
            AtomicRequest storage request = userAtomicRequest[users[i]][offer][want];

            if (request.inSolve) {
                // We know that the minimum price and deadline arguments are satisfied since this can only be true if they were.

                // Send user their share of assets.
                uint256 assetsToUser = _calculateAssetAmount(request.offerAmount, request.atomicPrice, offerDecimals);

                want.safeTransferFrom(solver, users[i], assetsToUser);

                emit AtomicRequestFulfilled(
                    users[i],
                    address(offer),
                    address(want),
                    request.offerAmount,
                    assetsToUser,
                    block.timestamp
                );

                // Set shares to withdraw to 0.
                request.offerAmount = 0;
                request.inSolve = false;
            } else revert AtomicQueue__UserNotInSolve(users[i]);
        }
    }

    /**
     * @notice Helper function solvers can use to determine if users are solvable, and the required amounts to do so.
     * @notice Repeated users are not accounted for in this setup, so if solvers have repeat users in their `users`
     *         array the results can be wrong.
     * @dev Since a user can have multiple requests with the same offer asset but different want asset, it is
     *      possible for `viewSolveMetaData` to report no errors, but for a solve to fail, if any solves were done
     *      between the time `viewSolveMetaData` and before `solve` is called.
     * @param offer the ERC20 offer token to check for solvability
     * @param want the ERC20 want token to check for solvability
     * @param users an array of user addresses to check for solvability
     */
    function viewSolveMetaData(
        ERC20 offer,
        ERC20 want,
        address[] calldata users
    ) external view returns (SolveMetaData[] memory metaData, uint256 totalAssetsForWant, uint256 totalAssetsToOffer) {
        // Save offer asset decimals.
        uint8 offerDecimals = offer.decimals();

        // Setup meta data.
        metaData = new SolveMetaData[](users.length);

        for (uint256 i; i < users.length; ++i) {
            AtomicRequest memory request = userAtomicRequest[users[i]][offer][want];

            metaData[i].user = users[i];

            if (block.timestamp > request.deadline) {
                metaData[i].flags |= uint8(1);
            }
            if (request.offerAmount == 0) {
                metaData[i].flags |= uint8(1) << 1;
            }
            if (offer.balanceOf(users[i]) < request.offerAmount) {
                metaData[i].flags |= uint8(1) << 2;
            }
            if (offer.allowance(users[i], address(this)) < request.offerAmount) {
                metaData[i].flags |= uint8(1) << 3;
            }

            metaData[i].assetsToOffer = request.offerAmount;

            // User gets whatever their execution share price is.
            uint256 userAssets = _calculateAssetAmount(request.offerAmount, request.atomicPrice, offerDecimals);
            metaData[i].assetsForWant = userAssets;

            // If flags is zero, no errors occurred.
            if (metaData[i].flags == 0) {
                totalAssetsForWant += userAssets;
                totalAssetsToOffer += request.offerAmount;
            }
        }
    }

    //============================== INTERNAL FUNCTIONS ===============================

    /**
     * @notice Helper function to calculate the amount of want assets a users wants in exchange for
     *         `offerAmount` of offer asset.
     */
    function _calculateAssetAmount(
        uint256 offerAmount,
        uint256 atomicPrice,
        uint8 offerDecimals
    ) internal pure returns (uint256) {
        return atomicPrice.mulDivDown(offerAmount, 10 ** offerDecimals);
    }
}

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Modern and gas efficient ERC20 + EIP-2612 implementation.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC20.sol)
/// @author Modified from Uniswap (https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol)
/// @dev Do not manually set balances without updating totalSupply, as the sum of all user balances must not exceed it.
abstract contract ERC20 {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event Transfer(address indexed from, address indexed to, uint256 amount);

    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /*//////////////////////////////////////////////////////////////
                            METADATA STORAGE
    //////////////////////////////////////////////////////////////*/

    string public name;

    string public symbol;

    uint8 public immutable decimals;

    /*//////////////////////////////////////////////////////////////
                              ERC20 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;

    mapping(address => mapping(address => uint256)) public allowance;

    /*//////////////////////////////////////////////////////////////
                            EIP-2612 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 internal immutable INITIAL_CHAIN_ID;

    bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;

    mapping(address => uint256) public nonces;

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;

        INITIAL_CHAIN_ID = block.chainid;
        INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
    }

    /*//////////////////////////////////////////////////////////////
                               ERC20 LOGIC
    //////////////////////////////////////////////////////////////*/

    function approve(address spender, uint256 amount) public virtual returns (bool) {
        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);

        return true;
    }

    function transfer(address to, uint256 amount) public virtual returns (bool) {
        balanceOf[msg.sender] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(msg.sender, to, amount);

        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual returns (bool) {
        uint256 allowed = allowance[from][msg.sender]; // Saves gas for limited approvals.

        if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;

        balanceOf[from] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(from, to, amount);

        return true;
    }

    /*//////////////////////////////////////////////////////////////
                             EIP-2612 LOGIC
    //////////////////////////////////////////////////////////////*/

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        require(deadline >= block.timestamp, "PERMIT_DEADLINE_EXPIRED");

        // Unchecked because the only math done is incrementing
        // the owner's nonce which cannot realistically overflow.
        unchecked {
            address recoveredAddress = ecrecover(
                keccak256(
                    abi.encodePacked(
                        "\x19\x01",
                        DOMAIN_SEPARATOR(),
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
                                ),
                                owner,
                                spender,
                                value,
                                nonces[owner]++,
                                deadline
                            )
                        )
                    )
                ),
                v,
                r,
                s
            );

            require(recoveredAddress != address(0) && recoveredAddress == owner, "INVALID_SIGNER");

            allowance[recoveredAddress][spender] = value;
        }

        emit Approval(owner, spender, value);
    }

    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
        return block.chainid == INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
    }

    function computeDomainSeparator() internal view virtual returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                    keccak256(bytes(name)),
                    keccak256("1"),
                    block.chainid,
                    address(this)
                )
            );
    }

    /*//////////////////////////////////////////////////////////////
                        INTERNAL MINT/BURN LOGIC
    //////////////////////////////////////////////////////////////*/

    function _mint(address to, uint256 amount) internal virtual {
        totalSupply += amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(address(0), to, amount);
    }

    function _burn(address from, uint256 amount) internal virtual {
        balanceOf[from] -= amount;

        // Cannot underflow because a user's balance
        // will never be larger than the total supply.
        unchecked {
            totalSupply -= amount;
        }

        emit Transfer(from, address(0), amount);
    }
}

// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.8.0;

import { ERC20 } from "@solmate/tokens/ERC20.sol";

interface IAtomicSolver {
    /**
     * @notice This function must be implemented in order for an address to be a `solver`
     *         for the AtomicQueue
     * @param runData arbitrary bytes data that is dependent on how each solver is setup
     *        it could contain swap data, or flash loan data, etc..
     * @param initiator the address that initiated a solve
     * @param offer the ERC20 asset sent to the solver
     * @param want the ERC20 asset the solver must approve the queue for
     * @param assetsToOffer the amount of `offer` sent to the solver
     * @param assetsForWant the amount of `want` the solver must approve the queue for
     */
    function finishSolve(
        bytes calldata runData,
        address initiator,
        ERC20 offer,
        ERC20 want,
        uint256 assetsToOffer,
        uint256 assetsForWant
    ) external;
}

// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.21;

library Math {
    /**
     * @notice Substract with a floor of 0 for the result.
     */
    function subMinZero(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? x - y : 0;
    }

    /**
     * @notice Used to change the decimals of precision used for an amount.
     */
    function changeDecimals(uint256 amount, uint8 fromDecimals, uint8 toDecimals) internal pure returns (uint256) {
        if (fromDecimals == toDecimals) {
            return amount;
        } else if (fromDecimals < toDecimals) {
            return amount * 10 ** (toDecimals - fromDecimals);
        } else {
            return amount / 10 ** (fromDecimals - toDecimals);
        }
    }

    // ===================================== OPENZEPPELIN'S MATH =====================================

    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    // ================================= SOLMATE's FIXEDPOINTMATHLIB =================================

    uint256 public constant WAD = 1e18; // The scalar of ETH and most ERC20s.

    function mulWadDown(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivDown(x, y, WAD); // Equivalent to (x * y) / WAD rounded down.
    }

    function mulDivDown(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 z) {
        assembly {
            // Store x * y in z for now.
            z := mul(x, y)

            // Equivalent to require(denominator != 0 && (x == 0 || (x * y) / x == y))
            if iszero(and(iszero(iszero(denominator)), or(iszero(x), eq(div(z, x), y)))) {
                revert(0, 0)
            }

            // Divide z by the denominator.
            z := div(z, denominator)
        }
    }

    function mulDivUp(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 z) {
        assembly {
            // Store x * y in z for now.
            z := mul(x, y)

            // Equivalent to require(denominator != 0 && (x == 0 || (x * y) / x == y))
            if iszero(and(iszero(iszero(denominator)), or(iszero(x), eq(div(z, x), y)))) {
                revert(0, 0)
            }

            // First, divide z - 1 by the denominator and add 1.
            // We allow z - 1 to underflow if z is 0, because we multiply the
            // end result by 0 if z is zero, ensuring we return 0 if z is zero.
            z := mul(iszero(iszero(z)), add(div(sub(z, 1), denominator), 1))
        }
    }
}

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Gas optimized reentrancy protection for smart contracts.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/ReentrancyGuard.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/security/ReentrancyGuard.sol)
abstract contract ReentrancyGuard {
    uint256 private locked = 1;

    modifier nonReentrant() virtual {
        require(locked == 1, "REENTRANCY");

        locked = 2;

        _;

        locked = 1;
    }
}

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

import {ERC20} from "../tokens/ERC20.sol";

/// @notice Safe ETH and ERC20 transfer library that gracefully handles missing return values.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/SafeTransferLib.sol)
/// @dev Use with caution! Some functions in this library knowingly create dirty bits at the destination of the free memory pointer.
/// @dev Note that none of the functions in this library check that a token has code at all! That responsibility is delegated to the caller.
library SafeTransferLib {
    /*//////////////////////////////////////////////////////////////
                             ETH OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferETH(address to, uint256 amount) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Transfer the ETH and store if it succeeded or not.
            success := call(gas(), to, amount, 0, 0, 0, 0)
        }

        require(success, "ETH_TRANSFER_FAILED");
    }

    /*//////////////////////////////////////////////////////////////
                            ERC20 OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferFrom(
        ERC20 token,
        address from,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), from) // Append the "from" argument.
            mstore(add(freeMemoryPointer, 36), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 100 because the length of our calldata totals up like so: 4 + 32 * 3.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 100, 0, 32)
            )
        }

        require(success, "TRANSFER_FROM_FAILED");
    }

    function safeTransfer(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "TRANSFER_FAILED");
    }

    function safeApprove(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x095ea7b300000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "APPROVE_FAILED");
    }
}

{
  "compilationTarget": {
    "src/modules/atomic-queue/AtomicQueue.sol": "AtomicQueue"
  },
  "evmVersion": "shanghai",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": [
    ":@balancer-labs/=lib/balancer-v2-monorepo/../../node_modules/@balancer-labs/",
    ":@balancer/=lib/balancer-v2-monorepo/pkg/",
    ":@ccip/=lib/ccip/",
    ":@chainlink/=lib/chainlink/",
    ":@ds-test/=lib/forge-std/lib/ds-test/src/",
    ":@forge-std/=lib/forge-std/src/",
    ":@openzeppelin/=lib/openzeppelin-contracts/",
    ":@pendle/=lib/pendle-core-v2-public/",
    ":@solmate/=lib/solmate/src/",
    ":@uniswap/v3-core/=lib/v3-core/",
    ":@uniswap/v3-periphery/=lib/v3-periphery/",
    ":@uniswapV3C/=lib/v3-core/contracts/",
    ":@uniswapV3P/=lib/v3-periphery/contracts/",
    ":axelar-gmp-sdk-solidity/=lib/axelar-gmp-sdk-solidity/contracts/",
    ":balancer-v2-monorepo/=lib/balancer-v2-monorepo/",
    ":ccip/=lib/ccip/contracts/",
    ":chainlink/=lib/chainlink/integration-tests/contracts/ethereum/src/",
    ":ds-test/=lib/forge-std/lib/ds-test/src/",
    ":forge-std/=lib/forge-std/src/",
    ":openzeppelin-contracts/=lib/openzeppelin-contracts/",
    ":pendle-core-v2-public/=lib/pendle-core-v2-public/contracts/",
    ":solmate/=lib/solmate/src/",
    ":v3-core/=lib/v3-core/contracts/",
    ":v3-periphery/=lib/v3-periphery/contracts/"
  ]
}