// SPDX-License-Identifier: Apache-2.0
pragma solidity =0.8.25 >=0.8.0;

// lib/solmate/src/tokens/ERC20.sol

/// @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);
    }
}

// lib/solmate/src/utils/FixedPointMathLib.sol

/// @notice Arithmetic library with operations for fixed-point numbers.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/FixedPointMathLib.sol)
/// @author Inspired by USM (https://github.com/usmfum/USM/blob/master/contracts/WadMath.sol)
library FixedPointMathLib {
    /*//////////////////////////////////////////////////////////////
                    SIMPLIFIED FIXED POINT OPERATIONS
    //////////////////////////////////////////////////////////////*/

    uint256 internal constant MAX_UINT256 = 2**256 - 1;

    uint256 internal 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 mulWadUp(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivUp(x, y, WAD); // Equivalent to (x * y) / WAD rounded up.
    }

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

    function divWadUp(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivUp(x, WAD, y); // Equivalent to (x * WAD) / y rounded up.
    }

    /*//////////////////////////////////////////////////////////////
                    LOW LEVEL FIXED POINT OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function mulDivDown(
        uint256 x,
        uint256 y,
        uint256 denominator
    ) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            // Equivalent to require(denominator != 0 && (y == 0 || x <= type(uint256).max / y))
            if iszero(mul(denominator, iszero(mul(y, gt(x, div(MAX_UINT256, y)))))) {
                revert(0, 0)
            }

            // Divide x * y by the denominator.
            z := div(mul(x, y), denominator)
        }
    }

    function mulDivUp(
        uint256 x,
        uint256 y,
        uint256 denominator
    ) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            // Equivalent to require(denominator != 0 && (y == 0 || x <= type(uint256).max / y))
            if iszero(mul(denominator, iszero(mul(y, gt(x, div(MAX_UINT256, y)))))) {
                revert(0, 0)
            }

            // If x * y modulo the denominator is strictly greater than 0,
            // 1 is added to round up the division of x * y by the denominator.
            z := add(gt(mod(mul(x, y), denominator), 0), div(mul(x, y), denominator))
        }
    }

    function rpow(
        uint256 x,
        uint256 n,
        uint256 scalar
    ) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            switch x
            case 0 {
                switch n
                case 0 {
                    // 0 ** 0 = 1
                    z := scalar
                }
                default {
                    // 0 ** n = 0
                    z := 0
                }
            }
            default {
                switch mod(n, 2)
                case 0 {
                    // If n is even, store scalar in z for now.
                    z := scalar
                }
                default {
                    // If n is odd, store x in z for now.
                    z := x
                }

                // Shifting right by 1 is like dividing by 2.
                let half := shr(1, scalar)

                for {
                    // Shift n right by 1 before looping to halve it.
                    n := shr(1, n)
                } n {
                    // Shift n right by 1 each iteration to halve it.
                    n := shr(1, n)
                } {
                    // Revert immediately if x ** 2 would overflow.
                    // Equivalent to iszero(eq(div(xx, x), x)) here.
                    if shr(128, x) {
                        revert(0, 0)
                    }

                    // Store x squared.
                    let xx := mul(x, x)

                    // Round to the nearest number.
                    let xxRound := add(xx, half)

                    // Revert if xx + half overflowed.
                    if lt(xxRound, xx) {
                        revert(0, 0)
                    }

                    // Set x to scaled xxRound.
                    x := div(xxRound, scalar)

                    // If n is even:
                    if mod(n, 2) {
                        // Compute z * x.
                        let zx := mul(z, x)

                        // If z * x overflowed:
                        if iszero(eq(div(zx, x), z)) {
                            // Revert if x is non-zero.
                            if iszero(iszero(x)) {
                                revert(0, 0)
                            }
                        }

                        // Round to the nearest number.
                        let zxRound := add(zx, half)

                        // Revert if zx + half overflowed.
                        if lt(zxRound, zx) {
                            revert(0, 0)
                        }

                        // Return properly scaled zxRound.
                        z := div(zxRound, scalar)
                    }
                }
            }
        }
    }

    /*//////////////////////////////////////////////////////////////
                        GENERAL NUMBER UTILITIES
    //////////////////////////////////////////////////////////////*/

    function sqrt(uint256 x) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            let y := x // We start y at x, which will help us make our initial estimate.

            z := 181 // The "correct" value is 1, but this saves a multiplication later.

            // This segment is to get a reasonable initial estimate for the Babylonian method. With a bad
            // start, the correct # of bits increases ~linearly each iteration instead of ~quadratically.

            // We check y >= 2^(k + 8) but shift right by k bits
            // each branch to ensure that if x >= 256, then y >= 256.
            if iszero(lt(y, 0x10000000000000000000000000000000000)) {
                y := shr(128, y)
                z := shl(64, z)
            }
            if iszero(lt(y, 0x1000000000000000000)) {
                y := shr(64, y)
                z := shl(32, z)
            }
            if iszero(lt(y, 0x10000000000)) {
                y := shr(32, y)
                z := shl(16, z)
            }
            if iszero(lt(y, 0x1000000)) {
                y := shr(16, y)
                z := shl(8, z)
            }

            // Goal was to get z*z*y within a small factor of x. More iterations could
            // get y in a tighter range. Currently, we will have y in [256, 256*2^16).
            // We ensured y >= 256 so that the relative difference between y and y+1 is small.
            // That's not possible if x < 256 but we can just verify those cases exhaustively.

            // Now, z*z*y <= x < z*z*(y+1), and y <= 2^(16+8), and either y >= 256, or x < 256.
            // Correctness can be checked exhaustively for x < 256, so we assume y >= 256.
            // Then z*sqrt(y) is within sqrt(257)/sqrt(256) of sqrt(x), or about 20bps.

            // For s in the range [1/256, 256], the estimate f(s) = (181/1024) * (s+1) is in the range
            // (1/2.84 * sqrt(s), 2.84 * sqrt(s)), with largest error when s = 1 and when s = 256 or 1/256.

            // Since y is in [256, 256*2^16), let a = y/65536, so that a is in [1/256, 256). Then we can estimate
            // sqrt(y) using sqrt(65536) * 181/1024 * (a + 1) = 181/4 * (y + 65536)/65536 = 181 * (y + 65536)/2^18.

            // There is no overflow risk here since y < 2^136 after the first branch above.
            z := shr(18, mul(z, add(y, 65536))) // A mul() is saved from starting z at 181.

            // Given the worst case multiplicative error of 2.84 above, 7 iterations should be enough.
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))

            // If x+1 is a perfect square, the Babylonian method cycles between
            // floor(sqrt(x)) and ceil(sqrt(x)). This statement ensures we return floor.
            // See: https://en.wikipedia.org/wiki/Integer_square_root#Using_only_integer_division
            // Since the ceil is rare, we save gas on the assignment and repeat division in the rare case.
            // If you don't care whether the floor or ceil square root is returned, you can remove this statement.
            z := sub(z, lt(div(x, z), z))
        }
    }

    function unsafeMod(uint256 x, uint256 y) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            // Mod x by y. Note this will return
            // 0 instead of reverting if y is zero.
            z := mod(x, y)
        }
    }

    function unsafeDiv(uint256 x, uint256 y) internal pure returns (uint256 r) {
        /// @solidity memory-safe-assembly
        assembly {
            // Divide x by y. Note this will return
            // 0 instead of reverting if y is zero.
            r := div(x, y)
        }
    }

    function unsafeDivUp(uint256 x, uint256 y) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            // Add 1 to x * y if x % y > 0. Note this will
            // return 0 instead of reverting if y is zero.
            z := add(gt(mod(x, y), 0), div(x, y))
        }
    }
}

// lib/solmate/src/utils/ReentrancyGuard.sol

/// @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;
    }
}

// lib/solmate/src/utils/SafeTransferLib.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), and(from, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "from" argument.
            mstore(add(freeMemoryPointer, 36), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.
            mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.

            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), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.

            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), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.

            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");
    }
}

// src/atomic-queue/IAtomicSolver.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;
}

// src/atomic-queue/AtomicQueue.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
 * @custom:security-contact security@molecularlabs.io
 */
contract AtomicQueue is ReentrancyGuard {
    using SafeTransferLib for ERC20;
    using FixedPointMathLib 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);
    }
}

{
  "compilationTarget": {
    "AtomicQueue.sol": "AtomicQueue"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}