Contract Source Code:

// SPDX-License-Identifier: MIT
pragma experimental ABIEncoderV2;
pragma solidity ^0.8.13;

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

import "openzeppelin-contracts/access/Ownable.sol";
import {FullMath} from "./external/FullMath.sol";
import {Multicall} from "./external/Multicall.sol";
import {SelfPermit} from "./external/SelfPermit.sol";

/// @title ERC20StakingPool
/// @author zefram.eth
/// @notice A modern, gas optimized staking pool contract for rewarding ERC20 stakers
/// with ERC20 tokens periodically and continuously
contract ERC20StakingPool is Ownable, Multicall, SelfPermit {
    /// -----------------------------------------------------------------------
    /// Library usage
    /// -----------------------------------------------------------------------

    using SafeTransferLib for ERC20;

    /// -----------------------------------------------------------------------
    /// Errors
    /// -----------------------------------------------------------------------

    error Error_ZeroOwner();
    error Error_AlreadyInitialized();
    error Error_NotRewardDistributor();
    error Error_AmountTooLarge();

    /// -----------------------------------------------------------------------
    /// Events
    /// -----------------------------------------------------------------------

    event RewardAdded(uint256 reward);
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);

    /// -----------------------------------------------------------------------
    /// Constants
    /// -----------------------------------------------------------------------

    uint256 internal constant PRECISION = 1e30;

    /// -----------------------------------------------------------------------
    /// Storage variables
    /// -----------------------------------------------------------------------

    /// @notice The last Unix timestamp (in seconds) when rewardPerTokenStored was updated
    uint64 public lastUpdateTime;
    /// @notice The Unix timestamp (in seconds) at which the current reward period ends
    uint64 public periodFinish;

    /// @notice The per-second rate at which rewardPerToken increases
    uint256 public rewardRate;
    /// @notice The last stored rewardPerToken value
    uint256 public rewardPerTokenStored;
    /// @notice The total tokens staked in the pool
    uint256 public totalSupply;

    /// @notice Tracks if an address can call notifyReward()
    mapping(address => bool) public isRewardDistributor;

    /// @notice The time this account started staking
    mapping(address => uint256) public startedStaking;
    /// @notice The amount of tokens staked by an account
    mapping(address => uint256) public balanceOf;
    /// @notice The rewardPerToken value when an account last staked/withdrew/withdrew rewards
    mapping(address => uint256) public userRewardPerTokenPaid;
    /// @notice The earned() value when an account last staked/withdrew/withdrew rewards
    mapping(address => uint256) public rewards;

    /// -----------------------------------------------------------------------
    /// Immutable parameters
    /// -----------------------------------------------------------------------

    /// @notice The token being rewarded to stakers
    ERC20 public immutable rewardToken;

    /// @notice The token being staked in the pool
    ERC20 public immutable stakeToken;

    /// @notice The length of each reward period, in seconds
    uint64 public immutable duration;

    /// -----------------------------------------------------------------------
    /// Initialization
    /// -----------------------------------------------------------------------

    /// @notice Initializes the contract
    /// @param _rewardToken The token to be rewarded to stakers
    /// @param _stakeToken The token to be staked by stakers
    /// @param _duration The duration of the staking
    constructor(
        ERC20 _rewardToken,
        ERC20 _stakeToken,
        uint64 _duration
    ) {
        rewardToken = _rewardToken;
        stakeToken = _stakeToken;
        duration = _duration;
        _transferOwnership(msg.sender);
    }

    /// -----------------------------------------------------------------------
    /// User actions
    /// -----------------------------------------------------------------------

    /// @notice Stakes tokens in the pool to earn rewards
    /// @param amount The amount of tokens to stake
    function stake(uint256 amount) external {
        /// -----------------------------------------------------------------------
        /// Validation
        /// -----------------------------------------------------------------------

        if (amount == 0) {
            return;
        }

        /// -----------------------------------------------------------------------
        /// Storage loads
        /// -----------------------------------------------------------------------

        uint256 accountBalance = balanceOf[msg.sender];
        uint64 lastTimeRewardApplicable_ = lastTimeRewardApplicable();
        uint256 totalSupply_ = totalSupply;
        uint256 rewardPerToken_ = _rewardPerToken(totalSupply_, lastTimeRewardApplicable_, rewardRate);

        /// -----------------------------------------------------------------------
        /// State updates
        /// -----------------------------------------------------------------------

        // accrue rewards
        rewardPerTokenStored = rewardPerToken_;
        lastUpdateTime = lastTimeRewardApplicable_;
        rewards[msg.sender] = _earned(msg.sender, accountBalance, rewardPerToken_, rewards[msg.sender]);
        userRewardPerTokenPaid[msg.sender] = rewardPerToken_;

        // stake
        totalSupply = totalSupply_ + amount;
        balanceOf[msg.sender] = accountBalance + amount;
        startedStaking[msg.sender] = block.timestamp;

        /// -----------------------------------------------------------------------
        /// Effects
        /// -----------------------------------------------------------------------

        stakeToken.safeTransferFrom(msg.sender, address(this), amount);

        emit Staked(msg.sender, amount);
    }

    /// @notice Withdraws staked tokens from the pool
    /// @param amount The amount of tokens to withdraw
    function withdraw(uint256 amount) external {
        /// -----------------------------------------------------------------------
        /// Validation
        /// -----------------------------------------------------------------------

        if (amount == 0) {
            return;
        }

        /// -----------------------------------------------------------------------
        /// Storage loads
        /// -----------------------------------------------------------------------

        uint256 accountBalance = balanceOf[msg.sender];
        uint64 lastTimeRewardApplicable_ = lastTimeRewardApplicable();
        uint256 totalSupply_ = totalSupply;
        uint256 rewardPerToken_ = _rewardPerToken(totalSupply_, lastTimeRewardApplicable_, rewardRate);

        /// -----------------------------------------------------------------------
        /// State updates
        /// -----------------------------------------------------------------------

        // accrue rewards
        rewardPerTokenStored = rewardPerToken_;
        lastUpdateTime = lastTimeRewardApplicable_;
        rewards[msg.sender] = _earned(msg.sender, accountBalance, rewardPerToken_, rewards[msg.sender]);
        userRewardPerTokenPaid[msg.sender] = rewardPerToken_;

        // withdraw stake
        balanceOf[msg.sender] = accountBalance - amount;
        // total supply has 1:1 relationship with staked amounts
        // so can't ever underflow
        unchecked {
            totalSupply = totalSupply_ - amount;
        }

        /// -----------------------------------------------------------------------
        /// Effects
        /// -----------------------------------------------------------------------

        stakeToken.safeTransfer(msg.sender, amount);

        emit Withdrawn(msg.sender, amount);
    }

    /// @notice Withdraws all staked tokens and earned rewards
    function exit() external {
        /// -----------------------------------------------------------------------
        /// Validation
        /// -----------------------------------------------------------------------

        uint256 accountBalance = balanceOf[msg.sender];

        /// -----------------------------------------------------------------------
        /// Storage loads
        /// -----------------------------------------------------------------------

        uint64 lastTimeRewardApplicable_ = lastTimeRewardApplicable();
        uint256 totalSupply_ = totalSupply;
        uint256 rewardPerToken_ = _rewardPerToken(totalSupply_, lastTimeRewardApplicable_, rewardRate);

        /// -----------------------------------------------------------------------
        /// State updates
        /// -----------------------------------------------------------------------

        // give rewards
        uint256 reward = _earned(msg.sender, accountBalance, rewardPerToken_, rewards[msg.sender]);
        if (reward > 0) {
            rewards[msg.sender] = 0;
        }

        // accrue rewards
        rewardPerTokenStored = rewardPerToken_;
        lastUpdateTime = lastTimeRewardApplicable_;
        userRewardPerTokenPaid[msg.sender] = rewardPerToken_;

        // withdraw stake
        balanceOf[msg.sender] = 0;
        // total supply has 1:1 relationship with staked amounts
        // so can't ever underflow
        unchecked {
            totalSupply = totalSupply_ - accountBalance;
        }

        /// -----------------------------------------------------------------------
        /// Effects
        /// -----------------------------------------------------------------------

        // transfer stake
        stakeToken.safeTransfer(msg.sender, accountBalance);
        emit Withdrawn(msg.sender, accountBalance);

        // transfer rewards
        if (reward > 0) {
            rewardToken.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    /// @notice Withdraws all earned rewards
    function getReward() external {
        /// -----------------------------------------------------------------------
        /// Storage loads
        /// -----------------------------------------------------------------------

        uint256 accountBalance = balanceOf[msg.sender];
        uint64 lastTimeRewardApplicable_ = lastTimeRewardApplicable();
        uint256 totalSupply_ = totalSupply;
        uint256 rewardPerToken_ = _rewardPerToken(totalSupply_, lastTimeRewardApplicable_, rewardRate);

        /// -----------------------------------------------------------------------
        /// State updates
        /// -----------------------------------------------------------------------

        uint256 reward = _earned(msg.sender, accountBalance, rewardPerToken_, rewards[msg.sender]);

        // accrue rewards
        rewardPerTokenStored = rewardPerToken_;
        lastUpdateTime = lastTimeRewardApplicable_;
        userRewardPerTokenPaid[msg.sender] = rewardPerToken_;

        // withdraw rewards
        if (reward > 0) {
            rewards[msg.sender] = 0;

            /// -----------------------------------------------------------------------
            /// Effects
            /// -----------------------------------------------------------------------

            rewardToken.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    /// -----------------------------------------------------------------------
    /// Getters
    /// -----------------------------------------------------------------------

    /// @notice The latest time at which stakers are earning rewards.
    function lastTimeRewardApplicable() public view returns (uint64) {
        return block.timestamp < periodFinish ? uint64(block.timestamp) : periodFinish;
    }

    /// @notice The amount of reward tokens each staked token has earned so far
    function rewardPerToken() external view returns (uint256) {
        return _rewardPerToken(totalSupply, lastTimeRewardApplicable(), rewardRate);
    }

    /// @notice The amount of reward tokens an account has accrued so far. Does not
    /// include already withdrawn rewards.
    function earned(address account) external view returns (uint256) {
        return
            _earned(
                account,
                balanceOf[account],
                _rewardPerToken(totalSupply, lastTimeRewardApplicable(), rewardRate),
                rewards[account]
            );
    }

    /// -----------------------------------------------------------------------
    /// Owner actions
    /// -----------------------------------------------------------------------

    /// @notice Lets a reward distributor start a new reward period. The reward tokens must have already
    /// been transferred to this contract before calling this function. If it is called
    /// when a reward period is still active, a new reward period will begin from the time
    /// of calling this function, using the leftover rewards from the old reward period plus
    /// the newly sent rewards as the reward.
    /// @dev If the reward amount will cause an overflow when computing rewardPerToken, then
    /// this function will revert.
    /// @param reward The amount of reward tokens to use in the new reward period.
    function notifyRewardAmount(uint256 reward) external {
        /// -----------------------------------------------------------------------
        /// Validation
        /// -----------------------------------------------------------------------

        if (reward == 0) {
            return;
        }
        if (!isRewardDistributor[msg.sender]) {
            revert Error_NotRewardDistributor();
        }

        /// -----------------------------------------------------------------------
        /// Storage loads
        /// -----------------------------------------------------------------------

        uint256 rewardRate_ = rewardRate;
        uint64 periodFinish_ = periodFinish;
        uint64 lastTimeRewardApplicable_ = block.timestamp < periodFinish_ ? uint64(block.timestamp) : periodFinish_;
        uint64 DURATION_ = duration;
        uint256 totalSupply_ = totalSupply;

        /// -----------------------------------------------------------------------
        /// State updates
        /// -----------------------------------------------------------------------

        // accrue rewards
        rewardPerTokenStored = _rewardPerToken(totalSupply_, lastTimeRewardApplicable_, rewardRate_);
        lastUpdateTime = lastTimeRewardApplicable_;

        // record new reward
        uint256 newRewardRate;
        if (block.timestamp >= periodFinish_) {
            newRewardRate = reward / DURATION_;
        } else {
            uint256 remaining = periodFinish_ - block.timestamp;
            uint256 leftover = remaining * rewardRate_;
            newRewardRate = (reward + leftover) / DURATION_;
        }
        // prevent overflow when computing rewardPerToken
        if (newRewardRate >= ((type(uint256).max / PRECISION) / DURATION_)) {
            revert Error_AmountTooLarge();
        }
        rewardRate = newRewardRate;
        lastUpdateTime = uint64(block.timestamp);
        periodFinish = uint64(block.timestamp + DURATION_);

        emit RewardAdded(reward);
    }

    /// @notice Lets the owner add/remove accounts from the list of reward distributors.
    /// Reward distributors can call notifyRewardAmount()
    /// @param rewardDistributor The account to add/remove
    /// @param isRewardDistributor_ True to add the account, false to remove the account
    function setRewardDistributor(address rewardDistributor, bool isRewardDistributor_) external onlyOwner {
        isRewardDistributor[rewardDistributor] = isRewardDistributor_;
    }

    /// -----------------------------------------------------------------------
    /// Internal functions
    /// -----------------------------------------------------------------------

    function _earned(
        address account,
        uint256 accountBalance,
        uint256 rewardPerToken_,
        uint256 accountRewards
    ) internal view returns (uint256) {
        return
            FullMath.mulDiv(accountBalance, rewardPerToken_ - userRewardPerTokenPaid[account], PRECISION) +
            accountRewards;
    }

    function _rewardPerToken(
        uint256 totalSupply_,
        uint256 lastTimeRewardApplicable_,
        uint256 rewardRate_
    ) internal view returns (uint256) {
        if (totalSupply_ == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored +
            FullMath.mulDiv((lastTimeRewardApplicable_ - lastUpdateTime) * PRECISION, rewardRate_, totalSupply_);
    }

    function withdrawETH(address _recipient) external onlyOwner {
        (bool success, ) = _recipient.call{value: address(this).balance}("");
        require(success, "Could not send ETH");
    }

    function withdrawToken(ERC20 _token, address _recipient) external onlyOwner {
        _token.transfer(_recipient, _token.balanceOf(address(this)));
    }
}

// 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: 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;

        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;

        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;

        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;

        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");
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

/// @title Contains 512-bit math functions
/// @notice Facilitates multiplication and division that can have overflow of an intermediate value without any loss of precision
/// @dev Handles "phantom overflow" i.e., allows multiplication and division where an intermediate value overflows 256 bits
library FullMath {
    /// @notice Calculates floor(a×b÷denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
    /// @param a The multiplicand
    /// @param b The multiplier
    /// @param denominator The divisor
    /// @return result The 256-bit result
    /// @dev Credit to Remco Bloemen under MIT license https://xn--2-umb.com/21/muldiv
    function mulDiv(
        uint256 a,
        uint256 b,
        uint256 denominator
    ) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = a * b
            // Compute the product mod 2**256 and mod 2**256 - 1
            // then use the Chinese Remainder Theorem to reconstruct
            // the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2**256 + prod0
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(a, b, not(0))
                prod0 := mul(a, b)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division
            if (prod1 == 0) {
                require(denominator > 0);
                assembly {
                    result := div(prod0, denominator)
                }
                return result;
            }

            // Make sure the result is less than 2**256.
            // Also prevents denominator == 0
            require(denominator > prod1);

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0]
            // Compute remainder using mulmod
            uint256 remainder;
            assembly {
                remainder := mulmod(a, b, denominator)
            }
            // Subtract 256 bit number from 512 bit number
            assembly {
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator
            // Compute largest power of two divisor of denominator.
            // Always >= 1.
            uint256 twos = (type(uint256).max - denominator + 1) & denominator;
            // Divide denominator by power of two
            assembly {
                denominator := div(denominator, twos)
            }

            // Divide [prod1 prod0] by the factors of two
            assembly {
                prod0 := div(prod0, twos)
            }
            // Shift in bits from prod1 into prod0. For this we need
            // to flip `twos` such that it is 2**256 / twos.
            // If twos is zero, then it becomes one
            assembly {
                twos := add(div(sub(0, twos), twos), 1)
            }
            prod0 |= prod1 * twos;

            // Invert denominator mod 2**256
            // Now that denominator is an odd number, it has an inverse
            // modulo 2**256 such that denominator * inv = 1 mod 2**256.
            // Compute the inverse by starting with a seed that is correct
            // correct for four bits. That is, denominator * inv = 1 mod 2**4
            uint256 inv = (3 * denominator) ^ 2;
            // Now use Newton-Raphson iteration to improve the precision.
            // Thanks to Hensel's lifting lemma, this also works in modular
            // arithmetic, doubling the correct bits in each step.
            inv *= 2 - denominator * inv; // inverse mod 2**8
            inv *= 2 - denominator * inv; // inverse mod 2**16
            inv *= 2 - denominator * inv; // inverse mod 2**32
            inv *= 2 - denominator * inv; // inverse mod 2**64
            inv *= 2 - denominator * inv; // inverse mod 2**128
            inv *= 2 - denominator * inv; // inverse mod 2**256

            // Because the division is now exact we can divide by multiplying
            // with the modular inverse of denominator. This will give us the
            // correct result modulo 2**256. Since the precoditions guarantee
            // that the outcome is less than 2**256, this is the final result.
            // We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inv;
            return result;
        }
    }

    /// @notice Calculates ceil(a×b÷denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
    /// @param a The multiplicand
    /// @param b The multiplier
    /// @param denominator The divisor
    /// @return result The 256-bit result
    function mulDivRoundingUp(
        uint256 a,
        uint256 b,
        uint256 denominator
    ) internal pure returns (uint256 result) {
        result = mulDiv(a, b, denominator);
        unchecked {
            if (mulmod(a, b, denominator) > 0) {
                require(result < type(uint256).max);
                result++;
            }
        }
    }
}

// SPDX-License-Identifier: AGPL-3.0
pragma solidity ^0.8.4;

/// @title Multicall
/// @notice Enables calling multiple methods in a single call to the contract
abstract contract Multicall {
    function multicall(bytes[] calldata data) external payable returns (bytes[] memory results) {
        results = new bytes[](data.length);
        for (uint256 i = 0; i < data.length; i++) {
            (bool success, bytes memory result) = address(this).delegatecall(data[i]);

            if (!success) {
                // Next 5 lines from https://ethereum.stackexchange.com/a/83577
                if (result.length < 68) revert();
                assembly {
                    result := add(result, 0x04)
                }
                revert(abi.decode(result, (string)));
            }

            results[i] = result;
        }
    }
}

// SPDX-License-Identifier: AGPL-3.0
pragma solidity >=0.5.0;

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

/// @title Self Permit
/// @notice Functionality to call permit on any EIP-2612-compliant token for use in the route
/// @dev These functions are expected to be embedded in multicalls to allow EOAs to approve a contract and call a function
/// that requires an approval in a single transaction.
abstract contract SelfPermit {
    function selfPermit(
        ERC20 token,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public payable {
        token.permit(msg.sender, address(this), value, deadline, v, r, s);
    }

    function selfPermitIfNecessary(
        ERC20 token,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external payable {
        if (token.allowance(msg.sender, address(this)) < value) selfPermit(token, value, deadline, v, r, s);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}