// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity 0.8.15;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
       *
       * [IMPORTANT]
       * ====
       * It is unsafe to assume that an address for which this function returns
       * false is an externally-owned account (EOA) and not a contract.
       *
       * Among others, `isContract` will return false for the following
       * types of addresses:
       *
       *  - an externally-owned account
       *  - a contract in construction
       *  - an address where a contract will be created
       *  - an address where a contract lived, but was destroyed
       * ====
       *
       * [IMPORTANT]
       * ====
       * You shouldn't rely on `isContract` to protect against flash loan attacks!
       *
       * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
       * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
       * constructor.
       * ====
       */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");
        (bool success, bytes memory returndata) = target.call(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
       * revert reason using the provided one.
       *
       * _Available since v4.3._
       */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

interface ICallee {
    function hook(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

import "./IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

import "./IERC721.sol";

/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Metadata is IERC721 {
    /**
    * @dev Returns the token collection name.
    */
    function name() external view returns (string memory);

    /**
    * @dev Returns the token collection symbol.
    */
    function symbol() external view returns (string memory);

    /**
    * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
    */
    function tokenURI(uint tokenId) external view returns (string memory);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

interface IFactory {
    function treasury() external view returns (address);

    function isPair(address pair) external view returns (bool);

    function getInitializable() external view returns (address, address, bool);

    function isPaused() external view returns (bool);

    function pairCodeHash() external pure returns (bytes32);

    function getPair(address tokenA, address token, bool stable) external view returns (address);

    function createPair(address tokenA, address tokenB, bool stable) external returns (address pair);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

interface IPair {

    // Structure to capture time period obervations every 30 minutes, used for local oracles
    struct Observation {
        uint timestamp;
        uint reserve0Cumulative;
        uint reserve1Cumulative;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;

    function burn(address to) external returns (uint amount0, uint amount1);

    function mint(address to) external returns (uint liquidity);

    function getReserves() external view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast);

    function getAmountOut(uint, address) external view returns (uint);

    function claimFees() external returns (uint, uint);

    function tokens() external view returns (address, address);

    function token0() external view returns (address);

    function token1() external view returns (address);

    function stable() external view returns (bool);

    function metadata() external view returns (
        uint dec0,
        uint dec1,
        uint r0,
        uint r1,
        bool st,
        address t0,
        address t1
    );
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

interface IUnderlying {
    function approve(address spender, uint value) external returns (bool);

    function mint(address, uint) external;

    function totalSupply() external view returns (uint);

    function balanceOf(address) external view returns (uint);

    function transfer(address, uint) external returns (bool);

    function decimals() external returns (uint8);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

library Math {

    function max(uint a, uint b) internal pure returns (uint) {
        return a >= b ? a : b;
    }

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

    function positiveInt128(int128 value) internal pure returns (int128) {
        return value < 0 ? int128(0) : value;
    }

    function closeTo(uint a, uint b, uint target) internal pure returns (bool) {
        if (a > b) {
            if (a - b <= target) {
                return true;
            }
        } else {
            if (b - a <= target) {
                return true;
            }
        }
        return false;
    }

    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }

}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

import "../../interface/IERC20.sol";
import "../../lib/SafeERC20.sol";

/// @title Base V1 Fees contract is used as a 1:1 pair relationship to split out fees,
///        this ensures that the curve does not need to be modified for LP shares
contract PairFees {
    using SafeERC20 for IERC20;

    /// @dev The pair it is bonded to
    address internal immutable pair;
    /// @dev Token0 of pair, saved localy and statically for gas optimization
    address internal immutable token0;
    /// @dev Token1 of pair, saved localy and statically for gas optimization
    address internal immutable token1;

    constructor(address _token0, address _token1) {
        pair = msg.sender;
        token0 = _token0;
        token1 = _token1;
    }

    // Allow the pair to transfer fees to users
    function claimFeesFor(
        address recipient,
        uint256 amount0,
        uint256 amount1
    ) external {
        require(msg.sender == pair, "Not pair");
        if (amount0 > 0) {
            _safeTransfer(token0, recipient, amount0);
        }
        if (amount1 > 0) {
            _safeTransfer(token1, recipient, amount1);
        }
    }

    function _safeTransfer(address token, address to, uint256 value) internal {
        require(token.code.length > 0);
        (bool success, bytes memory data) = token.call(
            abi.encodeWithSelector(IERC20.transfer.selector, to, value)
        );
        require(success && (data.length == 0 || abi.decode(data, (bool))));
    }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

abstract contract Reentrancy {

    /// @dev simple re-entrancy check
    uint internal _unlocked = 1;

    modifier lock() {
        require(_unlocked == 1, "Reentrant call");
        _unlocked = 2;
        _;
        _unlocked = 1;
    }

}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity 0.8.15;

import "../interface/IERC20.sol";
import "./Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint value
    ) internal {
        uint newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
       * on the return value: the return value is optional (but if data is returned, it must not be false).
       * @param token The token targeted by the call.
       * @param data The call data (encoded using abi.encode or one of its variants).
       */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }

}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.15;

import "../../interface/IERC20.sol";
import "../../interface/IERC721Metadata.sol";
import "../../interface/IPair.sol";
import "../../interface/IFactory.sol";
import "../../interface/ICallee.sol";
import "../../interface/IUnderlying.sol";
import "./PairFees.sol";
import "../../lib/Math.sol";
import "../../lib/SafeERC20.sol";
import "../Reentrancy.sol";

// The base pair of pools, either stable or volatile
contract SoluneaPair is IERC20, IPair, Reentrancy {
    using SafeERC20 for IERC20;

    string public name;
    string public symbol;
    uint8 public constant decimals = 18;

    /// @dev Used to denote stable or volatile pair
    bool public immutable stable;

    uint256 public override totalSupply = 0;

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

    bytes32 public immutable DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    uint256 internal constant _FEE_PRECISION = 1e32;
    mapping(address => uint256) public nonces;
    uint256 public immutable chainId;

    uint256 internal constant MINIMUM_LIQUIDITY = 10**3;
    /// @dev 0.04% swap fee
    uint256 internal constant SWAP_FEE_STABLE = 2500;
    /// @dev 0.2% swap fee
    uint256 internal constant SWAP_FEE_VOLATILE = 500;
    /// @dev 1% max allowed swap fee
    uint256 internal constant SWAP_FEE_MAX = 100;
    /// @dev 50% of swap fee
    uint256 public treasuryFee;
    /// @dev Capture oracle reading every 30 minutes
    uint256 internal constant PERIOD_SIZE = 1800;

    address public immutable override token0;
    address public immutable override token1;
    address public immutable fees;
    address public immutable factory;
    address public immutable treasury;

    Observation[] public observations;

    uint256 public swapFee;
    uint256 internal immutable decimals0;
    uint256 internal immutable decimals1;

    uint256 public reserve0;
    uint256 public reserve1;
    uint256 public blockTimestampLast;

    uint256 public reserve0CumulativeLast;
    uint256 public reserve1CumulativeLast;

    // index0 and index1 are used to accumulate fees,
    // this is split out from normal trades to keep the swap "clean"
    // this further allows LP holders to easily claim fees for tokens they have/staked
    uint256 public index0 = 0;
    uint256 public index1 = 0;

    // position assigned to each LP to track their current index0 & index1 vs the global position
    mapping(address => uint256) public supplyIndex0;
    mapping(address => uint256) public supplyIndex1;

    // tracks the amount of unclaimed, but claimable tokens off of fees for token0 and token1
    mapping(address => uint256) public claimable0;
    mapping(address => uint256) public claimable1;

    event Treasury(address indexed sender, uint256 amount0, uint256 amount1);
    event Fees(address indexed sender, uint256 amount0, uint256 amount1);
    event Mint(address indexed sender, uint256 amount0, uint256 amount1);
    event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint256 amount0In,
        uint256 amount1In,
        uint256 amount0Out,
        uint256 amount1Out,
        address indexed to
    );
    event Sync(uint256 reserve0, uint256 reserve1);
    event Claim(address indexed sender, address indexed recipient, uint256 amount0, uint256 amount1);
    event FeesChanged(uint256 newValue);

    constructor() {
        factory = msg.sender;
        treasury = IFactory(msg.sender).treasury();
        (address _token0, address _token1, bool _stable) = IFactory(msg.sender).getInitializable();
        (token0, token1, stable) = (_token0, _token1, _stable);
        fees = address(new PairFees(_token0, _token1));

        swapFee = _stable ? SWAP_FEE_STABLE : SWAP_FEE_VOLATILE;
        treasuryFee = 1;

        if (_stable) {
            name = string(
                abi.encodePacked(
                    "Stable - ",
                    IERC721Metadata(_token0).symbol(),
                    "/",
                    IERC721Metadata(_token1).symbol()
                )
            );
            symbol = string(
                abi.encodePacked("s-", IERC721Metadata(_token0).symbol(), "/", IERC721Metadata(_token1).symbol())
            );
        } else {
            name = string(
                abi.encodePacked(
                    "Volatile - ",
                    IERC721Metadata(_token0).symbol(),
                    "/",
                    IERC721Metadata(_token1).symbol()
                )
            );
            symbol = string(
                abi.encodePacked("v-", IERC721Metadata(_token0).symbol(), "/", IERC721Metadata(_token1).symbol())
            );
        }

        decimals0 = 10**IUnderlying(_token0).decimals();
        decimals1 = 10**IUnderlying(_token1).decimals();

        observations.push(Observation(block.timestamp, 0, 0));

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                keccak256(bytes(name)),
                keccak256("1"),
                block.chainid,
                address(this)
            )
        );
        chainId = block.chainid;
    }

    function setSwapFee(uint256 value) external {
        require(msg.sender == factory, "!factory");
        require(value >= SWAP_FEE_MAX, "max");
        swapFee = value;
        emit FeesChanged(value);
    }

    function setTreasuryFee(uint256 value) external {
        require(msg.sender == factory, "!factory");
        require(value >= 1 , "max 0");
        treasuryFee = value;
        emit FeesChanged(value);
    }

    function observationLength() external view returns (uint256) {
        return observations.length;
    }

    function lastObservation() public view returns (Observation memory) {
        return observations[observations.length - 1];
    }

    function metadata()
        external
        view
        returns (
            uint256 dec0,
            uint256 dec1,
            uint256 r0,
            uint256 r1,
            bool st,
            address t0,
            address t1
        )
    {
        return (decimals0, decimals1, reserve0, reserve1, stable, token0, token1);
    }

    function tokens() external view override returns (address, address) {
        return (token0, token1);
    }

    /// @dev Claim accumulated but unclaimed fees (viewable via claimable0 and claimable1)
    function claimFees() external override returns (uint256 claimed0, uint256 claimed1) {
        _updateFor(msg.sender);

        claimed0 = claimable0[msg.sender];
        claimed1 = claimable1[msg.sender];

        if (claimed0 > 0 || claimed1 > 0) {
            claimable0[msg.sender] = 0;
            claimable1[msg.sender] = 0;

            PairFees(fees).claimFeesFor(msg.sender, claimed0, claimed1);

            emit Claim(msg.sender, msg.sender, claimed0, claimed1);
        }
    }

    /// @dev Accrue fees on token0
    function _update0(uint256 amount) internal {
        uint256 toTreasury = amount / treasuryFee;
        uint256 toFees = amount - toTreasury;

        // transfer the fees out to PairFees and Treasury
        if (toTreasury > 0) {
            _safeTransfer(token0,treasury,toTreasury);
        }
        
        if (toFees > 0) {
            _safeTransfer(token0,fees,toFees);
        }
        // 1e32 adjustment is removed during claim
        uint256 _ratio = (toFees * _FEE_PRECISION) / totalSupply;
        if (_ratio > 0) {
            index0 += _ratio;
        }
        // keep the same structure of events for compatability
        // emit Treasury(msg.sender, toTreasury, 0);
        emit Fees(msg.sender, toFees, 0);
    }

    /// @dev Accrue fees on token1
    function _update1(uint256 amount) internal {
        uint256 toTreasury = amount / treasuryFee;
        uint256 toFees = amount - toTreasury;

        if (toTreasury > 0) {
            _safeTransfer(token1,treasury,toTreasury);
        }

        if (toFees > 0) {
            _safeTransfer(token1,fees,toFees);
        }
        uint256 _ratio = (toFees * _FEE_PRECISION) / totalSupply;
        if (_ratio > 0) {
            index1 += _ratio;
        }
        // keep the same structure of events for compatability
        // emit Treasury(msg.sender, 0, toTreasury);
        emit Fees(msg.sender, 0, toFees);
    }

    /// @dev This function MUST be called on any balance changes,
    ///      otherwise can be used to infinitely claim fees
    //       Fees are segregated from core funds, so fees can never put liquidity at risk
    function _updateFor(address recipient) internal {
        uint256 _supplied = balanceOf[recipient];
        // get LP balance of `recipient`
        if (_supplied > 0) {
            uint256 _supplyIndex0 = supplyIndex0[recipient];
            // get last adjusted index0 for recipient
            uint256 _supplyIndex1 = supplyIndex1[recipient];
            uint256 _index0 = index0;
            // get global index0 for accumulated fees
            uint256 _index1 = index1;
            supplyIndex0[recipient] = _index0;
            // update user current position to global position
            supplyIndex1[recipient] = _index1;
            uint256 _delta0 = _index0 - _supplyIndex0;
            // see if there is any difference that need to be accrued
            uint256 _delta1 = _index1 - _supplyIndex1;
            if (_delta0 > 0) {
                uint256 _share = (_supplied * _delta0) / _FEE_PRECISION;
                // add accrued difference for each supplied token
                claimable0[recipient] += _share;
            }
            if (_delta1 > 0) {
                uint256 _share = (_supplied * _delta1) / _FEE_PRECISION;
                claimable1[recipient] += _share;
            }
        } else {
            supplyIndex0[recipient] = index0;
            // new users are set to the default global state
            supplyIndex1[recipient] = index1;
        }
    }

    function getReserves()
        public
        view
        override
        returns (
            uint112 _reserve0,
            uint112 _reserve1,
            uint32 _blockTimestampLast
        )
    {
        _reserve0 = uint112(reserve0);
        _reserve1 = uint112(reserve1);
        _blockTimestampLast = uint32(blockTimestampLast);
    }

    /// @dev Update reserves and, on the first call per block, price accumulators
    function _update(
        uint256 balance0,
        uint256 balance1,
        uint256 _reserve0,
        uint256 _reserve1
    ) internal {
        uint256 blockTimestamp = block.timestamp;
        uint256 timeElapsed = blockTimestamp - blockTimestampLast;
        // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            unchecked {
                reserve0CumulativeLast += _reserve0 * timeElapsed;
                reserve1CumulativeLast += _reserve1 * timeElapsed;
            }
        }

        Observation memory _point = lastObservation();
        timeElapsed = blockTimestamp - _point.timestamp;
        // compare the last observation with current timestamp,
        // if greater than 30 minutes, record a new event
        if (timeElapsed > PERIOD_SIZE) {
            observations.push(Observation(blockTimestamp, reserve0CumulativeLast, reserve1CumulativeLast));
        }
        reserve0 = balance0;
        reserve1 = balance1;
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    /// @dev Produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices()
        public
        view
        returns (
            uint256 reserve0Cumulative,
            uint256 reserve1Cumulative,
            uint256 blockTimestamp
        )
    {
        blockTimestamp = block.timestamp;
        reserve0Cumulative = reserve0CumulativeLast;
        reserve1Cumulative = reserve1CumulativeLast;

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint256 _reserve0, uint256 _reserve1, uint256 _blockTimestampLast) = getReserves();
        if (_blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint256 timeElapsed = blockTimestamp - _blockTimestampLast;
            unchecked {
                reserve0Cumulative += _reserve0 * timeElapsed;
                reserve1Cumulative += _reserve1 * timeElapsed;
            }
        }
    }

    /// @dev Gives the current twap price measured from amountIn * tokenIn gives amountOut
    function current(address tokenIn, uint256 amountIn) external view returns (uint256 amountOut) {
        Observation memory _observation = lastObservation();
        (uint256 reserve0Cumulative, uint256 reserve1Cumulative, ) = currentCumulativePrices();
        if (block.timestamp == _observation.timestamp) {
            _observation = observations[observations.length - 2];
        }

        uint256 timeElapsed = block.timestamp - _observation.timestamp;
        uint256 _reserve0 = (reserve0Cumulative - _observation.reserve0Cumulative) / timeElapsed;
        uint256 _reserve1 = (reserve1Cumulative - _observation.reserve1Cumulative) / timeElapsed;
        amountOut = _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
    }

    /// @dev As per `current`, however allows user configured granularity, up to the full window size
    function quote(
        address tokenIn,
        uint256 amountIn,
        uint256 granularity
    ) external view returns (uint256 amountOut) {
        uint256[] memory _prices = sample(tokenIn, amountIn, granularity, 1);
        uint256 priceAverageCumulative;
        for (uint256 i = 0; i < _prices.length; i++) {
            priceAverageCumulative += _prices[i];
        }
        return priceAverageCumulative / granularity;
    }

    /// @dev Returns a memory set of twap prices
    function prices(
        address tokenIn,
        uint256 amountIn,
        uint256 points
    ) external view returns (uint256[] memory) {
        return sample(tokenIn, amountIn, points, 1);
    }

    function sample(
        address tokenIn,
        uint256 amountIn,
        uint256 points,
        uint256 window
    ) public view returns (uint256[] memory) {
        uint256[] memory _prices = new uint256[](points);

        uint256 length = observations.length - 1;
        uint256 i = length - (points * window);
        uint256 nextIndex = 0;
        uint256 index = 0;

        for (; i < length; i += window) {
            nextIndex = i + window;
            uint256 timeElapsed = observations[nextIndex].timestamp - observations[i].timestamp;
            uint256 _reserve0 = (observations[nextIndex].reserve0Cumulative - observations[i].reserve0Cumulative) /
                timeElapsed;
            uint256 _reserve1 = (observations[nextIndex].reserve1Cumulative - observations[i].reserve1Cumulative) /
                timeElapsed;
            _prices[index] = _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
            index = index + 1;
        }
        return _prices;
    }

    /// @dev This low-level function should be called from a contract which performs important safety checks
    ///      standard uniswap v2 implementation
    function mint(address to) external override lock returns (uint256 liquidity) {
        (uint256 _reserve0, uint256 _reserve1) = (reserve0, reserve1);
        uint256 _balance0 = IERC20(token0).balanceOf(address(this));
        uint256 _balance1 = IERC20(token1).balanceOf(address(this));
        uint256 _amount0 = _balance0 - _reserve0;
        uint256 _amount1 = _balance1 - _reserve1;

        uint256 _totalSupply = totalSupply;
        // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(_amount0 * _amount1) - MINIMUM_LIQUIDITY;
            // permanently lock the first MINIMUM_LIQUIDITY tokens
            _mint(address(0), MINIMUM_LIQUIDITY);
        } else {
            liquidity = Math.min((_amount0 * _totalSupply) / _reserve0, (_amount1 * _totalSupply) / _reserve1);
        }
        require(liquidity > 0, "SoluneaPair: INSUFFICIENT_LIQUIDITY_MINTED");
        _mint(to, liquidity);

        _update(_balance0, _balance1, _reserve0, _reserve1);
        emit Mint(msg.sender, _amount0, _amount1);
    }

    /// @dev This low-level function should be called from a contract which performs important safety checks
    ///      standard uniswap v2 implementation
    function burn(address to) external override lock returns (uint256 amount0, uint256 amount1) {
        (uint256 _reserve0, uint256 _reserve1) = (reserve0, reserve1);
        (address _token0, address _token1) = (token0, token1);
        uint256 _balance0 = IERC20(_token0).balanceOf(address(this));
        uint256 _balance1 = IERC20(_token1).balanceOf(address(this));
        uint256 _liquidity = balanceOf[address(this)];

        // gas savings, must be defined here since totalSupply can update in _mintFee
        uint256 _totalSupply = totalSupply;
        // using balances ensures pro-rata distribution
        amount0 = (_liquidity * _balance0) / _totalSupply;
        // using balances ensures pro-rata distribution
        amount1 = (_liquidity * _balance1) / _totalSupply;
        require(amount0 > 0 && amount1 > 0, "SoluneaPair: INSUFFICIENT_LIQUIDITY_BURNED");
        _burn(address(this), _liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        _balance0 = IERC20(_token0).balanceOf(address(this));
        _balance1 = IERC20(_token1).balanceOf(address(this));

        _update(_balance0, _balance1, _reserve0, _reserve1);
        emit Burn(msg.sender, amount0, amount1, to);
    }

    /// @dev This low-level function should be called from a contract which performs important safety checks
    function swap(
        uint256 amount0Out,
        uint256 amount1Out,
        address to,
        bytes calldata data
    ) external override lock {
        require(!IFactory(factory).isPaused(), "SoluneaPair: PAUSE");
        require(amount0Out > 0 || amount1Out > 0, "SoluneaPair: INSUFFICIENT_OUTPUT_AMOUNT");
        (uint256 _reserve0, uint256 _reserve1) = (reserve0, reserve1);
        require(amount0Out < _reserve0 && amount1Out < _reserve1, "SoluneaPair: INSUFFICIENT_LIQUIDITY");
        uint256 _balance0;
        uint256 _balance1;
        {
            // scope for _token{0,1}, avoids stack too deep errors
            (address _token0, address _token1) = (token0, token1);
            require(to != _token0 && to != _token1, "SoluneaPair: INVALID_TO");
            // optimistically transfer tokens
            if (amount0Out > 0) _safeTransfer(_token0, to ,amount0Out);
            // optimistically transfer tokens
            if (amount1Out > 0) _safeTransfer(_token1, to ,amount1Out);
            // callback, used for flash loans
            if (data.length > 0) ICallee(to).hook(msg.sender, amount0Out, amount1Out, data);
            _balance0 = IERC20(_token0).balanceOf(address(this));
            _balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint256 amount0In = _balance0 > _reserve0 - amount0Out ? _balance0 - (_reserve0 - amount0Out) : 0;
        uint256 amount1In = _balance1 > _reserve1 - amount1Out ? _balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, "SoluneaPair: INSUFFICIENT_INPUT_AMOUNT");
        {
            // scope for reserve{0,1}Adjusted, avoids stack too deep errors
            (address _token0, address _token1) = (token0, token1);
            // accrue fees for token0 and move them out of pool
            if (amount0In > 0) _update0(amount0In / swapFee);
            // accrue fees for token1 and move them out of pool
            if (amount1In > 0) _update1(amount1In / swapFee);
            // since we removed tokens, we need to reconfirm balances,
            // can also simply use previous balance - amountIn/ SWAP_FEE,
            // but doing balanceOf again as safety check
            _balance0 = IERC20(_token0).balanceOf(address(this));
            _balance1 = IERC20(_token1).balanceOf(address(this));
            // The curve, either x3y+y3x for stable pools, or x*y for volatile pools
            require(_k(_balance0, _balance1) >= _k(_reserve0, _reserve1), "SoluneaPair: K");
        }

        _update(_balance0, _balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    /// @dev Force balances to match reserves
    function skim(address to) external lock {
        (address _token0, address _token1) = (token0, token1);
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)) - (reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)) - (reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }

    function _f(uint256 x0, uint256 y) internal pure returns (uint256) {
        return (x0 * ((((y * y) / 1e18) * y) / 1e18)) / 1e18 + (((((x0 * x0) / 1e18) * x0) / 1e18) * y) / 1e18;
    }

    function _d(uint256 x0, uint256 y) internal pure returns (uint256) {
        return (3 * x0 * ((y * y) / 1e18)) / 1e18 + ((((x0 * x0) / 1e18) * x0) / 1e18);
    }

    function _getY(
        uint256 x0,
        uint256 xy,
        uint256 y
    ) internal pure returns (uint256) {
        for (uint256 i = 0; i < 255; i++) {
            uint256 yPrev = y;
            uint256 k = _f(x0, y);
            if (k < xy) {
                uint256 dy = ((xy - k) * 1e18) / _d(x0, y);
                y = y + dy;
            } else {
                uint256 dy = ((k - xy) * 1e18) / _d(x0, y);
                y = y - dy;
            }
            if (Math.closeTo(y, yPrev, 1)) {
                break;
            }
        }
        return y;
    }

    function getAmountOut(uint256 amountIn, address tokenIn) external view override returns (uint256) {
        (uint256 _reserve0, uint256 _reserve1) = (reserve0, reserve1);
        // remove fee from amount received
        amountIn -= amountIn / swapFee;
        return _getAmountOut(amountIn, tokenIn, _reserve0, _reserve1);
    }

    function _getAmountOut(
        uint256 amountIn,
        address tokenIn,
        uint256 _reserve0,
        uint256 _reserve1
    ) internal view returns (uint256) {
        if (stable) {
            uint256 xy = _k(_reserve0, _reserve1);
            _reserve0 = (_reserve0 * 1e18) / decimals0;
            _reserve1 = (_reserve1 * 1e18) / decimals1;
            (uint256 reserveA, uint256 reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
            amountIn = tokenIn == token0 ? (amountIn * 1e18) / decimals0 : (amountIn * 1e18) / decimals1;
            uint256 y = reserveB - _getY(amountIn + reserveA, xy, reserveB);
            return (y * (tokenIn == token0 ? decimals1 : decimals0)) / 1e18;
        } else {
            (uint256 reserveA, uint256 reserveB) = tokenIn == token0 ? (_reserve0, _reserve1) : (_reserve1, _reserve0);
            return (amountIn * reserveB) / (reserveA + amountIn);
        }
    }

    function _k(uint256 x, uint256 y) internal view returns (uint256) {
        if (stable) {
            uint256 _x = (x * 1e18) / decimals0;
            uint256 _y = (y * 1e18) / decimals1;
            uint256 _a = (_x * _y) / 1e18;
            uint256 _b = ((_x * _x) / 1e18 + (_y * _y) / 1e18);
            // x3y+y3x >= k
            return (_a * _b) / 1e18;
        } else {
            // xy >= k
            return x * y;
        }
    }

    //****************************************************************************
    //**************************** ERC20 *****************************************
    //****************************************************************************

    function _mint(address dst, uint256 amount) internal {
        // balances must be updated on mint/burn/transfer
        _updateFor(dst);
        totalSupply += amount;
        balanceOf[dst] += amount;
        emit Transfer(address(0), dst, amount);
    }

    function _burn(address dst, uint256 amount) internal {
        _updateFor(dst);
        totalSupply -= amount;
        balanceOf[dst] -= amount;
        emit Transfer(dst, address(0), amount);
    }

    function approve(address spender, uint256 amount) external override returns (bool) {
        require(spender != address(0), "SoluneaPair: Approve to the zero address");
        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external override {
        require(deadline >= block.timestamp, "SoluneaPair: EXPIRED");
        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, "SoluneaPair: INVALID_SIGNATURE");
        allowance[owner][spender] = value;

        emit Approval(owner, spender, value);
    }

    function transfer(address dst, uint256 amount) external override returns (bool) {
        _transferTokens(msg.sender, dst, amount);
        return true;
    }

    function transferFrom(
        address src,
        address dst,
        uint256 amount
    ) external override returns (bool) {
        address spender = msg.sender;
        uint256 spenderAllowance = allowance[src][spender];

        if (spender != src && spenderAllowance != type(uint256).max) {
            require(spenderAllowance >= amount, "SoluneaPair: Insufficient allowance");
            unchecked {
                uint256 newAllowance = spenderAllowance - amount;
                allowance[src][spender] = newAllowance;
                emit Approval(src, spender, newAllowance);
            }
        }

        _transferTokens(src, dst, amount);
        return true;
    }

    function _transferTokens(
        address src,
        address dst,
        uint256 amount
    ) internal {
        require(dst != address(0), "SoluneaPair: Transfer to the zero address");

        // update fee position for src
        _updateFor(src);
        // update fee position for dst
        _updateFor(dst);

        uint256 srcBalance = balanceOf[src];
        require(srcBalance >= amount, "SoluneaPair: Transfer amount exceeds balance");
        unchecked {
            balanceOf[src] = srcBalance - amount;
        }

        balanceOf[dst] += amount;

        emit Transfer(src, dst, amount);
    }

    function _safeTransfer(address token, address to, uint256 value) internal {
        require(token.code.length > 0);
        (bool success, bytes memory data) = token.call(
            abi.encodeWithSelector(IERC20.transfer.selector, to, value)
        );
        require(success && (data.length == 0 || abi.decode(data, (bool))));
    }
}

{
  "compilationTarget": {
    "contracts/contract/base/SoluneaPair.sol": "SoluneaPair"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}