// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(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 ^0.8.0;

/**
 * @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;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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: GPL-3.0

pragma solidity >=0.5.0;

interface IUniswapV2ERC20 {
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);

  function name() external pure returns (string memory);

  function symbol() external pure returns (string memory);

  function decimals() external pure returns (uint8);

  function totalSupply() external view returns (uint256);

  function balanceOf(address owner) external view returns (uint256);

  function allowance(address owner, address spender)
    external
    view
    returns (uint256);

  function approve(address spender, uint256 value) external returns (bool);

  function transfer(address to, uint256 value) external returns (bool);

  function transferFrom(
    address from,
    address to,
    uint256 value
  ) external returns (bool);

  function DOMAIN_SEPARATOR() external view returns (bytes32);

  function PERMIT_TYPEHASH() external pure returns (bytes32);

  function nonces(address owner) external view returns (uint256);

  function permit(
    address owner,
    address spender,
    uint256 value,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external;
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
  event PairCreated(
    address indexed token0,
    address indexed token1,
    address pair,
    uint256
  );

  function feeTo() external view returns (address);

  function feeToSetter() external view returns (address);

  function migrator() external view returns (address);

  function getPair(address tokenA, address tokenB)
    external
    view
    returns (address pair);

  function allPairs(uint256) external view returns (address pair);

  function allPairsLength() external view returns (uint256);

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

  function setFeeTo(address) external;

  function setFeeToSetter(address) external;

  function setMigrator(address) external;
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);

  function name() external pure returns (string memory);

  function symbol() external pure returns (string memory);

  function decimals() external pure returns (uint8);

  function totalSupply() external view returns (uint256);

  function balanceOf(address owner) external view returns (uint256);

  function allowance(address owner, address spender)
    external
    view
    returns (uint256);

  function approve(address spender, uint256 value) external returns (bool);

  function transfer(address to, uint256 value) external returns (bool);

  function transferFrom(
    address from,
    address to,
    uint256 value
  ) external returns (bool);

  function DOMAIN_SEPARATOR() external view returns (bytes32);

  function PERMIT_TYPEHASH() external pure returns (bytes32);

  function nonces(address owner) external view returns (uint256);

  function permit(
    address owner,
    address spender,
    uint256 value,
    uint256 deadline,
    uint8 v,
    bytes32 r,
    bytes32 s
  ) external;

  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(uint112 reserve0, uint112 reserve1);

  function MINIMUM_LIQUIDITY() external pure returns (uint256);

  function factory() external view returns (address);

  function token0() external view returns (address);

  function token1() external view returns (address);

  function getReserves()
    external
    view
    returns (
      uint112 reserve0,
      uint112 reserve1,
      uint32 blockTimestampLast
    );

  function price0CumulativeLast() external view returns (uint256);

  function price1CumulativeLast() external view returns (uint256);

  function kLast() external view returns (uint256);

  function mint(address to) external returns (uint256 liquidity);

  function burn(address to) external returns (uint256 amount0, uint256 amount1);

  function swap(
    uint256 amount0Out,
    uint256 amount1Out,
    address to,
    bytes calldata data
  ) external;

  function skim(address to) external;

  function sync() external;

  function initialize(address, address) external;
}

// SPDX-License-Identifier: MIT

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() {
        _setOwner(_msgSender());
    }

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

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

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/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,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - 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 ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./interfaces/IUniswapV2ERC20.sol";
import "./interfaces/IUniswapV2Pair.sol";
import "./interfaces/IUniswapV2Factory.sol";

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

// T1 - T4: OK
contract UbeMaker is Ownable {
  using SafeMath for uint256;
  using SafeERC20 for IERC20;

  // V1 - V5: OK
  IUniswapV2Factory public immutable factory;
  //0x62d5b84bE28a183aBB507E125B384122D2C25fAE
  // V1 - V5: OK
  address public immutable bar;
  //0x97A9681612482A22b7877afbF8430EDC76159Cae
  // V1 - V5: OK
  address private immutable ube;
  //0x00Be915B9dCf56a3CBE739D9B9c202ca692409EC
  // V1 - V5: OK
  address private immutable celo;
  //0x471EcE3750Da237f93B8E339c536989b8978a438

  // V1 - V5: OK
  mapping(address => address) internal _bridges;

  // E1: OK
  event LogBridgeSet(address indexed token, address indexed bridge);
  // E1: OK
  event LogConvert(
    address indexed server,
    address indexed token0,
    address indexed token1,
    uint256 amount0,
    uint256 amount1,
    uint256 amountUBE
  );
  event Recovered(address token, uint256 amount);

  constructor(
    address _factory,
    address _bar,
    address _ube,
    address _celo
  ) {
    factory = IUniswapV2Factory(_factory);
    bar = _bar;
    ube = _ube;
    celo = _celo;
  }

  // F1 - F10: OK
  // C1 - C24: OK
  function bridgeFor(address token) public view returns (address bridge) {
    bridge = _bridges[token];
    if (bridge == address(0)) {
      bridge = celo;
    }
  }

  // F1 - F10: OK
  // C1 - C24: OK
  function setBridge(address token, address bridge) external onlyOwner {
    // Checks
    require(
      token != ube && token != celo && token != bridge,
      "UbeMaker: Invalid bridge"
    );

    // Effects
    _bridges[token] = bridge;
    emit LogBridgeSet(token, bridge);
  }

  // F1 - F10: OK
  // F6: There is an exploit to add lots of UBE to the bar, run convert, then remove the UBE again.
  //     As the size of the UbeBar has grown, this requires large amounts of funds and isn't super profitable anymore
  // C1 - C24: OK
  function convert(address token0, address token1) external {
    _convert(token0, token1);
  }

  // F1 - F10: OK, see convert
  // C1 - C24: OK
  // C3: Loop is under control of the caller
  function convertMultiple(address[] calldata token0, address[] calldata token1)
    external
  {
    // TODO: This can be optimized a fair bit, but this is safer and simpler for now
    uint256 len = token0.length;
    for (uint256 i = 0; i < len; i++) {
      _convert(token0[i], token1[i]);
    }
  }

  // F1 - F10: OK
  // C1- C24: OK
  function _convert(address token0, address token1) internal {
    // Interactions
    // S1 - S4: OK
    IUniswapV2Pair pair = IUniswapV2Pair(factory.getPair(token0, token1));
    require(address(pair) != address(0), "UbeMaker: Invalid pair");
    // balanceOf: S1 - S4: OK
    // transfer: X1 - X5: OK
    IERC20(address(pair)).safeTransfer(
      address(pair),
      pair.balanceOf(address(this))
    );
    // X1 - X5: OK
    (uint256 amount0, uint256 amount1) = pair.burn(address(this));
    if (token0 != pair.token0()) {
      (amount0, amount1) = (amount1, amount0);
    }
    emit LogConvert(
      msg.sender,
      token0,
      token1,
      amount0,
      amount1,
      _convertStep(token0, token1, amount0, amount1)
    );
  }

  // F1 - F10: OK
  // C1 - C24: OK
  // All safeTransfer, _swap, _toUBE, _convertStep: X1 - X5: OK
  function _convertStep(
    address token0,
    address token1,
    uint256 amount0,
    uint256 amount1
  ) internal returns (uint256 ubeOut) {
    // Interactions
    if (token0 == token1) {
      uint256 amount = amount0.add(amount1);
      if (token0 == ube) {
        IERC20(ube).safeTransfer(bar, amount);
        ubeOut = amount;
      } else if (token0 == celo) {
        ubeOut = _toUBE(celo, amount);
      } else {
        address bridge = bridgeFor(token0);
        amount = _swap(token0, bridge, amount, address(this));
        ubeOut = _convertStep(bridge, bridge, amount, 0);
      }
    } else if (token0 == ube) {
      // eg. UBE - ETH
      IERC20(ube).safeTransfer(bar, amount0);
      ubeOut = _toUBE(token1, amount1).add(amount0);
    } else if (token1 == ube) {
      // eg. USDT - UBE
      IERC20(ube).safeTransfer(bar, amount1);
      ubeOut = _toUBE(token0, amount0).add(amount1);
    } else if (token0 == celo) {
      // eg. CELO - mcUSD
      ubeOut = _toUBE(
        celo,
        _swap(token1, celo, amount1, address(this)).add(amount0)
      );
    } else if (token1 == celo) {
      // eg. mcUSD - CELO
      ubeOut = _toUBE(
        celo,
        _swap(token0, celo, amount0, address(this)).add(amount1)
      );
    } else {
      // eg. MIC - USDT
      address bridge0 = bridgeFor(token0);
      address bridge1 = bridgeFor(token1);
      if (bridge0 == token1) {
        // eg. MIC - USDT - and bridgeFor(MIC) = USDT
        ubeOut = _convertStep(
          bridge0,
          token1,
          _swap(token0, bridge0, amount0, address(this)),
          amount1
        );
      } else if (bridge1 == token0) {
        // eg. WBTC - DSD - and bridgeFor(DSD) = WBTC
        ubeOut = _convertStep(
          token0,
          bridge1,
          amount0,
          _swap(token1, bridge1, amount1, address(this))
        );
      } else {
        ubeOut = _convertStep(
          bridge0,
          bridge1, // eg. USDT - DSD - and bridgeFor(DSD) = WBTC
          _swap(token0, bridge0, amount0, address(this)),
          _swap(token1, bridge1, amount1, address(this))
        );
      }
    }
  }

  // F1 - F10: OK
  // C1 - C24: OK
  // All safeTransfer, swap: X1 - X5: OK
  function _swap(
    address fromToken,
    address toToken,
    uint256 amountIn,
    address to
  ) internal returns (uint256 amountOut) {
    // Checks
    // X1 - X5: OK
    IUniswapV2Pair pair = IUniswapV2Pair(factory.getPair(fromToken, toToken));
    require(address(pair) != address(0), "UbeMaker: Cannot convert");

    // Interactions
    // X1 - X5: OK
    (uint256 reserve0, uint256 reserve1, ) = pair.getReserves();
    uint256 amountInWithFee = amountIn.mul(997);
    if (fromToken == pair.token0()) {
      amountOut =
        amountInWithFee.mul(reserve1) /
        reserve0.mul(1000).add(amountInWithFee);
      IERC20(fromToken).safeTransfer(address(pair), amountIn);
      pair.swap(0, amountOut, to, new bytes(0));
      // TODO: Add maximum slippage?
    } else {
      amountOut =
        amountInWithFee.mul(reserve0) /
        reserve1.mul(1000).add(amountInWithFee);
      IERC20(fromToken).safeTransfer(address(pair), amountIn);
      pair.swap(amountOut, 0, to, new bytes(0));
      // TODO: Add maximum slippage?
    }
  }

  // F1 - F10: OK
  // C1 - C24: OK
  function _toUBE(address token, uint256 amountIn)
    internal
    returns (uint256 amountOut)
  {
    // X1 - X5: OK
    amountOut = _swap(token, ube, amountIn, bar);
  }

  function recoverERC20(address tokenAddress) external onlyOwner {
    IERC20 token = IERC20(tokenAddress);
    uint256 contractBalance = token.balanceOf(address(this));
    token.safeTransfer(owner(), contractBalance);
    emit Recovered(tokenAddress, contractBalance);
  }
}

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