// File: contracts/lib/InitializableOwnable.sol

/*

    Copyright 2020 DODO ZOO.
    SPDX-License-Identifier: Apache-2.0

*/

pragma solidity 0.8.4;

/**
 * @title Ownable
 * @author DODO Breeder
 *
 * @notice Ownership related functions
 */
contract InitializableOwnable {
    address public _OWNER_;
    address public _NEW_OWNER_;
    bool internal _INITIALIZED_;

    // ============ Events ============

    event OwnershipTransferPrepared(address indexed previousOwner, address indexed newOwner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    // ============ Modifiers ============

    modifier notInitialized() {
        require(!_INITIALIZED_, "DODO_INITIALIZED");
        _;
    }

    modifier onlyOwner() {
        require(msg.sender == _OWNER_, "NOT_OWNER");
        _;
    }

    // ============ Functions ============

    function initOwner(address newOwner) public notInitialized {
        _INITIALIZED_ = true;
        _OWNER_ = newOwner;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        emit OwnershipTransferPrepared(_OWNER_, newOwner);
        _NEW_OWNER_ = newOwner;
    }

    function claimOwnership() public {
        require(msg.sender == _NEW_OWNER_, "INVALID_CLAIM");
        emit OwnershipTransferred(_OWNER_, _NEW_OWNER_);
        _OWNER_ = _NEW_OWNER_;
        _NEW_OWNER_ = address(0);
    }
}

// File: contracts/intf/IERC20.sol


/**
 * @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);

    function decimals() external view returns (uint8);

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    /**
     * @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);
}

// File: contracts/lib/SafeMath.sol


/**
 * @title SafeMath
 * @author DODO Breeder
 *
 * @notice Math operations with safety checks that revert on error
 */
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "MUL_ERROR");

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "DIVIDING_ERROR");
        return a / b;
    }

    function divCeil(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 quotient = div(a, b);
        uint256 remainder = a - quotient * b;
        if (remainder > 0) {
            return quotient + 1;
        } else {
            return quotient;
        }
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SUB_ERROR");
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "ADD_ERROR");
        return c;
    }

    function sqrt(uint256 x) internal pure returns (uint256 y) {
        uint256 z = x / 2 + 1;
        y = x;
        while (z < y) {
            y = z;
            z = (x / z + z) / 2;
        }
    }
}

// File: contracts/lib/SafeERC20.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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;

    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)
        );
    }

    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'
        // solhint-disable-next-line max-line-length
        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));
    }

    /**
     * @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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/DODOLimitOrderBot.sol




/**
 * @title DODOLimitOrderBot
 * @author DODO Breeder
 */

 contract DODOLimitOrderBot is InitializableOwnable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    //=============== Storage ===============
    address public _DODO_LIMIT_ORDER_;
    address public _TOKEN_RECEIVER_;
    address public _DODO_APPROVE_;
    mapping (address => bool) public isAdminListed;
    
    //=============== Event ===============
    event addAdmin(address admin);
    event removeAdmin(address admin);
    event changeReceiver(address newReceiver);
    event Fill();

    function init(
        address owner, 
        address dodoLimitOrder,
        address tokenReceiver,
        address dodoApprove
    ) external {
        initOwner(owner);
        _DODO_LIMIT_ORDER_ = dodoLimitOrder;
        _TOKEN_RECEIVER_ = tokenReceiver;
        _DODO_APPROVE_ = dodoApprove;
    }
     
     function fillDODOLimitOrder(
        bytes memory callExternalData, //call DODOLimitOrder
        address takerToken, 
        uint256 minTakerTokenAmount
     ) external {
        require(isAdminListed[msg.sender], "ACCESS_DENIED");
        uint256 originTakerBalance = IERC20(takerToken).balanceOf(address(this));

        (bool success, ) = _DODO_LIMIT_ORDER_.call(callExternalData);
        require(success, "EXEC_DODO_LIMIT_ORDER_ERROR");

        uint256 takerBalance = IERC20(takerToken).balanceOf(address(this));
        uint256 leftTakerAmount = takerBalance.sub(originTakerBalance);

        require(leftTakerAmount >= minTakerTokenAmount, "TAKER_AMOUNT_NOT_ENOUGH");
        
        IERC20(takerToken).safeTransfer(_TOKEN_RECEIVER_, leftTakerAmount);
        
        emit Fill();
     }

    //call by DODOLimitOrder
    function doLimitOrderSwap(
        uint256 curTakerFillAmount,
        uint256 curMakerFillAmount,
        address makerToken, //fromToken
        address takerToken, //toToken
        address dodoRouteProxy,
        bytes memory dodoApiData
    ) external {
        require(msg.sender == _DODO_LIMIT_ORDER_, "ACCESS_NENIED");
        uint256 originTakerBalance = IERC20(takerToken).balanceOf(address(this));
     
        _approveMax(IERC20(makerToken), _DODO_APPROVE_, curMakerFillAmount);
        
        (bool success, ) = dodoRouteProxy.call(dodoApiData);
        require(success, "API_SWAP_FAILED");

        uint256 takerBalance = IERC20(takerToken).balanceOf(address(this));
        uint256 returnTakerAmount = takerBalance.sub(originTakerBalance);

        require(returnTakerAmount >= curTakerFillAmount, "SWAP_TAKER_AMOUNT_NOT_ENOUGH");
        
        _approveMax(IERC20(takerToken), _DODO_LIMIT_ORDER_, curTakerFillAmount);
    }


    //============  Ownable ============
    function addAdminList (address userAddr) external onlyOwner {
        isAdminListed[userAddr] = true;
        emit addAdmin(userAddr);
    }

    function removeAdminList (address userAddr) external onlyOwner {
        isAdminListed[userAddr] = false;
        emit removeAdmin(userAddr);
    }

    function changeTokenReceiver(address newTokenReceiver) external onlyOwner {
        _TOKEN_RECEIVER_ = newTokenReceiver;
        emit changeReceiver(newTokenReceiver);
    }


    //============  internal ============
    function _approveMax(IERC20 token,address to,uint256 amount) internal {
        uint256 allowance = token.allowance(address(this), to);
        if (allowance < amount) {
            if (allowance > 0) {
                token.safeApprove(to, 0);
            }
            token.safeApprove(to, type(uint256).max);
        }
    }
 }