// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

// File: contracts/CeFiSmartTransfer.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./OperatorTransfer.sol";

contract CeFiSmartTransfer is OperatorTransfer {
    Transfer public current;

    constructor(address[] memory _operators) OperatorTransfer(_operators) {}

    function prepareNativeTransfer(
        Transfer memory transfer
    ) external onlyOperator {
        require(
            transfer.token == address(0),
            "This method can only send native tokens"
        );

        // auto cancel on a re-initiation
        if (bytes(current.id).length > 0) {
            emit SmartTransferCancel(current.id);
        }

        current = transfer;
        emit SmartTransferReady(current.id);
    }

    function cancel() external onlyOperator {
        require(
            bytes(current.id).length > 0,
            "Smart transfer is not initiated"
        );

        emit SmartTransferCancel(current.id);
        delete current;
    }

    receive() external payable {
        require(
            bytes(current.id).length > 0,
            "Smart transfer is not initiated"
        );
        require(
            current.token == address(0),
            "Transfer is not set to transfer ETH"
        );
        require(msg.value == current.amount, "Invalid amount of ETH provided");

        current.receiver.transfer(current.amount - current.fee);
        current.feeReceiver.transfer(current.fee);

        emit SmartTransferComplete(current.id);
        delete current;
    }

    function executeErc20Transfer(
        Transfer memory transfer
    ) external onlyOperator {
        require(
            transfer.token != address(0),
            "This method can only send ERC20 tokens"
        );

        IERC20(transfer.token).transfer(
            transfer.receiver,
            transfer.amount - transfer.fee
        );
        IERC20(transfer.token).transfer(transfer.feeReceiver, transfer.fee);

        emit SmartTransferComplete(transfer.id);
    }
}

// File: contracts/OperatorTransfer.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.20;

contract OperatorTransfer {
    mapping(address => bool) public operators;

    struct Transfer {
        string id;
        uint amount;
        uint fee;
        address payable feeReceiver;
        address payer;
        address payable receiver;
        address token;
    }

    event SmartTransferReady(string id);
    event SmartTransferComplete(string id);
    event SmartTransferCancel(string id);

    constructor(address[] memory _operators) {
        for (uint256 i = 0; i < _operators.length; i += 1) {
            operators[_operators[i]] = true;
        }
    }

    modifier onlyOperator {
        require(operators[msg.sender], "Only operators are allowed");
        _;
    }

    function addOperator(address _operator) onlyOperator() public {
        operators[_operator] = true;
    }

    function removeOperator(address _operator) onlyOperator() public {
        operators[_operator] = false;
    }
}