pragma solidity ^0.4.24;

import "./FundsManager.sol";
import "./GnosisSafe.sol";
import "./ERC20.sol";

// TODO: Check that the gnosis safe funds are kept directly in the safe and not some other address/contract
// This contract must be granted the permission to transfer funds on the Gnosis Safe it accepts
contract GnosisSafeFundsManager is FundsManager {

    bytes4 public constant TRANSFER_SELECTOR = 0xa9059cbb; // Equivalent of bytes4(keccak256("transfer(address,uint256)"))

    address public owner;
    GnosisSafe public gnosisSafe;

    modifier onlyOwner {
        require(msg.sender == owner, "ERR:NOT_OWNER");
        _;
    }

    constructor(GnosisSafe _gnosisSafe) public {
        owner = msg.sender;
        gnosisSafe = _gnosisSafe;
    }

    function setOwner(address _owner) public onlyOwner {
        owner = _owner;
    }

    function balance(address _token) public view returns (uint256) {
        ERC20 token = ERC20(_token);
        return token.balanceOf(address(gnosisSafe));
    }

    function transfer(address _token, address _beneficiary, uint256 _amount) public onlyOwner {
        bytes memory transferBytes = abi.encodeWithSelector(TRANSFER_SELECTOR, _beneficiary, _amount);
        (bool success, bytes memory returnData) = gnosisSafe.execTransactionFromModuleReturnData(_token, 0, transferBytes, GnosisSafe.Operation.Call);

        bool returnBool = false;
        assembly {
            // Load the data after 32 bytes length slot, eg add 0x20
            returnBool := mload(add(returnData, 0x20))
        }

        require(success, "ERR:TRANSFER_REVERTED");
        require(returnBool, "ERR:TRANSFER_NOT_RETURN_TRUE");
    }
}