pragma solidity ^0.6.0;

import "./DSAuth.sol";
import "./DSNote.sol";


abstract contract DSProxy is DSAuth, DSNote {
    DSProxyCache public cache; // global cache for contracts

    constructor(address _cacheAddr) public {
        require(setCache(_cacheAddr));
    }

    // solhint-disable-next-line no-empty-blocks
    receive() external payable {}

    // use the proxy to execute calldata _data on contract _code
    // function execute(bytes memory _code, bytes memory _data)
    //     public
    //     payable
    //     virtual
    //     returns (address target, bytes32 response);

    function execute(address _target, bytes memory _data)
        public
        payable
        virtual
        returns (bytes32 response);

    //set new cache
    function setCache(address _cacheAddr) public virtual payable returns (bool);
}


contract DSProxyCache {
    mapping(bytes32 => address) cache;

    function read(bytes memory _code) public view returns (address) {
        bytes32 hash = keccak256(_code);
        return cache[hash];
    }

    function write(bytes memory _code) public returns (address target) {
        assembly {
            target := create(0, add(_code, 0x20), mload(_code))
            switch iszero(extcodesize(target))
                case 1 {
                    // throw if contract failed to deploy
                    revert(0, 0)
                }
        }
        bytes32 hash = keccak256(_code);
        cache[hash] = target;
    }
}