EscrowReserve.sol

pragma solidity ^0.4.24;

import "../interfaces/EscrowReserveInterface.sol";
import "../interfaces/BurnableERC20.sol";

interface Events {
  function transaction(string _message, address _from, address _to, uint _amount, address _token)  external;
}
interface DB {
  function addressStorage(bytes32 _key) external view returns (address);
  function uintStorage(bytes32 _key) external view returns (uint);
  function setUint(bytes32 _key, uint _value) external;
  function deleteUint(bytes32 _key) external;
  function setBool(bytes32 _key, bool _value) external;
  function boolStorage(bytes32 _key) external view returns (bool);
}

contract EscrowReserve is EscrowReserveInterface{
  DB private database;
  Events private events;

  constructor(address _database, address _events) public {
    database = DB(_database);
    events = Events(_events);
  }
  function issueERC20(address _receiver, uint256 _amount, address _tokenAddress) external returns (bool){
    require(msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "AssetManagerEscrow"))));
    BurnableERC20 erc20 = BurnableERC20(_tokenAddress);
    require(erc20.balanceOf(this) >= _amount);
    require(erc20.transfer(_receiver, _amount));
    events.transaction("ERC20 withdrawn from escrow reserve", address(this), _receiver, _amount, _tokenAddress);
    return true;
  }
  function requestERC20(address _payer, uint256 _amount, address _tokenAddress) external returns (bool){
    require(msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "AssetManagerEscrow"))) ||
            msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "CrowdsaleGeneratorETH"))) ||
            msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "CrowdsaleGeneratorERC20"))));
    require(BurnableERC20(_tokenAddress).transferFrom(_payer, address(this), _amount));
    events.transaction("ERC20 received by escrow reserve", _payer, address(this), _amount, _tokenAddress);
  }
  function approveERC20(address _receiver, uint256 _amount, address _tokenAddress) external returns (bool){
    require(msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "AssetManagerEscrow"))));
    BurnableERC20(_tokenAddress).approve(_receiver, _amount); //always returns true
    events.transaction("ERC20 approval given by escrow reserve", address(this), _receiver, _amount, _tokenAddress);
    return true;
  }
  function burnERC20(uint256 _amount, address _tokenAddress) external returns (bool){
    require(msg.sender == database.addressStorage(keccak256(abi.encodePacked("contract", "AssetManagerEscrow"))));
    require(BurnableERC20(_tokenAddress).burn(_amount));
    events.transaction("ERC20 burnt by escrow reserve", address(this), address(0), _amount, _tokenAddress);
    return true;
  }
}