/**
 * Copyright 2017-2020, bZeroX, LLC. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0.
 */

pragma solidity 0.5.17;

import "../core/State.sol";
import "../openzeppelin/SafeERC20.sol";

/**
 * @title The Protocol Token User contract.
 * @notice This contract code comes from bZx. bZx is a protocol for tokenized margin
 * trading and lending https://bzx.network similar to the dYdX protocol.
 *
 * This contract implements functionality to withdraw protocol tokens.
 * */
contract ProtocolTokenUser is State {
	using SafeERC20 for IERC20;

	/**
	 * @notice Internal function to withdraw an amount of protocol tokens from this contract.
	 *
	 * @param receiver The address of the recipient.
	 * @param amount The amount of tokens to withdraw.
	 *
	 * @return The protocol token address.
	 * @return Withdrawal success (true/false).
	 * */
	function _withdrawProtocolToken(address receiver, uint256 amount) internal returns (address, bool) {
		uint256 withdrawAmount = amount;

		uint256 tokenBalance = protocolTokenHeld;
		if (withdrawAmount > tokenBalance) {
			withdrawAmount = tokenBalance;
		}
		if (withdrawAmount == 0) {
			return (protocolTokenAddress, false);
		}

		protocolTokenHeld = tokenBalance.sub(withdrawAmount);

		IERC20(protocolTokenAddress).safeTransfer(receiver, withdrawAmount);

		return (protocolTokenAddress, true);
	}
}