pragma solidity ^0.7.0;

import { TokenInterface } from "../../common/interfaces.sol";
import { DSMath } from "../../common/math.sol";
import { Basic } from "../../common/basic.sol";
import { IQuickSwapRouter, IQuickSwapFactory } from "./interface.sol";

abstract contract Helpers is DSMath, Basic {
	/**
	 * @dev IQuickSwapRouter
	 */
	IQuickSwapRouter internal constant router =
		IQuickSwapRouter(0xa5E0829CaCEd8fFDD4De3c43696c57F7D7A678ff);

	function getExpectedBuyAmt(address[] memory paths, uint256 sellAmt)
		internal
		view
		returns (uint256 buyAmt)
	{
		uint256[] memory amts = router.getAmountsOut(sellAmt, paths);
		buyAmt = amts[1];
	}

	function getExpectedSellAmt(address[] memory paths, uint256 buyAmt)
		internal
		view
		returns (uint256 sellAmt)
	{
		uint256[] memory amts = router.getAmountsIn(buyAmt, paths);
		sellAmt = amts[0];
	}

	function checkPair(address[] memory paths) internal view {
		address pair = IQuickSwapFactory(router.factory()).getPair(
			paths[0],
			paths[1]
		);
		require(pair != address(0), "No-exchange-address");
	}

	function getPaths(address buyAddr, address sellAddr)
		internal
		pure
		returns (address[] memory paths)
	{
		paths = new address[](2);
		paths[0] = address(sellAddr);
		paths[1] = address(buyAddr);
	}

	function getMinAmount(
		TokenInterface token,
		uint256 amt,
		uint256 slippage
	) internal view returns (uint256 minAmt) {
		uint256 _amt18 = convertTo18(token.decimals(), amt);
		minAmt = wmul(_amt18, sub(WAD, slippage));
		minAmt = convert18ToDec(token.decimals(), minAmt);
	}

	function _addLiquidity(
		address tokenA,
		address tokenB,
		uint256 _amt,
		uint256 unitAmt,
		uint256 slippage
	)
		internal
		returns (
			uint256 _amtA,
			uint256 _amtB,
			uint256 _liquidity
		)
	{
		(TokenInterface _tokenA, TokenInterface _tokenB) = changeMaticAddress(
			tokenA,
			tokenB
		);

		_amtA = _amt == uint256(-1)
			? getTokenBal(TokenInterface(tokenA))
			: _amt;
		_amtB = convert18ToDec(
			_tokenB.decimals(),
			wmul(unitAmt, convertTo18(_tokenA.decimals(), _amtA))
		);

		bool isMatic = address(_tokenA) == wmaticAddr;
		convertMaticToWmatic(isMatic, _tokenA, _amtA);

		isMatic = address(_tokenB) == wmaticAddr;
		convertMaticToWmatic(isMatic, _tokenB, _amtB);

		approve(_tokenA, address(router), _amtA);
		approve(_tokenB, address(router), _amtB);

		uint256 minAmtA = getMinAmount(_tokenA, _amtA, slippage);
		uint256 minAmtB = getMinAmount(_tokenB, _amtB, slippage);
		(_amtA, _amtB, _liquidity) = router.addLiquidity(
			address(_tokenA),
			address(_tokenB),
			_amtA,
			_amtB,
			minAmtA,
			minAmtB,
			address(this),
			block.timestamp + 1
		);
	}

	function _removeLiquidity(
		address tokenA,
		address tokenB,
		uint256 _amt,
		uint256 unitAmtA,
		uint256 unitAmtB
	)
		internal
		returns (
			uint256 _amtA,
			uint256 _amtB,
			uint256 _uniAmt
		)
	{
		TokenInterface _tokenA;
		TokenInterface _tokenB;
		(_tokenA, _tokenB, _uniAmt) = _getRemoveLiquidityData(
			tokenA,
			tokenB,
			_amt
		);
		{
			uint256 minAmtA = convert18ToDec(
				_tokenA.decimals(),
				wmul(unitAmtA, _uniAmt)
			);
			uint256 minAmtB = convert18ToDec(
				_tokenB.decimals(),
				wmul(unitAmtB, _uniAmt)
			);
			(_amtA, _amtB) = router.removeLiquidity(
				address(_tokenA),
				address(_tokenB),
				_uniAmt,
				minAmtA,
				minAmtB,
				address(this),
				block.timestamp + 1
			);
		}

		bool isMatic = address(_tokenA) == wmaticAddr;
		convertWmaticToMatic(isMatic, _tokenA, _amtA);

		isMatic = address(_tokenB) == wmaticAddr;
		convertWmaticToMatic(isMatic, _tokenB, _amtB);
	}

	function _getRemoveLiquidityData(
		address tokenA,
		address tokenB,
		uint256 _amt
	)
		internal
		returns (
			TokenInterface _tokenA,
			TokenInterface _tokenB,
			uint256 _uniAmt
		)
	{
		(_tokenA, _tokenB) = changeMaticAddress(tokenA, tokenB);
		address exchangeAddr = IQuickSwapFactory(router.factory()).getPair(
			address(_tokenA),
			address(_tokenB)
		);
		require(exchangeAddr != address(0), "pair-not-found.");

		TokenInterface uniToken = TokenInterface(exchangeAddr);
		_uniAmt = _amt == uint256(-1)
			? uniToken.balanceOf(address(this))
			: _amt;
		approve(uniToken, address(router), _uniAmt);
	}
}