contract Liquidity is PoolSetters, Permission {
    using SafeERC20 for IERC20;

    bytes32 private constant FILE = "Liquidity";

    address private constant UNISWAP_FACTORY = address(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f);
    IUniswapV2Router02 private constant router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);

    event Provide(address indexed account, uint256 value, uint256 lessDai, uint256 newUniv2);

    function provide(uint256 value) external onlyFrozen(msg.sender) notPaused validBalance {
        Require.that(totalBonded() > 0, FILE, "insufficient total bonded");

        Require.that(totalRewarded() > 0, FILE, "insufficient total rewarded");

        Require.that(balanceOfRewarded(msg.sender) >= value, FILE, "insufficient rewarded balance");

        (uint256 lessDai, uint256 newUniv2) = addLiquidity(value);

        uint256 totalRewardedWithPhantom = totalRewarded().add(totalPhantom()).add(value);
        uint256 newPhantomFromBonded = totalRewardedWithPhantom.mul(newUniv2).div(totalBonded());

        incrementBalanceOfBonded(msg.sender, newUniv2);
        incrementBalanceOfPhantom(msg.sender, value.add(newPhantomFromBonded));

        emit Provide(msg.sender, value, lessDai, newUniv2);
    }

    function provideOneSided(uint256 value) external onlyFrozen(msg.sender) notPaused validBalance {
        Require.that(totalBonded() > 0, FILE, "insufficient total bonded");
        Require.that(totalRewarded() > 0, FILE, "insufficient total rewarded");
        Require.that(balanceOfRewarded(msg.sender) >= value, FILE, "insufficient rewarded balance");

        uint256 newUniv2 = optimalOneSidedAddLiquidity(value);

        uint256 totalRewardedWithPhantom = totalRewarded().add(totalPhantom()).add(value);
        uint256 newPhantomFromBonded = totalRewardedWithPhantom.mul(newUniv2).div(totalBonded());

        incrementBalanceOfBonded(msg.sender, newUniv2);
        incrementBalanceOfPhantom(msg.sender, value.add(newPhantomFromBonded));

        emit Provide(msg.sender, value, 0, newUniv2);
    }

    // https://github.com/AlphaFinanceLab/alphahomora/blob/734affeb76695c16517fe184d714dfa3033a6484/contracts/5/StrategyAddETHOnly.sol#L40
    function optimalOneSidedAddLiquidity(uint256 dollarAmount) internal returns (uint256) {
        // Optimal one side liquidity supply
        IUniswapV2Pair pair = IUniswapV2Pair(address(stakingToken()));

        address dai = dai();
        address dollar = pair.token0() == dai ? pair.token1() : pair.token0();

        // Compute optimal amount of dollar to be converted to DAI
        (uint256 r0, uint256 r1, ) = pair.getReserves();
        uint256 rIn = pair.token0() == dollar ? r0 : r1;
        uint256 aIn = getOptimalSwapAmount(rIn, dollarAmount);

        // Convert that portion into DAI
        address[] memory path = new address[](2);
        path[0] = dollar;
        path[1] = dai;

        IERC20(dollar).safeApprove(address(router), 0);
        IERC20(dollar).safeApprove(address(router), uint256(-1));
        uint256[] memory outputs = router.swapExactTokensForTokens(aIn, 0, path, address(this), now + 60);

        // Supply liquidity
        uint256 supplyDollarAmount = dollarAmount.sub(aIn);
        uint256 supplyDaiAmount = outputs[1];

        IERC20(dollar).safeApprove(address(router), 0);
        IERC20(dollar).safeApprove(address(router), supplyDollarAmount);

        IERC20(dai).safeApprove(address(router), 0);
        IERC20(dai).safeApprove(address(router), supplyDaiAmount);
        (, , uint256 lpAmountMinted) =
            router.addLiquidity(dollar, dai, supplyDollarAmount, supplyDaiAmount, 0, 0, address(this), now + 60);

        return lpAmountMinted;
    }

    function getOptimalSwapAmount(uint256 amt, uint256 res) internal pure returns (uint256) {
        return sqrt(amt.mul(res.mul(3988000).add(amt.mul(3988009)))).sub(amt.mul(1997)) / 1994;
    }

    function addLiquidity(uint256 dollarAmount) internal returns (uint256, uint256) {
        IUniswapV2Pair pair = IUniswapV2Pair(address(stakingToken()));

        (address tokenA, address tokenB) = (pair.token0(), pair.token1());
        (address dollar, address dai) = (tokenA == dai() ? tokenB : tokenA, dai());
        (uint256 reserveA, uint256 reserveB) = getReserves(dollar, dai);

        uint256 daiAmount =
            (reserveA == 0 && reserveB == 0) ? dollarAmount : UniswapV2Library.quote(dollarAmount, reserveA, reserveB);

        // Assume that the staking token is the pair
        IERC20(dollar).transfer(address(pair), dollarAmount);
        IERC20(dai).transferFrom(msg.sender, address(pair), daiAmount);
        return (daiAmount, pair.mint(address(this)));
    }

    // overridable for testing
    function getReserves(address tokenA, address tokenB) internal view returns (uint256 reserveA, uint256 reserveB) {
        (address token0, ) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (uint256 reserve0, uint256 reserve1, ) =
            IUniswapV2Pair(UniswapV2Library.pairFor(UNISWAP_FACTORY, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    function sqrt(uint256 y) internal pure returns (uint256 z) {
        if (y > 3) {
            z = y;
            uint256 x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}
function getReserves(address tokenA, address tokenB) internal view returns (uint256 reserveA, uint256 reserveB) {
        (address token0, ) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (uint256 reserve0, uint256 reserve1, ) =
            IUniswapV2Pair(UniswapV2Library.pairFor(UNISWAP_FACTORY, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }
// overridable for testing