// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

import "./FullMath.sol";
import "./TickMath.sol";
import "./IUniswapV3Pool.sol";
import "./LowGasSafeMath.sol";
import "./PoolAddress.sol";

/// @title Oracle library
/// @notice Provides functions to integrate with V3 pool oracle
library OracleLibrary {
    /// @notice Fetches time-weighted average tick using Uniswap V3 oracle
    /// @param pool Address of Uniswap V3 pool that we want to observe
    /// @param period Number of seconds in the past to start calculating time-weighted average
    /// @return timeWeightedAverageTick The time-weighted average tick from (block.timestamp - period) to block.timestamp
    function consult(address pool, uint32 period)
        internal
        view
        returns (int24 timeWeightedAverageTick)
    {
        require(period != 0, "BP");

        uint32[] memory secondAgos = new uint32[](2);
        secondAgos[0] = period;
        secondAgos[1] = 0;

        (int56[] memory tickCumulatives, ) = IUniswapV3Pool(pool).observe(
            secondAgos
        );
        int56 tickCumulativesDelta = tickCumulatives[1] - tickCumulatives[0];

        timeWeightedAverageTick = int24(
            tickCumulativesDelta / int56(uint56(period))
        );

        // Always round to negative infinity
        if (
            tickCumulativesDelta < 0 &&
            (tickCumulativesDelta % int56(uint56(period)) != 0)
        ) timeWeightedAverageTick--;
    }

    /// @notice Given a tick and a token amount, calculates the amount of token received in exchange
    /// @param tick Tick value used to calculate the quote
    /// @param baseAmount Amount of token to be converted
    /// @param baseToken Address of an ERC20 token contract used as the baseAmount denomination
    /// @param quoteToken Address of an ERC20 token contract used as the quoteAmount denomination
    /// @return quoteAmount Amount of quoteToken received for baseAmount of baseToken
    function getQuoteAtTick(
        int24 tick,
        uint128 baseAmount,
        address baseToken,
        address quoteToken
    ) internal pure returns (uint256 quoteAmount) {
        uint160 sqrtRatioX96 = TickMath.getSqrtRatioAtTick(tick);

        // Calculate quoteAmount with better precision if it doesn't overflow when multiplied by itself
        if (sqrtRatioX96 <= type(uint128).max) {
            uint256 ratioX192 = uint256(sqrtRatioX96) * sqrtRatioX96;
            quoteAmount = baseToken < quoteToken
                ? FullMath.mulDiv(ratioX192, baseAmount, 1 << 192)
                : FullMath.mulDiv(1 << 192, baseAmount, ratioX192);
        } else {
            uint256 ratioX128 = FullMath.mulDiv(
                sqrtRatioX96,
                sqrtRatioX96,
                1 << 64
            );
            quoteAmount = baseToken < quoteToken
                ? FullMath.mulDiv(ratioX128, baseAmount, 1 << 128)
                : FullMath.mulDiv(1 << 128, baseAmount, ratioX128);
        }
    }
}