// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.14;

import "@yield-protocol/yieldspace-interfaces/IPool.sol";
import "../YieldMath.sol";


library YieldMathExtensions {

    /// @dev Calculate the invariant for this pool
    function invariant(IPool pool) external view returns (uint128) {
        uint32 maturity = pool.maturity();
        uint32 timeToMaturity = (maturity > uint32(block.timestamp)) ? maturity - uint32(block.timestamp) : 0;
        return YieldMath.invariant(
            pool.getBaseBalance(),
            pool.getFYTokenBalance(),
            pool.totalSupply(),
            timeToMaturity,
            pool.ts()
        );
    }

    /// @dev max amount of fyTokens that can be bought from the pool
    function maxFYTokenOut(IPool pool) external view returns (uint128) {
        (uint112 _baseCached, uint112 _fyTokenCached,) = pool.getCache();
        uint96 scaleFactor = pool.scaleFactor();
        return YieldMath.maxFYTokenOut(
            _baseCached * scaleFactor,
            _fyTokenCached * scaleFactor,
            pool.maturity() - uint32(block.timestamp),
            pool.ts(),
            pool.g1()
        ) / scaleFactor;
    }

    /// @dev max amount of fyTokens that can be sold into the pool
    function maxFYTokenIn(IPool pool) external view returns (uint128) {
        (uint112 _baseCached, uint112 _fyTokenCached,) = pool.getCache();
        uint96 scaleFactor = pool.scaleFactor();
        return YieldMath.maxFYTokenIn(
            _baseCached * scaleFactor,
            _fyTokenCached * scaleFactor,
            pool.maturity() - uint32(block.timestamp),
            pool.ts(),
            pool.g2()
        ) / scaleFactor;
    }

    /// @dev max amount of Base that can be sold to the pool
    function maxBaseIn(IPool pool) external view returns (uint128) {
        (uint112 _baseCached, uint112 _fyTokenCached,) = pool.getCache();
        uint96 scaleFactor = pool.scaleFactor();
        return YieldMath.maxBaseIn(
            _baseCached * scaleFactor,
            _fyTokenCached * scaleFactor,
            pool.maturity() - uint32(block.timestamp),
            pool.ts(),
            pool.g1()
        ) / scaleFactor;
    }

    /// @dev max amount of Base that can be bought from the pool
    function maxBaseOut(IPool pool) external view returns (uint128) {
        (uint112 _baseCached, uint112 _fyTokenCached,) = pool.getCache();
        uint96 scaleFactor = pool.scaleFactor();
        return YieldMath.maxBaseOut(
            _baseCached * scaleFactor,
            _fyTokenCached * scaleFactor,
            pool.maturity() - uint32(block.timestamp),
            pool.ts(),
            pool.g2()
        ) / scaleFactor;
    }
}