Smart Contract | How to Judge From and to Addresses Are Operations of Adding and Removing Liquidity

contract LiquidityActivity {
    
    //check address is a add liquidity address
    function isAddLiquidity(address from, address to, address liquidityPoolAddress) external view returns (bool) {
        IUniswapV2Pair pool = IUniswapV2Pair(liquidityPoolAddress);

        // Check if `from` is the liquidity pool contract and `to` is a user
        if (from == liquidityPoolAddress && !isContract(to)) {
            // Check if `to` holds both tokens of the pool (add liquidity)
            return (to == pool.token0() || to == pool.token1());
        }

        return false;
    }
    
    //check address is remove liquidity address
    function isRemoveLiquidity(address from, address to, address liquidityPoolAddress) external view returns (bool) {
        IUniswapV2Pair pool = IUniswapV2Pair(liquidityPoolAddress);

        // Check if `to` is the liquidity pool contract and `from` is a user
        if (to == liquidityPoolAddress && !isContract(from)) {
            // Check if `from` holds both tokens of the pool (remove liquidity)
            return (from == pool.token0() || from == pool.token1());
        }

        return false;
    }

    // check address is a contract address
    function isContract(address addr) internal view returns (bool) {
        uint32 size;
        assembly {
            size := extcodesize(addr)
        }
        return (size > 0);
    }
}