// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0;
pragma experimental ABIEncoderV2;

// https://github.com/makerdao/multicall/blob/master/src/Multicall.sol

/// @title Multicall - Aggregate results from multiple read-only function calls
/// @author Michael Elliot <mike@makerdao.com>
/// @author Joshua Levine <joshua@makerdao.com>
/// @author Nick Johnson <arachnid@notdot.net>

contract Multicall {
    struct Call {
        address target;
        bytes callData;
    }

    function aggregate(Call[] memory calls) public returns (uint256 blockNumber, bytes[] memory returnData) {
        blockNumber = block.number;
        returnData = new bytes[](calls.length);
        for (uint256 i = 0; i < calls.length; i++) {
            (bool success, bytes memory ret) = calls[i].target.call(calls[i].callData);
            require(success);
            returnData[i] = ret;
        }
    }
    // Helper functions
    function getEthBalance(address addr) public view returns (uint256 balance) {
        balance = addr.balance;
    }

    function getBlockHash(uint256 blockNumber) public view returns (bytes32 blockHash) {
        blockHash = blockhash(blockNumber);
    }

    function getLastBlockHash() public view returns (bytes32 blockHash) {
        blockHash = blockhash(block.number - 1);
    }

    function getCurrentBlockTimestamp() public view returns (uint256 timestamp) {
        timestamp = block.timestamp;
    }

    function getCurrentBlockDifficulty() public view returns (uint256 difficulty) {
        difficulty = block.difficulty;
    }

    function getCurrentBlockGasLimit() public view returns (uint256 gaslimit) {
        gaslimit = block.gaslimit;
    }

    function getCurrentBlockCoinbase() public view returns (address coinbase) {
        coinbase = block.coinbase;
    }
}
