// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./AddressUpgradeable.sol";
import "../proxy/utils/Initializable.sol";

/**
 * @dev Provides a function to batch together multiple calls in a single external call.
 *
 * _Available since v4.1._
 */
abstract contract MulticallUpgradeable is Initializable {
    function __Multicall_init() internal initializer {
        __Multicall_init_unchained();
    }

    function __Multicall_init_unchained() internal initializer {
    }
    /**
     * @dev Receives and executes a batch of function calls on this contract.
     */
    function multicall(bytes[] calldata data) external returns (bytes[] memory results) {
        results = new bytes[](data.length);
        for (uint256 i = 0; i < data.length; i++) {
            results[i] = _functionDelegateCall(address(this), data[i]);
        }
        return results;
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function _functionDelegateCall(address target, bytes memory data) private returns (bytes memory) {
        require(AddressUpgradeable.isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, "Address: low-level delegate call failed");
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
    uint256[50] private __gap;
}
