library ExitPayloadReader {
    using RLPReader for bytes;
    using RLPReader for RLPReader.RLPItem;

    uint8 constant WORD_SIZE = 32;

    struct ExitPayload {
        RLPReader.RLPItem[] data;
    }

    struct Receipt {
        RLPReader.RLPItem[] data;
        bytes raw;
        uint256 logIndex;
    }

    struct Log {
        RLPReader.RLPItem data;
        RLPReader.RLPItem[] list;
    }

    struct LogTopics {
        RLPReader.RLPItem[] data;
    }

    // copy paste of private copy() from RLPReader to avoid changing of existing contracts
    function copy(
        uint256 src,
        uint256 dest,
        uint256 len
    ) private pure {
        if (len == 0) return;

        // copy as many word sizes as possible
        for (; len >= WORD_SIZE; len -= WORD_SIZE) {
            assembly {
                mstore(dest, mload(src))
            }

            src += WORD_SIZE;
            dest += WORD_SIZE;
        }

        // left over bytes. Mask is used to remove unwanted bytes from the word
        uint256 mask = 256**(WORD_SIZE - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask)) // zero out src
            let destpart := and(mload(dest), mask) // retrieve the bytes
            mstore(dest, or(destpart, srcpart))
        }
    }

    function toExitPayload(bytes memory data) internal pure returns (ExitPayload memory) {
        RLPReader.RLPItem[] memory payloadData = data.toRlpItem().toList();

        return ExitPayload(payloadData);
    }

    function getHeaderNumber(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[0].toUint();
    }

    function getBlockProof(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[1].toBytes();
    }

    function getBlockNumber(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[2].toUint();
    }

    function getBlockTime(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[3].toUint();
    }

    function getTxRoot(ExitPayload memory payload) internal pure returns (bytes32) {
        return bytes32(payload.data[4].toUint());
    }

    function getReceiptRoot(ExitPayload memory payload) internal pure returns (bytes32) {
        return bytes32(payload.data[5].toUint());
    }

    function getReceipt(ExitPayload memory payload) internal pure returns (Receipt memory receipt) {
        receipt.raw = payload.data[6].toBytes();
        RLPReader.RLPItem memory receiptItem = receipt.raw.toRlpItem();

        if (receiptItem.isList()) {
            // legacy tx
            receipt.data = receiptItem.toList();
        } else {
            // pop first byte before parsting receipt
            bytes memory typedBytes = receipt.raw;
            bytes memory result = new bytes(typedBytes.length - 1);
            uint256 srcPtr;
            uint256 destPtr;
            assembly {
                srcPtr := add(33, typedBytes)
                destPtr := add(0x20, result)
            }

            copy(srcPtr, destPtr, result.length);
            receipt.data = result.toRlpItem().toList();
        }

        receipt.logIndex = getReceiptLogIndex(payload);
        return receipt;
    }

    function getReceiptProof(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[7].toBytes();
    }

    function getBranchMaskAsBytes(ExitPayload memory payload) internal pure returns (bytes memory) {
        return payload.data[8].toBytes();
    }

    function getBranchMaskAsUint(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[8].toUint();
    }

    function getReceiptLogIndex(ExitPayload memory payload) internal pure returns (uint256) {
        return payload.data[9].toUint();
    }

    // Receipt methods
    function toBytes(Receipt memory receipt) internal pure returns (bytes memory) {
        return receipt.raw;
    }

    function getLog(Receipt memory receipt) internal pure returns (Log memory) {
        RLPReader.RLPItem memory logData = receipt.data[3].toList()[receipt.logIndex];
        return Log(logData, logData.toList());
    }

    // Log methods
    function getEmitter(Log memory log) internal pure returns (address) {
        return RLPReader.toAddress(log.list[0]);
    }

    function getTopics(Log memory log) internal pure returns (LogTopics memory) {
        return LogTopics(log.list[1].toList());
    }

    function getData(Log memory log) internal pure returns (bytes memory) {
        return log.list[2].toBytes();
    }

    function toRlpBytes(Log memory log) internal pure returns (bytes memory) {
        return log.data.toRlpBytes();
    }

    // LogTopics methods
    function getField(LogTopics memory topics, uint256 index) internal pure returns (RLPReader.RLPItem memory) {
        return topics.data[index];
    }
}
function getField(LogTopics memory topics, uint256 index) internal pure returns (RLPReader.RLPItem memory) {
        return topics.data[index];
    }
// LogTopics methods