#pragma once

#include <xrpl/beast/hash/hash_append.h>

#include <cstdint>

namespace xrpl {

namespace detail {

constexpr std::uint32_t
makeHashPrefix(char a, char b, char c)
{
    return (static_cast<std::uint32_t>(a) << 24) + (static_cast<std::uint32_t>(b) << 16) +
        (static_cast<std::uint32_t>(c) << 8);
}

}  // namespace detail

/**
 * Prefix for hashing functions.
 *
 * These prefixes are inserted before the source material used to generate
 * various hashes. This is done to put each hash in its own "space." This way,
 * two different types of objects with the same binary data will produce
 * different hashes.
 *
 * Each prefix is a 4-byte value with the last byte set to zero and the first
 * three bytes formed from the ASCII equivalent of some arbitrary string. For
 * example "TXN".
 *
 * @note Hash prefixes are part of the protocol; you cannot, arbitrarily,
 *       change the type or the value of any of these without causing breakage.
 */
enum class HashPrefix : std::uint32_t {
    /**
     * transaction plus signature to give transaction ID
     */
    TransactionId = detail::makeHashPrefix('T', 'X', 'N'),

    /**
     * transaction plus metadata
     */
    TxNode = detail::makeHashPrefix('S', 'N', 'D'),

    /**
     * account state
     */
    LeafNode = detail::makeHashPrefix('M', 'L', 'N'),

    /**
     * inner node in V1 tree
     */
    InnerNode = detail::makeHashPrefix('M', 'I', 'N'),

    /**
     * ledger master data for signing
     */
    LedgerMaster = detail::makeHashPrefix('L', 'W', 'R'),

    /**
     * inner transaction to sign
     */
    TxSign = detail::makeHashPrefix('S', 'T', 'X'),

    /**
     * inner transaction to multi-sign
     */
    TxMultiSign = detail::makeHashPrefix('S', 'M', 'T'),

    /**
     * validation for signing
     */
    Validation = detail::makeHashPrefix('V', 'A', 'L'),

    /**
     * proposal for signing
     */
    Proposal = detail::makeHashPrefix('P', 'R', 'P'),

    /**
     * Manifest
     */
    Manifest = detail::makeHashPrefix('M', 'A', 'N'),

    /**
     * Payment Channel Claim
     */
    PaymentChannelClaim = detail::makeHashPrefix('C', 'L', 'M'),

    /**
     * Batch
     */
    Batch = detail::makeHashPrefix('B', 'C', 'H'),
};

template <class Hasher>
void
hash_append(Hasher& h, HashPrefix const& hp) noexcept
{
    using beast::hash_append;
    hash_append(h, static_cast<std::uint32_t>(hp));
}

}  // namespace xrpl