// DragonX Wallet - ImGui Edition
// Copyright 2024-2026 The Hush Developers
// Released under the GPLv3

#include "transaction_history_store_policy.h"

#include <cstring>

namespace dragonx {
namespace data {

namespace {

constexpr std::uint64_t kOffset = 0xcbf29ce484222325ULL;
constexpr std::uint64_t kMul = 0x9E3779B97F4A7C15ULL;   // odd

static_assert(sizeof(double) == sizeof(std::uint64_t), "amount bit pattern is hashed as 64 bits");

// 8 bytes per step: a 5k-row wallet (~1.5 MB of row text) hashes in about a millisecond. Endianness-dependent
// on purpose: the value never leaves the process.
inline void mixBytes(std::uint64_t& h, const void* data, std::size_t n)
{
    const auto* b = static_cast<const unsigned char*>(data);
    while (n >= 8) {
        std::uint64_t w;
        std::memcpy(&w, b, 8);
        h = (h ^ w) * kMul;
        h ^= h >> 32;
        b += 8;
        n -= 8;
    }
    if (n) {
        std::uint64_t w = 0;
        std::memcpy(&w, b, n);
        h = (h ^ w ^ (static_cast<std::uint64_t>(n) << 56)) * kMul;
        h ^= h >> 32;
    }
}
inline void mixU64(std::uint64_t& h, std::uint64_t v) { mixBytes(h, &v, sizeof(v)); }
inline void mixStr(std::uint64_t& h, const std::string& s)
{
    mixU64(h, s.size());   // length first: ("ab","c") != ("a","bc")
    mixBytes(h, s.data(), s.size());
}
inline std::uint64_t finalize(std::uint64_t x)   // splitmix64 finalizer
{
    x += 0x9e3779b97f4a7c15ULL;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9ULL;
    x = (x ^ (x >> 27)) * 0x94d049bb133111ebULL;
    return x ^ (x >> 31);
}
// The thresholds a stored row is read at: transactions_tab.cpp:788-793 / transaction_details_dialog.cpp:80-85
// (0 pending, < 10 counted, >= 100 mature for mined), mining_earnings.cpp:102 (>= 100), the confirmed-tx cache
// (>= 10, app_network.cpp:1915) and conflicted (< 0, network_refresh_service.cpp:1470).
inline std::uint64_t confirmationBucket(int c)
{
    return c < 0 ? 0 : c == 0 ? 1 : c < 10 ? 2 : c < 100 ? 3 : 4;
}

} // namespace

HistorySnapshotSig historySnapshotSignature(const std::vector<TransactionInfo>& transactions,
                                            const std::unordered_set<std::string>& skipTxids,
                                            const std::string& walletHash,
                                            std::uint64_t keyId,
                                            const std::unordered_map<std::string, int>& shieldedScanHeights,
                                            int tipHeight,
                                            const std::string& tipHash,
                                            int sentHeight,
                                            int sentAnchorHeight,
                                            const std::string& sentAnchorHash,
                                            const std::unordered_set<std::string>& sentBacklog)
{
    HistorySnapshotSig sig;
    std::uint64_t rowSum = 0;     // sums: commutative, so row order does not matter; duplicates still count
    std::uint64_t exactSum = 0;
    for (const auto& tx : transactions) {
        if (!skipTxids.empty() && skipTxids.count(tx.txid)) continue;
        std::uint64_t h = kOffset;
        mixStr(h, tx.txid);
        mixStr(h, tx.type);
        std::uint64_t amountBits = 0;
        std::memcpy(&amountBits, &tx.amount, sizeof(amountBits));
        mixU64(h, amountBits);
        mixU64(h, static_cast<std::uint64_t>(tx.timestamp));
        mixStr(h, tx.address);
        mixStr(h, tx.from_address);
        mixStr(h, tx.memo);
        std::uint64_t e = h;
        mixU64(h, confirmationBucket(tx.confirmations));
        mixU64(e, static_cast<std::uint64_t>(static_cast<std::int64_t>(tx.confirmations)));
        rowSum += finalize(h);
        exactSum += finalize(e);
        ++sig.rows;
    }
    std::uint64_t backlogSum = 0;   // order-independent: a set, so sum is commutative
    for (const auto& txid : sentBacklog) {
        if (txid.empty()) continue;
        std::uint64_t h = kOffset;
        mixStr(h, txid);
        backlogSum += finalize(h);
    }
    std::uint64_t c = kOffset;
    mixU64(c, rowSum);
    mixU64(c, sig.rows);
    mixStr(c, walletHash);
    mixU64(c, keyId);
    mixU64(c, backlogSum);
    sig.content = finalize(c);

    std::uint64_t heightSum = 0;
    for (const auto& [address, height] : shieldedScanHeights) {
        if (address.empty() || height < 0) continue;   // exactly what replace() persists
        std::uint64_t h = kOffset;
        mixStr(h, address);
        mixU64(h, static_cast<std::uint64_t>(height));
        heightSum += finalize(h);
    }
    std::uint64_t s = kOffset;
    mixU64(s, heightSum);
    mixU64(s, exactSum);
    mixU64(s, static_cast<std::uint64_t>(static_cast<std::int64_t>(tipHeight)));
    mixStr(s, tipHash);
    mixU64(s, static_cast<std::uint64_t>(static_cast<std::int64_t>(sentHeight)));
    mixU64(s, static_cast<std::uint64_t>(static_cast<std::int64_t>(sentAnchorHeight)));
    mixStr(s, sentAnchorHash);
    sig.slow = finalize(s);
    return sig;
}

HistoryStoreAction decideHistoryStore(const HistoryStoreInput& in)
{
    const bool contentDirty = !in.haveStored || in.stored.content != in.current.content;
    const bool slowDirty = in.haveStored && in.stored.slow != in.current.slow;
    if (in.mode == HistoryStoreMode::Now)
        return (contentDirty || slowDirty) ? HistoryStoreAction::Store : HistoryStoreAction::Skip;
    if (contentDirty)
        return in.sinceLastSubmitSec >= kHistoryMinStoreIntervalSec ? HistoryStoreAction::Store
                                                                    : HistoryStoreAction::Defer;
    if (slowDirty && in.sinceLastSubmitSec >= kHistorySlowStoreIntervalSec) return HistoryStoreAction::Store;
    return HistoryStoreAction::Skip;
}

} // namespace data
} // namespace dragonx