#include "db_manager.h"
#include "../src/debug_ui.h"
#include "../../lib/debug_config.h"
#include <openssl/sha.h>
#include <openssl/evp.h>
#include <cstring>
#include <QSet>
#include <QElapsedTimer>

/* ── helpers ── */

static QByteArray parseJsonField(const QByteArray& json, const char* key) {
    QByteArray pat = "\"" + QByteArray(key) + "\":\"";
    int idx = json.indexOf(pat);
    if (idx < 0) return {};
    idx += pat.size();
    int end = idx;
    while (end < json.size() && !(json[end] == '"' && (end == idx || json[end - 1] != '\\'))) end++;
    if (end > idx) return QByteArray(json.constData() + idx, end - idx);
    return {};
}

QString DbManager::sanitizeTableName(const QString& chId) {
    QString s;
    s.reserve(chId.size());
    for (int i = 0; i < chId.size(); i++) {
        QChar c = chId[i];
        if (c.isLetterOrNumber() || c == '_') s += c;
        else s += '_';
    }
    return s;
}

QString DbManager::msgTableName(const QString& chId) const {
    return QStringLiteral("msg_") + sanitizeTableName(chId);
}
QString DbManager::peersTableName(const QString& chId) const {
    return QStringLiteral("peers_") + sanitizeTableName(chId);
}

uint64_t DbManager::computeDatahash(const QByteArray& data) {
    uint8_t hash[32];
    SHA256((const unsigned char*)data.constData(), data.size(), hash);
    uint64_t dh; memcpy(&dh, hash, 8); return dh;
}

QByteArray DbManager::computeChainHash(const QByteArray& prevChain,
                                        qint64 timestamp, uint64_t datahash) {
    uint8_t buf[32 + 8 + 8];
    memcpy(buf, prevChain.constData(), 32);
    memcpy(buf + 32, &timestamp, 8);
    memcpy(buf + 40, &datahash, 8);
    uint8_t hash[32];
    SHA256(buf, 48, hash);
    return QByteArray((const char*)hash, 32);
}

QByteArray DbManager::getLastChainHash(const QString& chId) const {
    QString tbl = msgTableName(chId);
    QByteArray sql = QStringLiteral(
        "SELECT chain_hash FROM \"%1\" ORDER BY timestamp, author_signature DESC LIMIT 1")
        .arg(tbl).toUtf8();
    sqlite3_stmt* stmt = prepareOrNull(sql.constData());
    if (!stmt) return QByteArray(32, '\0');
    QByteArray r = (sqlite3_step(stmt) == SQLITE_ROW) ? colBlob(stmt, 0)
                                                       : QByteArray(32, '\0');
    sqlite3_finalize(stmt);
    return r.size() == 32 ? r : QByteArray(32, '\0');
}

/* ── lifecycle ── */

DbManager::DbManager(QObject* parent)
    : QObject(parent)
{
}

DbManager::~DbManager() {
    for (auto it = m_cursors.begin(); it != m_cursors.end(); ++it)
        sqlite3_finalize(it.value());
    m_cursors.clear();
    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "DbManager: destroyed");
}

sqlite3_stmt* DbManager::prepareOrNull(const char* sql) const {
    sqlite3_stmt* stmt = nullptr;
    if (sqlite3_prepare_v2(m_db, sql, -1, &stmt, nullptr) != SQLITE_OK) {
        const char* err = sqlite3_errmsg(m_db);
        if (!strstr(err, "no such table")) GUI_ERROR("prepare failed: %s — %s", sql, err);
        return nullptr;
    }
    return stmt;
}

QString DbManager::colText(sqlite3_stmt* stmt, int col) {
    return QString::fromUtf8(
        reinterpret_cast<const char*>(sqlite3_column_text(stmt, col)));
}

QByteArray DbManager::colBlob(sqlite3_stmt* stmt, int col) {
    int len = sqlite3_column_bytes(stmt, col);
    if (len <= 0) return {};
    return QByteArray(static_cast<const char*>(sqlite3_column_blob(stmt, col)), len);
}

/* ── channels ── */

QList<ChannelRow> DbManager::getChannels() const {
    QList<ChannelRow> list;
    sqlite3_stmt* stmt = prepareOrNull(
        "SELECT channel_id, name, owner_node_id,"
        " x25519_pubkey, x25519_privkey, ed25519_pubkey, ed25519_privkey, signature,"
        " last_read_msg_id, last_pos_msg_id, created_at"
        " FROM channels ORDER BY created_at ASC");
    if (!stmt) return list;
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        ChannelRow r;
        r.channelId       = colText(stmt, 0);
        r.name            = colText(stmt, 1);
        r.ownerNodeId     = (quint64)sqlite3_column_int64(stmt, 2);
        r.x25519_pubkey   = colBlob(stmt, 3);
        r.x25519_privkey  = colBlob(stmt, 4);
        r.ed25519_pubkey  = colBlob(stmt, 5);
        r.ed25519_privkey = colBlob(stmt, 6);
        r.signature       = colBlob(stmt, 7);
        r.lastReadMsgId   = sqlite3_column_int64(stmt, 8);
        r.lastPosMsgId    = sqlite3_column_int64(stmt, 9);
        r.createdAt       = sqlite3_column_int64(stmt, 10);
        list.append(r);
    }
    sqlite3_finalize(stmt);
    for (auto& ch : list) {
        ch.lastReadMsgId = getUiStateInt64(
            QStringLiteral("ch_%1_last_read").arg(ch.channelId), 0);
        ch.lastPosMsgId = getUiStateInt64(
            QStringLiteral("ch_%1_last_pos").arg(ch.channelId), 0);
        ch.unreadCount = getUnreadCount(ch.channelId, ch.lastReadMsgId);
    }
    return list;
}

/* ── messages (UI) ── */

QList<MessageRow> DbManager::getMessages(const QString& chId, int limit) const {
    QList<MessageRow> list;
    QString sql = QStringLiteral(
        "SELECT id, node_id, data, timestamp, chain_hash, author_signature"
        " FROM \"%1\" ORDER BY timestamp DESC, author_signature DESC LIMIT ?").arg(msgTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return list;
    sqlite3_bind_int(stmt, 1, limit);
    uint64_t myId = 0;
    { sqlite3_stmt* ms = prepareOrNull("SELECT node_id FROM local_identity WHERE id=1");
      if (ms) { if (sqlite3_step(ms) == SQLITE_ROW) myId = (uint64_t)sqlite3_column_int64(ms, 0); sqlite3_finalize(ms); } }
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        MessageRow m;
        m.id           = sqlite3_column_int64(stmt, 0);
        m.authorNodeId = (quint64)sqlite3_column_int64(stmt, 1);
        QByteArray jdata = colBlob(stmt, 2);
        m.contentType  = QString::fromUtf8(parseJsonField(jdata, "ct"));
        if (m.contentType.isEmpty()) m.contentType = "text/plain";
        m.data         = parseJsonField(jdata, "d");
        m.timestamp    = sqlite3_column_int64(stmt, 3);
        m.datahash     = 0;
        m.chainHash    = colBlob(stmt, 4);
        m.signature    = colBlob(stmt, 5);
        m.isOutgoing   = (m.authorNodeId == myId);
        m.isRead       = true;
        list.prepend(m);
    }
    sqlite3_finalize(stmt);
    return list;
}

QList<MessageRow> DbManager::getMessagesSince(const QString& chId, qint64 sinceId) const {
    QList<MessageRow> list;
    QString sql = QStringLiteral(
        "SELECT id, node_id, data, timestamp, chain_hash, author_signature"
        " FROM \"%1\" WHERE id > ? ORDER BY id ASC").arg(msgTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return list;
    sqlite3_bind_int64(stmt, 1, sinceId);
    uint64_t myId = m_myNodeId;
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        MessageRow m;
        m.id           = sqlite3_column_int64(stmt, 0);
        m.authorNodeId = (quint64)sqlite3_column_int64(stmt, 1);
        QByteArray jdata = colBlob(stmt, 2);
        m.data         = parseJsonField(jdata, "d");
        m.timestamp    = sqlite3_column_int64(stmt, 3);
        m.datahash     = 0;
        m.chainHash    = colBlob(stmt, 4);
        m.signature    = colBlob(stmt, 5);
        m.isOutgoing   = (m.authorNodeId == myId);
        m.isRead       = true;
        list.append(m);
    }
    sqlite3_finalize(stmt);
    return list;
}

/* ── peers (UI) ── */

int DbManager::getChannelMemberCount(const QString& chId) const {
    QString sql = QStringLiteral("SELECT COUNT(*) FROM \"%1\"").arg(peersTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return 0;
    int c = 0;
    if (sqlite3_step(stmt) == SQLITE_ROW) c = sqlite3_column_int(stmt, 0);
    sqlite3_finalize(stmt);
    return c;
}

QList<ChannelMember> DbManager::getChannelMembers(const QString& chId, int offset, int limit) const {
    QList<ChannelMember> list;
    QString sql = QStringLiteral(
        "SELECT p.node_id, COALESCE(n.online,0), COALESCE(n.name,''), COALESCE(p.local_nick,'')"
        " FROM \"%1\" p LEFT JOIN nodes n ON p.node_id=n.node_id"
        " ORDER BY n.online DESC, p.node_id ASC LIMIT ? OFFSET ?"
    ).arg(peersTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return list;
    sqlite3_bind_int(stmt, 1, limit);
    sqlite3_bind_int(stmt, 2, offset);
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        ChannelMember m;
        m.nodeId = (quint64)sqlite3_column_int64(stmt, 0);
        m.online = sqlite3_column_int(stmt, 1) != 0;
        m.name = colText(stmt, 2);
        m.localNick = colText(stmt, 3);
        list.append(m);
    }
    sqlite3_finalize(stmt);
    return list;
}

QMap<quint64, QString> DbManager::getLocalNicknames(const QString& chId) const {
    QMap<quint64, QString> m;
    if (!m_db) return m;
    QString sql = QStringLiteral(
        "SELECT node_id, local_nick FROM \"%1\" WHERE local_nick IS NOT NULL AND local_nick != ''"
    ).arg(peersTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return m;
    while (sqlite3_step(stmt) == SQLITE_ROW)
        m.insert((quint64)sqlite3_column_int64(stmt, 0), colText(stmt, 1));
    sqlite3_finalize(stmt);
    return m;
}

void DbManager::cleanOrphanedPeers(const QString& chId) const {
    if (!m_db) return;
    QString sql = QStringLiteral(
        "DELETE FROM \"%1\" WHERE node_id NOT IN (SELECT node_id FROM nodes)"
    ).arg(peersTableName(chId));
    char* err = nullptr;
    int rc = sqlite3_exec(m_db, sql.toUtf8().constData(), nullptr, nullptr, &err);
    if (rc != SQLITE_OK) {
        qWarning("cleanOrphanedPeers: %s", err ? err : "?");
        sqlite3_free(err);
    }
}

QString DbManager::getDisplayName(quint64 nodeId) const {
    sqlite3_stmt* st = prepareOrNull(
        "SELECT display_name FROM accounts WHERE node_id=?");
    if (st) {
        sqlite3_bind_int64(st, 1, (sqlite3_int64)nodeId);
        if (sqlite3_step(st) == SQLITE_ROW) {
            QString s = colText(st, 0);
            sqlite3_finalize(st);
            if (!s.isEmpty()) return s;
        } else sqlite3_finalize(st);
    }
    st = prepareOrNull("SELECT name FROM nodes WHERE node_id=?");
    if (st) {
        sqlite3_bind_int64(st, 1, (sqlite3_int64)nodeId);
        if (sqlite3_step(st) == SQLITE_ROW) {
            QString s = colText(st, 0);
            sqlite3_finalize(st);
            if (!s.isEmpty()) return s;
        } else sqlite3_finalize(st);
    }
    return QString("node_%1").arg(nodeId);
}

QByteArray DbManager::loadNodeInfo(quint64 nodeId) const {
    /* binary format: [x25519:32][ed25519:32][addr_count:1]([family:1][proto:1][addr_len:1][addr:4|16][port:2][rtt:2])... */
    sqlite3_stmt* stmt = prepareOrNull(
        "SELECT x25519_pubkey, ed25519_pubkey FROM nodes WHERE node_id=?");
    if (!stmt) return {};
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)nodeId);
    if (sqlite3_step(stmt) != SQLITE_ROW) { sqlite3_finalize(stmt); return {}; }
    QByteArray x25519 = colBlob(stmt, 0);
    QByteArray ed25519 = colBlob(stmt, 1);
    sqlite3_finalize(stmt);

    QByteArray result;
    result.append(x25519.isEmpty() ? QByteArray(32, '\0') : x25519);
    result.append(ed25519.isEmpty() ? QByteArray(32, '\0') : ed25519);

    /* запросить адреса */
    stmt = prepareOrNull(
        "SELECT family, protocol, address, port, rtt FROM node_addresses WHERE node_id=?");
    if (!stmt) { result.append('\0'); return result; }
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)nodeId);
    QByteArray addrsPart;
    uint8_t cnt = 0;
    while (sqlite3_step(stmt) == SQLITE_ROW && cnt < 255) {
        int family = sqlite3_column_int(stmt, 0);
        int proto  = sqlite3_column_int(stmt, 1);
        QByteArray addr = colBlob(stmt, 2);
        uint16_t port = (uint16_t)sqlite3_column_int(stmt, 3);
        int16_t rtt   = (int16_t)(sqlite3_column_int(stmt, 4));
        addrsPart.append((char)family);
        addrsPart.append((char)proto);
        addrsPart.append((char)addr.size());
        addrsPart.append(addr);
        addrsPart.append((const char*)&port, 2);
        addrsPart.append((const char*)&rtt, 2);
        cnt++;
    }
    sqlite3_finalize(stmt);
    result.append((char)cnt);
    result.append(addrsPart);
    return result;
}

QList<quint64> DbManager::getOnlinePeers() const {
    QList<quint64> peers;
    /* без is_online: получаем всех кроме себя */
    sqlite3_stmt* stmt = prepareOrNull("SELECT node_id FROM nodes WHERE node_id != ?");
    if (!stmt) return peers;
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)m_myNodeId);
    while (sqlite3_step(stmt) == SQLITE_ROW)
        peers.append((quint64)sqlite3_column_int64(stmt, 0));
    sqlite3_finalize(stmt);
    return peers;
}

QByteArray DbManager::getNodeEdPub(quint64 nodeId) const {
    sqlite3_stmt* stmt = prepareOrNull("SELECT ed25519_pubkey FROM nodes WHERE node_id=?");
    if (!stmt) return {};
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)nodeId);
    QByteArray r;
    if (sqlite3_step(stmt) == SQLITE_ROW) r = colBlob(stmt, 0);
    sqlite3_finalize(stmt);
    return r;
}

QList<NodeAddr> DbManager::getOnlinePeerAddresses(quint64 excludeNodeId) const {
    QList<NodeAddr> list;
    sqlite3_stmt* stmt = prepareOrNull(
        "SELECT na.node_id, na.family, na.protocol, na.address, na.port, na.rtt, na.addr_type"
        " FROM node_addresses na JOIN nodes n ON na.node_id = n.node_id"
        " WHERE na.addr_type=0 AND na.node_id != ?"
        " ORDER BY RANDOM()");
    if (!stmt) return list;
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)excludeNodeId);
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        NodeAddr a;
        a.nodeId   = (quint64)sqlite3_column_int64(stmt, 0);
        a.family   = sqlite3_column_int(stmt, 1);
        a.protocol = sqlite3_column_int(stmt, 2);
        a.address  = colBlob(stmt, 3);
        a.port     = (quint16)sqlite3_column_int(stmt, 4);
        a.rtt      = sqlite3_column_int(stmt, 5);
        a.addrType  = sqlite3_column_int(stmt, 6);
        list.append(a);
    }
    sqlite3_finalize(stmt);
    return list;
}

/* ── accounts ── */

QList<AccountRow> DbManager::getAccounts(bool contactsOnly) const {
    QList<AccountRow> list;
    const char* sql = contactsOnly
        ? "SELECT node_id, display_name, avatar_color, avatar_letter, is_contact"
          " FROM accounts WHERE is_contact=1 ORDER BY display_name"
        : "SELECT node_id, display_name, avatar_color, avatar_letter, is_contact"
          " FROM accounts ORDER BY display_name";
    sqlite3_stmt* stmt = prepareOrNull(sql);
    if (!stmt) return list;
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        AccountRow a;
        a.nodeId       = (quint64)sqlite3_column_int64(stmt, 0);
        a.displayName  = colText(stmt, 1);
        a.avatarColor  = colText(stmt, 2);
        a.avatarLetter = colText(stmt, 3);
        a.isContact    = sqlite3_column_int(stmt, 4) != 0;
        list.append(a);
    }
    sqlite3_finalize(stmt);
    return list;
}

AccountRow DbManager::getAccount(quint64 nodeId) const {
    AccountRow a;
    sqlite3_stmt* stmt = prepareOrNull(
        "SELECT node_id, display_name, avatar_color, avatar_letter, is_contact"
        " FROM accounts WHERE node_id=?");
    if (!stmt) return a;
    sqlite3_bind_int64(stmt, 1, (sqlite3_int64)nodeId);
    if (sqlite3_step(stmt) == SQLITE_ROW) {
        a.nodeId       = (quint64)sqlite3_column_int64(stmt, 0);
        a.displayName  = colText(stmt, 1);
        a.avatarColor  = colText(stmt, 2);
        a.avatarLetter = colText(stmt, 3);
        a.isContact    = sqlite3_column_int(stmt, 4) != 0;
    }
    sqlite3_finalize(stmt);
    return a;
}

/* ── ui_state ── */

QString DbManager::getUiState(const QString& key) const {
    sqlite3_stmt* stmt = prepareOrNull("SELECT value FROM ui_state WHERE key=?");
    if (!stmt) return {};
    sqlite3_bind_text(stmt, 1, key.toUtf8().constData(), -1, SQLITE_TRANSIENT);
    QString val;
    if (sqlite3_step(stmt) == SQLITE_ROW) val = colText(stmt, 0);
    sqlite3_finalize(stmt);
    return val;
}

int DbManager::getUiStateInt(const QString& key, int defaultVal) const {
    QString val = getUiState(key);
    if (val.isEmpty()) return defaultVal;
    bool ok = false;
    int v = val.toInt(&ok);
    return ok ? v : defaultVal;
}

qint64 DbManager::getUiStateInt64(const QString& key, qint64 defaultVal) const {
    QString val = getUiState(key);
    if (val.isEmpty()) return defaultVal;
    bool ok = false;
    qint64 v = val.toLongLong(&ok);
    return ok ? v : defaultVal;
}

int DbManager::getUnreadCount(const QString& channelId, qint64 lastReadMsgId) const {
    QString sql = QStringLiteral(
        "SELECT COUNT(*) FROM \"%1\" WHERE id > ?").arg(msgTableName(channelId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return 0;
    sqlite3_bind_int64(stmt, 1, lastReadMsgId);
    int count = 0;
    if (sqlite3_step(stmt) == SQLITE_ROW) count = sqlite3_column_int(stmt, 0);
    sqlite3_finalize(stmt);
    return count;
}

/* ── sync operations (read-only, for gui_bridge) ── */

QByteArray DbManager::syncListChannels() const {
    /* binary: [count:2]([chId_len:1][chId:var])... */
    QList<ChannelRow> chs = getChannels();
    QByteArray out;
    uint16_t cnt = (uint16_t)chs.size();
    out.append((const char*)&cnt, 2);
    for (auto& ch : chs) {
        QByteArray id = ch.channelId.toUtf8();
        out.append((char)(uint8_t)id.size());
        out.append(id);
    }
    return out;
}

QByteArray DbManager::syncCount(const QString& chId) const {
    QString sql = QStringLiteral("SELECT COUNT(*) FROM \"%1\"").arg(msgTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return {};
    uint32_t cnt = 0;
    if (sqlite3_step(stmt) == SQLITE_ROW) cnt = (uint32_t)sqlite3_column_int64(stmt, 0);
    sqlite3_finalize(stmt);
    QByteArray out; out.append((const char*)&cnt, 4); return out;
}

QByteArray DbManager::syncChainHashAt(const QString& chId, uint32_t pos) const {
    QString sql = QStringLiteral(
        "SELECT chain_hash FROM \"%1\" ORDER BY timestamp, author_signature ASC LIMIT 1 OFFSET ?")
        .arg(msgTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) return QByteArray(32, '\0');
    sqlite3_bind_int64(stmt, 1, pos);
    QByteArray r;
    if (sqlite3_step(stmt) == SQLITE_ROW) r = colBlob(stmt, 0);
    sqlite3_finalize(stmt);
    return r.size() == 32 ? r : QByteArray(32, '\0');
}

QByteArray DbManager::syncCursorOpen(const QString& chId) {
    QString sql = QStringLiteral(
        "SELECT timestamp, node_id, data, author_signature"
        " FROM \"%1\" ORDER BY timestamp, author_signature ASC").arg(msgTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) { QByteArray r(4, '\0'); return r; }
    uint32_t id = m_nextCursorId++;
    m_cursors[id] = stmt;
    QByteArray r; r.append((const char*)&id, 4); return r;
}

QByteArray DbManager::syncCursorNext(uint32_t cursorId) {
    auto it = m_cursors.find(cursorId);
    if (it == m_cursors.end()) return {};
    if (sqlite3_step(it.value()) != SQLITE_ROW) return {};

    /* return: [ts:8][dh:8][nid:8][ct_len:1][ct:var][data_len:4][data:var] */
    qint64 ts = sqlite3_column_int64(it.value(), 0);
    uint64_t nid = (uint64_t)sqlite3_column_int64(it.value(), 1);
    QByteArray jdata = colBlob(it.value(), 2);
    /* parse JSON from data column */
    auto jField = [](const QByteArray& j, const char* k) -> QByteArray {
        QByteArray p = "\"" + QByteArray(k) + "\":\"";
        int i = j.indexOf(p); if (i < 0) return {};
        i += p.size(); int e = i;
        while (e < j.size() && !(j[e] == '"' && (e == i || j[e - 1] != '\\'))) e++;
        return (e > i) ? QByteArray(j.constData() + i, e - i) : QByteArray();
    };
    QByteArray ct_raw = jField(jdata, "ct");
    QString ct = QString::fromUtf8(ct_raw);
    if (ct.isEmpty()) ct = "text/plain";
    QByteArray ddata = jField(jdata, "d");
    /* compute datahash for wire format compat */
    uint8_t dh_buf[32]; SHA256((const uint8_t*)ddata.constData(), ddata.size(), dh_buf);
    uint64_t dh; memcpy(&dh, dh_buf, 8);

    QByteArray out;
    out.append((const char*)&ts, 8);
    out.append((const char*)&dh, 8);
    out.append((const char*)&nid, 8);
    QByteArray ctb = ct.toUtf8();
    out.append((char)(uint8_t)ctb.size());
    out.append(ctb);
    uint32_t dLen = (uint32_t)ddata.size();
    out.append((const char*)&dLen, 4);
    out.append(ddata);
    return out;
}

void DbManager::syncCursorClose(uint32_t cursorId) {
    auto it = m_cursors.find(cursorId);
    if (it != m_cursors.end()) { sqlite3_finalize(it.value()); m_cursors.erase(it); }
}

QByteArray DbManager::syncListPeers(const QString& chId) const {
    /* binary: [count:2]([node_id:8])... */
    QString sql = QStringLiteral("SELECT node_id FROM \"%1\"").arg(peersTableName(chId));
    sqlite3_stmt* stmt = prepareOrNull(sql.toUtf8().constData());
    if (!stmt) { QByteArray r(2, '\0'); return r; }
    QList<uint64_t> ids;
    while (sqlite3_step(stmt) == SQLITE_ROW)
        ids.append((uint64_t)sqlite3_column_int64(stmt, 0));
    sqlite3_finalize(stmt);
    QByteArray out;
    uint16_t cnt = (uint16_t)ids.size();
    out.append((const char*)&cnt, 2);
    for (auto id : ids) out.append((const char*)&id, 8);
    return out;
}

/* ── integrity checks ── */

static int integrityCallback(void* data, int nCols, char** values, char** /*names*/) {
    auto* result = (IntegrityResult*)data;
    for (int i = 0; i < nCols; i++) {
        if (values[i]) {
            QString line = QString::fromUtf8(values[i]);
            if (result->message.isEmpty()) result->message = line;
            else if (line != "ok") result->errors.append(line);
        }
    }
    return 0;
}

static IntegrityResult runPragma(DbManager* self, const char* pragma) {
    IntegrityResult result;
    if (!self->m_db) {
        result.ok = false;
        result.message = "Database not open";
        return result;
    }
    QElapsedTimer timer;
    timer.start();
    char* errMsg = nullptr;
    int rc = sqlite3_exec(self->m_db, pragma, integrityCallback, &result, &errMsg);
    result.elapsedMs = (int)timer.elapsed();
    if (rc != SQLITE_OK) {
        result.ok = false;
        result.message = QString::fromUtf8(errMsg ? errMsg : "unknown error");
        sqlite3_free(errMsg);
        return result;
    }
    if (errMsg) sqlite3_free(errMsg);
    result.ok = (result.message == "ok" && result.errors.isEmpty());
    return result;
}

IntegrityResult DbManager::integrityCheckQuick() const {
    return runPragma(const_cast<DbManager*>(this), "PRAGMA quick_check");
}

IntegrityResult DbManager::integrityCheckFull() const {
    return runPragma(const_cast<DbManager*>(this), "PRAGMA integrity_check");
}

IntegrityResult DbManager::integrityOptimize() const {
    return runPragma(const_cast<DbManager*>(this), "PRAGMA optimize");
}