/**
 * database.js
 * JSON file-based database module (replaces database.php)
 * Uses atomic writes and file locking for concurrency safety.
 */

const fs = require("fs");
const path = require("path");
const crypto = require("crypto");

// Git sync for persistent storage on GitHub
let gitSync = null;
try {
  gitSync = require("./git-sync");
} catch (e) {
  // git-sync module not available, no-op
}

class Database {
  constructor(dataDir) {
    this.dataDir = dataDir;
    this.usersFile = path.join(dataDir, "users.json");
    this.keysFile = path.join(dataDir, "license_keys.json");
    this.hitsFile = path.join(dataDir, "hits.json");
    this.settingsFile = path.join(dataDir, "settings.json");
    this.binLibraryFile = path.join(dataDir, "bin_library.json");
    this.hitCountsFile = path.join(dataDir, "hit_counts.json");

    // Ensure data directory exists
    if (!fs.existsSync(dataDir)) {
      fs.mkdirSync(dataDir, { recursive: true });
    }
  }

  // ─── Atomic file read/write ───────────────────────────────────

  _readJson(filePath) {
    try {
      if (!fs.existsSync(filePath)) return [];
      const raw = fs.readFileSync(filePath, "utf-8");
      const parsed = JSON.parse(raw);
      return parsed;
    } catch (e) {
      return [];
    }
  }

  _writeJson(filePath, data) {
    const tmp = filePath + ".tmp." + process.pid;
    try {
      fs.writeFileSync(tmp, JSON.stringify(data, null, 2), "utf-8");
      fs.renameSync(tmp, filePath);
      // Schedule git sync after successful write
      if (gitSync && gitSync.scheduleSync) gitSync.scheduleSync();
      return true;
    } catch (e) {
      try {
        fs.unlinkSync(tmp);
      } catch (_) {}
      return false;
    }
  }

  _readObj(filePath) {
    try {
      if (!fs.existsSync(filePath)) return {};
      const raw = fs.readFileSync(filePath, "utf-8");
      return JSON.parse(raw) || {};
    } catch (e) {
      return {};
    }
  }

  // ─── Users ─────────────────────────────────────────────────────

  getAllUsers() {
    return this._readJson(this.usersFile);
  }

  getUser(userId) {
    const users = this.getAllUsers();
    return users.find((u) => String(u.user_id) === String(userId)) || null;
  }

  getUserByToken(token) {
    const users = this.getAllUsers();
    return users.find((u) => u.token === token) || null;
  }

  isTokenExists(token) {
    return !!this.getUserByToken(token);
  }

  createUser(data) {
    const users = this.getAllUsers();
    const user = {
      user_id: data.user_id,
      username: data.username || "",
      first_name: data.first_name || "",
      pfp_url: data.pfp_url || "",
      token: data.token || null,
      hits: 0,
      attempts: 0,
      banned: false,
      created_at: new Date().toISOString(),
      last_active: new Date().toISOString(),
    };
    users.push(user);
    this._writeJson(this.usersFile, users);
    return user;
  }

  updateUser(userId, updates) {
    const users = this.getAllUsers();
    const idx = users.findIndex((u) => String(u.user_id) === String(userId));
    if (idx === -1) return false;
    Object.assign(users[idx], updates);
    this._writeJson(this.usersFile, users);
    return true;
  }

  // ─── Hits ──────────────────────────────────────────────────────

  getAllHits() {
    return this._readJson(this.hitsFile);
  }

  addHitRecord(userId, details) {
    const hits = this.getAllHits();
    hits.push({
      user_id: String(userId),
      ...details,
      timestamp: new Date().toISOString(),
    });
    this._writeJson(this.hitsFile, hits);
  }

  getHitCounts(userId) {
    const counts = this._readObj(this.hitCountsFile);
    return {
      global_hits: counts.global || 0,
      user_hits: userId ? counts.users?.[String(userId)] || 0 : 0,
    };
  }

  incrementStat(userId, field) {
    const users = this.getAllUsers();
    const idx = users.findIndex((u) => String(u.user_id) === String(userId));
    if (idx === -1) return 0;

    users[idx][field] = (users[idx][field] || 0) + 1;
    this._writeJson(this.usersFile, users);

    // Also update hit_counts.json for fast O(1) reads
    if (field === "hits") {
      const counts = this._readObj(this.hitCountsFile);
      if (!counts.users) counts.users = {};
      counts.users[String(userId)] = users[idx].hits;
      counts.global = (counts.global || 0) + 1;
      this._writeJson(this.hitCountsFile, counts);
    }

    return users[idx][field];
  }

  getUserHits(userId, limit = 50) {
    const hits = this.getAllHits();
    return hits
      .filter((h) => String(h.user_id) === String(userId))
      .slice(-limit)
      .reverse();
  }

  getUserHitsTotal(userId) {
    const hits = this.getAllHits();
    return hits.filter((h) => String(h.user_id) === String(userId)).length;
  }

  // ─── License Keys ──────────────────────────────────────────────

  getAllLicenseKeys() {
    return this._readJson(this.keysFile);
  }

  createLicenseKey(key, version, active = true) {
    const keys = this.getAllLicenseKeys();
    keys.push({
      key,
      version,
      active,
      created_at: new Date().toISOString(),
    });
    this._writeJson(this.keysFile, keys);
  }

  validateLicenseKey(key) {
    const keys = this.getAllLicenseKeys();
    const found = keys.find((k) => k.key === key);
    if (!found) return { valid: false };
    return { valid: found.active !== false, version: found.version };
  }

  revokeLicenseKey(key) {
    const keys = this.getAllLicenseKeys();
    const idx = keys.findIndex((k) => k.key === key);
    if (idx === -1) return false;
    keys[idx].active = false;
    this._writeJson(this.keysFile, keys);
    return true;
  }

  activateLicenseKey(key) {
    const keys = this.getAllLicenseKeys();
    const idx = keys.findIndex((k) => k.key === key);
    if (idx === -1) return false;
    keys[idx].active = true;
    this._writeJson(this.keysFile, keys);
    return true;
  }

  deleteLicenseKey(key) {
    const keys = this.getAllLicenseKeys();
    const idx = keys.findIndex((k) => k.key === key);
    if (idx === -1) return false;
    keys.splice(idx, 1);
    this._writeJson(this.keysFile, keys);
    return true;
  }

  // ─── Settings ──────────────────────────────────────────────────

  getSetting(name) {
    const settings = this._readObj(this.settingsFile);
    return settings[name] || null;
  }

  setSetting(name, value) {
    const settings = this._readObj(this.settingsFile);
    settings[name] = value;
    this._writeJson(this.settingsFile, settings);
  }

  getAllSettings() {
    return this._readObj(this.settingsFile);
  }

  // ─── BIN Library ───────────────────────────────────────────────

  getBinLibrary() {
    return this._readJson(this.binLibraryFile);
  }

  saveBinLibrary(bins) {
    this._writeJson(this.binLibraryFile, bins);
  }

  addBinToLibrary(binObj) {
    const bins = this.getBinLibrary();
    bins.push(binObj);
    return this._writeJson(this.binLibraryFile, bins);
  }

  removeBinFromLibrary(binId, binNumber) {
    const bins = this.getBinLibrary();
    const idx = bins.findIndex(
      (b) => (binId && b.id === binId) || (binNumber && b.bin === binNumber),
    );
    if (idx === -1) return null;
    const removed = bins.splice(idx, 1)[0];
    this._writeJson(this.binLibraryFile, bins);
    return removed;
  }

  clearBinLibrary() {
    return this._writeJson(this.binLibraryFile, []);
  }

  // ─── Stats / Leaderboard ───────────────────────────────────────

  getGlobalStats() {
    const users = this.getAllUsers();
    const hits = this.getAllHits();
    let totalAttempts = 0;
    let totalHits = 0;
    for (const u of users) {
      totalAttempts += u.attempts || 0;
      totalHits += u.hits || 0;
    }
    return {
      total_users: users.length,
      total_attempts: totalAttempts,
      total_hits: totalHits,
    };
  }

  getTopUsers(limit = 10) {
    const users = this.getAllUsers();
    return users
      .filter((u) => (u.hits || 0) > 0)
      .sort((a, b) => (b.hits || 0) - (a.hits || 0))
      .slice(0, limit);
  }

  getUserRank(userId) {
    const users = this.getAllUsers();
    const sorted = users
      .filter((u) => (u.hits || 0) > 0)
      .sort((a, b) => (b.hits || 0) - (a.hits || 0));
    const idx = sorted.findIndex((u) => String(u.user_id) === String(userId));
    if (idx === -1) return null;
    return {
      rank: idx + 1,
      user_id: String(sorted[idx].user_id),
      username: sorted[idx].username || "",
      hits: sorted[idx].hits || 0,
    };
  }

  // ─── Admin ─────────────────────────────────────────────────────

  clearAllTokensAndStats() {
    const users = this.getAllUsers();
    let count = 0;
    for (const u of users) {
      u.token = null;
      u.hits = 0;
      u.attempts = 0;
      count++;
    }
    this._writeJson(this.usersFile, users);
    this._writeJson(this.hitCountsFile, { global: 0, users: {} });
    return count;
  }

  cleanFakeHits() {
    const hits = this.getAllHits();
    const before = hits.length;
    const cleaned = hits.filter(
      (h) => h.full_card && h.full_card.length >= 13 && h.full_card.includes("|"),
    );
    this._writeJson(this.hitsFile, cleaned);
    return before - cleaned.length;
  }

  resetDatabase() {
    const files = [this.usersFile, this.keysFile, this.hitsFile, this.hitCountsFile];
    let deleted = 0;
    for (const f of files) {
      if (fs.existsSync(f)) {
        fs.unlinkSync(f);
        deleted++;
      }
    }
    return deleted;
  }

  rebuildHitCounters() {
    const users = this.getAllUsers();
    const counts = { global: 0, users: {} };
    let usersWithHits = 0;
    for (const u of users) {
      const h = u.hits || 0;
      if (h > 0) {
        counts.users[String(u.user_id)] = h;
        counts.global += h;
        usersWithHits++;
      }
    }
    this._writeJson(this.hitCountsFile, counts);
    return { total_hits: counts.global, users_with_hits: usersWithHits };
  }

  migrateOldHitCounters() {
    // No-op for JS version (migration was for old PHP data)
  }

  autoSyncHitCounters() {
    if (!fs.existsSync(this.hitCountsFile)) {
      this.rebuildHitCounters();
    }
  }
}

module.exports = Database;