const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { DatabaseSync } = require('node:sqlite');

const DB_PATH = process.env.DB_PATH || path.join(__dirname, 'data', 'app.db');
fs.mkdirSync(path.dirname(DB_PATH), { recursive: true });

const db = new DatabaseSync(DB_PATH);

db.exec(`
  CREATE TABLE IF NOT EXISTS streamers (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    google_id TEXT UNIQUE NOT NULL,
    email TEXT NOT NULL,
    name TEXT NOT NULL,
    picture TEXT,
    overlay_token TEXT UNIQUE NOT NULL,
    sender_token TEXT UNIQUE NOT NULL,
    tts_voice TEXT NOT NULL DEFAULT 'ru-RU-DmitryNeural',
    display_duration_seconds INTEGER NOT NULL DEFAULT 10,
    ai_name TEXT NOT NULL DEFAULT 'Альтушка Ирина',
    created_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS viewer_names (
    streamer_id INTEGER NOT NULL,
    google_id TEXT NOT NULL,
    display_name TEXT NOT NULL,
    updated_at INTEGER NOT NULL,
    PRIMARY KEY (streamer_id, google_id)
  );

  CREATE TABLE IF NOT EXISTS viewer_visits (
    streamer_id INTEGER NOT NULL,
    google_id TEXT NOT NULL,
    first_seen_at INTEGER NOT NULL,
    last_seen_at INTEGER NOT NULL,
    PRIMARY KEY (streamer_id, google_id)
  );

  CREATE TABLE IF NOT EXISTS messages (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    streamer_id INTEGER NOT NULL,
    google_id TEXT NOT NULL,
    created_at INTEGER NOT NULL
  );
`);

// Idempotent migration for databases created before display_duration_seconds existed.
const existingColumns = db.prepare('PRAGMA table_info(streamers)').all().map((c) => c.name);
if (!existingColumns.includes('display_duration_seconds')) {
  db.exec('ALTER TABLE streamers ADD COLUMN display_duration_seconds INTEGER NOT NULL DEFAULT 10');
}
if (!existingColumns.includes('ai_name')) {
  db.exec("ALTER TABLE streamers ADD COLUMN ai_name TEXT NOT NULL DEFAULT 'Альтушка Ирина'");
}

function generateToken() {
  return crypto.randomBytes(16).toString('hex');
}

function findStreamerByGoogleId(googleId) {
  return db.prepare('SELECT * FROM streamers WHERE google_id = ?').get(googleId);
}

function findStreamerByOverlayToken(token) {
  return db.prepare('SELECT * FROM streamers WHERE overlay_token = ?').get(token);
}

function findStreamerBySenderToken(token) {
  return db.prepare('SELECT * FROM streamers WHERE sender_token = ?').get(token);
}

function createStreamer({ googleId, email, name, picture }) {
  const overlayToken = generateToken();
  const senderToken = generateToken();
  db.prepare(
    `INSERT INTO streamers (google_id, email, name, picture, overlay_token, sender_token, created_at)
     VALUES (?, ?, ?, ?, ?, ?, ?)`
  ).run(googleId, email, name, picture || null, overlayToken, senderToken, Date.now());
  return findStreamerByGoogleId(googleId);
}

function getOrCreateStreamerByGoogle({ googleId, email, name, picture }) {
  return findStreamerByGoogleId(googleId) || createStreamer({ googleId, email, name, picture });
}

function getViewerName(streamerId, googleId) {
  const row = db
    .prepare('SELECT display_name FROM viewer_names WHERE streamer_id = ? AND google_id = ?')
    .get(streamerId, googleId);
  return row ? row.display_name : null;
}

function setViewerName(streamerId, googleId, displayName) {
  db.prepare(
    `INSERT INTO viewer_names (streamer_id, google_id, display_name, updated_at)
     VALUES (?, ?, ?, ?)
     ON CONFLICT(streamer_id, google_id) DO UPDATE SET display_name = excluded.display_name, updated_at = excluded.updated_at`
  ).run(streamerId, googleId, displayName, Date.now());
}

function updateDisplayDuration(streamerId, seconds) {
  db.prepare('UPDATE streamers SET display_duration_seconds = ? WHERE id = ?').run(seconds, streamerId);
}

function updateAiName(streamerId, aiName) {
  db.prepare('UPDATE streamers SET ai_name = ? WHERE id = ?').run(aiName, streamerId);
}

function recordVisit(streamerId, googleId) {
  const now = Date.now();
  db.prepare(
    `INSERT INTO viewer_visits (streamer_id, google_id, first_seen_at, last_seen_at)
     VALUES (?, ?, ?, ?)
     ON CONFLICT(streamer_id, google_id) DO UPDATE SET last_seen_at = excluded.last_seen_at`
  ).run(streamerId, googleId, now, now);
}

function recordMessage(streamerId, googleId) {
  db.prepare(
    'INSERT INTO messages (streamer_id, google_id, created_at) VALUES (?, ?, ?)'
  ).run(streamerId, googleId, Date.now());
}

function getStreamerStats(streamerId) {
  const visitors = db.prepare('SELECT COUNT(*) AS c FROM viewer_visits WHERE streamer_id = ?').get(streamerId).c;
  const messages = db.prepare('SELECT COUNT(*) AS c FROM messages WHERE streamer_id = ?').get(streamerId).c;
  const uniqueSenders = db
    .prepare('SELECT COUNT(DISTINCT google_id) AS c FROM messages WHERE streamer_id = ?')
    .get(streamerId).c;
  return { visitors, messages, uniqueSenders };
}

module.exports = {
  findStreamerByOverlayToken,
  findStreamerBySenderToken,
  getOrCreateStreamerByGoogle,
  getViewerName,
  setViewerName,
  updateDisplayDuration,
  updateAiName,
  recordVisit,
  recordMessage,
  getStreamerStats,
};