import Database from 'better-sqlite3';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';
import { existsSync, mkdirSync } from 'fs';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

/**
 * Initialize the SQLite database with all required tables
 * @param {string} dbPath - Path to the SQLite database file
 * @returns {Database} - The initialized database instance
 */
export function initDatabase(dbPath) {
  // Ensure data directory exists
  const dataDir = dirname(dbPath);
  if (!existsSync(dataDir)) {
    mkdirSync(dataDir, { recursive: true });
  }

  const db = new Database(dbPath);

  // Enable WAL mode for better concurrent performance
  db.pragma('journal_mode = WAL');

  // Create tables
  // API keys for agent authentication
  db.exec(`
    CREATE TABLE IF NOT EXISTS api_keys (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      key TEXT UNIQUE NOT NULL,
      name TEXT NOT NULL,
      device_prefix TEXT NOT NULL,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      last_used_at DATETIME
    );
    `);

  // --- MIGRATION: Drop old tables if they exist ---
  // User requested deleting old sensor data but keeping keys.
  db.exec(`
      DROP TABLE IF EXISTS sensor_data;
      DROP TABLE IF EXISTS sensor_data_10m;
      DROP TABLE IF EXISTS sensor_data_1h;
    `);

  // --- NEW SCHEMA: Sensor Events with RLE support ---
  db.exec(`
    CREATE TABLE IF NOT EXISTS sensor_events (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      timestamp DATETIME NOT NULL,
      until DATETIME,             -- NULL if point, Time if duplicated range end
      device TEXT NOT NULL,
      channel TEXT NOT NULL,
      value REAL,                 -- Nullable
      data TEXT,                  -- Nullable (JSON)
      data_type TEXT NOT NULL     -- 'number' or 'json'
    );

    CREATE INDEX IF NOT EXISTS idx_sensor_events_search 
      ON sensor_events(device, channel, timestamp);

    -- Phase 2: Authentication & Views
    CREATE TABLE IF NOT EXISTS users (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      username TEXT UNIQUE NOT NULL,
      password_hash TEXT NOT NULL,
      role TEXT NOT NULL CHECK(role IN ('admin', 'normal')),
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP
    );

    CREATE TABLE IF NOT EXISTS views (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT UNIQUE NOT NULL,
      config TEXT NOT NULL, -- JSON string of view configuration
      created_by INTEGER,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      FOREIGN KEY(created_by) REFERENCES users(id)
    );
  `);

  console.log('[DB] Database initialized successfully');
  return db;
}

export default { initDatabase };