/**
 * CannaiQ Database Connection
 *
 * All database access for the CannaiQ platform goes through this module.
 *
 * SINGLE DATABASE ARCHITECTURE:
 * - All services (auth, orchestrator, crawlers, admin) use this ONE database
 * - States are modeled via states table + state_id on dispensaries (not separate DBs)
 *
 * CONFIGURATION (in priority order):
 * 1. CANNAIQ_DB_URL - Full connection string (preferred)
 * 2. Individual vars: CANNAIQ_DB_HOST, CANNAIQ_DB_PORT, CANNAIQ_DB_NAME, CANNAIQ_DB_USER, CANNAIQ_DB_PASS
 * 3. DATABASE_URL - Legacy fallback for K8s compatibility
 *
 * IMPORTANT:
 * - Do NOT create separate pools elsewhere
 * - All services should import from this module
 */

import { Pool, PoolClient } from 'pg';

/**
 * Get the database connection string from environment variables.
 * Supports multiple configuration methods with fallback for legacy compatibility.
 */
function getConnectionString(): string {
  // Priority 1: Full CANNAIQ connection URL
  if (process.env.CANNAIQ_DB_URL) {
    return process.env.CANNAIQ_DB_URL;
  }

  // Priority 2: Build from individual CANNAIQ env vars
  const host = process.env.CANNAIQ_DB_HOST;
  const port = process.env.CANNAIQ_DB_PORT;
  const name = process.env.CANNAIQ_DB_NAME;
  const user = process.env.CANNAIQ_DB_USER;
  const pass = process.env.CANNAIQ_DB_PASS;

  if (host && port && name && user && pass) {
    return `postgresql://${user}:${pass}@${host}:${port}/${name}`;
  }

  // Priority 3: Fallback to DATABASE_URL for legacy/K8s compatibility
  if (process.env.DATABASE_URL) {
    return process.env.DATABASE_URL;
  }

  // Report what's missing
  const required = ['CANNAIQ_DB_HOST', 'CANNAIQ_DB_PORT', 'CANNAIQ_DB_NAME', 'CANNAIQ_DB_USER', 'CANNAIQ_DB_PASS'];
  const missing = required.filter((key) => !process.env[key]);

  throw new Error(
    `[CannaiQ DB] Missing database configuration.\n` +
      `Set CANNAIQ_DB_URL, DATABASE_URL, or all of: ${missing.join(', ')}`
  );
}

let pool: Pool | null = null;

/**
 * Get the CannaiQ database pool (singleton)
 *
 * This is the canonical pool for all CannaiQ services.
 * Do NOT create separate pools elsewhere.
 */
export function getPool(): Pool {
  if (!pool) {
    pool = new Pool({
      connectionString: getConnectionString(),
      max: 10,
      idleTimeoutMillis: 30000,
      connectionTimeoutMillis: 5000,
    });

    pool.on('error', (err) => {
      console.error('[CannaiQ DB] Unexpected error on idle client:', err);
    });

    console.log('[CannaiQ DB] Pool initialized');
  }
  return pool;
}

/**
 * @deprecated Use getPool() instead
 */
export function getDutchieAZPool(): Pool {
  console.warn('[CannaiQ DB] getDutchieAZPool() is deprecated. Use getPool() instead.');
  return getPool();
}

/**
 * Execute a query on the CannaiQ database
 */
export async function query<T = any>(text: string, params?: any[]): Promise<{ rows: T[]; rowCount: number }> {
  const p = getPool();
  const result = await p.query(text, params);
  return { rows: result.rows as T[], rowCount: result.rowCount || 0 };
}

/**
 * Get a client from the pool for transaction use
 */
export async function getClient(): Promise<PoolClient> {
  const p = getPool();
  return p.connect();
}

/**
 * Close the pool connection
 */
export async function closePool(): Promise<void> {
  if (pool) {
    await pool.end();
    pool = null;
    console.log('[CannaiQ DB] Pool closed');
  }
}

/**
 * Check if the database is accessible
 */
export async function healthCheck(): Promise<boolean> {
  try {
    const result = await query('SELECT 1 as ok');
    return result.rows.length > 0 && result.rows[0].ok === 1;
  } catch (error) {
    console.error('[CannaiQ DB] Health check failed:', error);
    return false;
  }
}