import pg from 'pg';
import type { DB } from '../../server';

const { Pool } = pg;

let pool: pg.Pool | null = null;

export function getPgPool(): pg.Pool | null {
  if (pool) return pool;

  const connectionString =
    process.env.DATABASE_URL ||
    process.env.POSTGRES_URL ||
    process.env.DATABASE_PRIVATE_URL;

  const host = process.env.POSTGRES_HOST || process.env.SQL_HOST;
  const user = process.env.POSTGRES_USER || process.env.SQL_USER;
  const password = process.env.POSTGRES_PASSWORD || process.env.SQL_PASSWORD;
  const database = process.env.POSTGRES_DB || process.env.SQL_DB_NAME || 'balance_sheet_db';
  const port = parseInt(process.env.POSTGRES_PORT || '5432', 10);

  if (connectionString) {
    console.log('[PostgreSQL] Initializing connection pool via DATABASE_URL');
    pool = new Pool({
      connectionString,
      max: 10,
      idleTimeoutMillis: 30000,
      connectionTimeoutMillis: 5000,
    });
  } else if (host && user) {
    console.log(`[PostgreSQL] Initializing connection pool via host ${host}:${port}, db: ${database}`);
    pool = new Pool({
      host,
      port,
      user,
      password,
      database,
      max: 10,
      idleTimeoutMillis: 30000,
      connectionTimeoutMillis: 5000,
    });
  } else {
    console.log('[PostgreSQL] No DATABASE_URL or POSTGRES_HOST provided. Operating in file-backed mode.');
    return null;
  }

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

  return pool;
}

/**
 * Initializes PostgreSQL schema table if needed
 */
export async function initPgDatabase(): Promise<boolean> {
  const p = getPgPool();
  if (!p) return false;

  try {
    const client = await p.connect();
    try {
      await client.query(`
        CREATE TABLE IF NOT EXISTS app_portal_state (
          id VARCHAR(50) PRIMARY KEY,
          data JSONB NOT NULL,
          updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
        );
      `);
      console.log('[PostgreSQL] Database table app_portal_state ensured.');
      return true;
    } finally {
      client.release();
    }
  } catch (err) {
    console.error('[PostgreSQL] Initialization failed:', err);
    return false;
  }
}

/**
 * Load state from PostgreSQL
 */
export async function loadStateFromPg(): Promise<DB | null> {
  const p = getPgPool();
  if (!p) return null;

  try {
    const res = await p.query(`SELECT data FROM app_portal_state WHERE id = $1`, ['main_state']);
    if (res.rows.length > 0 && res.rows[0].data) {
      console.log('[PostgreSQL] Successfully restored portal state from PostgreSQL database.');
      return res.rows[0].data as DB;
    }
    return null;
  } catch (err) {
    console.error('[PostgreSQL] Error loading state:', err);
    return null;
  }
}

/**
 * Save state to PostgreSQL asynchronously
 */
export async function saveStateToPg(state: DB): Promise<void> {
  const p = getPgPool();
  if (!p) return;

  try {
    await p.query(
      `
      INSERT INTO app_portal_state (id, data, updated_at)
      VALUES ($1, $2, NOW())
      ON CONFLICT (id) DO UPDATE
      SET data = EXCLUDED.data, updated_at = NOW();
      `,
      ['main_state', JSON.stringify(state)]
    );
  } catch (err) {
    console.error('[PostgreSQL] Error saving state:', err);
  }
}