/**
 * Database Migration Script
 * Executes SQL migration files in order
 */

import { readFileSync, readdirSync } from 'fs';
import { join } from 'path';
import pg from 'pg';

const { Pool } = pg;

// Database configuration
const dbConfig = {
  host: process.env.DB_HOST || 'localhost',
  port: parseInt(process.env.DB_PORT || '5433', 10),
  database: process.env.DB_NAME || 'clinic_tests',
  user: process.env.DB_USER || 'developer',
  password: process.env.DB_PASSWORD || 'dev_password',
};

const MIGRATIONS_DIR = join(process.cwd(), 'src', 'db', 'migrations');

/**
 * Get list of migration files sorted by name
 */
function getMigrationFiles() {
  const files = readdirSync(MIGRATIONS_DIR)
    .filter((file) => file.endsWith('.sql'))
    .sort();

  return files;
}

/**
 * Create migrations tracking table if not exists
 */
async function ensureMigrationsTable(pool) {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS migrations (
      id SERIAL PRIMARY KEY,
      name VARCHAR(255) NOT NULL UNIQUE,
      executed_at TIMESTAMP DEFAULT NOW()
    )
  `);
}

/**
 * Get list of already executed migrations
 */
async function getExecutedMigrations(pool) {
  const result = await pool.query('SELECT name FROM migrations ORDER BY name');
  return result.rows.map((row) => row.name);
}

/**
 * Execute a single migration file
 */
async function executeMigration(pool, filename) {
  const filePath = join(MIGRATIONS_DIR, filename);
  const sql = readFileSync(filePath, 'utf-8');

  console.log(`Executing migration: ${filename}`);
  
  await pool.query('BEGIN');
  try {
    await pool.query(sql);
    await pool.query(
      'INSERT INTO migrations (name) VALUES ($1)',
      [filename]
    );
    await pool.query('COMMIT');
    console.log(`✓ Migration ${filename} completed successfully`);
  } catch (error) {
    await pool.query('ROLLBACK');
    console.error(`✗ Migration ${filename} failed:`, error.message);
    throw error;
  }
}

/**
 * Main migration function
 */
async function migrate() {
  const pool = new Pool(dbConfig);

  try {
    console.log('Connecting to database...');
    await pool.connect();
    console.log('Connected to database\n');

    // Ensure migrations table exists
    await ensureMigrationsTable(pool);

    // Get migration files and already executed migrations
    const migrationFiles = getMigrationFiles();
    const executedMigrations = await getExecutedMigrations(pool);

    console.log(`Found ${migrationFiles.length} migration file(s)`);
    console.log(`Already executed: ${executedMigrations.length} migration(s)\n`);

    // Execute pending migrations
    const pendingMigrations = migrationFiles.filter(
      (file) => !executedMigrations.includes(file)
    );

    if (pendingMigrations.length === 0) {
      console.log('All migrations already executed.');
    } else {
      console.log(`Pending migrations: ${pendingMigrations.length}\n`);
      
      for (const filename of pendingMigrations) {
        await executeMigration(pool, filename);
      }

      console.log(`\n✓ Successfully executed ${pendingMigrations.length} migration(s)`);
    }
  } catch (error) {
    console.error('\n✗ Migration failed:', error.message);
    process.exit(1);
  } finally {
    await pool.end();
  }
}

// Run migrations if this script is executed directly
migrate();