const fs = require('fs');
const path = require('path');
const pool = require('./db');

async function migrate() {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      filename TEXT PRIMARY KEY,
      applied_at TIMESTAMPTZ DEFAULT now()
    )
  `);

  const dir = path.join(__dirname, '..', 'migrations');
  const files = fs.readdirSync(dir).filter((f) => f.endsWith('.sql')).sort();

  for (const file of files) {
    const { rows } = await pool.query('SELECT 1 FROM schema_migrations WHERE filename = $1', [file]);
    if (rows.length) continue;

    const sql = fs.readFileSync(path.join(dir, file), 'utf8');
    console.log(`[migrate] applying ${file}`);
    const client = await pool.connect();
    try {
      await client.query('BEGIN');
      await client.query(sql);
      await client.query('INSERT INTO schema_migrations (filename) VALUES ($1)', [file]);
      await client.query('COMMIT');
    } catch (err) {
      await client.query('ROLLBACK');
      throw err;
    } finally {
      client.release();
    }
  }
}

module.exports = migrate;