const fs = require('fs');
const path = require('path');
const DatabaseClient = require('./db');
const config = require('../../config/app');

const LOCK_MIGRATION_FILE = '002_outbox_locks.sql';

async function ensureMigrationTable(db) {
  await db.exec(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      filename TEXT PRIMARY KEY,
      applied_at TEXT NOT NULL DEFAULT (datetime('now'))
    );
  `);
}

async function migrationIsApplied(db, filename) {
  const row = await db.get(
    'SELECT filename FROM schema_migrations WHERE filename = ? LIMIT 1',
    [filename]
  );
  return Boolean(row);
}

async function markMigrationApplied(db, filename) {
  await db.run(
    'INSERT OR IGNORE INTO schema_migrations (filename) VALUES (?)',
    [filename]
  );
}

async function applyOutboxLockMigration(db) {
  const columns = await db.all('PRAGMA table_info(outbox_result)');
  const columnNames = new Set(columns.map((column) => column.name));

  if (!columnNames.has('locked_at')) {
    await db.exec('ALTER TABLE outbox_result ADD COLUMN locked_at INTEGER NULL;');
  }

  if (!columnNames.has('locked_by')) {
    await db.exec('ALTER TABLE outbox_result ADD COLUMN locked_by TEXT NULL;');
  }
}

async function migrate() {
  const db = new DatabaseClient(config.db);
  const migrationsDir = path.join(__dirname, '..', '..', 'db', 'migrations');
  const files = fs
    .readdirSync(migrationsDir)
    .filter((name) => name.endsWith('.sql'))
    .sort();

  await ensureMigrationTable(db);

  for (const file of files) {
    if (await migrationIsApplied(db, file)) {
      continue;
    }

    if (file === LOCK_MIGRATION_FILE) {
      await applyOutboxLockMigration(db);
      await markMigrationApplied(db, file);
      continue;
    }

    const payload = fs.readFileSync(path.join(migrationsDir, file), 'utf8');
    await db.exec(payload);
    await markMigrationApplied(db, file);
  }

  await db.close();
}

if (require.main === module) {
  migrate()
    .then(() => console.log('migrations applied'))
    .catch((err) => {
      console.error('migration failed', err);
      process.exit(1);
    });
}

module.exports = migrate;