index.js

async function init ({ db: r, dbName, metadata, logger }) {
  const databases = await r.dbList().run()

  if (!databases.includes(dbName)) {
    logger.info('Creating database %s.', dbName)

    await r.dbCreate(dbName).run()
  } else {
    logger.debug('Database %s already exists.', dbName)
  }

  const tables = await r.db(dbName).tableList().run()

  if (!tables.includes(metadata)) {
    logger.info('Creating metadata table %s.', metadata)

    await r.db(dbName).tableCreate(metadata).run()
  } else {
    logger.debug('Metadata table %s already exists.', metadata)
  }
}

async function getCompletedMigrationIds ({ db: r, metadata, logger }) {
  const completed = await r.table(metadata).pluck('id').run()

  logger.debug('○ Found %s completed migrations in metadata table "%s".', completed.length, metadata)

  return completed.map(({ id }) => id)
}

async function registerMigration ({ id, db: r, metadata }) {
  await r.table(metadata).insert({ id, completed: new Date() }).run()
}

async function unregisterMigration ({ id, db: r, metadata }) {
  await r.table(metadata).get(id).delete().run()
}

module.exports = {
  init,
  getCompletedMigrationIds,
  registerMigration,
  unregisterMigration
}