text: require('module-alias/register');
  const logger = require('@alias/logger')('growi:migrate:drop-pages-indices');
  
  const mongoose = require('mongoose');
  const config = require('@root/config/migrate');
  
  async function dropIndexIfExists(collection, indexName) {
    if (await collection.indexExists(indexName)) {
      await collection.dropIndex(indexName);
    }
  }
  
  module.exports = {
    async up(db) {
      logger.info('Apply migration');
      mongoose.connect(config.mongoUri, config.mongodb.options);
  
      const collection = db.collection('pages');
      await dropIndexIfExists(collection, 'lastUpdateUser_1');
      await dropIndexIfExists(collection, 'liker_1');
      await dropIndexIfExists(collection, 'seenUsers_1');
  
      logger.info('Migration has successfully applied');
    },
  
    down(db) {
      // do not rollback
    },
  };
  