const isFunction = require('lodash/isFunction');
const isObject = require('lodash/isObject');
const isString = require('lodash/isString');

const { runMigrations } = require('./run_migrations');


// IMPORTANT: The migrations below are run on a database that may be very large
// due to attachments being directly stored inside the database. Please avoid
// any expensive operations, e.g. modifying all messages / attachments, etc., as
// it may cause out-of-memory errors for users with long histories:
// https://github.com/signalapp/Signal-Desktop/issues/2163
const migrations = [
  {
    version: '12.0',
    migrate(transaction, next) {
      console.log('Migration 12');
      console.log('creating object stores');
      const messages = transaction.db.createObjectStore('messages');
      messages.createIndex('conversation', ['conversationId', 'received_at'], {
        unique: false,
      });
      messages.createIndex('receipt', 'sent_at', { unique: false });
      messages.createIndex('unread', ['conversationId', 'unread'], { unique: false });
      messages.createIndex('expires_at', 'expires_at', { unique: false });

      const conversations = transaction.db.createObjectStore('conversations');
      conversations.createIndex('inbox', 'active_at', { unique: false });
      conversations.createIndex('group', 'members', {
        unique: false,
        multiEntry: true,
      });
      conversations.createIndex('type', 'type', {
        unique: false,
      });
      conversations.createIndex('search', 'tokens', {
        unique: false,
        multiEntry: true,
      });

      transaction.db.createObjectStore('groups');

      transaction.db.createObjectStore('sessions');
      transaction.db.createObjectStore('identityKeys');
      transaction.db.createObjectStore('preKeys');
      transaction.db.createObjectStore('signedPreKeys');
      transaction.db.createObjectStore('items');

      console.log('creating debug log');
      transaction.db.createObjectStore('debug');

      next();
    },
  },
  {
    version: '13.0',
    migrate(transaction, next) {
      console.log('Migration 13');
      console.log('Adding fields to identity keys');
      const identityKeys = transaction.objectStore('identityKeys');
      const request = identityKeys.openCursor();
      const promises = [];
      request.onsuccess = (event) => {
        const cursor = event.target.result;
        if (cursor) {
          const attributes = cursor.value;
          attributes.timestamp = 0;
          attributes.firstUse = false;
          attributes.nonblockingApproval = false;
          attributes.verified = 0;
          promises.push(new Promise(((resolve, reject) => {
            const putRequest = identityKeys.put(attributes, attributes.id);
            putRequest.onsuccess = resolve;
            putRequest.onerror = (e) => {
              console.log(e);
              reject(e);
            };
          })));
          cursor.continue();
        } else {
          // no more results
          // eslint-disable-next-line more/no-then
          Promise.all(promises).then(() => {
            next();
          });
        }
      };
      request.onerror = (event) => {
        console.log(event);
      };
    },
  },
  {
    version: '14.0',
    migrate(transaction, next) {
      console.log('Migration 14');
      console.log('Adding unprocessed message store');
      const unprocessed = transaction.db.createObjectStore('unprocessed');
      unprocessed.createIndex('received', 'timestamp', { unique: false });
      next();
    },
  },
  {
    version: '15.0',
    migrate(transaction, next) {
      console.log('Migration 15');
      console.log('Adding messages index for de-duplication');
      const messages = transaction.objectStore('messages');
      messages.createIndex('unique', ['source', 'sourceDevice', 'sent_at'], {
        unique: true,
      });
      next();
    },
  },
  {
    version: '16.0',
    migrate(transaction, next) {
      console.log('Migration 16');
      console.log('Dropping log table, since we now log to disk');
      transaction.db.deleteObjectStore('debug');
      next();
    },
  },
  {
    version: 17,
    async migrate(transaction, next) {
      console.log('Migration 17');

      const start = Date.now();

      const messagesStore = transaction.objectStore('messages');
      console.log('Create index from attachment schema version to attachment');
      messagesStore.createIndex('schemaVersion', 'schemaVersion', { unique: false });

      const duration = Date.now() - start;

      console.log(
        'Complete migration to database version 17.',
        `Duration: ${duration}ms`
      );
      next();
    },
  },
];

const database = {
  id: 'signal',
  nolog: true,
  migrations,
};

exports.run = ({ Backbone } = {}) =>
  runMigrations({ Backbone, database });

exports.createCollection = ({ Backbone, storeName }) => {
  if (!isObject(Backbone) || !isObject(Backbone.Collection) ||
      !isFunction(Backbone.Collection.extend)) {
    throw new TypeError('"Backbone" is required');
  }

  if (!isString(storeName)) {
    throw new TypeError('"database" is required');
  }

  const collection = new (Backbone.Collection.extend({
    database,
    storeName,
  }))();

  return collection;
};