// Migrate challenges collection to new schema (except for members)

// The console-stamp module must be installed (not included in package.json)

// It requires two environment variables: MONGODB_OLD and MONGODB_NEW

// Due to some big user profiles it needs more RAM than is allowed by default by v8 (arounf 1.7GB).
// Run the script with --max-old-space-size=4096 to allow up to 4GB of RAM

// IMPORTANT NOTE: this migration was written when we were using version 3 of lodash.
// We've now upgraded to lodash v4 but the code used in this migration has not been
// adapted to work with it. Before this migration is used again any lodash method should
// be checked for compatibility against the v4 changelog and changed if necessary.
// https://github.com/lodash/lodash/wiki/Changelog#v400
console.log('Starting migrations/api_v3/challenges.js.');

require('babel-register');
require('babel-polyfill');

var Bluebird = require('bluebird');
var MongoDB = require('mongodb');
var nconf = require('nconf');
var mongoose = require('mongoose');
var _ = require('lodash');
var uuid = require('uuid');
var consoleStamp = require('console-stamp');
var fs = require('fs');

// Add timestamps to console messages
consoleStamp(console);

// Initialize configuration
require('../../website/server/libs/api-v3/setupNconf')();

var MONGODB_OLD = nconf.get('MONGODB_OLD');
var MONGODB_NEW = nconf.get('MONGODB_NEW');

var MongoClient = MongoDB.MongoClient;

mongoose.Promise = Bluebird; // otherwise mongoose models won't work

// Load new models
var NewChallenge = require('../../website/server/models/challenge').model;
var Tasks = require('../../website/server/models/task');

// To be defined later when MongoClient connects
var mongoDbOldInstance;
var oldChallengeCollection;

var mongoDbNewInstance;
var newChallengeCollection;
var newTaskCollection;

var BATCH_SIZE = 1000;

var processedChallenges = 0;
var totoalProcessedTasks = 0;

var newTasksIds = {}; // a map of old id -> [new id, challengeId]

// Only process challenges that fall in a interval ie -> up to 0000-4000-0000-0000
var AFTER_CHALLENGE_ID = nconf.get('AFTER_CHALLENGE_ID');
var BEFORE_CHALLENGE_ID = nconf.get('BEFORE_CHALLENGE_ID');

function processChallenges (afterId) {
  var processedTasks = 0;
  var lastChallenge = null;
  var oldChallenges;

  var query = {};

  if (BEFORE_CHALLENGE_ID) {
    query._id = {$lte: BEFORE_CHALLENGE_ID};
  }

  if ((afterId || AFTER_CHALLENGE_ID) && !query._id) {
    query._id = {};
  }

  if (afterId) {
    query._id.$gt = afterId;
  } else if (AFTER_CHALLENGE_ID) {
    query._id.$gt = AFTER_CHALLENGE_ID;
  }

  var batchInsertTasks = newTaskCollection.initializeUnorderedBulkOp();
  var batchInsertChallenges = newChallengeCollection.initializeUnorderedBulkOp();

  console.log(`Executing challenges query.\nMatching challenges after ${afterId ? afterId : AFTER_CHALLENGE_ID} and before ${BEFORE_CHALLENGE_ID} (included).`);

  return oldChallengeCollection
  .find(query)
  .sort({_id: 1})
  .limit(BATCH_SIZE)
  .toArray()
  .then(function (oldChallengesR) {
    oldChallenges = oldChallengesR;

    console.log(`Processing ${oldChallenges.length} challenges. Already processed ${processedChallenges} challenges and ${totoalProcessedTasks} tasks.`);

    if (oldChallenges.length === BATCH_SIZE) {
      lastChallenge = oldChallenges[oldChallenges.length - 1]._id;
    }

    oldChallenges.forEach(function (oldChallenge) {
      var oldTasks = oldChallenge.habits.concat(oldChallenge.dailys).concat(oldChallenge.rewards).concat(oldChallenge.todos);
      delete oldChallenge.habits;
      delete oldChallenge.dailys;
      delete oldChallenge.rewards;
      delete oldChallenge.todos;

      var createdAt = oldChallenge.timestamp;

      oldChallenge.memberCount = oldChallenge.members.length;
      if (oldChallenge.prize <= 0) oldChallenge.prize = 0;
      if (!oldChallenge.name) oldChallenge.name = 'challenge name';
      if (!oldChallenge.shortName) oldChallenge.name = 'challenge-name';

      if (!oldChallenge.group) throw new Error('challenge.group is required');
      if (!oldChallenge.leader) throw new Error('challenge.leader is required');


      if (oldChallenge.leader === '9') {
        oldChallenge.leader = '00000000-0000-4000-9000-000000000000';
      }

      if (oldChallenge.group === 'habitrpg') {
        oldChallenge.group = '00000000-0000-4000-A000-000000000000';
      }

      delete oldChallenge.id;

      var newChallenge = new NewChallenge(oldChallenge);

      newChallenge.createdAt = createdAt;

      oldTasks.forEach(function (oldTask) {
        oldTask._id = uuid.v4();
        oldTask._legacyId = oldTask.id; // store the old task id
        delete oldTask.id;

        oldTask.challenge = oldTask.challenge || {};
        oldTask.challenge.id = newChallenge._id;

        if (newTasksIds[oldTask._legacyId + '-' + newChallenge._id]) {
          throw new Error('duplicate :(');
        } else {
          newTasksIds[oldTask._legacyId + '-' + newChallenge._id] = oldTask._id;
        }

        oldTask.tags = _.map(oldTask.tags || {}, function (tagPresent, tagId) {
          return tagPresent && tagId;
        }).filter(function (tag) {
          return tag !== false;
        });

        if (!oldTask.text) oldTask.text = 'task text'; // required

        oldTask.createdAt = oldTask.dateCreated;

        newChallenge.tasksOrder[`${oldTask.type}s`].push(oldTask._id);
        if (oldTask.completed) oldTask.completed = false;

        var newTask = new Tasks[oldTask.type](oldTask);

        batchInsertTasks.insert(newTask.toObject());
        processedTasks++;
      });

      batchInsertChallenges.insert(newChallenge.toObject());
    });

    console.log(`Saving ${oldChallenges.length} challenges and ${processedTasks} tasks.`);

    return Bluebird.all([
      batchInsertChallenges.execute(),
      batchInsertTasks.execute(),
    ]);
  })
  .then(function () {
    totoalProcessedTasks += processedTasks;
    processedChallenges += oldChallenges.length;

    console.log(`Saved ${oldChallenges.length} challenges and their tasks.`);

    if (lastChallenge) {
      return processChallenges(lastChallenge);
    } else {
      console.log('Writing newTasksIds.json...')
      fs.writeFileSync('newTasksIds.json', JSON.stringify(newTasksIds, null, 4), 'utf8');
      return console.log('Done!');
    }
  });
}

// Connect to the databases
Bluebird.all([
  MongoClient.connect(MONGODB_OLD),
  MongoClient.connect(MONGODB_NEW),
])
.then(function (result) {
  var oldInstance = result[0];
  var newInstance = result[1];

  mongoDbOldInstance = oldInstance;
  oldChallengeCollection = mongoDbOldInstance.collection('challenges');

  mongoDbNewInstance = newInstance;
  newChallengeCollection = mongoDbNewInstance.collection('challenges');
  newTaskCollection = mongoDbNewInstance.collection('tasks');

  console.log(`Connected with MongoClient to ${MONGODB_OLD} and ${MONGODB_NEW}.`);

  return processChallenges();
})
.catch(function (err) {
  console.error(err.stack || err);
});