/*
 * IMPORTANT:
 *
 * DO NOT TRUST THIS SCRIPT YET
 *
 *
 * This has been written by Alys to identify and remove duplicated tasks
 * i.e., tasks that have the same `id` value as another task.
 * However it could almost certainly be improved (the aggregation step HAS
 * to be easier that this!) and Alys is still working on it. Improvements
 * welcome.
 *
 * If you use it, do ALL of the following things:
 *
 * - configuration, as described below
 * - make a full backup of the user's data
 * - be aware of how to restore the user's data from that backup
 * - test the script first on a local copy of the database
 * - dump the user's data to a text file before running the script so that
 *   it can later be compared to a dump made afterwards
 * - run the script once first with both of the db.users.update() commands
 *   commented-out and check that the printed task IDs are correct
 * - run the script with all code enabled
 * - dump the user's data to a text file after running the script
 * - diff the two dumps to ensure that only the correct tasks were removed
 *
 *
 * When two tasks exist with the same ID, only one of those tasks will be
 * removed (whichever copy the script finds first).
 * If three tasks exist with the same ID, you'll probably need to run this
 * script twice.
 *
 */


// CONFIGURATION:
// - Change the uuid below to be the user's uuid.
// - Change ALL instances of "todos" to "habits"/"dailys"/"rewards" as
//   needed. Do not miss any of them!


var uuid='30fb2640-7121-4968-ace5-f385e60ea6c5';

db.users.aggregate([
  {$match: {
    '_id': uuid
  }},
  {$project: {
    '_id':0, 'todos':1
  }},
  {$unwind: '$todos'},
  {$group: {
    _id: { taskid: '$todos.id' },
    count: { $sum: 1 }
  }},
  {$match: {
    count: { $gt: 1 }
  }},
  {$project: {
    '_id.taskid':1,
  }},
  {$group: {
    _id: { taskid: '$todos.id' },
    troublesomeIds: { $addToSet: "$_id.taskid" },
  }},
  {$project: {
    '_id':0,
    troublesomeIds:1,
  }},
]).forEach(
  function(data) {
    // print( "\n" ); printjson(data);
    data.troublesomeIds.forEach( function(taskid) {
      print('non-unique task: ' + taskid);
      db.users.update({
        '_id': uuid,
        'todos': { $elemMatch: { id: taskid } }
      },{
        $set: { "todos.$.id" : 'de666' }
      });
    });
  }
);

db.users.update(
  {'_id': uuid},
  {$pull: { todos: { id: 'de666' } } },
  {multi: false }
);