// Insert per-day active user counts into analytics.perdays collection

// Usage:
// mongo <address>:<port>/<database> <script file> -u <username> -p <password>

try {
  logDB = new Mongo("localhost").getDB("analytics")
  var scriptStartTime = new Date();
  var analyticsStringCache = {};

  var numDays = 40;
  var daysInMonth = 30;

  var startDay = new Date();
  today = startDay.toISOString().substr(0, 10);
  startDay.setUTCDate(startDay.getUTCDate() - numDays);
  startDay = startDay.toISOString().substr(0, 10);

  var activeUserEvents = ['Finished Signup', 'Started Level'];

  log("Today is " + today);
  log("Start day is " + startDay);

  log("Getting active user counts...");
  var activeUserCounts = getActiveUserCounts(startDay, activeUserEvents);
  // printjson(activeUserCounts);
  log("Inserting active user counts...");
  for (day in activeUserCounts) {
    if (today === day) continue; // Never save data for today because it's incomplete
    for (event in activeUserCounts[day]) {
      insertEventCount(event, day, activeUserCounts[day][event]);
    }
  }

  log("Script runtime: " + (new Date() - scriptStartTime));
}
catch(err) {
  log("ERROR: " + err);
  printjson(err);
}

function getActiveUserCounts(startDay, activeUserEvents) {
  // Counts active users per day
  if (!startDay) return {};

  var startObj = objectIdWithTimestamp(ISODate(startDay + "T00:00:00.000Z"));
  var queryParams = {$and: [
    {_id: {$gte: startObj}},
    {'event': {$in: activeUserEvents}}
  ]};
  var cursor = logDB['log'].find(queryParams);

  var dayUserMap = {};
  while (cursor.hasNext()) {
    var doc = cursor.next();
    var created = doc._id.getTimestamp().toISOString();
    var day = created.substring(0, 10);
    var user = doc.user;

    if (!dayUserMap[day]) dayUserMap[day] = {};
    dayUserMap[day][user] = true;
  }

  var activeUsersCounts = {};
  var monthlyActives = [];
  for (day in dayUserMap) {
    activeUsersCounts[day] = {'Daily Active Users': Object.keys(dayUserMap[day]).length};
    monthlyActives.push({day: day, users: dayUserMap[day]});
  }

  monthlyActives.sort(function (a, b) {return a.day.localeCompare(b.day);});

  // Calculate monthly actives for each day, starting when we have enough data
  for (var i = daysInMonth - 1; i < monthlyActives.length; i++) {
    var monthUserMap = {};
    for (var j = i - daysInMonth + 1; j <= i; j++) {
      for (var user in monthlyActives[j].users) {
        monthUserMap[user] = true;
      }
    }
    activeUsersCounts[monthlyActives[i].day]['Monthly Active Users'] = Object.keys(monthUserMap).length;
  }
  return activeUsersCounts;
}


// *** Helper functions ***

function slugify(text)
// https://gist.github.com/mathewbyrne/1280286
{
  return text.toString().toLowerCase()
    .replace(/\s+/g, '-')           // Replace spaces with -
    .replace(/[^\w\-]+/g, '')       // Remove all non-word chars
    .replace(/\-\-+/g, '-')         // Replace multiple - with single -
    .replace(/^-+/, '')             // Trim - from start of text
    .replace(/-+$/, '');            // Trim - from end of text
}

function log(str) {
  print(new Date().toISOString() + " " + str);
}

function objectIdWithTimestamp(timestamp) {
  // Convert string date to Date object (otherwise assume timestamp is a date)
  if (typeof(timestamp) == 'string') timestamp = new Date(timestamp);
  // Convert date object to hex seconds since Unix epoch
  var hexSeconds = Math.floor(timestamp/1000).toString(16);
  // Create an ObjectId with that hex timestamp
  var constructedObjectId = ObjectId(hexSeconds + "0000000000000000");
  return constructedObjectId
}

function getAnalyticsString(str) {
  if (analyticsStringCache[str]) return analyticsStringCache[str];

  // Find existing string
  var doc = db['analytics.strings'].findOne({v: str});
  if (doc) {
    analyticsStringCache[str] = doc._id;
    return analyticsStringCache[str];
  }

  // Insert string
  // http://docs.mongodb.org/manual/tutorial/create-an-auto-incrementing-field/#auto-increment-optimistic-loop
  doc = {v: str};
  while (true) {
    var cursor = db['analytics.strings'].find({}, {_id: 1}).sort({_id: -1}).limit(1);
    var seq = cursor.hasNext() ? cursor.next()._id + 1 : 1;
    doc._id = seq;
    var results = db['analytics.strings'].insert(doc);
    if (results.hasWriteError()) {
      if ( results.writeError.code == 11000 /* dup key */ ) continue;
      else throw new Error("ERROR: Unexpected error inserting data: " + tojson(results));
    }
    break;
  }

  // Find new string entry
  doc = db['analytics.strings'].findOne({v: str});
  if (doc) {
    analyticsStringCache[str] = doc._id;
    return analyticsStringCache[str];
  }
  throw new Error("ERROR: Did not find analytics.strings insert for: " + str);
}

function insertEventCount(event, day, count) {
  // analytics.perdays schema in server/analytics/AnalyticsPeryDay.coffee
  day = day.replace(/-/g, '');

  var eventID = getAnalyticsString(event);
  var filterID = getAnalyticsString('all');

  var startObj = objectIdWithTimestamp(new Date(startDay + "T00:00:00.000Z"));
  var queryParams = {$and: [{d: day}, {e: eventID}, {f: filterID}]};
  var doc = db['analytics.perdays'].findOne(queryParams);
  if (doc && doc.c === count) return;

  if (doc && doc.c !== count) {
    // Update existing count, assume new one is more accurate
    // log("Updating count in db for " + day + " " + event + " " + doc.c + " => " + count);
    var results = db['analytics.perdays'].update(queryParams, {$set: {c: count}});
    if (results.nMatched !== 1 && results.nModified !== 1) {
      log("ERROR: update event count failed");
      printjson(results);
    }
  }
  else {
    var insertDoc = {d: day, e: eventID, f: filterID, c: count};
    var results = db['analytics.perdays'].insert(insertDoc);
    if (results.nInserted !== 1) {
      log("ERROR: insert event failed");
      printjson(results);
      printjson(insertDoc);
    }
    // else {
    //   log("Added " + day + " " + event + " " + count);
    // }
  }
}