Start /api/stats endpoint with total track length

src/routes/api/index.js

@@ -5,6 +5,7 @@ router.use('/profiles', require('./profiles'));
 router.use('/tracks', require('./tracks'));
 router.use('/tags', require('./tags'));
 router.use('/accounts', require('../../accounts/accounts.controller'));
+router.use('/stats', require('./stats'));
 
 router.use(function (err, req, res, next) {
   if (err.name === 'ValidationError') {

src/routes/api/stats.js

@@ -0,0 +1,29 @@
+const router = require('express').Router();
+const mongoose = require('mongoose');
+const Track = mongoose.model('Track');
+const wrapRoute = require('../../_helpers/wrapRoute');
+
+// round to this number of meters for privacy reasons
+const TRACK_LENGTH_ROUNDING = 1000
+
+router.get(
+  '/',
+  wrapRoute(async (req, res) => {
+    const [{totalTrackLength, totalPublicTrackLength}] = await Track.aggregate([
+      {$lookup: { from: 'trackdatas', localField: 'publicTrackData', foreignField: '_id', as: 'publicTrackDatas' }},
+      {$lookup: { from: 'trackdatas', localField: 'trackData', foreignField: '_id', as: 'trackDatas' }},
+      {$addFields: {publicTrackLength: {$first: '$publicTrackDatas.trackLength'}, trackLength: {$first: '$trackDatas.trackLength'}}},
+      {$project: {publicTrackLength: true, trackLength: true}},
+      {$group: {_id: "sum", totalTrackLength: {$sum: '$trackLength'}, totalPublicTrackLength: {$sum: '$publicTrackLength'}}},
+    ])
+
+    const totalTrackLengthPrivatized = Math.floor(totalTrackLength / TRACK_LENGTH_ROUNDING) * TRACK_LENGTH_ROUNDING;
+
+    return res.json({
+      totalTrackLength: totalTrackLengthPrivatized ,
+      totalPublicTrackLength,
+    });
+  })
+);
+
+module.exports = router;