Merge pull request #1 from jamesbarnett91/websocketsv0.2

Switch from http polling to websockets

14 files changed, 552 insertions, 419 deletions

diff --git a/README.md b/README.md
index e1fa2e2..fd28b6a 100644
--- a/README.md
+++ b/README.md
@@ -51,10 +51,10 @@ If you hit this issue you can try disabling the VirtualBox adapter in `Control P
 - [x] Show historical data
 - [x] Build dists
 - [x] Docker image
-- [ ] Support switching between multiple plugs (currently only works for the fist plug discovered)
+- [x] Support switching between multiple plugs
+- [x] Switch to websockets
 - [ ] Rescan for devices on the fly
 - [ ] Add daily cost metrics
-- [ ] Configurable poll rates
-- [ ] Switch to websockets
+
 
 
diff --git a/app.js b/app.js
index 5512f07..1d24419 100644
--- a/app.js
+++ b/app.js
@@ -1,14 +1,14 @@
-var createError = require('http-errors');
-var express = require('express');
-var path = require('path');
-var cookieParser = require('cookie-parser');
-var logger = require('morgan');
+const createError = require('http-errors');
+const express = require('express');
+const path = require('path');
+const cookieParser = require('cookie-parser');
+const logger = require('morgan');
 
-var indexRouter = require('./routes/index');
-var energyUsageRouter = require('./routes/energy-usage');
-var powerStateRouter = require('./routes/power-state');
+const app = express();
+const expressWs =  require('express-ws')(app);
 
-var app = express();
+const indexRouter = require('./routes/index');
+const wsRouter = require('./routes/ws');
 
 // view engine setup
 app.set('views', path.join(__dirname, 'views'));
@@ -21,8 +21,7 @@ app.use(cookieParser());
 app.use(express.static(path.join(__dirname, 'public')));
 
 app.use('/', indexRouter);
-app.use('/energy-usage', energyUsageRouter);
-app.use('/power-state', powerStateRouter);
+app.use('/ws', wsRouter);
 
 // catch 404 and forward to error handler
 app.use(function(req, res, next) {
@@ -40,4 +39,12 @@ app.use(function(err, req, res, next) {
   res.render('error');
 });
 
-module.exports = app;
+app.listen(process.env.PORT || '3000');
+
+module.exports.getWsClientCount = function() {
+  return expressWs.getWss().clients.size;
+};
+
+module.exports.getWsClients = function() {
+  return expressWs.getWss().clients;
+};
diff --git a/bin/www b/bin/www
deleted file mode 100755
index 7356b2b..0000000
--- a/bin/www
+++ /dev/null
@@ -1,90 +0,0 @@
-#!/usr/bin/env node
-
-/**
- * Module dependencies.
- */
-
-var app = require('../app');
-var debug = require('debug')('tplink-monitor:server');
-var http = require('http');
-
-/**
- * Get port from environment and store in Express.
- */
-
-var port = normalizePort(process.env.PORT || '3000');
-app.set('port', port);
-
-/**
- * Create HTTP server.
- */
-
-var server = http.createServer(app);
-
-/**
- * Listen on provided port, on all network interfaces.
- */
-
-server.listen(port);
-server.on('error', onError);
-server.on('listening', onListening);
-
-/**
- * Normalize a port into a number, string, or false.
- */
-
-function normalizePort(val) {
-  var port = parseInt(val, 10);
-
-  if (isNaN(port)) {
-    // named pipe
-    return val;
-  }
-
-  if (port >= 0) {
-    // port number
-    return port;
-  }
-
-  return false;
-}
-
-/**
- * Event listener for HTTP server "error" event.
- */
-
-function onError(error) {
-  if (error.syscall !== 'listen') {
-    throw error;
-  }
-
-  var bind = typeof port === 'string'
-    ? 'Pipe ' + port
-    : 'Port ' + port;
-
-  // handle specific listen errors with friendly messages
-  switch (error.code) {
-    case 'EACCES':
-      console.error(bind + ' requires elevated privileges');
-      process.exit(1);
-      break;
-    case 'EADDRINUSE':
-      console.error(bind + ' is already in use');
-      process.exit(1);
-      break;
-    default:
-      throw error;
-  }
-}
-
-/**
- * Event listener for HTTP server "listening" event.
- */
-
-function onListening() {
-  var addr = server.address();
-  var bind = typeof addr === 'string'
-    ? 'pipe ' + addr
-    : 'port ' + addr.port;
-  debug('Listening on ' + bind);
-}
diff --git a/package.json b/package.json
index 41b6569..b97fe2e 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "name": "James Barnett"
   },
   "scripts": {
-    "start": "node ./bin/www",
+    "start": "node ./app.js",
     "dist": "pkg . --out-path ./dist"
   },
   "dependencies": {
@@ -19,13 +19,14 @@
     "http-errors": "~1.6.2",
     "morgan": "~1.9.0",
     "tplink-smarthome-api": "0.22.0",
-    "moment": "2.22.0"
+    "moment": "2.22.0",
+    "express-ws": "3.0.0"
   },
   "devDependencies": {
     "pkg": "4.3.1"
   },
   "bin" : {
-    "tplink-monitor": "./bin/www"
+    "tplink-monitor": "./app.js"
   },
   "pkg": {
     "scripts": "node_modules/hbs/lib/hbs.js",
diff --git a/public/javascripts/dash.js b/public/javascripts/dash.js
index 43524ad..821e9c1 100644
--- a/public/javascripts/dash.js
+++ b/public/javascripts/dash.js
@@ -1,8 +1,5 @@
 var dash = {
-  realtimeUsagePollRateMs: 1000,
-  powerStatePollRateMs: 60000,
-  historicalStatsPollRateMs: 300000,
-  pollingEnabled: true,
+  deviceId: null,
 
   realtimeGauge: null,
   realtimeTrendChart: null,
@@ -11,13 +8,59 @@ var dash = {
   dailyUsageChart: null,
   monthlyUsageChart: null,
 
-  init: function() {
+  init: function(deviceId) {
+    this.deviceId = deviceId;
+
+    $('.' + deviceId).addClass('active');
+
     this.initRealtimeGauge();
     this.initRealtimeTrendChart();
     this.initDailyUsageChart();
     this.initMonthlyUsageChart();
     
-    this.startPolling();
+    this.initWsConnection();
+  },
+
+  initWsConnection: function() {
+    var wsUri = 'ws://' + window.location.host + '/ws'
+    var ws = new WebSocket(wsUri);
+    ws.onopen = function () {
+      console.log('Websocket connection established');
+      $('#connection-error').hide(200);
+      ws.send(JSON.stringify(
+        {
+          requestType: 'getCachedData',
+          deviceId: dash.deviceId
+        }
+      ));
+    }
+    ws.onmessage = dash.wsMessageHandler;
+
+    ws.onclose = function() {
+      // Usually caused by mobile devices going to sleep or the user minimising the browser app.
+      // The setTimeout will begin once the device wakes from sleep or the browser regains focus.
+      $('#connection-error').show();
+      setTimeout(dash.initWsConnection, 2000);
+    }
+  },
+
+  wsMessageHandler: function(messageEvent) {
+    let message = JSON.parse(messageEvent.data);
+    if(message.deviceId === dash.deviceId) {
+      if(message.dataType === 'realtimeUsage') {
+        dash.refreshRealtimeDisplay(message.data);
+      }
+      else if(message.dataType === 'dailyUsage') {
+        dash.parseDailyUsageData(message.data);
+      }
+      else if(message.dataType === 'monthlyUsage') {
+        dash.parseMonthlyUsageData(message.data);
+      }
+      else if(message.dataType === 'powerState') {
+        dash.refreshPowerState(message.data);
+      }
+    }
+
   },
 
   initRealtimeGauge: function() {
@@ -81,6 +124,15 @@ var dash = {
         tooltips: {
           intersect: false
         },
+        plugins: {
+          streaming: {
+            duration: 60000,
+            refresh: 1000,
+            delay: 1000,
+            frameRate: 30,
+            onRefresh: dash.realtimeTrendChartOnRefresh
+          }
+        }
       }
     });
   },
@@ -156,22 +208,6 @@ var dash = {
     });
   },
 
-  // TODO - should probably use websockets 
-  pollUsage: function() {
-    if(this.pollingEnabled) {
-      $.ajax({
-        url: "/energy-usage/1/realtime",
-        type: "GET",
-        success: function(data) {
-          dash.refreshRealtimeDisplay(data);
-        },
-        dataType: "json",
-        complete: setTimeout(function() {dash.pollUsage()}, dash.realtimeUsagePollRateMs),
-        timeout: 2000
-      });
-    }
-  },
-
   refreshRealtimeDisplay: function(realtime) {
 
     var power = Math.round(realtime.power);
@@ -187,41 +223,6 @@ var dash = {
     this.realtimeTrendLastSample = power;
   },
 
-  startPolling: function() {
-    this.pollingEnabled = true;
-    this.realtimeTrendChart.options.plugins.streaming = {
-      duration: 60000,
-      refresh: 1000,
-      delay: 1000,
-      frameRate: 30,
-      onRefresh: dash.realtimeTrendChartOnRefresh
-    };
-    
-    this.pollUsage();
-    this.pollPowerStatus();
-    this.pollDayStats();
-    this.pollMonthStats();
-  },
-
-  stopPolling: function() {
-    this.pollingEnabled = false;
-    this.realtimeTrendChart.options.plugins.streaming = false;
-  },
-
-  pollDayStats: function() {
-    if(this.pollingEnabled) {
-      $.ajax({
-        url: "/energy-usage/1/day-stats",
-        type: "GET",
-        success: function(data) {
-          dash.parseDailyUsageData(data);
-        },
-        dataType: "json",
-        complete: setTimeout(function() {dash.pollDayStats()}, dash.historicalStatsPollRateMs),
-        timeout: 4000
-      });
-    }
-  },
 
   parseDailyUsageData: function(usageData) {
 
@@ -260,21 +261,6 @@ var dash = {
 
   },
 
-  pollMonthStats: function() {
-    if(this.pollingEnabled) {
-      $.ajax({
-        url: "/energy-usage/1/month-stats",
-        type: "GET",
-        success: function(data) {
-          dash.parseMonthlyUsageData(data);
-        },
-        dataType: "json",
-        complete: setTimeout(function() {dash.pollMonthStats()}, dash.historicalStatsPollRateMs),
-        timeout: 4000
-      });
-    }
-  },
-
   parseMonthlyUsageData: function(usageData) {
     
     // Clear previous data
@@ -311,21 +297,6 @@ var dash = {
     $("#avg-month").text(avg.toFixed(2));
   },
 
-  pollPowerStatus: function() {
-    if(this.pollingEnabled) {
-      $.ajax({
-        url: "/power-state/1",
-        type: "GET",
-        success: function(data) {
-          dash.refreshPowerState(data);
-        },
-        dataType: "json",
-        complete: setTimeout(function() {dash.pollPowerStatus()}, dash.powerStatePollRateMs),
-        timeout: 2000
-      });
-    }
-  },
-
   refreshPowerState: function(powerState) {
     if(powerState.isOn) {
       $("#power-state").text("ON").attr("class", "label label-success");
@@ -334,23 +305,13 @@ var dash = {
       $("#power-state").text("OFF").attr("class", "label label-danger");
     }
 
-    $("#uptime").text(moment.duration(powerState.uptime, "seconds").format("d[d] h[h] m[m]"));
-  },
-
-};
-
-
-$(document).ready(function () {
-
-  dash.init();
-
-  $("#toggle-polling").change(function() {
-    if(this.checked) {
-      dash.startPolling();
+    if(powerState.uptime === 0) {
+      $("#uptime").text("-");
     }
     else {
-      dash.stopPolling();
+      $("#uptime").text(moment.duration(powerState.uptime, "seconds").format("d[d] h[h] m[m]", {largest: 2}));
     }
-  });
+    
+  },
 
-});
+};
diff --git a/public/stylesheets/style.css b/public/stylesheets/style.css
index 3f4c1ca..2057c4d 100644
--- a/public/stylesheets/style.css
+++ b/public/stylesheets/style.css
@@ -25,4 +25,65 @@ footer ul {
   color: #fff;
   background-color: #5cb85c;
   border-color: #4cae4c;
-}
\ No newline at end of file
+}
+
+.alert-danger {
+  color: #a94442;
+  background-color: #f2dede;
+  border-color: #ebccd1;
+}
+
+.list-inline > .active {
+  font-weight: bold;
+}
+
+.nav_title { 
+  width: 170px;
+}
+
+.nav-md .container.body .col-md-3.left_col {
+  width: 170px;
+}
+
+.nav-md .container.body .right_col {
+  margin-left: 170px;
+}
+
+@media (min-width: 992px) {
+  footer {
+    margin-left: 170px;
+  }
+}
+
+@media (max-width: 991px) {
+  .nav-md .container.body .right_col {
+    padding-right: 0;
+    margin-left: 0;
+  }
+}
+
+@media (max-width: 1100px) {
+  .col-md-2, .col-md-3, .col-md-4, .col-md-6, .col-md-8, .col-md-9,  .col-xs-12, .col-lg-2 {
+    padding-left: 5px;
+    padding-right: 5px;
+  }
+}
+
+@media (min-width: 1635px) {
+  .col-xl-2,{
+    float: left;
+  }
+  .col-xl-2 {
+    width: 16.66666667%;
+  }
+}
+
+.device-list-small{
+  display: none;
+}
+
+@media (max-width: 991px) {
+  .device-list-small{
+      display: inline;
+  }
+}
diff --git a/routes/energy-usage.js b/routes/energy-usage.js
deleted file mode 100644
index eb21eb9..0000000
--- a/routes/energy-usage.js
+++ /dev/null
@@ -1,166 +0,0 @@
-const express = require('express');
-const router = express.Router();
-
-const deviceManager = require('../services/device-manager');
-const moment = require('moment');
-
-router.get('/:deviceId/realtime', function(req, res, next) {
-
-  let deviceId = req.params.deviceId;
-
-  let realtimeUsage = {};
-  // TODO - cache results with a short TTL so we don't hammer the plug if multiple clients are requesting data
-  deviceManager.getDevice(deviceId).emeter.getRealtime().then(response => {
-
-    // Voltage seems to be reported as its peak to peak value, not RMS.
-    // Show the RMS value since thats what would you expect to see.
-    // i.e. 220v not 310v (in the U.K)
-    response.voltage = response.voltage / Math.sqrt(2);
-
-    res.json(response);
-  });
-
-});
-
-router.get('/:deviceId/day-stats', function(req, res, next) {
-  
-  let deviceId = req.params.deviceId;
-
-  // Get last x days
-  let totalDaysRequired = 30; // TODO currently only works for up to 2 months spans
-  let currentMoment = moment();
-  let previousMoment = moment().subtract(totalDaysRequired, 'days');
-
-  // Month + 1 as the API months are index 1 based.
-  deviceManager.getDevice(deviceId).emeter.getDayStats(currentMoment.year(), currentMoment.month() +1).then(currentPeriodStats => {
-
-    // Check if we also need the previous month to meet the required total number of samples
-    if(currentMoment.month() !== previousMoment.month()) {
-      
-      // Get previous month. This currently wont work if the previousMoment is more than 1 month before the currentMoment (see above)
-      deviceManager.getDevice(deviceId).emeter.getDayStats(previousMoment.year(), previousMoment.month() +1).then(previousPeriodStats => {
-
-        let currentMonthStats = fillMissingDays(currentPeriodStats, currentMoment);
-        let previousMonthStats = fillMissingDays(previousPeriodStats, previousMoment);
-        let combinedStats = previousMonthStats.concat(currentMonthStats);
-
-        res.json(trimStatResults(combinedStats, totalDaysRequired));
-
-      });
-    }
-    else {
-      let dayStats = fillMissingDays(currentPeriodStats, currentMoment);
-  
-      res.json(trimStatResults(dayStats, totalDaysRequired));
-    }
-
-  });
-
-});
-
-router.get('/:deviceId/month-stats', function(req, res, next) {
-  let deviceId = req.params.deviceId;
-
-  // Get last x months
-  let totalMonthsRequired = 12; // TODO currently only works for up to 14 month (2 year) spans
-  let currentMoment = moment();
-  let previousMoment = moment().subtract(totalMonthsRequired, 'months');
-
-  deviceManager.getDevice(deviceId).emeter.getMonthStats(currentMoment.year()).then(currentPeriodStats => {
-
-    // Check if we also need the previous year to meet the required total number of samples
-    if(currentMoment.month() + 1 < totalMonthsRequired) {
-      
-      // Get previous year (assuming the totalMonthsRequired limit described above).
-      deviceManager.getDevice(deviceId).emeter.getMonthStats(previousMoment.year()).then(previousPeriodStats => {
-
-        let currentYearStats = fillMissingMonths(currentPeriodStats, currentMoment);
-        let previousYearStats = fillMissingMonths(previousPeriodStats, previousMoment);
-        let combinedStats = previousYearStats.concat(currentYearStats);
-
-        res.json(trimStatResults(combinedStats, totalMonthsRequired));
-
-      });
-    }
-    else {
-      let monthStats = fillMissingMonths(currentPeriodStats, currentMoment);
-
-      res.json(trimStatResults(monthStats, totalMonthsRequired));
-    }
-
-  });
-
-});
-
-function fillMissingDays(sparseDayStats, statsMoment) {
-  let denseDayStats = [];
-
-  let totalDays;
-  // If these stats are for the current month, fill up to the current day of the month
-  // Otherwise fill the whole month
-  if(moment().month() === statsMoment.month()) {
-    totalDays = statsMoment.date();
-  }
-  else {
-    totalDays = statsMoment.daysInMonth();
-  }
-
-  Array.from({length: totalDays}, (x,i) => i + 1).forEach(d => {
-
-    let stat = sparseDayStats.day_list.find(i => i.day === d);
-
-    if(stat === undefined) {
-      denseDayStats.push({
-        year: statsMoment.year(),
-        month: statsMoment.month() +1,
-        day: d,
-        energy: 0
-      })
-    }
-    else {
-      denseDayStats.push(stat);
-    }
-
-  });
-
-  return denseDayStats;
-}
-
-function fillMissingMonths(sparseMonthStats, statsMoment) {
-  let denseMonthStats = [];
-
-  let maxMonths;
-  // Dont fill in months which exist in the future
-  if(statsMoment.year() === moment().year()) {
-    maxMonths = moment().month() + 1; // API months are 1 based
-  }
-  else {
-    maxMonths = 12;
-  }
-
-  // Fill in any missing months up to the max amount
-  Array.from({length: maxMonths}, (x,i) => i + 1).forEach(m => {
-
-    let stat = sparseMonthStats.month_list.find(i => i.month === m);
-
-    if(stat === undefined) {
-      denseMonthStats.push({
-        year: statsMoment.year(),
-        month: m,
-        energy: 0
-      })
-    }
-    else {
-      denseMonthStats.push(stat);
-    }
-
-  });
-
-  return denseMonthStats;
-}
-
-function trimStatResults(stats, maxSamples) {
-  return stats.splice(stats.length - maxSamples, stats.length);
-}
-
-module.exports = router;
\ No newline at end of file
diff --git a/routes/index.js b/routes/index.js
index 4909ff8..12c62cd 100644
--- a/routes/index.js
+++ b/routes/index.js
@@ -5,11 +5,27 @@ const deviceManager = require('../services/device-manager');
 
 router.get('/', function(req, res, next) {
 
+  let deviceId = sortDevices(deviceManager.getAllDevices())[0].deviceId;
+
+  res.redirect('/' + deviceId);
+
+});
+
+router.get('/:deviceId', function(req, res, next) {
+
+  let deviceId = req.params.deviceId;
+
   res.render('index', {
-    device: deviceManager.getDevice(),
-    devices: deviceManager.getAllDevices()
+    device: deviceManager.getDevice(deviceId),
+    devices: sortDevices(deviceManager.getAllDevices())
   });
 
 });
 
+function sortDevices(devices) {
+  return devices.slice().sort((a, b) => {
+    return a.alias.toLowerCase().localeCompare(b.alias.toLowerCase())
+  })
+}
+
 module.exports = router;
diff --git a/routes/power-state.js b/routes/power-state.js
deleted file mode 100644
index 6333863..0000000
--- a/routes/power-state.js
+++ /dev/null
@@ -1,23 +0,0 @@
-const express = require('express');
-const router = express.Router();
-
-const deviceManager = require('../services/device-manager');
-const moment = require('moment');
-
-router.get('/:deviceId', function(req, res, next) {
-
-  let deviceId = req.params.deviceId;
-
-  deviceManager.getDevice(deviceId).getSysInfo().then(response => {
-
-    let powerState = {
-      isOn: (response.relay_state === 1),
-      uptime: response.on_time
-    };
-
-    res.json(powerState);
-  });
-
-});
-
-module.exports = router;
\ No newline at end of file
diff --git a/routes/ws.js b/routes/ws.js
new file mode 100644
index 0000000..08b0a18
--- /dev/null
+++ b/routes/ws.js
@@ -0,0 +1,28 @@
+const express = require('express');
+const router = express.Router();
+
+const deviceManager = require('../services/device-manager');
+const dataFetcher = require('../services/data-fetcher');
+const dataBroadcaster = require('../services/data-broadcaster');
+
+router.ws('/', function(ws, req) {
+
+  ws.on('message', msg => {
+
+    let message = JSON.parse(msg);
+
+    // Latest data is always pushed out to clients, but clients can also request cached data at any time.
+    if(message.requestType === 'getCachedData') {
+      let deviceId = message.deviceId;
+      let cachedData = dataFetcher.getCachedData(deviceId);
+
+      ws.send(dataBroadcaster.generatePayload('realtimeUsage', deviceId, cachedData.realtimeUsage));
+      ws.send(dataBroadcaster.generatePayload('dailyUsage', deviceId, cachedData.dailyUsage));
+      ws.send(dataBroadcaster.generatePayload('monthlyUsage', deviceId, cachedData.monthlyUsage));
+      ws.send(dataBroadcaster.generatePayload('powerState', deviceId, cachedData.powerState));
+    }
+  });
+
+});
+
+module.exports = router;
diff --git a/services/data-broadcaster.js b/services/data-broadcaster.js
new file mode 100644
index 0000000..9e0c5d0
--- /dev/null
+++ b/services/data-broadcaster.js
@@ -0,0 +1,43 @@
+const app = require('../app');
+
+function broadcastRealtimeUsageUpdate(deviceId, data) {
+  broadcast(generatePayload('realtimeUsage', deviceId, data));
+}
+
+function broadcastDailyUsageUpdate(deviceId, data) {
+  broadcast(generatePayload('dailyUsage', deviceId, data));
+}
+
+function broadcastMonthlyUsageUpdate(deviceId, data) {
+  broadcast(generatePayload('monthlyUsage', deviceId, data));
+}
+
+function broadcastPowerStateUpdate(deviceId, data) {
+  broadcast(generatePayload('powersState', deviceId, data));
+}
+
+function broadcast(payload) {
+  app.getWsClients().forEach(client => {
+    client.send(payload);
+  })
+}
+
+function generatePayload(dataType, deviceId, data) {
+
+  let payload = {
+    dataType: dataType,
+    deviceId: deviceId,
+    data: data
+  }
+
+  return JSON.stringify(payload);
+}
+
+
+module.exports = {
+  broadcastRealtimeUsageUpdate: broadcastRealtimeUsageUpdate,
+  broadcastDailyUsageUpdate: broadcastDailyUsageUpdate,
+  broadcastMonthlyUsageUpdate: broadcastMonthlyUsageUpdate,
+  broadcastPowerStateUpdate: broadcastPowerStateUpdate,
+  generatePayload: generatePayload
+}
\ No newline at end of file
diff --git a/services/data-fetcher.js b/services/data-fetcher.js
new file mode 100644
index 0000000..7ef3594
--- /dev/null
+++ b/services/data-fetcher.js
@@ -0,0 +1,277 @@
+const deviceManager = require('./device-manager');
+const dataBroadcaster = require('./data-broadcaster');
+const app = require('../app');
+const moment = require('moment');
+
+// Get initial data after a short delay to allow the device manager to find devices
+// TODO run once device manager notifies its complete instead
+setTimeout(function() {
+  fetchRealtimeUsage();
+  fetchDailyUsage();
+  fetchMonthlyUsage();
+  fetchPowerState();
+}, 2000)
+
+let cachedRealtimeUsageData = [];
+let cachedDailyUsageData = [];
+let cachedMonthlyUsageData = [];
+let cachedPowerState = [];
+
+function fetchRealtimeUsage() {
+
+  if(app.getWsClientCount() > 0 || cachedRealtimeUsageData.length === 0) {
+
+    deviceManager.getAllDevices().forEach(device => {
+
+      let deviceId = device.deviceId;
+      device.emeter.getRealtime().then(response => {
+
+        // Voltage seems to be reported as its peak to peak value, not RMS.
+        // Show the RMS value since thats what would you expect to see.
+        // i.e. 220v not 310v (in the U.K)
+        response.voltage = response.voltage / Math.sqrt(2);
+  
+        updateCache(cachedRealtimeUsageData, deviceId, response);
+
+        dataBroadcaster.broadcastRealtimeUsageUpdate(deviceId, response);
+      });
+
+    });
+
+  }
+
+  setTimeout(fetchRealtimeUsage, 1000);
+}
+
+function fetchDailyUsage() {
+
+  if(app.getWsClientCount() > 0 || cachedDailyUsageData.length === 0) {
+
+    // Get last x days
+    let totalDaysRequired = 30; // TODO currently only works for up to 2 months spans
+    let currentMoment = moment();
+    let previousMoment = moment().subtract(totalDaysRequired, 'days');
+
+    // Month + 1 as the API months are index 1 based.
+    deviceManager.getAllDevices().forEach(device => {
+
+      let deviceId = device.deviceId;
+      device.emeter.getDayStats(currentMoment.year(), currentMoment.month() +1).then(currentPeriodStats => {
+
+        // Check if we also need the previous month to meet the required total number of samples
+        if(currentMoment.month() !== previousMoment.month()) {
+          
+          // Get previous month. This currently wont work if the previousMoment is more than 1 month before the currentMoment (see above)
+          device.emeter.getDayStats(previousMoment.year(), previousMoment.month() +1).then(previousPeriodStats => {
+    
+            let currentMonthStats = fillMissingDays(currentPeriodStats, currentMoment);
+            let previousMonthStats = fillMissingDays(previousPeriodStats, previousMoment);
+            let combinedStats = previousMonthStats.concat(currentMonthStats);
+    
+            let result = trimStatResults(combinedStats, totalDaysRequired);
+    
+            updateCache(cachedDailyUsageData, deviceId, result);
+            
+            dataBroadcaster.broadcastDailyUsageUpdate(deviceId, result);
+    
+          });
+        }
+        else {
+          let dayStats = fillMissingDays(currentPeriodStats, currentMoment);
+      
+          let result = trimStatResults(dayStats, totalDaysRequired);
+          updateCache(cachedDailyUsageData, deviceId, result);
+    
+          dataBroadcaster.broadcastDailyUsageUpdate(deviceId, result);
+        }
+    
+      });
+
+    });
+
+  }
+
+  setTimeout(fetchDailyUsage, 300000); // 5 mins;
+}
+
+function fetchMonthlyUsage() {
+
+  if(app.getWsClientCount() > 0 || cachedMonthlyUsageData.length === 0) {
+
+    // Get last x months
+    let totalMonthsRequired = 12; // TODO currently only works for up to 14 month (2 year) spans
+    let currentMoment = moment();
+    let previousMoment = moment().subtract(totalMonthsRequired, 'months');
+
+    deviceManager.getAllDevices().forEach(device => {
+
+      let deviceId = device.deviceId;
+      device.emeter.getMonthStats(currentMoment.year()).then(currentPeriodStats => {
+
+        // Check if we also need the previous year to meet the required total number of samples
+        if(currentMoment.month() + 1 < totalMonthsRequired) {
+          
+          // Get previous year (assuming the totalMonthsRequired limit described above).
+          device.emeter.getMonthStats(previousMoment.year()).then(previousPeriodStats => {
+    
+            let currentYearStats = fillMissingMonths(currentPeriodStats, currentMoment);
+            let previousYearStats = fillMissingMonths(previousPeriodStats, previousMoment);
+            let combinedStats = previousYearStats.concat(currentYearStats);
+    
+            let result = trimStatResults(combinedStats, totalMonthsRequired);
+    
+            updateCache(cachedMonthlyUsageData, deviceId, result);
+    
+            dataBroadcaster.broadcastMonthlyUsageUpdate(deviceId, result);
+    
+          });
+        }
+        else {
+          let monthStats = fillMissingMonths(currentPeriodStats, currentMoment);
+    
+          let result = trimStatResults(monthStats, totalMonthsRequired);
+    
+          updateCache(cachedMonthlyUsageData, deviceId, result);
+
+          dataBroadcaster.broadcastMonthlyUsageUpdate(deviceId, result);
+        }
+    
+      });
+
+    });
+
+  }
+
+  setTimeout(fetchMonthlyUsage, 1800000);  // 30 mins
+}
+
+function fetchPowerState() {
+
+  if(app.getWsClientCount() > 0 || cachedPowerState.length === 0) {
+
+    deviceManager.getAllDevices().forEach(device => {
+
+      let deviceId = device.deviceId;
+      device.getSysInfo().then(response => {
+
+        let powerState = {
+          isOn: (response.relay_state === 1),
+          uptime: response.on_time
+        };
+    
+        updateCache(cachedPowerState, deviceId, powerState);
+
+        dataBroadcaster.broadcastPowerStateUpdate(deviceId, powerState);
+      });
+    });
+
+  }
+  setTimeout(fetchPowerState, 60000);
+}
+
+
+function fillMissingDays(sparseDayStats, statsMoment) {
+  let denseDayStats = [];
+
+  let totalDays;
+  // If these stats are for the current month, fill up to the current day of the month
+  // Otherwise fill the whole month
+  if(moment().month() === statsMoment.month()) {
+    totalDays = statsMoment.date();
+  }
+  else {
+    totalDays = statsMoment.daysInMonth();
+  }
+
+  Array.from({length: totalDays}, (x,i) => i + 1).forEach(d => {
+
+    let stat = sparseDayStats.day_list.find(i => i.day === d);
+
+    if(stat === undefined) {
+      denseDayStats.push({
+        year: statsMoment.year(),
+        month: statsMoment.month() +1,
+        day: d,
+        energy: 0
+      })
+    }
+    else {
+      denseDayStats.push(stat);
+    }