Switch from http polling to data push via websockets

2 files changed, 270 insertions, 0 deletions

diff --git a/services/data-broadcaster.js b/services/data-broadcaster.js
new file mode 100644
index 0000000..a49f4a7
--- /dev/null
+++ b/services/data-broadcaster.js
@@ -0,0 +1,42 @@
+const app = require('../app');
+
+function broadcastRealtimeUsageUpdate(data) {
+  broadcast(generatePayload('realtimeUsage', data));
+}
+
+function broadcastDailyUsageUpdate(data) {
+  broadcast(generatePayload('dailyUsage', data));
+}
+
+function broadcastMonthlyUsageUpdate(data) {
+  broadcast(generatePayload('monthlyUsage', data));
+}
+
+function broadcastPowerStateUpdate(data) {
+  broadcast(generatePayload('powersState', data));
+}
+
+function broadcast(payload) {
+  app.getWsClients().forEach(client => {
+    client.send(payload);
+  })
+}
+
+function generatePayload(dataType, data) {
+
+  let payload = {
+    dataType: dataType,
+    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..93f5020
--- /dev/null
+++ b/services/data-fetcher.js
@@ -0,0 +1,228 @@
+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();
+}, 5000)
+
+let cachedRealtimeUsageData = {};
+let cachedDailyUsageData = {};
+let cachedMonthlyUsageData = {};
+let cachedPowerState = {};
+
+function fetchRealtimeUsage() {
+
+  let deviceId = 1; // TODO
+
+  console.log('connected clients', app.getWsClientCount());
+  if(app.getWsClientCount() > 0) {
+    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);
+
+      cachedRealtimeUsageData = response;
+  
+      dataBroadcaster.broadcastRealtimeUsageUpdate(response);
+  
+    });
+  }
+
+  setTimeout(fetchRealtimeUsage, 1000);
+}
+
+function fetchDailyUsage() {
+
+  let deviceId = 1;
+
+  // 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);
+
+        let result = trimStatResults(combinedStats, totalDaysRequired);
+
+        cachedDailyUsageData = result;
+
+        dataBroadcaster.broadcastDailyUsageUpdate(result);
+
+      });
+    }
+    else {
+      let dayStats = fillMissingDays(currentPeriodStats, currentMoment);
+  
+      let result = trimStatResults(dayStats, totalDaysRequired);
+      cachedDailyUsageData = result;
+
+      dataBroadcaster.broadcastDailyUsageUpdate(result);
+    }
+
+  });
+
+  setTimeout(fetchDailyUsage, 300000); // 5 mins;
+}
+
+function fetchMonthlyUsage() {
+
+  let deviceId = 1;
+
+  // 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);
+
+        let result = trimStatResults(combinedStats, totalMonthsRequired);
+
+        cachedMonthlyUsageData = result;
+
+        dataBroadcaster.broadcastMonthlyUsageUpdate(result);
+
+      });
+    }
+    else {
+      let monthStats = fillMissingMonths(currentPeriodStats, currentMoment);
+
+      let result = trimStatResults(monthStats, totalMonthsRequired);
+
+      cachedMonthlyUsageData = result;
+
+      dataBroadcaster.broadcastMonthlyUsageUpdate(result);
+    }
+
+  });
+
+  setTimeout(fetchMonthlyUsage, 1800000);  // 30 mins
+}
+
+function fetchPowerState() {
+
+  let deviceId = 1
+
+  deviceManager.getDevice(deviceId).getSysInfo().then(response => {
+
+    let powerState = {
+      isOn: (response.relay_state === 1),
+      uptime: response.on_time
+    };
+
+    cachedPowerState = powerState;
+    dataBroadcaster.broadcastPowerStateUpdate(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);
+    }
+
+  });
+
+  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.getCachedData = function() {
+  return {
+    realtimeUsage: cachedRealtimeUsageData,
+    dailyUsage: cachedDailyUsageData,
+    monthlyUsage: cachedMonthlyUsageData,
+    powerState: cachedPowerState
+  }
+}
\ No newline at end of file