3 files changed, 67 insertions, 0 deletions
diff --git a/services/data-broadcaster.js b/services/data-broadcaster.js
index 60c2368..4905eda 100644
--- a/services/data-broadcaster.js
+++ b/services/data-broadcaster.js
@@ -16,6 +16,10 @@ function broadcastPowerStateUpdate(deviceId, data) {
   broadcast(generatePayload('powerState', deviceId, data));
 }
 
+function broadcastNewLogEntry(deviceId, data) {
+  broadcast(generatePayload('newLogEntry', deviceId, data));
+}
+
 function broadcast(payload) {
   app.getWsClients().forEach(client => {
     client.send(payload);
@@ -39,5 +43,6 @@ module.exports = {
   broadcastDailyUsageUpdate: broadcastDailyUsageUpdate,
   broadcastMonthlyUsageUpdate: broadcastMonthlyUsageUpdate,
   broadcastPowerStateUpdate: broadcastPowerStateUpdate,
+  broadcastNewLogEntry: broadcastNewLogEntry,
   generatePayload: generatePayload
 }
diff --git a/services/data-logger.js b/services/data-logger.js
new file mode 100644
index 0000000..0948221
--- /dev/null
+++ b/services/data-logger.js
@@ -0,0 +1,59 @@
+const fs = require('fs');
+const dataBroadcaster = require('./data-broadcaster');
+
+function startLogging(device) {
+  setInterval(() => { log(device); }, 60000);
+  console.log('Logging started for ' + device.alias + ' [' + device.deviceId + ']');
+}
+
+function log(device) {
+
+  device.emeter.getRealtime().then(response => {
+
+    let logEntry = {
+      timestamp: Date.now(),
+      power: (('power_mw' in response) ? (response.power_mw / 1000) : response.power)
+    }
+
+    // TODO only log up to a max number of entries
+
+    fs.writeFile(device.deviceId + '-log.json', JSON.stringify(logEntry) + '\n', { flag: 'a' }, (err) => {
+      if(err) {
+        console.warn('Error writing log entry for ' + device.alias + ' [' + device.deviceId + ']', err);
+      }
+      else {
+        dataBroadcaster.broadcastNewLogEntry(device.deviceId, logEntry);
+      }
+
+    });
+
+  });
+
+}
+
+function getAllEntries(deviceId, callback) {
+  fs.readFile(deviceId + '-log.json', 'utf8', (err, data) => {
+    if(err) {
+      console.warn('Error reading usage log ' + deviceId + '-log.json', err);
+      return;
+   }
+   else {
+      let logLines = data.split(/\r?\n/);
+      let logEntries = [];
+
+      logLines.forEach(line => {
+        if(line.length > 0) {
+          logEntries.push(JSON.parse(line))
+        }
+      });
+
+     callback(logEntries);
+    }
+  });
+}
+
+module.exports = {
+  startLogging: startLogging,
+  log: log,
+  getAllEntries: getAllEntries
+}
+\ No newline at end of file
diff --git a/services/device-manager.js b/services/device-manager.js
index e4d18f3..1e17f75 100644
--- a/services/device-manager.js
+++ b/services/device-manager.js
@@ -1,4 +1,5 @@
 const { Client } = require('tplink-smarthome-api');
+const dataLogger = require('./data-logger');
 
 const client = new Client();
 var devices = [];
@@ -9,6 +10,8 @@ client.startDiscovery({
   }).on('plug-new', plug => {
   console.log('Found device: ' + plug.alias + ' [' + plug.deviceId + ']');
   devices.push(plug);
+
+  dataLogger.startLogging(plug);
 });
 
 module.exports.getDevice = function(deviceId) {