limit notifications for low battery

sw.js

@@ -2,6 +2,56 @@
 const CACHE_VERSION = 'v1.0.2';
 const CACHE_NAME = `game-timer-${CACHE_VERSION}`;
 
+// Store last battery warning timestamp to prevent repeated notifications
+let lastBatteryWarningTimestamp = 0;
+const FOUR_HOURS_MS = 4 * 60 * 60 * 1000; // 4 hours in milliseconds
+
+// Settings cache for storing timestamps
+const SETTINGS_CACHE = 'settings-cache-v1';
+const TIMESTAMP_URL = new Request('/_timestamp/battery-warning');
+
+// Function to load the timestamp from cache
+async function loadTimestamp() {
+  try {
+    const cache = await caches.open(SETTINGS_CACHE);
+    const response = await cache.match(TIMESTAMP_URL);
+    
+    if (response) {
+      const data = await response.json();
+      lastBatteryWarningTimestamp = data.timestamp;
+      console.log('[ServiceWorker] Loaded battery warning timestamp:', new Date(lastBatteryWarningTimestamp));
+    } else {
+      console.log('[ServiceWorker] No saved timestamp found');
+    }
+    return true;
+  } catch (error) {
+    console.error('[ServiceWorker] Error loading timestamp:', error);
+    return false;
+  }
+}
+
+// Function to save the timestamp to cache
+async function saveTimestamp(timestamp) {
+  try {
+    const cache = await caches.open(SETTINGS_CACHE);
+    const response = new Response(JSON.stringify({ timestamp }), {
+      headers: { 'Content-Type': 'application/json' }
+    });
+    
+    await cache.put(TIMESTAMP_URL, response);
+    console.log('[ServiceWorker] Saved battery warning timestamp:', new Date(timestamp));
+    return true;
+  } catch (error) {
+    console.error('[ServiceWorker] Error saving timestamp:', error);
+    return false;
+  }
+}
+
+// Initialize and load data when the service worker starts
+loadTimestamp().then(success => {
+  console.log('[ServiceWorker] Timestamp loading ' + (success ? 'successful' : 'failed'));
+});
+
 // Files to cache
 const CACHE_FILES = [
   '/',
@@ -136,14 +186,32 @@ self.addEventListener('push', event => {
   console.log('[ServiceWorker] Preparing message payload:', messagePayload);
   
   // Check if this is a low battery alert that needs a notification
-  const isBatteryAlert = messagePayload.batteryLevel !== undefined && 
-                         messagePayload.batteryLevel < 50; // Use the same threshold as in the app
+  const batteryLevel = messagePayload.batteryLevel;
+  const isBatteryLow = batteryLevel !== undefined && batteryLevel < 50; // Use the same threshold as in the app
   
-  if (isBatteryAlert) {
-    console.log(`[ServiceWorker] Low battery alert detected: ${messagePayload.batteryLevel}%`);
-    // Change notification title/body for battery alerts
-    pushData.title = 'Flic Button Low Battery';
-    pushData.body = `Battery level is ${messagePayload.batteryLevel}%. Please replace batteries soon.`;
+  // Determine if we should show a battery notification (throttle to once every 4 hours)
+  let shouldShowBatteryNotification = false;
+  
+  if (isBatteryLow) {
+    const now = Date.now();
+    if (now - lastBatteryWarningTimestamp > FOUR_HOURS_MS) {
+      // It's been more than 4 hours since the last battery notification
+      console.log(`[ServiceWorker] Low battery (${batteryLevel}%) - showing notification`);
+      lastBatteryWarningTimestamp = now;
+      
+      // Save the timestamp to cache
+      saveTimestamp(now).catch(error => {
+        console.warn('[ServiceWorker] Failed to save battery warning timestamp:', error);
+      });
+      
+      shouldShowBatteryNotification = true;
+      
+      // Change notification title/body for battery alerts
+      pushData.title = 'Flic Button Low Battery';
+      pushData.body = `Battery level is ${batteryLevel}%. Please replace batteries soon.`;
+    } else {
+      console.log(`[ServiceWorker] Low battery (${batteryLevel}%) - suppressing notification (shown recently)`);
+    }
   }
 
   // Send message to all open PWA windows controlled by this SW
@@ -154,8 +222,8 @@ self.addEventListener('push', event => {
     }).then(clientList => {
       if (!clientList || clientList.length === 0) {
         console.log('[ServiceWorker] No client windows found to send message to.');
-        // If no window is open AND this is a battery alert, show a notification
-        if (isBatteryAlert) {
+        // If no window is open AND this is a battery alert that should be shown, show a notification
+        if (shouldShowBatteryNotification) {
           return self.registration.showNotification(pushData.title, {
             body: pushData.body,
             icon: '/icons/android-chrome-192x192.png', // Updated path
@@ -184,21 +252,48 @@ self.addEventListener('push', event => {
       });
 
       return Promise.all(sendPromises).then(() => {
-        // Only show a notification if this is a battery alert
-        if (isBatteryAlert) {
+        // Only show a notification if this is a battery alert that should be shown
+        if (shouldShowBatteryNotification) {
           return self.registration.showNotification(pushData.title, {
             body: pushData.body,
             icon: '/icons/android-chrome-192x192.png',
             data: pushData.data
           });
         }
-        // For regular button presses, don't show notifications
+        // For regular button presses or throttled battery alerts, don't show notifications
         return Promise.resolve();
       });
     })
   );
 });
 
+// Listen for messages from client
+self.addEventListener('message', event => {
+  const message = event.data;
+  
+  if (!message || typeof message !== 'object') {
+    return;
+  }
+  
+  // Handle get timestamp request
+  if (message.type === 'get-battery-timestamp') {
+    console.log('[ServiceWorker] Client requested battery warning timestamp');
+    event.source.postMessage({
+      type: 'battery-timestamp',
+      timestamp: lastBatteryWarningTimestamp
+    });
+  }
+  
+  // Handle update timestamp request
+  if (message.type === 'update-battery-timestamp' && message.timestamp) {
+    console.log('[ServiceWorker] Updating battery warning timestamp to:', new Date(message.timestamp));
+    lastBatteryWarningTimestamp = message.timestamp;
+    saveTimestamp(message.timestamp).catch(error => {
+      console.warn('[ServiceWorker] Failed to save updated battery warning timestamp:', error);
+    });
+  }
+});
+
 // This helps with navigation after app is installed
 self.addEventListener('notificationclick', event => {
   console.log('[ServiceWorker] Notification click received');