feat: ✨ one notification per product

- only one notification per price change
- notification tap handling for closed and in-memory states of the app
- introduced 3 types of notifications

lib/models/product.dart

@@ -28,6 +28,8 @@ class Product {
   bool get parseSuccess => _parseSuccess;
   set parseSuccess(bool newVal) => this._parseSuccess = newVal;
 
+  double get latestPrice => _prices[_prices.length - 1];
+
   var formatter = new DateFormat('yyyy-MM-dd');
 
   @override
@@ -185,6 +187,8 @@ class Product {
     return roundToPlace(last - secondLast, 2);
   }
 
+  // Returns the saved price percentage
+  // e.g. 200 -> 100 = 50.0
   double percentageToYesterday() {
     int length = prices.length;
 
@@ -193,7 +197,7 @@ class Product {
     double last = prices[length - 1];
     double secondLast = prices[length - 2];
 
-    return roundToPlace((1 - (last / secondLast)) * -100, 2);
+    return (roundToPlace((1 - (last / secondLast)).abs() * 100, 2));
   }
 
   List<double> prices2List(String prices) {

lib/screens/home/home.dart

@@ -2,7 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:price_tracker/components/widget_view/widget_view.dart';
 import 'package:price_tracker/screens/home/components/product_list_tile.dart';
 import 'package:price_tracker/screens/home/home_controller.dart';
-import 'package:price_tracker/services/notifications.dart';
 import 'package:price_tracker/services/product_utils.dart';
 import 'package:toast/toast.dart';
 import 'package:workmanager/workmanager.dart';
@@ -33,8 +32,7 @@ class HomeScreenView extends WidgetView<HomeScreen, HomeScreenController> {
         if (NOTIFICATION_TEST_BUTTON)
           IconButton(
             icon: Icon(Icons.speaker_notes),
-            onPressed: () => NotificationService.sendPushNotification(
-                0, "test", "test body"),
+            onPressed: () => state.testNotification(),
             color: Colors.redAccent,
           ),
         if (BACKGROUND_TEST_BUTTON)

lib/screens/home/home_controller.dart

@@ -7,6 +7,7 @@ import 'package:flutter_clipboard_manager/flutter_clipboard_manager.dart';
 import 'package:price_tracker/models/product.dart';
 import 'package:price_tracker/screens/home/home.dart';
 import 'package:price_tracker/services/database.dart';
+import 'package:price_tracker/services/notifications.dart';
 import 'package:price_tracker/services/product_utils.dart';
 import 'package:price_tracker/services/scraper.dart';
 import 'package:price_tracker/services/share_intent.dart';
@@ -32,6 +33,8 @@ class HomeScreenController extends State<HomeScreen> {
   void init() async {
     await _loadProducts();
     await checkInternet();
+    await _checkForNotificationTap();
+
     if (iConnectivity) await _checkForSharedText();
   }
 
@@ -42,14 +45,20 @@ class HomeScreenController extends State<HomeScreen> {
   }
 
   _checkForSharedText() async {
-    if (ShareIntentService.sharedText != null) {
-      String input = ShareIntentService.sharedText;
+    String input = ShareIntentService.sharedText;
+    if (input != null) {
       ShareIntentService.sharedText = null;
-
       await addProduct(input);
     }
   }
 
+  _checkForNotificationTap() async {
+    String payload = NotificationService.currentPayload;
+    if (payload != null) {
+      notificationTapCallback(payload);
+    }
+  }
+
   Future<bool> checkInternet() async {
     try {
       final result = await InternetAddress.lookup('google.com')
@@ -194,6 +203,24 @@ class HomeScreenController extends State<HomeScreen> {
         curve: Curves.easeInOut, duration: Duration(milliseconds: 1000));
   }
 
+  testNotification() {
+    Product p = Product.fromMap({
+      "_id": 5,
+      "name": "Apple iPad (10.2-inch, WiFi, 32GB) - Gold (latest model)",
+      "productUrl": "testUrl.com",
+      "prices": "[-1.0, 269.0, 260.0]",
+      "dates":
+          "[2020-07-02 00:00:00.000, 2020-07-03 15:43:12.345, 2020-07-04 04:00:45.000]",
+      "targetPrice": "261.0",
+      "imageUrl": "",
+      "parseSuccess": "true",
+    });
+    // Only one can be send at a time (same id)
+    sendPriceFallNotification(p);
+    // sendUnderTargetNotification(p);
+    // sendAvailableAgainNotification(p);
+  }
+
   @override
   Widget build(BuildContext context) => HomeScreenView(this);
 }

lib/services/notifications.dart

@@ -1,10 +1,13 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+import 'package:price_tracker/services/init.dart';
+import 'package:price_tracker/services/product_utils.dart';
+
 import 'package:rxdart/subjects.dart';
 
 class NotificationService {
   static FlutterLocalNotificationsPlugin _flutterLocalNotificationsPlugin;
-
+  static String currentPayload;
   NotificationService._privateConstructor();
 
   static final NotificationService _instance =
@@ -35,22 +38,47 @@ class NotificationService {
         onSelectNotification: (String payload) async {
       if (payload != null) {
         debugPrint('notification payload: ' + payload);
+        currentPayload = payload;
+
+        // If state is mounted, the app is in memory,
+        // else the app starts and the callback gets triggered in the home view
+        if (navigatorKey.currentState.mounted) notificationTapCallback(payload);
       }
       selectNotificationSubject.add(payload);
     });
   }
 
-  static Future<void> sendPushNotification(
-      int id, String title, String body) async {
+  static Future<void> sendAlertPushNotificationSmall(
+      int id, String title, String body,
+      {String payload = ""}) async {
     var androidPlatformChannelSpecifics = AndroidNotificationDetails(
-        'your channel id', 'your channel name', 'your channel description',
+        '0', 'Price Alerts', 'Price change alerts for tracked products',
         importance: Importance.Max, priority: Priority.High, ticker: 'ticker');
     var iOSPlatformChannelSpecifics = IOSNotificationDetails();
     var platformChannelSpecifics = NotificationDetails(
         androidPlatformChannelSpecifics, iOSPlatformChannelSpecifics);
 
     await _flutterLocalNotificationsPlugin
-        .show(id, title, body, platformChannelSpecifics, payload: 'item x');
+        .show(id, title, body, platformChannelSpecifics, payload: payload);
+
+    print("Push notifications was sent!");
+  }
+
+  static Future<void> sendAlertPushNotificationBig(
+      int id, String title, String body,
+      {String payload = ""}) async {
+    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
+        '0', 'Price Alerts', 'Price change alerts for tracked products',
+        importance: Importance.Max,
+        priority: Priority.High,
+        ticker: 'ticker',
+        styleInformation: BigTextStyleInformation(body));
+    var iOSPlatformChannelSpecifics = IOSNotificationDetails();
+    var platformChannelSpecifics = NotificationDetails(
+        androidPlatformChannelSpecifics, iOSPlatformChannelSpecifics);
+
+    await _flutterLocalNotificationsPlugin
+        .show(id, title, body, platformChannelSpecifics, payload: payload);
 
     print("Push notifications was sent!");
   }

lib/services/product_utils.dart

@@ -1,46 +1,12 @@
 import 'package:price_tracker/models/product.dart';
+import 'package:price_tracker/screens/product_detail/product_detail.dart';
 import 'package:price_tracker/services/database.dart';
 import 'package:flutter/material.dart';
+import 'package:price_tracker/services/init.dart';
 import 'package:price_tracker/services/notifications.dart';
 
 double reloadProgress;
 
-Future<int> countPriceFall() async {
-  final _db = await DatabaseService.getInstance();
-
-  List<Product> products = await _db.getAllProducts();
-
-  int count = 0;
-
-  for (int i = 0; i < products.length; i++) {
-    if (products[i].priceFall()) {
-      count++;
-
-      debugPrint(products[i].name);
-      debugPrint(
-          "Price diff: " + products[i].priceDifferenceToYesterday().toString());
-      debugPrint(
-          "Percentage: " + products[i].percentageToYesterday().toString());
-      debugPrint("Available again: " + products[i].availableAgain().toString());
-    }
-  }
-  return count;
-}
-
-//Returns number of products that fell under the set target
-Future<int> countPriceUnderTarget() async {
-  final _db = await DatabaseService.getInstance();
-
-  List<Product> products = await _db.getAllProducts();
-
-  int count = 0;
-
-  for (int i = 0; i < products.length; i++) {
-    if (products[i].underTarget()) count++;
-  }
-  return count;
-}
-
 //Returns number of products that fell under the set target
 Future<int> countFailedParsing() async {
   final _db = await DatabaseService.getInstance();
@@ -63,42 +29,68 @@ Future<void> updatePrices(Function perUpdate, {test: false}) async {
   List<Product> products = await _db.getAllProducts();
 
   for (int i = 0; i < products.length; i++) {
+    double lastPrice = products[i].latestPrice;
     await products[i].update(test: test);
     await _db.update(products[i]);
     reloadProgress = i / products.length;
     perUpdate();
-  }
 
-  products = await _db.getAllProducts();
-  int countFall = await countPriceFall();
-  int countTarget = await countPriceUnderTarget();
-
-  if (countFall > 0) {
-    if (countFall == 1) {
-      NotificationService.sendPushNotification(
-          0,
-          '$countFall product is cheaper',
-          'We detected that $countFall product is cheaper today!'); //Display Notification
-    } else {
-      NotificationService.sendPushNotification(
-          0,
-          '$countFall products are cheaper',
-          'We detected that $countFall products are cheaper today!'); //Display Notification
-    }
-  }
-  if (countTarget > 0) {
-    if (countTarget == 1) {
-      NotificationService.sendPushNotification(
-          1,
-          '$countTarget product is under their target!',
-          'We detected that $countTarget product is under the set target today!'); //Display Notification
-    } else {
-      NotificationService.sendPushNotification(
-          1,
-          '$countTarget products are under their target!',
-          'We detected that $countTarget products are under the set targets today!'); //Display Notification
-    }
+    // Send notifications only when price changed
+    // otherwise the app notified twice per day.
+    if (lastPrice != products[i].latestPrice)
+      checkAndSendNotifications(products[i]);
   }
 
   reloadProgress = null;
 }
+
+// Opens the corresponding details view of the product by product id in payload
+Future<void> notificationTapCallback(String payload) async {
+  // get Product by id
+  Product product = await (await DatabaseService.getInstance())
+      .getProduct(payload != "" ? int.parse(payload) : null);
+
+  // Clear payload variable
+  NotificationService.currentPayload = null;
+
+  if (product != null)
+    navigatorKey.currentState.push(MaterialPageRoute(
+        builder: (context) => ProductDetail(
+              product: product,
+            )));
+}
+
+sendPriceFallNotification(Product p) {
+  NotificationService.sendAlertPushNotificationBig(
+      p.id,
+      "A Product is cheaper by ${p.percentageToYesterday()}%!",
+      p.getShortName() +
+          "\nThe price fell by ${-p.priceDifferenceToYesterday()} and it costs now ${p.latestPrice}",
+      payload: p.id.toString());
+}
+
+sendUnderTargetNotification(Product p) {
+  NotificationService.sendAlertPushNotificationBig(
+      p.id,
+      "A Product is under their Target!",
+      p.getShortName() + " is under the set target and costs ${p.latestPrice}",
+      payload: p.id.toString());
+}
+
+sendAvailableAgainNotification(Product p) {
+  NotificationService.sendAlertPushNotificationBig(
+      p.id,
+      "A Product is available again!",
+      p.getShortName() + " is available again and costs ${p.latestPrice}",
+      payload: p.id.toString());
+}
+
+// Checks theproduct and sends the relevant Notification if any
+checkAndSendNotifications(Product p) {
+  if (p.priceFall()) {
+    if (p.underTarget())
+      sendUnderTargetNotification(p);
+    else
+      sendPriceFallNotification(p);
+  } else if (p.availableAgain()) sendAvailableAgainNotification(p);
+}

test/product_test.dart

@@ -403,15 +403,15 @@ void main() {
         productMap2["dates"] = "[2020-07-02, 2020-07-03]";
         p = Product.fromMap(productMap2);
 
-        expect(p.percentageToYesterday(), -50.0);
+        expect(p.percentageToYesterday(), 50.0);
       });
 
       test('100 -> 200 -> 100', () {
         productMap2["prices"] = "[100, 200, 100]";
         productMap2["dates"] = "[2020-07-01, 2020-07-02, 2020-07-03]";
         p = Product.fromMap(productMap2);
 
-        expect(p.percentageToYesterday(), -50.0);
+        expect(p.percentageToYesterday(), 50.0);
       });
 
       test('100 -> 200 -> 220', () {
@@ -427,7 +427,7 @@ void main() {
         productMap2["dates"] = "[2020-07-02, 2020-07-03]";
         p = Product.fromMap(productMap2);
 
-        expect(p.percentageToYesterday(), -21.45);
+        expect(p.percentageToYesterday(), 21.45);
       });
     });
   });