feature/#21 - scan now uses local database, for product look up and f…

…or its history

New file:
* `scan_page.dart`: helper class to be used on top of `AlternativeContinuousScanPage` and `ContinuousScanPage`

Impacted files:
* `alternative_continuous_scan_page.dart`: `ContinuousScanModel` is now initialized upstream by `ScanPage`
* `continuous_scan_model.dart`: now a `ChangeNotifier`, uses a `ProductList` and database cache
* `continuous_scan_page.dart`: `ContinuousScanModel` is now initialized upstream by `ScanPage`
* `contribution_page.dart`: uses the new `ScanPage` widget instead of the 2 scan pages
* `local_database.dart`: removed the dummy notify listener method
* `main.dart`: uses the new `ScanPage` widget instead of the 2 scan pages
* `personalized_ranking_page.dart`: now we use a `ProductList` as input
* `product_list.dart`: added a `getProduct` method and a "scan list" identifier
* `product_page.dart`: unrelated UI fixes
* `product_query_page.dart`: slight refactoring
* `smooth_it_model.dart`: now we use `ProductList`
* `smooth_product_carousel.dart`: added the new "CACHED" product possibility; fixed an init bug

packages/smooth_app/lib/data_models/continuous_scan_model.dart

@@ -5,103 +5,144 @@ import 'package:qr_code_scanner/qr_code_scanner.dart';
 import 'package:smooth_app/database/barcode_product_query.dart';
 import 'package:smooth_app/database/dao_product.dart';
 import 'package:smooth_app/database/local_database.dart';
+import 'package:smooth_app/data_models/product_list.dart';
+import 'package:smooth_app/database/dao_product_list.dart';
 
 enum ScannedProductState {
   FOUND,
   NOT_FOUND,
   LOADING,
   THANKS,
+  CACHED,
 }
 
-class ContinuousScanModel {
+class ContinuousScanModel with ChangeNotifier {
   ContinuousScanModel({@required bool contributionMode})
       : _contributionMode = contributionMode;
 
   final Map<String, ScannedProductState> _states =
       <String, ScannedProductState>{};
-  final Map<String, Product> _products = <String, Product>{};
   final List<String> _barcodes = <String>[];
+  final ProductList _productList =
+      ProductList(listType: ProductList.LIST_TYPE_SCAN, parameters: '');
+
   bool _contributionMode;
-  QRViewController _scannerController;
+  String _barcodeLatest;
   String _barcodeTrustCheck;
-  LocalDatabase _localDatabase;
+  DaoProduct _daoProduct;
+  DaoProductList _daoProductList;
 
   bool get isNotEmpty => getBarcodes().isNotEmpty;
   bool get contributionMode => _contributionMode;
+  ProductList get productList => _productList;
 
   List<String> getBarcodes() => _barcodes;
 
+  Future<ContinuousScanModel> load(final LocalDatabase localDatabase) async {
+    try {
+      _daoProduct = DaoProduct(localDatabase);
+      _daoProductList = DaoProductList(localDatabase);
+      await _daoProductList.get(_productList);
+      for (final String barcode in _productList.barcodes) {
+        _barcodes.add(barcode);
+        _states[barcode] = ScannedProductState.CACHED;
+        _barcodeLatest = barcode;
+      }
+      return this;
+    } catch (e) {
+      print('exception: $e');
+    }
+    return null;
+  }
+
   void setBarcodeState(
     final String barcode,
     final ScannedProductState state,
   ) {
     _states[barcode] = state;
-    _localDatabase.dummyNotifyListeners();
+    notifyListeners();
   }
 
   ScannedProductState getBarcodeState(final String barcode) => _states[barcode];
 
-  Product getProduct(final String barcode) => _products[barcode];
+  Product getProduct(final String barcode) => _productList.getProduct(barcode);
 
-  void setLocalDatabase(final LocalDatabase localDatabase) =>
-      _localDatabase = localDatabase;
+  void setupScanner(QRViewController controller) =>
+      controller.scannedDataStream.listen((String barcode) => onScan(barcode));
 
-  void setupScanner(QRViewController controller) {
-    _scannerController = controller;
-    _scannerController.scannedDataStream.listen(
-      (String barcode) => onScan(barcode),
-    );
-  }
+  List<Product> getProducts() => _productList.getList();
 
-  List<Product> getFoundProducts() {
-    final List<Product> result = <Product>[];
-    for (final String barcode in _barcodes) {
-      if (getBarcodeState(barcode) == ScannedProductState.FOUND) {
-        result.add(_products[barcode]);
-      }
-    }
-    return result;
-  }
-
-  Future<void> onScan(String code) async {
-    print('Barcode detected : $code');
+  Future<void> onScan(final String code) async {
     if (_barcodeTrustCheck != code) {
       _barcodeTrustCheck = code;
       return;
     }
-    _addBarcode(code);
-  }
-
-  Future<void> onScanAlt(String code, List<Offset> offsets) async {
-    print('Barcode detected : $code');
+    if (_barcodeLatest == code) {
+      return;
+    }
+    _barcodeLatest = code;
     _addBarcode(code);
   }
 
   void contributionModeSwitch(bool value) {
     if (_contributionMode != value) {
       _contributionMode = value;
-      _localDatabase.dummyNotifyListeners();
+      notifyListeners();
     }
   }
 
-  bool _addBarcode(final String barcode) {
-    if (getBarcodeState(barcode) == null) {
+  Future<bool> _addBarcode(final String barcode) async {
+    final ScannedProductState state = getBarcodeState(barcode);
+    if (state == null) {
       _barcodes.add(barcode);
       setBarcodeState(barcode, ScannedProductState.LOADING);
-      _loadBarcode(barcode);
+      _cacheOrLoadBarcode(barcode);
+      return true;
+    }
+    if (state == ScannedProductState.FOUND ||
+        state == ScannedProductState.CACHED) {
+      final Product product = getProduct(barcode);
+      _barcodes.add(barcode);
+      _addProduct(product, state);
       return true;
     }
     return false;
   }
 
-  Future<void> _loadBarcode(final String barcode) async {
+  Future<void> _cacheOrLoadBarcode(final String barcode) async {
+    final bool cached = await _cachedBarcode(barcode);
+    if (!cached) {
+      _loadBarcode(barcode, ScannedProductState.NOT_FOUND);
+    }
+  }
+
+  Future<bool> _cachedBarcode(final String barcode) async {
+    final int latestUpdate = await _daoProduct.getLastUpdate(barcode);
+    if (latestUpdate != null) {
+      _addProduct(await _daoProduct.get(barcode), ScannedProductState.CACHED);
+      return true;
+    }
+    return false;
+  }
+
+  Future<void> _loadBarcode(
+    final String barcode,
+    final ScannedProductState notFound,
+  ) async {
     final Product product = await BarcodeProductQuery(barcode).getProduct();
     if (product != null) {
-      await DaoProduct(_localDatabase).put(product);
-      _products[barcode] = product;
-      setBarcodeState(barcode, ScannedProductState.FOUND);
+      _addProduct(product, ScannedProductState.FOUND);
     } else {
-      setBarcodeState(barcode, ScannedProductState.NOT_FOUND);
+      setBarcodeState(barcode, notFound);
     }
   }
+
+  Future<void> _addProduct(
+    final Product product,
+    final ScannedProductState state,
+  ) async {
+    _productList.add(product);
+    _daoProductList.put(_productList);
+    setBarcodeState(product.barcode, state);
+  }
 }

packages/smooth_app/lib/data_models/product_list.dart

@@ -15,6 +15,7 @@ class ProductList {
 
   static const String LIST_TYPE_HTTP_SEARCH_GROUP = 'http/search/group';
   static const String LIST_TYPE_HTTP_SEARCH_KEYWORDS = 'http/search/keywords';
+  static const String LIST_TYPE_SCAN = 'scan';
 
   List<String> get barcodes => _barcodes;
 
@@ -25,6 +26,8 @@ class ProductList {
     _products.clear();
   }
 
+  Product getProduct(final String barcode) => _products[barcode];
+
   void add(final Product product) {
     if (product == null) {
       throw Exception('null product');
@@ -59,4 +62,23 @@ class ProductList {
     }
     return result;
   }
+
+  List<Product> getUniqueList({final bool ascending = true}) {
+    final List<Product> result = <Product>[];
+    final Set<String> done = <String>{};
+    final Iterable<String> orderedBarcodes =
+        ascending ? _barcodes : _barcodes.reversed;
+    for (final String barcode in orderedBarcodes) {
+      if (done.contains(barcode)) {
+        continue;
+      }
+      done.add(barcode);
+      final Product product = _products[barcode];
+      if (product == null) {
+        throw Exception('no product for barcode $barcode');
+      }
+      result.add(product);
+    }
+    return result;
+  }
 }

packages/smooth_app/lib/data_models/smooth_it_model.dart

@@ -3,6 +3,7 @@ import 'package:smooth_app/structures/ranked_product.dart';
 import 'package:smooth_app/data_models/user_preferences_model.dart';
 import 'package:smooth_app/data_models/match.dart';
 import 'package:smooth_app/temp/user_preferences.dart';
+import 'package:smooth_app/data_models/product_list.dart';
 
 class SmoothItModel {
   static const int MATCH_INDEX_YES = 0;
@@ -16,14 +17,15 @@ class SmoothItModel {
   bool _nextRefreshIsJustChangingTabs = false;
 
   void refresh(
-    final List<Product> unprocessedProducts,
+    final ProductList productList,
     final UserPreferences userPreferences,
     final UserPreferencesModel userPreferencesModel,
   ) {
     if (_nextRefreshIsJustChangingTabs) {
       _nextRefreshIsJustChangingTabs = false;
       return;
     }
+    final List<Product> unprocessedProducts = productList.getUniqueList();
     _allProducts =
         Match.sort(unprocessedProducts, userPreferences, userPreferencesModel);
     _categorizedProducts.clear();

packages/smooth_app/lib/database/local_database.dart

@@ -40,10 +40,6 @@ class LocalDatabase extends ChangeNotifier {
   }
 
   static int nowInMillis() => DateTime.now().millisecondsSinceEpoch;
-
-  void dummyNotifyListeners() {
-    notifyListeners(); // TODO(monsieurtanuki): create a ScanNotifier instead
-  }
 }
 
 class TableStats {

packages/smooth_app/lib/lists/smooth_product_carousel.dart

@@ -32,7 +32,10 @@ class _SmoothProductCarouselState extends State<SmoothProductCarousel> {
     if (_length != barcodesLength) {
       _length = barcodesLength;
       if (_length > 1) {
-        _controller.animateToPage(_length - 1);
+        Future<void>.delayed(
+          const Duration(seconds: 0),
+          () => _controller.animateToPage(_length - 1),
+        );
       }
     }
     return CarouselSlider.builder(
@@ -55,6 +58,7 @@ class _SmoothProductCarouselState extends State<SmoothProductCarousel> {
     final Product product = widget.continuousScanModel.getProduct(barcode);
     switch (widget.continuousScanModel.getBarcodeState(barcode)) {
       case ScannedProductState.FOUND:
+      case ScannedProductState.CACHED:
         if (widget.continuousScanModel.contributionMode) {
           return SmoothProductCardEdit(heroTag: barcode, product: product);
         }

packages/smooth_app/lib/main.dart

@@ -10,10 +10,9 @@ import 'package:sentry/sentry.dart';
 import 'package:provider/provider.dart';
 
 import 'package:smooth_app/data_models/user_preferences_model.dart';
-import 'package:smooth_app/pages/alternative_continuous_scan_page.dart';
+import 'package:smooth_app/pages/scan_page.dart';
 import 'package:smooth_app/pages/choose_page.dart';
 import 'package:smooth_app/pages/contribution_page.dart';
-import 'package:smooth_app/pages/continuous_scan_page.dart';
 import 'package:smooth_app/pages/profile_page.dart';
 import 'package:smooth_app/pages/tracking_page.dart';
 import 'package:smooth_app/themes/smooth_theme.dart';
@@ -222,16 +221,15 @@ class SmoothApp extends StatelessWidget {
           icon: 'assets/actions/scanner_alt_2.svg',
           iconPadding: _navigationIconPadding,
           iconSize: _navigationIconSize,
-          onTap: () {
-            final Widget newPage = mlKitState
-                ? const ContinuousScanPage()
-                : const AlternativeContinuousScanPage();
-            Navigator.push<Widget>(
-              context,
-              MaterialPageRoute<Widget>(
-                  builder: (BuildContext context) => newPage),
-            );
-          },
+          onTap: () => Navigator.push<Widget>(
+            context,
+            MaterialPageRoute<Widget>(
+              builder: (BuildContext context) => ScanPage(
+                contributionMode: false,
+                mlKit: mlKitState,
+              ),
+            ),
+          ),
         ),
       );
 }