Fix bug that left PerDate widget empty when popped to.

Previously, when you would navigate to a PerDate widget that already
exists on the Navigation stack, a food that is entered will not be
visible when popping to the PerDate widget with the same date.

This is because the state is not updated (the BLoC exists per PerDate
widget, and a change in one widget does not cause firing an event in the previous widget's BLoC).

With this fix, we call setState() and update the entries for the widget
from storage.

lib/perdate/perdate_widget.dart

@@ -71,9 +71,60 @@ class _PerDateWidgetState extends State<PerDateWidget> {
                             color: Theme.of(context).colorScheme.secondary,
                             child: SumWidget(foodEntries: state.foodEntries)),
                         drawer: const AppDrawer(),
-                        floatingActionButton: OverflowBar(children: [
+                        floatingActionButton: OverflowBar(
-                          ScanFoodFloatingButton(
+                          children: [
-                            onPressed: () async {
+                            ScanFoodFloatingButton(onPressed: () {
+                              _onScanButtonPressed(context);
+                            }),
+                            const SizedBox(width: 8),
+                            CalendarFloatingButton(
+                              startFromDate: widget.date,
+                              onDateSelected: (dateSelected) {
+                                _onDateSelected(dateSelected);
+                              },
+                            ),
+                          ],
+                        ),
+                        floatingActionButtonLocation:
+                            FloatingActionButtonLocation.endDocked);
+                  },
+                ),
+              );
+      },
+    );
+  }
+
+  void showNewSnackbarWith(BuildContext context, String text) {
+    var snackbar =
+        ErrorSnackbar(colorScheme: Theme.of(context).colorScheme, text: text);
+
+    ScaffoldMessenger.of(context)
+      ..removeCurrentSnackBar()
+      ..showSnackBar(snackbar);
+  }
+
+  void _onDateSelected(DateTime date) {
+    Navigator.of(context).push(
+      MaterialPageRoute(
+        builder: (context) {
+          return PerDateWidget(date: date);
+        },
+      ),
+    ).then((val) {
+      setState(
+        () {
+          entriesFuture = storage.getEntriesForDate(widget.date);
+          entriesFuture.then(
+            (val) {
+              entries = val;
+            },
+          );
+        },
+      );
+    });
+  }
+
+  void _onScanButtonPressed(BuildContext context) async {
     var client = FoodFactLookupClient();
 
     var scanResult = await BarcodeScanner.scan();
@@ -85,26 +136,20 @@ class _PerDateWidgetState extends State<PerDateWidget> {
     if (!context.mounted) return;
 
     if (scanResult.type == ResultType.Error) {
-                                showNewSnackbarWith(context,
+      showNewSnackbarWith(context, "Fehler beim Scannen des Barcodes.");
-                                    "Fehler beim Scannen des Barcodes.");
     }
-                              var response = await client
+    var response = await client.retrieveFoodInfo(scanResult.rawContent);
-                                  .retrieveFoodInfo(scanResult.rawContent);
 
     if (!context.mounted) return;
 
-                              if (response.status ==
+    if (response.status == FoodFactResponseStatus.barcodeNotFound) {
-                                  FoodFactResponseStatus.barcodeNotFound) {
+      showNewSnackbarWith(context, "Barcode konnte nicht gefunden werden.");
-                                showNewSnackbarWith(context,
-                                    "Barcode konnte nicht gefunden werden.");
       return;
     }
 
-                              if (response.status ==
+    if (response.status == FoodFactResponseStatus.foodFactServerNotReachable) {
-                                  FoodFactResponseStatus
+      showNewSnackbarWith(
-                                      .foodFactServerNotReachable) {
+          context, "OpenFoodFacts-Server konnte nicht erreicht werden.");
-                                showNewSnackbarWith(context,
-                                    "OpenFoodFacts-Server konnte nicht erreicht werden.");
       return;
     }
 
@@ -112,35 +157,6 @@ class _PerDateWidgetState extends State<PerDateWidget> {
           response.food!.name,
           response.food!.kcalPer100g.toString(),
         );
-                            },
-                          ),
-                          const SizedBox(width: 8),
-                          CalendarFloatingButton(
-                            startFromDate: widget.date,
-                            onDateSelected: (dateSelected) {
-                              Navigator.of(context).push(
-                                MaterialPageRoute(
-                                  builder: (context) {
-                                    return PerDateWidget(date: dateSelected);
-                                  },
-                                ),
-                              );
-                            },
-                          ),
-                        ]),
-                        floatingActionButtonLocation:
-                            FloatingActionButtonLocation.endDocked);
-                  }),
-                );
-        });
-  }
-
-  void showNewSnackbarWith(BuildContext context, String text) {
-    var snackbar =
-        ErrorSnackbar(colorScheme: Theme.of(context).colorScheme, text: text);
-
-    ScaffoldMessenger.of(context).clearSnackBars();
-    ScaffoldMessenger.of(context).showSnackBar(snackbar);
   }
 }