feat(mobile): Added "jump to date" functionality to the memory view (#7323)

* implemented jump to date from memory

* Changed implementation to a ValueNotifier & fixes

* remove debug code

* feat(mobile):
- Added index bound checks
- Handled edge cases when scrolling to the very bottom of the grid-view
- removing the listener on dispose

* feat(mobile): fixed debug index offset & added debug toast for scroll errors

* feat(mobile): added more debug toasts...

* feat(mobile): scroll to month, if timeline is not grouped by days

---------

Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

mobile/lib/modules/asset_viewer/providers/scroll_to_date_notifier.provider.dart

@@ -0,0 +1,14 @@
+import 'package:flutter/material.dart';
+
+final scrollToDateNotifierProvider = ScrollToDateNotifier(null);
+
+class ScrollToDateNotifier extends ValueNotifier<DateTime?> {
+  ScrollToDateNotifier(super.value);
+
+  void scrollToDate(DateTime date) {
+    value = date;
+
+    // Manually notify listeners to trigger the scroll, even if the value hasn't changed
+    notifyListeners();
+  }
+}

mobile/lib/modules/home/ui/asset_grid/immich_asset_grid_view.dart

@@ -13,8 +13,11 @@ import 'package:immich_mobile/modules/asset_viewer/providers/scroll_notifier.pro
 import 'package:immich_mobile/modules/home/ui/asset_grid/asset_drag_region.dart';
 import 'package:immich_mobile/modules/home/ui/asset_grid/thumbnail_image.dart';
 import 'package:immich_mobile/modules/home/ui/asset_grid/thumbnail_placeholder.dart';
+import 'package:immich_mobile/shared/ui/immich_toast.dart';
+import 'package:fluttertoast/fluttertoast.dart';
 import 'package:immich_mobile/modules/home/ui/control_bottom_app_bar.dart';
 import 'package:immich_mobile/shared/models/asset.dart';
+import 'package:immich_mobile/modules/asset_viewer/providers/scroll_to_date_notifier.provider.dart';
 import 'package:immich_mobile/shared/providers/haptic_feedback.provider.dart';
 import 'package:scrollable_positioned_list/scrollable_positioned_list.dart';
 
@@ -150,6 +153,23 @@ class ImmichAssetGridViewState extends ConsumerState<ImmichAssetGridView> {
         assets.firstWhereOrNull((e) => !_selectedAssets.contains(e)) == null;
   }
 
+  Future<void> _scrollToIndex(int index) async {
+    // if the index is so far down, that the end of the list is reached on the screen
+    // the scroll_position widget crashes. This is a workaround to prevent this.
+    // If the index is within the last 10 elements, we jump instead of scrolling.
+    if (widget.renderList.elements.length <= index + 10) {
+      _itemScrollController.jumpTo(
+        index: index,
+      );
+      return;
+    }
+    await _itemScrollController.scrollTo(
+      index: index,
+      alignment: 0,
+      duration: const Duration(milliseconds: 500),
+    );
+  }
+
   Widget _itemBuilder(BuildContext c, int position) {
     int index = position;
     if (widget.topWidget != null) {
@@ -247,6 +267,48 @@ class ImmichAssetGridViewState extends ConsumerState<ImmichAssetGridView> {
         : RefreshIndicator(onRefresh: widget.onRefresh!, child: child);
   }
 
+  void _scrollToDate() {
+    final date = scrollToDateNotifierProvider.value;
+    if (date == null) {
+      ImmichToast.show(
+        context: context,
+        msg: "Scroll To Date failed, date is null.",
+        gravity: ToastGravity.BOTTOM,
+        toastType: ToastType.error,
+      );
+      return;
+    }
+
+    // Search for the index of the exact date in the list
+    var index = widget.renderList.elements.indexWhere(
+      (e) =>
+          e.date.year == date.year &&
+          e.date.month == date.month &&
+          e.date.day == date.day,
+    );
+
+    // If the exact date is not found, the timeline is grouped by month,
+    // thus we search for the month
+    if (index == -1) {
+      index = widget.renderList.elements.indexWhere(
+        (e) => e.date.year == date.year && e.date.month == date.month,
+      );
+    }
+
+    if (index != -1 && index < widget.renderList.elements.length) {
+      // Not sure why the index is shifted, but it works. :3
+      _scrollToIndex(index + 1);
+    } else {
+      ImmichToast.show(
+        context: context,
+        msg:
+            "The date (${DateFormat.yMd().format(date)}) could not be found in the timeline.",
+        gravity: ToastGravity.BOTTOM,
+        toastType: ToastType.error,
+      );
+    }
+  }
+
   @override
   void didUpdateWidget(ImmichAssetGridView oldWidget) {
     super.didUpdateWidget(oldWidget);
@@ -261,6 +323,8 @@ class ImmichAssetGridViewState extends ConsumerState<ImmichAssetGridView> {
   void initState() {
     super.initState();
     scrollToTopNotifierProvider.addListener(_scrollToTop);
+    scrollToDateNotifierProvider.addListener(_scrollToDate);
+
     if (widget.visibleItemsListener != null) {
       _itemPositionsListener.itemPositions.addListener(_positionListener);
     }
@@ -274,6 +338,7 @@ class ImmichAssetGridViewState extends ConsumerState<ImmichAssetGridView> {
   @override
   void dispose() {
     scrollToTopNotifierProvider.removeListener(_scrollToTop);
+    scrollToDateNotifierProvider.removeListener(_scrollToDate);
     if (widget.visibleItemsListener != null) {
       _itemPositionsListener.itemPositions.removeListener(_positionListener);
     }

mobile/lib/modules/memories/ui/memory_bottom_info.dart

@@ -1,6 +1,10 @@
+// ignore_for_file: require_trailing_commas
+
+import 'package:auto_route/auto_route.dart';
 import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:immich_mobile/modules/memories/models/memory.dart';
+import 'package:immich_mobile/modules/asset_viewer/providers/scroll_to_date_notifier.provider.dart';
 
 class MemoryBottomInfo extends StatelessWidget {
   final Memory memory;
@@ -12,33 +16,46 @@ class MemoryBottomInfo extends StatelessWidget {
     final df = DateFormat.yMMMMd();
     return Padding(
       padding: const EdgeInsets.all(16.0),
-      child: Row(
-        children: [
-          Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              Text(
-                memory.title,
-                style: TextStyle(
-                  color: Colors.grey[400],
-                  fontSize: 13.0,
-                  fontWeight: FontWeight.w500,
-                ),
+      child: Row(mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [
+        Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              memory.title,
+              style: TextStyle(
+                color: Colors.grey[400],
+                fontSize: 13.0,
+                fontWeight: FontWeight.w500,
               ),
-              Text(
-                df.format(
-                  memory.assets[0].fileCreatedAt,
-                ),
-                style: const TextStyle(
-                  color: Colors.white,
-                  fontSize: 15.0,
-                  fontWeight: FontWeight.w500,
-                ),
+            ),
+            Text(
+              df.format(
+                memory.assets[0].fileCreatedAt,
               ),
-            ],
+              style: const TextStyle(
+                color: Colors.white,
+                fontSize: 15.0,
+                fontWeight: FontWeight.w500,
+              ),
+            ),
+          ],
+        ),
+        MaterialButton(
+          minWidth: 0,
+          onPressed: () {
+            context.popRoute();
+            scrollToDateNotifierProvider
+                .scrollToDate(memory.assets[0].fileCreatedAt);
+          },
+          shape: const CircleBorder(),
+          color: Colors.white.withOpacity(0.2),
+          elevation: 0,
+          child: const Icon(
+            Icons.open_in_new,
+            color: Colors.white,
           ),
-        ],
-      ),
+        ),
+      ]),
     );
   }
 }