neon: let apps provide a NavigationDestination

packages/neon/neon/lib/src/utils/app_implementation.dart

@@ -41,6 +41,18 @@ abstract class AppImplementation<T extends Bloc, R extends NextcloudAppSpecificO
 
   Widget get page;
 
+  NeonNavigationDestination destination(final BuildContext context) {
+    final accountsBloc = Provider.of<AccountsBloc>(context, listen: false);
+    final account = accountsBloc.activeAccount.value!;
+    final bloc = getBloc(account);
+
+    return NeonNavigationDestination(
+      label: name(context),
+      icon: buildIcon,
+      notificationCount: getUnreadCounter(bloc),
+    );
+  }
+
   Widget buildIcon({
     final Size size = const Size.square(32),
     final Color? color,

packages/neon/neon/lib/src/widgets/drawer_destination.dart

@@ -0,0 +1,137 @@
+import 'package:flutter/material.dart';
+import 'package:neon/neon.dart';
+import 'package:rxdart/subjects.dart';
+
+typedef DestinationIconBuilder = Widget Function({Size size, Color color});
+
+class NeonNavigationDestination {
+  const NeonNavigationDestination({
+    required this.label,
+    required this.icon,
+    this.selectedIcon,
+    this.notificationCount,
+  });
+
+  final String label;
+  final DestinationIconBuilder icon;
+  final Widget? selectedIcon;
+  final BehaviorSubject<int>? notificationCount;
+}
+
+extension NavigationDestinationExtension on NavigationDestination {
+  static NavigationDestination fromNeonDestination(final NeonNavigationDestination neonDestination) =>
+      NavigationDestination(
+        label: neonDestination.label,
+        icon: neonDestination.icon(),
+        selectedIcon: neonDestination.selectedIcon,
+      );
+}
+
+extension NavigationRailDestinationExtension on NavigationRailDestination {
+  static NavigationRailDestination fromNeonDestination(final NeonNavigationDestination neonDestination) {
+    final iconWIdget = StreamBuilder(
+      stream: neonDestination.notificationCount,
+      initialData: 0,
+      builder: (final context, final snapshot) {
+        final colorScheme = Theme.of(context).colorScheme;
+
+        final color = snapshot.data! > 0 ? colorScheme.primary : colorScheme.onBackground;
+        const size = Size.square(kAvatarSize * 2 / 3);
+
+        final icon = Container(
+          margin: const EdgeInsets.all(5),
+          child: neonDestination.icon(size: size, color: color),
+        );
+
+        if (snapshot.data! <= 0) {
+          return icon;
+        }
+
+        final notificationIdicator = Builder(
+          builder: (final context) {
+            final style = TextStyle(
+              color: Theme.of(context).colorScheme.primary,
+              fontWeight: FontWeight.bold,
+            );
+
+            return Text(
+              snapshot.data!.toString(),
+              style: style,
+            );
+          },
+        );
+
+        return Stack(
+          alignment: Alignment.bottomRight,
+          children: [
+            icon,
+            notificationIdicator,
+          ],
+        );
+      },
+    );
+
+    return NavigationRailDestination(
+      label: Text(neonDestination.label),
+      icon: iconWIdget,
+      selectedIcon: neonDestination.selectedIcon,
+    );
+  }
+}
+
+extension NavigationDrawerDestinationExtension on NavigationDrawerDestination {
+  static NavigationDrawerDestination fromNeonDestination(final NeonNavigationDestination neonDestination) {
+    final labelWidget = StreamBuilder(
+      stream: neonDestination.notificationCount,
+      initialData: 0,
+      builder: (final context, final snapshot) {
+        final label = Text(neonDestination.label);
+
+        if (snapshot.data! <= 0) {
+          return label;
+        }
+
+        final notificationIdicator = Padding(
+          padding: const EdgeInsets.only(left: 12, right: 24),
+          child: Builder(
+            builder: (final context) {
+              final style = TextStyle(
+                color: Theme.of(context).colorScheme.primary,
+                fontWeight: FontWeight.bold,
+                fontSize: 14,
+              );
+
+              return Text(
+                snapshot.data!.toString(),
+                style: style,
+              );
+            },
+          ),
+        );
+
+        return Expanded(
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              label,
+              notificationIdicator,
+            ],
+          ),
+        );
+      },
+    );
+
+    return NavigationDrawerDestination(
+      label: labelWidget,
+      icon: neonDestination.icon(),
+      selectedIcon: neonDestination.selectedIcon,
+    );
+  }
+}
+
+extension TabExtension on Tab {
+  static Tab fromNeonDestination(final NeonNavigationDestination neonDestination) => Tab(
+        text: neonDestination.label,
+        icon: neonDestination.icon(),
+      );
+}