import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:go_router/go_router.dart';
import 'package:halkyon_app/halkyon_app.dart';
import 'package:halkyon_learn_flutter/l10n/app_localizations.dart';
import 'package:halkyon_learn_flutter/src/core/dependencies/person_dependencies.dart';
import 'package:halkyon_learn_flutter/src/core/router/app_shell.dart';
import 'package:halkyon_learn_flutter/src/core/router/route_paths.dart';
import 'package:halkyon_learn_flutter/src/core/router/tab_visibility.dart';
import 'package:halkyon_learn_flutter/src/feature/assistant/widget/connect_claude_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/auth/widget/profile_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/card/bloc/card_composer_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/card/widget/card_browser_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/card/widget/composer/card_composer_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/dictionary/widget/dictionary_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/discussion/model/discussion.dart';
import 'package:halkyon_learn_flutter/src/feature/discussion/widget/discussion_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/discussion/widget/discussions_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/explore/widget/explore_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/feedback/bloc/inbox_count_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/home/widget/home_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/jellyfin/widget/jellyfin_browser_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/jellyfin/widget/watch_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/bloc/path_editor_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/bloc/path_runner_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/bloc/step_editor_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/widget/path_editor_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/widget/path_runner_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/learning_path/widget/step_editor_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/note/bloc/note_editor_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/note/widget/note_editor_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/pdf_source/widget/pdf_reader_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/pdf_source/widget/reading_timeline_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/settings/widget/settings_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/study/bloc/study_session_bloc.dart';
import 'package:halkyon_learn_flutter/src/feature/study/model/study_focus.dart';
import 'package:halkyon_learn_flutter/src/feature/study/widget/study_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset.dart';
import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_tree.dart';
import 'package:halkyon_learn_flutter/src/feature/studyset/widget/library_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/studyset/widget/studyset_language_scope.dart';
import 'package:halkyon_learn_flutter/src/feature/studyset/widget/studyset_screen.dart';
import 'package:halkyon_learn_flutter/src/feature/tag/bloc/jellyfin_tags_bloc.dart';
import 'package:halkyon_ui/halkyon_ui.dart';
import 'package:material_ui/material_ui.dart';

/// The router of one person's app: the four tabs in a shell, each with its own
/// stack of screens, and the focused surfaces over them. Every route is built
/// inside the person's scope, so screens read their repositories from
/// [PersonScope]. The app opens at [initialLocation].
GoRouter buildRouter({String initialLocation = RoutePaths.home}) => GoRouter(
  initialLocation: initialLocation,
  routes: [
    StatefulShellRoute(
      builder: (context, state, navigationShell) => AppShell(
        navigationShell: navigationShell,
        // Inside a studyset, its own bar at the bottom takes the
        // navigation bar's place.
        hidesNavigationBar: RoutePaths.isInsideStudyset(state.uri.path),
        // The inbox's threads with something new.
        profileBadge: (context) =>
            context.select<InboxCountBloc?, int>((bloc) => bloc?.state ?? 0),
      ),
      navigatorContainerBuilder: tabsContainer,
      // In the order of the shell's destinations.
      branches: [
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: RoutePaths.home,
              builder: (context, state) => const HomeScreen(),
            ),
          ],
        ),
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: RoutePaths.library,
              builder: (context, state) => const LibraryScreen(),
              // Nested, so a studyset's screen sits above the library in the
              // tab's stack.
              routes: [
                GoRoute(
                  path: 'studysets/:id',
                  // Keyed by the id: several studysets' screens can be on
                  // the stack at once, and must not share one page. Named by
                  // its location, so the way up finds it among them.
                  pageBuilder: (context, state) {
                    final id = state.pathParameters['id']!;
                    return MaterialPage<void>(
                      key: ValueKey('studyset-$id'),
                      name: RoutePaths.studyset(id),
                      child: _studysetScreen(
                        context,
                        id,
                        importOnOpen:
                            state.uri.queryParameters['import'] == 'content',
                      ),
                    );
                  },
                ),
              ],
            ),
            // A studyset's notes and paths keep the tabs beside them, as
            // its screen does: reading and writing them is part of being in
            // the library. What needs the whole window (studying, a card,
            // a PDF) stays over the tabs.
            // A note, new or stored; the new one's route first, as for cards.
            GoRoute(
              path: '/studysets/:studysetId/notes/new',
              builder: (context, state) =>
                  _noteEditor(context, state.pathParameters['studysetId']!),
            ),
            GoRoute(
              path: '/studysets/:studysetId/notes/:noteId',
              builder: (context, state) => _noteEditor(
                context,
                state.pathParameters['studysetId']!,
                noteId: state.pathParameters['noteId'],
              ),
            ),
            // The dictionary of a studyset's language, to add words from.
            GoRoute(
              path: '/studysets/:studysetId/dictionary',
              builder: (context, state) {
                final studysetId = state.pathParameters['studysetId']!;
                return _inStudyset(
                  context,
                  studysetId,
                  (_, _) => DictionaryScreen(studysetId: studysetId),
                );
              },
            ),
            // Watching from Jellyfin for a studyset: the libraries, or what
            // an item of them holds.
            GoRoute(
              path: '/studysets/:studysetId/jellyfin',
              builder: (context, state) {
                final studysetId = state.pathParameters['studysetId']!;
                return _inStudyset(
                  context,
                  studysetId,
                  (_, _) => JellyfinBrowserScreen(
                    key: ValueKey(state.uri.queryParameters['in']),
                    studysetId: studysetId,
                    parentId: state.uri.queryParameters['in'],
                    name: state.uri.queryParameters['name'],
                  ),
                );
              },
            ),
            // A learning path: worked through, written, and one of its steps
            // written.
            GoRoute(
              path: '/studysets/:studysetId/paths/:pathId',
              builder: (context, state) => _pathRunner(
                context,
                state.pathParameters['studysetId']!,
                state.pathParameters['pathId']!,
              ),
            ),
            GoRoute(
              path: '/studysets/:studysetId/paths/:pathId/edit',
              builder: (context, state) => _pathEditor(
                context,
                state.pathParameters['studysetId']!,
                state.pathParameters['pathId']!,
              ),
            ),
            GoRoute(
              path: '/studysets/:studysetId/paths/:pathId/steps/:stepId',
              builder: (context, state) => _stepEditor(
                context,
                state.pathParameters['studysetId']!,
                state.pathParameters['pathId']!,
                state.pathParameters['stepId']!,
              ),
            ),
          ],
        ),
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: RoutePaths.explore,
              builder: (context, state) => const ExploreScreen(),
            ),
          ],
        ),
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: RoutePaths.profile,
              builder: (context, state) => ProfileScreen(
                signsInWithEmail:
                    state.uri.queryParameters['signIn'] == 'email',
              ),
            ),
          ],
        ),
      ],
    ),
    // Over the tabs: they need the whole window.
    GoRoute(
      path: '/study/:studysetId',
      builder: (context, state) {
        final person = PersonDependencies.of(context);
        final studysetId = state.pathParameters['studysetId']!;
        return _inStudyset(
          context,
          studysetId,
          (studyset, _) => FramedScreen(
            child: MultiBlocProvider(
              providers: [
                BlocProvider(
                  create: (context) => StudySessionBloc(
                    person.studysets,
                    person.cards,
                    person.cardDeletions,
                    person.reviews,
                    person.tags,
                    person.paths,
                    person.settings,
                    studysetId,
                    focus: StudyFocus.fromQuery(state.uri.queryParameters),
                  )..add(const StudySessionEventStarted()),
                ),
                BlocProvider(
                  create: (context) =>
                      JellyfinTagsBloc(person.settings)
                        ..add(const JellyfinTagsEventStarted()),
                ),
              ],
              child: StudyScreen(
                studysetId: studysetId,
                title: studyset.content.title,
              ),
            ),
          ),
        );
      },
    ),
    // Browsing a studyset's cards: searching, filtering and changing many at
    // once.
    GoRoute(
      path: '/studysets/:studysetId/flashcards',
      builder: (context, state) => _inStudyset(
        context,
        state.pathParameters['studysetId']!,
        (studyset, all) => FramedScreen(
          child: CardBrowserScreen(
            studyset: studyset,
            all: all,
            subtree: state.uri.queryParameters['subtree'] == '1',
          ),
        ),
      ),
    ),
    // The composer: writing a studyset's cards, opened on a new card or on
    // one of them. Before the card route: its `new` would otherwise read as
    // a card's id.
    GoRoute(
      path: '/studysets/:studysetId/cards/new',
      builder: (context, state) =>
          _composer(context, state.pathParameters['studysetId']!),
    ),
    GoRoute(
      path: '/studysets/:studysetId/cards/:cardId',
      builder: (context, state) => _composer(
        context,
        state.pathParameters['studysetId']!,
        cardId: state.pathParameters['cardId'],
      ),
    ),
    GoRoute(
      path: RoutePaths.readingTimeline,
      builder: (context, state) => const ReadingTimelineScreen(),
    ),
    // A video of the Jellyfin server, watched in the whole window to learn
    // the words of its subtitles into a studyset.
    GoRoute(
      path: '/watch/:studysetId/:itemId',
      builder: (context, state) {
        final studysetId = state.pathParameters['studysetId']!;
        return _inStudyset(
          context,
          studysetId,
          (_, _) => WatchScreen(
            studysetId: studysetId,
            itemId: state.pathParameters['itemId']!,
          ),
        );
      },
    ),
    // A PDF, read in the whole window; at a page when asked.
    GoRoute(
      path: '/pdfs/:pdfId',
      builder: (context, state) => PdfReaderScreen(
        pdfId: state.pathParameters['pdfId']!,
        page: int.tryParse(state.uri.queryParameters['page'] ?? ''),
      ),
    ),
    // A published studyset's discussions, and each of them (ADR 0013).
    GoRoute(
      path: '/discussions/:publicId',
      builder: (context, state) => FramedScreen(
        child: DiscussionsScreen(
          publicId: state.pathParameters['publicId']!,
          topic: state.uri.queryParameters['topic'],
          version: int.tryParse(state.uri.queryParameters['version'] ?? ''),
          title: state.uri.queryParameters['title'],
          ask: targetFromQuery(state.uri.queryParameters['ask']),
        ),
      ),
      routes: [
        GoRoute(
          path: ':questionId',
          builder: (context, state) => FramedScreen(
            child: DiscussionScreen(
              questionId: state.pathParameters['questionId']!,
            ),
          ),
        ),
      ],
    ),
    GoRoute(
      path: RoutePaths.settings,
      builder: (context, state) => const FramedScreen(child: SettingsScreen()),
      routes: [
        GoRoute(
          path: 'assistant',
          builder: (context, state) =>
              const FramedScreen(child: ConnectClaudeScreen()),
        ),
      ],
    ),
  ],
);

/// The learning path [pathId] of the studyset [studysetId], to work
/// through; a studyset gone says so.
Widget _pathRunner(BuildContext context, String studysetId, String pathId) {
  final person = PersonDependencies.of(context);
  return _inStudyset(
    context,
    studysetId,
    (studyset, _) => BlocProvider(
      create: (context) =>
          PathRunnerBloc(person.paths, person.pathProgress, studysetId, pathId)
            ..add(const PathRunnerEventStarted()),
      child: PathRunnerScreen(studysetId: studysetId, pathId: pathId),
    ),
  );
}

/// The learning path [pathId] of the studyset [studysetId], to write.
/// Leaving closes its bloc, which saves what is unsaved.
Widget _pathEditor(BuildContext context, String studysetId, String pathId) {
  final person = PersonDependencies.of(context);
  return _inStudyset(
    context,
    studysetId,
    (studyset, _) => BlocProvider(
      create: (context) => PathEditorBloc(
        person.paths,
        person.tags,
        person.stepDeletions,
        studysetId,
        pathId,
      )..add(const PathEditorEventStarted()),
      child: PathEditorScreen(studysetId: studysetId, pathId: pathId),
    ),
  );
}

/// The step [stepId] of the learning path [pathId], to write. Leaving
/// closes its bloc, which saves what is unsaved.
Widget _stepEditor(
  BuildContext context,
  String studysetId,
  String pathId,
  String stepId,
) {
  final person = PersonDependencies.of(context);
  return _inStudyset(
    context,
    studysetId,
    (studyset, _) => BlocProvider(
      create: (context) =>
          StepEditorBloc(person.paths, pathId, stepId)
            ..add(const StepEditorEventStarted()),
      child: const StepEditorScreen(),
    ),
  );
}

Widget _studysetScreen(
  BuildContext context,
  String id, {
  bool importOnOpen = false,
}) => _inStudyset(
  context,
  id,
  (studyset, all) =>
      StudysetScreen(studyset: studyset, all: all, importOnOpen: importOnOpen),
  wayBack: (
    label: AppLocalizations.of(context).studysetBackToLibrary,
    onPressed: () => context.go(RoutePaths.library),
  ),
);

/// The studyset [id] among the person's, for [builder]'s screen, its text
/// set for the studyset's languages ([StudysetLanguageScope]); a studyset
/// gone (deleted, or an old link) says so, leading back by [wayBack].
Widget _inStudyset(
  BuildContext context,
  String id,
  Widget Function(Studyset studyset, List<Studyset> all) builder, {
  ({String label, VoidCallback onPressed})? wayBack,
}) => FoundById<Studyset>(
  id: id,
  items: PersonDependencies.of(context).studysets.watchAll,
  idOf: (studyset) => studyset.id,
  wayBack: wayBack,
  builder: (studyset, all) => StudysetLanguageScope(
    studyset: studyset,
    all: all,
    // Every screen of a studyset washes its colour, its own or the nearest
    // above it.
    child: ScreenColor(
      color:
          PaletteColor.byName(colorNameOf(studyset.id, all))?.background ??
          Brand.primary,
      child: builder(studyset, all),
    ),
  ),
);

/// The note [noteId] of the studyset [studysetId], or a new one without; a
/// studyset gone (deleted, or an old link) says so. Leaving the note closes
/// its bloc, which saves what is unsaved.
Widget _noteEditor(BuildContext context, String studysetId, {String? noteId}) {
  final person = PersonDependencies.of(context);
  return _inStudyset(
    context,
    studysetId,
    (_, _) => BlocProvider(
      create: (context) =>
          NoteEditorBloc(person.notes, person.tags, studysetId, noteId: noteId)
            ..add(const NoteEditorEventStarted()),
      child: const NoteEditorScreen(),
    ),
  );
}

/// The composer of the studyset [studysetId]'s cards, opened on [cardId] if
/// given; a studyset gone (deleted, or an old link) says so.
Widget _composer(BuildContext context, String studysetId, {String? cardId}) {
  final person = PersonDependencies.of(context);
  return _inStudyset(
    context,
    studysetId,
    (studyset, _) => FramedScreen(
      child: BlocProvider(
        create: (context) =>
            CardComposerBloc(person.cards, person.tags, studysetId)
              ..add(const CardComposerEventStarted()),
        child: CardComposerScreen(
          studysetTitle: studyset.content.title,
          initialCardId: cardId,
        ),
      ),
    ),
  );
}