import 'package:badges/badges.dart' as b;
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:paperless_api/paperless_api.dart';
import 'package:paperless_mobile/core/bloc/connectivity_cubit.dart';
import 'package:paperless_mobile/core/delegate/customizable_sliver_persistent_header_delegate.dart';
import 'package:paperless_mobile/core/widgets/material/colored_tab_bar.dart';
import 'package:paperless_mobile/extensions/flutter_extensions.dart';
import 'package:paperless_mobile/features/app_drawer/view/app_drawer.dart';
import 'package:paperless_mobile/features/document_search/view/sliver_search_bar.dart';
import 'package:paperless_mobile/features/documents/cubit/documents_cubit.dart';
import 'package:paperless_mobile/features/documents/view/widgets/adaptive_documents_view.dart';
import 'package:paperless_mobile/features/documents/view/widgets/documents_empty_state.dart';
import 'package:paperless_mobile/features/documents/view/widgets/search/document_filter_panel.dart';
import 'package:paperless_mobile/features/documents/view/widgets/selection/document_selection_sliver_app_bar.dart';
import 'package:paperless_mobile/features/documents/view/widgets/selection/view_type_selection_widget.dart';
import 'package:paperless_mobile/features/documents/view/widgets/sort_documents_button.dart';
import 'package:paperless_mobile/features/saved_view/cubit/saved_view_cubit.dart';
import 'package:paperless_mobile/features/saved_view/view/add_saved_view_page.dart';
import 'package:paperless_mobile/features/saved_view/view/saved_view_list.dart';
import 'package:paperless_mobile/features/tasks/cubit/task_status_cubit.dart';
import 'package:paperless_mobile/generated/l10n/app_localizations.dart';
import 'package:paperless_mobile/helpers/message_helpers.dart';
import 'package:paperless_mobile/routes/document_details_route.dart';

class DocumentFilterIntent {
  final DocumentFilter? filter;
  final bool shouldReset;

  DocumentFilterIntent({
    this.filter,
    this.shouldReset = false,
  });
}

//TODO: Refactor this
class DocumentsPage extends StatefulWidget {
  const DocumentsPage({Key? key}) : super(key: key);

  @override
  State<DocumentsPage> createState() => _DocumentsPageState();
}

class _DocumentsPageState extends State<DocumentsPage>
    with SingleTickerProviderStateMixin {
  final SliverOverlapAbsorberHandle searchBarHandle =
      SliverOverlapAbsorberHandle();
  final SliverOverlapAbsorberHandle tabBarHandle =
      SliverOverlapAbsorberHandle();
  late final TabController _tabController;

  int _currentTab = 0;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(
      length: 2,
      vsync: this,
    );
    Future.wait([
      context.read<DocumentsCubit>().reload(),
      context.read<SavedViewCubit>().reload(),
    ]).onError<PaperlessServerException>(
      (error, stackTrace) {
        showErrorMessage(context, error, stackTrace);
        return [];
      },
    );
    _tabController.addListener(_tabChangesListener);
  }

  void _tabChangesListener() {
    setState(() => _currentTab = _tabController.index);
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return BlocListener<TaskStatusCubit, TaskStatusState>(
      listenWhen: (previous, current) =>
          !previous.isSuccess && current.isSuccess,
      listener: (context, state) {
        showSnackBar(
          context,
          S.of(context)!.newDocumentAvailable,
          action: SnackBarActionConfig(
            label: S.of(context)!.reload,
            onPressed: () {
              context.read<TaskStatusCubit>().acknowledgeCurrentTask();
              context.read<DocumentsCubit>().reload();
            },
          ),
          duration: const Duration(seconds: 10),
        );
      },
      child: BlocConsumer<ConnectivityCubit, ConnectivityState>(
        listenWhen: (previous, current) =>
            previous != ConnectivityState.connected &&
            current == ConnectivityState.connected,
        listener: (context, state) {
          try {
            context.read<DocumentsCubit>().reload();
          } on PaperlessServerException catch (error, stackTrace) {
            showErrorMessage(context, error, stackTrace);
          }
        },
        builder: (context, connectivityState) {
          return SafeArea(
            top: context.read<DocumentsCubit>().state.selection.isEmpty,
            child: Scaffold(
              drawer: const AppDrawer(),
              floatingActionButton: BlocBuilder<DocumentsCubit, DocumentsState>(
                builder: (context, state) {
                  final appliedFiltersCount = state.filter.appliedFiltersCount;
                  final show = state.selection.isEmpty;
                  return AnimatedScale(
                    scale: show ? 1 : 0,
                    duration: const Duration(milliseconds: 200),
                    curve: Curves.easeIn,
                    child: b.Badge(
                      position: b.BadgePosition.topEnd(top: -12, end: -6),
                      showBadge: appliedFiltersCount > 0,
                      badgeContent: Text(
                        '$appliedFiltersCount',
                        style: const TextStyle(
                          color: Colors.white,
                        ),
                      ),
                      animationType: b.BadgeAnimationType.fade,
                      badgeColor: Colors.red,
                      child: _currentTab == 0
                          ? FloatingActionButton(
                              child: const Icon(Icons.filter_alt_outlined),
                              onPressed: _openDocumentFilter,
                            )
                          : FloatingActionButton(
                              child: const Icon(Icons.add),
                              onPressed: () => _onCreateSavedView(state.filter),
                            ),
                    ),
                  );
                },
              ),
              resizeToAvoidBottomInset: true,
              body: WillPopScope(
                onWillPop: () async {
                  if (context
                      .read<DocumentsCubit>()
                      .state
                      .selection
                      .isNotEmpty) {
                    context.read<DocumentsCubit>().resetSelection();
                  }
                  return false;
                },
                child: Stack(
                  children: [
                    NestedScrollView(
                      floatHeaderSlivers: true,
                      headerSliverBuilder: (context, innerBoxIsScrolled) => [
                        SliverOverlapAbsorber(
                          handle: searchBarHandle,
                          sliver: BlocBuilder<DocumentsCubit, DocumentsState>(
                            builder: (context, state) {
                              if (state.selection.isNotEmpty) {
                                // Show selection app bar when selection mode is active
                                return DocumentSelectionSliverAppBar(
                                  state: state,
                                );
                              }
                              return const SliverSearchBar(floating: true);
                            },
                          ),
                        ),
                        SliverOverlapAbsorber(
                          handle: tabBarHandle,
                          sliver: BlocBuilder<DocumentsCubit, DocumentsState>(
                            builder: (context, state) {
                              if (state.selection.isNotEmpty) {
                                return const SliverToBoxAdapter(
                                  child: SizedBox.shrink(),
                                );
                              }
                              return SliverPersistentHeader(
                                pinned: true,
                                delegate:
                                    CustomizableSliverPersistentHeaderDelegate(
                                  minExtent: kTextTabBarHeight,
                                  maxExtent: kTextTabBarHeight,
                                  child: ColoredTabBar(
                                    tabBar: TabBar(
                                      controller: _tabController,
                                      tabs: [
                                        Tab(text: S.of(context)!.documents),
                                        Tab(text: S.of(context)!.views),
                                      ],
                                    ),
                                  ),
                                ),
                              );
                            },
                          ),
                        ),
                      ],
                      body: NotificationListener<ScrollNotification>(
                        onNotification: (notification) {
                          final metrics = notification.metrics;
                          if (metrics.maxScrollExtent == 0) {
                            return true;
                          }
                          final desiredTab =
                              (metrics.pixels / metrics.maxScrollExtent)
                                  .round();
                          if (metrics.axis == Axis.horizontal &&
                              _currentTab != desiredTab) {
                            setState(() => _currentTab = desiredTab);
                          }
                          return false;
                        },
                        child: TabBarView(
                          controller: _tabController,
                          physics: context
                                  .watch<DocumentsCubit>()
                                  .state
                                  .selection
                                  .isNotEmpty
                              ? const NeverScrollableScrollPhysics()
                              : null,
                          children: [
                            Builder(
                              builder: (context) {
                                return _buildDocumentsTab(
                                  connectivityState,
                                  context,
                                );
                              },
                            ),
                            Builder(
                              builder: (context) {
                                return _buildSavedViewsTab(
                                  connectivityState,
                                  context,
                                );
                              },
                            ),
                          ],
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ),
          );
        },
      ),
    );
  }

  Widget _buildSavedViewsTab(
    ConnectivityState connectivityState,
    BuildContext context,
  ) {
    return RefreshIndicator(
      edgeOffset: kTextTabBarHeight,
      onRefresh: _onReloadSavedViews,
      notificationPredicate: (_) => connectivityState.isConnected,
      child: CustomScrollView(
        key: const PageStorageKey<String>("savedViews"),
        slivers: <Widget>[
          SliverOverlapInjector(
            handle: searchBarHandle,
          ),
          SliverOverlapInjector(
            handle: tabBarHandle,
          ),
          const SavedViewList(),
        ],
      ),
    );
  }

  Widget _buildDocumentsTab(
    ConnectivityState connectivityState,
    BuildContext context,
  ) {
    return NotificationListener<ScrollNotification>(
      onNotification: (notification) {
        // Listen for scroll notifications to load new data.
        // Scroll controller does not work here due to nestedscrollview limitations.

        final currState = context.read<DocumentsCubit>().state;
        final max = notification.metrics.maxScrollExtent;
        if (max == 0 ||
            _currentTab != 0 ||
            currState.isLoading ||
            currState.isLastPageLoaded) {
          return false;
        }

        final offset = notification.metrics.pixels;
        if (offset >= max * 0.7) {
          context
              .read<DocumentsCubit>()
              .loadMore()
              .onError<PaperlessServerException>(
                (error, stackTrace) => showErrorMessage(
                  context,
                  error,
                  stackTrace,
                ),
              );
          return true;
        }
        return false;
      },
      child: RefreshIndicator(
        edgeOffset: kTextTabBarHeight,
        onRefresh: _onReloadDocuments,
        notificationPredicate: (_) => connectivityState.isConnected,
        child: CustomScrollView(
          key: const PageStorageKey<String>("documents"),
          slivers: <Widget>[
            SliverOverlapInjector(handle: searchBarHandle),
            SliverOverlapInjector(handle: tabBarHandle),
            _buildViewActions(),
            BlocBuilder<DocumentsCubit, DocumentsState>(
              builder: (context, state) {
                if (state.hasLoaded && state.documents.isEmpty) {
                  return SliverToBoxAdapter(
                    child: DocumentsEmptyState(
                      state: state,
                      onReset: context.read<DocumentsCubit>().resetFilter,
                    ),
                  );
                }

                return SliverAdaptiveDocumentsView(
                  viewType: state.viewType,
                  onTap: _openDetails,
                  onSelected:
                      context.read<DocumentsCubit>().toggleDocumentSelection,
                  hasInternetConnection: connectivityState.isConnected,
                  onTagSelected: _addTagToFilter,
                  onCorrespondentSelected: _addCorrespondentToFilter,
                  onDocumentTypeSelected: _addDocumentTypeToFilter,
                  onStoragePathSelected: _addStoragePathToFilter,
                  documents: state.documents,
                  hasLoaded: state.hasLoaded,
                  isLabelClickable: true,
                  isLoading: state.isLoading,
                  selectedDocumentIds: state.selectedIds,
                  correspondents: state.correspondents,
                  documentTypes: state.documentTypes,
                  tags: state.tags,
                  storagePaths: state.storagePaths,
                );
              },
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildViewActions() {
    return SliverToBoxAdapter(
      child: BlocBuilder<DocumentsCubit, DocumentsState>(
        builder: (context, state) {
          return Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              SortDocumentsButton(
                enabled: state.selection.isEmpty,
              ),
              ViewTypeSelectionWidget(
                viewType: state.viewType,
                onChanged: context.read<DocumentsCubit>().setViewType,
              ),
            ],
          );
        },
      ).paddedSymmetrically(horizontal: 8, vertical: 4),
    );
  }

  void _onCreateSavedView(DocumentFilter filter) async {
    final newView = await Navigator.of(context).push<SavedView?>(
      MaterialPageRoute(
        builder: (context) => BlocBuilder<SavedViewCubit, SavedViewState>(
          builder: (context, state) {
            return AddSavedViewPage(
              currentFilter: filter,
              correspondents: state.correspondents,
              documentTypes: state.documentTypes,
              storagePaths: state.storagePaths,
              tags: state.tags,
            );
          },
        ),
      ),
    );
    if (newView != null) {
      try {
        await context.read<SavedViewCubit>().add(newView);
      } on PaperlessServerException catch (error, stackTrace) {
        showErrorMessage(context, error, stackTrace);
      }
    }
  }

  void _openDocumentFilter() async {
    final draggableSheetController = DraggableScrollableController();
    final filterIntent = await showModalBottomSheet<DocumentFilterIntent>(
      useSafeArea: true,
      context: context,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.only(
          topLeft: Radius.circular(16),
          topRight: Radius.circular(16),
        ),
      ),
      isScrollControlled: true,
      builder: (_) => BlocProvider.value(
        value: context.read<DocumentsCubit>(),
        child: DraggableScrollableSheet(
          controller: draggableSheetController,
          expand: false,
          snap: true,
          snapSizes: const [0.9, 1],
          initialChildSize: .9,
          maxChildSize: 1,
          builder: (context, controller) =>
              BlocBuilder<DocumentsCubit, DocumentsState>(
            builder: (context, state) {
              return DocumentFilterPanel(
                initialFilter: context.read<DocumentsCubit>().state.filter,
                scrollController: controller,
                draggableSheetController: draggableSheetController,
                correspondents: state.correspondents,
                documentTypes: state.documentTypes,
                storagePaths: state.storagePaths,
                tags: state.tags,
              );
            },
          ),
        ),
      ),
    );
    if (filterIntent != null) {
      try {
        if (filterIntent.shouldReset) {
          await context.read<DocumentsCubit>().resetFilter();
        } else {
          await context
              .read<DocumentsCubit>()
              .updateFilter(filter: filterIntent.filter!);
        }
      } on PaperlessServerException catch (error, stackTrace) {
        showErrorMessage(context, error, stackTrace);
      }
    }
  }

  void _openDetails(DocumentModel document) {
    Navigator.pushNamed(
      context,
      DocumentDetailsRoute.routeName,
      arguments: DocumentDetailsRouteArguments(
        document: document,
      ),
    );
  }

  void _addTagToFilter(int tagId) {
    try {
      final tagsQuery =
          context.read<DocumentsCubit>().state.filter.tags is IdsTagsQuery
              ? context.read<DocumentsCubit>().state.filter.tags as IdsTagsQuery
              : const IdsTagsQuery();
      if (tagsQuery.includedIds.contains(tagId)) {
        context.read<DocumentsCubit>().updateCurrentFilter(
              (filter) => filter.copyWith(
                tags: tagsQuery.withIdsRemoved([tagId]),
              ),
            );
      } else {
        context.read<DocumentsCubit>().updateCurrentFilter(
              (filter) => filter.copyWith(
                tags: tagsQuery.withIdQueriesAdded([IncludeTagIdQuery(tagId)]),
              ),
            );
      }
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }

  void _addCorrespondentToFilter(int? correspondentId) {
    final cubit = context.read<DocumentsCubit>();
    try {
      if (cubit.state.filter.correspondent.id == correspondentId) {
        cubit.updateCurrentFilter(
          (filter) =>
              filter.copyWith(correspondent: const IdQueryParameter.unset()),
        );
      } else {
        cubit.updateCurrentFilter(
          (filter) => filter.copyWith(
              correspondent: IdQueryParameter.fromId(correspondentId)),
        );
      }
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }

  void _addDocumentTypeToFilter(int? documentTypeId) {
    final cubit = context.read<DocumentsCubit>();
    try {
      if (cubit.state.filter.documentType.id == documentTypeId) {
        cubit.updateCurrentFilter(
          (filter) =>
              filter.copyWith(documentType: const IdQueryParameter.unset()),
        );
      } else {
        cubit.updateCurrentFilter(
          (filter) => filter.copyWith(
              documentType: IdQueryParameter.fromId(documentTypeId)),
        );
      }
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }

  void _addStoragePathToFilter(int? pathId) {
    final cubit = context.read<DocumentsCubit>();
    try {
      if (cubit.state.filter.correspondent.id == pathId) {
        cubit.updateCurrentFilter(
          (filter) =>
              filter.copyWith(storagePath: const IdQueryParameter.unset()),
        );
      } else {
        cubit.updateCurrentFilter(
          (filter) =>
              filter.copyWith(storagePath: IdQueryParameter.fromId(pathId)),
        );
      }
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }

  Future<void> _onReloadDocuments() async {
    try {
      // We do not await here on purpose so we can show a linear progress indicator below the app bar.
      await context.read<DocumentsCubit>().reload();
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }

  Future<void> _onReloadSavedViews() async {
    try {
      // We do not await here on purpose so we can show a linear progress indicator below the app bar.
      await context.read<SavedViewCubit>().reload();
    } on PaperlessServerException catch (error, stackTrace) {
      showErrorMessage(context, error, stackTrace);
    }
  }
}