import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:syncfusion_flutter_calendar/calendar.dart';

import '../../../extensions/dateTime.dart';
import '../../../state/app/infrastructure/loadableState/view/loadable_state_consumer.dart';
import '../../../state/app/modules/timetable/bloc/timetable_bloc.dart';
import '../../../state/app/modules/timetable/bloc/timetable_state.dart';
import '../../../state/app/modules/settings/bloc/settings_cubit.dart';
import 'custom_events/custom_event_edit_dialog.dart';
import 'custom_events/custom_events_view.dart';
import 'data/arbitrary_appointment.dart';
import 'data/timetable_appointment_factory.dart';
import 'details/appointment_details_dispatcher.dart';
import 'widgets/appointment_tile.dart';
import 'widgets/lesson_appointment_source.dart';
import 'widgets/special_regions_builder.dart';
import 'widgets/time_region_tile.dart';

enum _CalendarAction { addEvent, viewEvents }

class Timetable extends StatefulWidget {
  const Timetable({super.key});

  @override
  State<Timetable> createState() => _TimetableState();
}

class _TimetableState extends State<Timetable> {
  final CalendarController _controller = CalendarController();
  late Timer _highlightTicker;

  LessonAppointmentSource? _cachedSource;
  int? _lastDataVersion;

  @override
  void initState() {
    super.initState();
    _controller.displayDate = _initialDisplayDate();

    _highlightTicker = Timer.periodic(const Duration(seconds: 30), (_) {
      if (mounted) setState(() => _cachedSource = null);
    });
  }

  @override
  void dispose() {
    _highlightTicker.cancel();
    super.dispose();
  }

  DateTime _initialDisplayDate() => DateTime.now().add(const Duration(days: 2));

  void _jumpToToday() {
    _controller.displayDate = _initialDisplayDate();
  }

  void _onAction(_CalendarAction action) {
    switch (action) {
      case _CalendarAction.addEvent:
        showDialog(
          context: context,
          builder: (_) => const CustomEventEditDialog(),
          barrierDismissible: false,
        );
      case _CalendarAction.viewEvents:
        Navigator.of(context).push(MaterialPageRoute(builder: (_) => const CustomEventsView()));
    }
  }

  LessonAppointmentSource _appointmentSource(TimetableState state) {
    if (_cachedSource != null && _lastDataVersion == state.dataVersion) {
      return _cachedSource!;
    }
    _lastDataVersion = state.dataVersion;

    final settings = context.read<SettingsCubit>();
    final appointments = TimetableAppointmentFactory(
      lessons: state.getAllKnownLessons().toList(),
      customEvents: state.customEvents?.events ?? const [],
      rooms: state.rooms!,
      subjects: state.subjects!,
      settings: settings.val().timetableSettings,
      colorScheme: Theme.of(context).colorScheme,
      now: DateTime.now(),
    ).build();

    return _cachedSource = LessonAppointmentSource(appointments);
  }

  @override
  Widget build(BuildContext context) {
    final bloc = context.read<TimetableBloc>();
    return Scaffold(
      appBar: AppBar(
        title: const Text('Stunden & Vertretungsplan'),
        actions: [
          IconButton(icon: const Icon(Icons.home_outlined), onPressed: _jumpToToday),
          PopupMenuButton<_CalendarAction>(
            icon: const Icon(Icons.edit_calendar_outlined),
            onSelected: _onAction,
            itemBuilder: (_) => const [
              PopupMenuItem(
                value: _CalendarAction.addEvent,
                child: ListTile(title: Text('Kalendereintrag hinzufügen'), leading: Icon(Icons.add)),
              ),
              PopupMenuItem(
                value: _CalendarAction.viewEvents,
                child: ListTile(
                  title: Text('Kalendereinträge anzeigen'),
                  leading: Icon(Icons.perm_contact_calendar_outlined),
                ),
              ),
            ],
          ),
        ],
      ),
      body: LoadableStateConsumer<TimetableBloc, TimetableState>(
        child: (state, _) => _calendar(state, bloc),
      ),
    );
  }

  Widget _calendar(TimetableState state, TimetableBloc bloc) {
    if (!state.hasReferenceData) return const SizedBox.shrink();

    return SfCalendar(
      timeZone: 'W. Europe Standard Time',
      view: CalendarView.workWeek,
      dataSource: _appointmentSource(state),
      maxDate: DateTime.now().add(const Duration(days: 7)).nextWeekday(DateTime.saturday),
      minDate: DateTime.now().subtract(const Duration(days: 14)).nextWeekday(DateTime.sunday),
      controller: _controller,
      onViewChanged: (details) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          if (!mounted) return;
          bloc.changeWeek(details.visibleDates.first, details.visibleDates.last);
        });
      },
      onTap: (tap) {
        if (tap.appointments == null || tap.appointments!.isEmpty) return;
        AppointmentDetailsDispatcher.show(context, bloc, tap.appointments!.first);
      },
      firstDayOfWeek: DateTime.monday,
      specialRegions: SpecialRegionsBuilder(
        holidays: state.schoolHolidays!,
        colorScheme: Theme.of(context).colorScheme,
        disabledColor: Theme.of(context).disabledColor,
      ).build(),
      timeSlotViewSettings: const TimeSlotViewSettings(
        startHour: 7.5,
        endHour: 16.5,
        timeInterval: Duration(minutes: 30),
        timeFormat: 'HH:mm',
        dayFormat: 'EE',
        timeIntervalHeight: 40,
      ),
      timeRegionBuilder: (_, details) => TimeRegionTile(details: details),
      appointmentBuilder: (_, details) => AppointmentTile(
        details: details,
        crossedOut: _isCrossedOut(details),
      ),
      headerHeight: 0,
      selectionDecoration: const BoxDecoration(),
      allowAppointmentResize: false,
      allowDragAndDrop: false,
      allowViewNavigation: false,
    );
  }

  bool _isCrossedOut(CalendarAppointmentDetails details) {
    final appointment = details.appointments.first;
    final id = appointment.id;
    if (id is WebuntisAppointment) return id.lesson.code == 'cancelled';
    return false;
  }
}