import 'dart:async';

import 'package:flutter/material.dart';
import '../../../extensions/dateTime.dart';
import 'package:provider/provider.dart';
import 'package:syncfusion_flutter_calendar/calendar.dart';

import '../../../api/webuntis/queries/getHolidays/getHolidaysResponse.dart';
import '../../../api/webuntis/queries/getRooms/getRoomsResponse.dart';
import '../../../api/webuntis/queries/getSubjects/getSubjectsResponse.dart';
import '../../../api/webuntis/queries/getTimetable/getTimetableResponse.dart';
import '../../../model/timetable/timetableProps.dart';
import '../../../storage/base/settingsProvider.dart';
import '../../../widget/loadingSpinner.dart';
import '../../../widget/placeholderView.dart';
import 'appointmenetComponent.dart';
import 'appointmentDetails.dart';
import 'arbitraryAppointment.dart';
import 'customTimetableColors.dart';
import 'customTimetableEventEditDialog.dart';
import 'timeRegionComponent.dart';
import 'timetableEvents.dart';
import 'viewCustomTimetableEvents.dart';

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

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

enum CalendarActions { addEvent, viewEvents }

class _TimetableState extends State<Timetable> {
  CalendarController controller = CalendarController();
  late Timer updateTimings;
  late final SettingsProvider settings;

  @override
  void initState() {
    settings = Provider.of<SettingsProvider>(context, listen: false);

    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      Provider.of<TimetableProps>(context, listen: false).run();
    });

    controller.displayDate = DateTime.now().add(const Duration(days: 2));

    updateTimings = Timer.periodic(const Duration(seconds: 30), (Timer t) => setState((){}));

    super.initState();
  }

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(
        title: const Text('Stunden & Vertretungsplan'),
        actions: [
          IconButton(
              icon: const Icon(Icons.home_outlined),
              onPressed: () {
                controller.displayDate = DateTime.now().add(const Duration(days: 2));
              }
          ),
          PopupMenuButton<CalendarActions>(
            icon: const Icon(Icons.edit_calendar_outlined),
            itemBuilder: (context) {
              return CalendarActions.values.map(
                (e) {
                  String title;
                  Icon icon;
                  switch(e) {
                    case CalendarActions.addEvent:
                      title = 'Kalendereintrag hinzufügen';
                      icon = const Icon(Icons.add);
                    case CalendarActions.viewEvents:
                    default:
                      title = 'Kalendereinträge anzeigen';
                      icon = const Icon(Icons.perm_contact_calendar_outlined);
                  }
                  return PopupMenuItem<CalendarActions>(
                    value: e,
                    child: ListTile(
                      title: Text(title),
                      leading: icon,
                    )
                  );
                }
              ).toList();
            },
            onSelected: (value) {
              switch(value) {
                case CalendarActions.addEvent:
                  showDialog(
                    context: context,
                    builder: (context) => const CustomTimetableEventEditDialog(),
                    barrierDismissible: false,
                  );
                case CalendarActions.viewEvents:
                  Navigator.of(context).push(MaterialPageRoute(builder: (context) => const ViewCustomTimetableEvents()));
              }
            },
          )
        ],
      ),
      body: Consumer<TimetableProps>(
        builder: (context, value, child) {

          if(value.hasError) {
            return PlaceholderView(
              icon: Icons.calendar_month,
              text: 'Webuntis error: ${value.error.toString()}',
              button: TextButton(
                child: const Text('Neu laden'),
                onPressed: () {
                  controller.displayDate = DateTime.now().add(const Duration(days: 2));
                  Provider.of<TimetableProps>(context, listen: false).resetWeek();
                },
              ),
            );
          }

          if(value.primaryLoading()) return const LoadingSpinner();

          GetHolidaysResponse holidays = value.getHolidaysResponse;

          return RefreshIndicator(
              child: SfCalendar(
                view: CalendarView.workWeek,
                dataSource: _buildTableEvents(value),

                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: (ViewChangedDetails details) {
                  WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                    Provider.of<TimetableProps>(context, listen: false).updateWeek(details.visibleDates.first, details.visibleDates.last);
                  });
                },

                onTap: (calendarTapDetails) {
                  if(calendarTapDetails.appointments == null) return;
                  Appointment tapped = calendarTapDetails.appointments!.first;
                  AppointmentDetails.show(context, value, tapped);
                },

                firstDayOfWeek: DateTime.monday,
                specialRegions: _buildSpecialTimeRegions(holidays),
                timeSlotViewSettings: const TimeSlotViewSettings(
                  startHour: 07.5,
                  endHour: 16.5,
                  timeInterval: Duration(minutes: 30),
                  timeFormat: 'HH:mm',
                  dayFormat: 'EE',
                  timeIntervalHeight: 40,
                ),

                timeRegionBuilder: (BuildContext context, TimeRegionDetails timeRegionDetails) => TimeRegionComponent(details: timeRegionDetails),
                appointmentBuilder: (BuildContext context, CalendarAppointmentDetails details) => AppointmentComponent(
                    details: details,
                    crossedOut: _isCrossedOut(details)
                ),

                headerHeight: 0,
                selectionDecoration: const BoxDecoration(),

                allowAppointmentResize: false,
                allowDragAndDrop: false,
                allowViewNavigation: false,
              ),
              onRefresh: () async {
                Provider.of<TimetableProps>(context, listen: false).run(renew: true);
                return Future.delayed(const Duration(seconds: 3));
              }
            );
        },
      ),
    );
  }

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

  List<TimeRegion> _buildSpecialTimeRegions(GetHolidaysResponse holidays) {
    DateTime lastMonday = DateTime.now().subtract(const Duration(days: 14)).nextWeekday(DateTime.monday);
    DateTime firstBreak = lastMonday.copyWith(hour: 10, minute: 15);
    DateTime secondBreak = lastMonday.copyWith(hour: 13, minute: 50);

    Iterable<TimeRegion> holidayList = holidays.result.map((holiday) {
        DateTime startDay = _parseWebuntisTimestamp(holiday.startDate, 0);
        int dayCount = _parseWebuntisTimestamp(holiday.endDate, 0)
            .difference(startDay)
            .inDays;
        List<DateTime> days = List.generate(dayCount, (index) => startDay.add(Duration(days: index)));

        return days.map((holidayDay) {
          return TimeRegion(
              startTime: holidayDay.copyWith(hour: 07, minute: 55),
              endTime: holidayDay.copyWith(hour: 16, minute: 30),
              text: 'holiday:${holiday.name}',
              color: Theme
                  .of(context)
                  .disabledColor
                  .withAlpha(50),
              iconData: Icons.holiday_village_outlined
          );
        });
    }).expand((e) => e);

    bool isInHoliday(DateTime time) {
      return holidayList.any((element) => element.startTime.isSameDay(time));
    }

    return [
      ...holidayList,

      if(!isInHoliday(firstBreak))
        TimeRegion(
            startTime: firstBreak,
            endTime: firstBreak.add(const Duration(minutes: 20)),
            recurrenceRule: 'FREQ=DAILY;INTERVAL=1',
            text: 'centerIcon',
            color: Theme.of(context).primaryColor.withAlpha(50),
            iconData: Icons.restaurant
        ),

      if(!isInHoliday(secondBreak))
        TimeRegion(
            startTime: secondBreak,
            endTime: secondBreak.add(const Duration(minutes: 15)),
            recurrenceRule: 'FREQ=DAILY;INTERVAL=1',
            text: 'centerIcon',
            color: Theme.of(context).primaryColor.withAlpha(50),
            iconData: Icons.restaurant
        ),
    ];
  }

  List<GetTimetableResponseObject> _removeDuplicates(TimetableProps data, Duration maxTimeBetweenDouble) {

    List<GetTimetableResponseObject> timetableList = data.getTimetableResponse.result.toList( );

    if ( timetableList.isEmpty ) return timetableList;

    timetableList.sort((a, b) => _parseWebuntisTimestamp(a.date, a.startTime).compareTo(_parseWebuntisTimestamp(b.date, b.startTime)));

    GetTimetableResponseObject previousElement = timetableList.first;
    for (var i = 1; i < timetableList.length; i++) {
      GetTimetableResponseObject currentElement = timetableList.elementAt(i);

      bool isSameLesson() {
        int? currentSubjectId = currentElement.su.firstOrNull?.id;
        int? previousSubjectId = previousElement.su.firstOrNull?.id;

        if( currentSubjectId == null || previousSubjectId == null || currentSubjectId != previousSubjectId ) return false;

        int? currentRoomId = currentElement.ro.firstOrNull?.id;
        int? previousRoomId = previousElement.ro.firstOrNull?.id;

        if( currentRoomId != previousRoomId ) return false;

        int? currentTeacherId = currentElement.te.firstOrNull?.id;
        int? previousTeacherId = previousElement.te.firstOrNull?.id;

        if( currentTeacherId != previousTeacherId ) return false;

        String? currentStatusCode = currentElement.code;
        String? previousStatusCode = previousElement.code;

        if( currentStatusCode != previousStatusCode ) return false;

        return true;
      }

      bool isNotSeparated() =>  _parseWebuntisTimestamp( previousElement.date, previousElement.endTime ).add( maxTimeBetweenDouble )
          .isSameOrAfter( _parseWebuntisTimestamp( currentElement.date, currentElement.startTime ) );

      if ( isSameLesson() && isNotSeparated() ) {
        previousElement.endTime = currentElement.endTime;
        timetableList.remove( currentElement );
        i--;
      } else {
        previousElement = currentElement;
      }
    }

    return timetableList;
  }

  TimetableEvents _buildTableEvents(TimetableProps data) {

    List<GetTimetableResponseObject> timetableList = data.getTimetableResponse.result.toList( );

    if( settings.val().timetableSettings.connectDoubleLessons ){
      timetableList = _removeDuplicates( data, const Duration(minutes: 5) );
    }

    List<Appointment> appointments = timetableList.map((element) {

      GetRoomsResponse rooms = data.getRoomsResponse;
      GetSubjectsResponse subjects = data.getSubjectsResponse;

      try {
        DateTime startTime = _parseWebuntisTimestamp(element.date, element.startTime);
        DateTime endTime = _parseWebuntisTimestamp(element.date, element.endTime);
        return Appointment(
          id: ArbitraryAppointment(webuntis: element),
          startTime: startTime,
          endTime: endTime,
          subject: subjects.result.firstWhere((subject) => subject.id == element.su[0].id).name,
          location: ''
              '${rooms.result.firstWhere((room) => room.id == element.ro[0].id).name}'
              '\n'
              '${element.te.first.longname}',
          notes: element.activityType,
          color: _getEventColor(element, startTime, endTime),
        );
      } catch(e) {
        DateTime endTime = _parseWebuntisTimestamp(element.date, element.endTime);
        return Appointment(
          id: ArbitraryAppointment(webuntis: element),
          startTime: _parseWebuntisTimestamp(element.date, element.startTime),
          endTime: endTime,
          subject: 'Änderung',
          notes: element.info,
          location: 'Unbekannt',
          color: endTime.isBefore(DateTime.now()) ? Theme.of(context).primaryColor.withAlpha(100) : Theme.of(context).primaryColor,
          startTimeZone: '',
          endTimeZone: '',
        );
      }
    }).toList();

    appointments.addAll(data.getCustomTimetableEventResponse.events.map((customEvent) {
      return Appointment(
        id: ArbitraryAppointment(custom: customEvent),
        startTime: customEvent.startDate,
        endTime: customEvent.endDate,
        location: customEvent.description,
        subject: customEvent.title,
        recurrenceRule: customEvent.rrule,
        color: TimetableColors.getColorFromString(customEvent.color ?? TimetableColors.defaultColor.name),
        startTimeZone: '',
        endTimeZone: '',
      );
    }));

    return TimetableEvents(appointments);
  }

  DateTime _parseWebuntisTimestamp(int date, int time) {
    String timeString = time.toString().padLeft(4, '0');
    return DateTime.parse('$date ${timeString.substring(0, 2)}:${timeString.substring(2, 4)}');
  }

  Color _getEventColor(GetTimetableResponseObject webuntisElement, DateTime startTime, DateTime endTime) {
    // Make element darker, when it already took place
    int alpha = endTime.isBefore(DateTime.now()) ? 100 : 255;

    // Cancelled
    if(webuntisElement.code == 'cancelled') return const Color(0xff000000).withAlpha(alpha);

    // Any changes or no teacher at this element
    if(webuntisElement.code == 'irregular' || webuntisElement.te.first.id == 0) return const Color(0xff8F19B3).withAlpha(alpha);

    // Event was in the past
    if(endTime.isBefore(DateTime.now())) return Theme.of(context).primaryColor.withAlpha(alpha);

    // Event takes currently place
    if(endTime.isAfter(DateTime.now()) && startTime.isBefore(DateTime.now())) return Theme.of(context).primaryColor.withRed(200);

    // Fallback
    return Theme.of(context).primaryColor.withAlpha(alpha);
  }

  bool _isCrossedOut(CalendarAppointmentDetails calendarEntry) {
    ArbitraryAppointment appointment = calendarEntry.appointments.first.id as ArbitraryAppointment;
    if(appointment.hasWebuntis()) {
      return appointment.webuntis!.code == 'cancelled';
    }
    return false;
  }
}