// GCG.MeinCantor - Die Schulplattform für Cantorianer.
// Copyright (C) 2021-2022 Georg-Cantor-Gymnasium Halle (Saale)

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

import 'dart:convert';

import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:intl/intl.dart';
import 'package:meincantor/timetable.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:http/http.dart' as http;

import 'package:meincantor/networking.dart';

Future<void> backgroundFetchTimetable() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();

  String? todayTimetable = prefs.getString("todayTimetable");
  String? tomorrowTimetable = prefs.getString("tomorrowTimetable");

  http.Response todayResponse = await fetchClassTimetable(
      "/${DateFormat("yyyyMMdd").format(DateTime.now())}", null);

  http.Response tomorrowResponse = await fetchClassTimetable(
      "/${DateFormat("yyyyMMdd").format(DateTime.now().add(const Duration(days: 1)))}",
      null);

  if (todayResponse.statusCode == 200) {
    if (todayTimetable != todayResponse.body) {
      FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
          FlutterLocalNotificationsPlugin();
      const AndroidNotificationDetails
          androidPlatformChannelSpecificsTodayPlan = AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.today.plan',
              'Vertretungsplan für heute',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsTodayPlan =
          NotificationDetails(
              android: androidPlatformChannelSpecificsTodayPlan);

      const AndroidNotificationDetails
          androidPlatformChannelSpecificsTodayInfo = AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.today.info',
              'Informationen für heute',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsTodayInfo =
          NotificationDetails(
              android: androidPlatformChannelSpecificsTodayInfo);

      List<TimetableLesson> lessonsList =
          ClassTimetable.fromJson(jsonDecode(todayResponse.body)).timetable;
      List<int> changedLessons = [];
      for (var element in lessonsList) {
        if (element.info.isNotEmpty) {
          changedLessons.add(element.count);
        }
      }
      String subtitle;
      if (changedLessons.isNotEmpty && changedLessons.length > 1) {
        subtitle = "Änderungen in den Stunden ";
        for (var i in changedLessons) {
          subtitle += "$i";
          if (changedLessons.indexOf(i) != changedLessons.length - 1) {
            subtitle += ", ";
          }
        }
      } else if (changedLessons.isNotEmpty && changedLessons.length == 1) {
        subtitle = "Änderungen in Stunde ${changedLessons[0]}";
      } else {
        subtitle = "Keine Änderungen im Plan gefunden!";
      }
      await flutterLocalNotificationsPlugin.show(
          0,
          'Neuer Vertretungsplan für heute geladen!',
          subtitle,
          platformChannelSpecificsTodayPlan,
          payload: 'item x');
      if ((jsonDecode(todayResponse.body)["info"] as String).isNotEmpty) {
        await flutterLocalNotificationsPlugin.show(
            1,
            'Informationen für heute',
            (jsonDecode(todayResponse.body)["info"] as String),
            platformChannelSpecificsTodayInfo,
            payload: 'item x');
      }
      prefs.setString("todayTimetable", todayResponse.body);
    }
  }

  if (tomorrowResponse.statusCode == 200) {
    if (tomorrowTimetable != tomorrowResponse.body) {
      FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
          FlutterLocalNotificationsPlugin();
      const AndroidNotificationDetails
          androidPlatformChannelSpecificsTomorrowPlan =
          AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.tomorrow.plan',
              'Vertretungsplan für morgen',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsTomorrowPlan =
          NotificationDetails(
              android: androidPlatformChannelSpecificsTomorrowPlan);

      const AndroidNotificationDetails
          androidPlatformChannelSpecificsTomorrowInfo =
          AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.tomorrow.info',
              'Informationen für morgen',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsTomorrowInfo =
          NotificationDetails(
              android: androidPlatformChannelSpecificsTomorrowInfo);

      List<TimetableLesson> lessonsList =
          ClassTimetable.fromJson(jsonDecode(tomorrowResponse.body)).timetable;
      List<int> changedLessons = [];
      for (var element in lessonsList) {
        if (element.info.isNotEmpty) {
          changedLessons.add(element.count);
        }
      }
      String subtitle;
      if (changedLessons.isNotEmpty && changedLessons.length > 1) {
        subtitle = "Änderungen in den Stunden ";
        for (var i in changedLessons) {
          subtitle += "$i";
          if (changedLessons.indexOf(i) != changedLessons.length - 1) {
            subtitle += ", ";
          }
        }
      } else if (changedLessons.isNotEmpty && changedLessons.length == 1) {
        subtitle = "Änderungen in Stunde ${changedLessons[0]}";
      } else {
        subtitle = "Keine Änderungen im Plan gefunden!";
      }
      await flutterLocalNotificationsPlugin.show(
          2,
          'Neuer Vertretungsplan für morgen geladen!',
          subtitle,
          platformChannelSpecificsTomorrowPlan,
          payload: 'item x');
      if ((jsonDecode(tomorrowResponse.body)["info"] as String).isNotEmpty) {
        await flutterLocalNotificationsPlugin.show(
            3,
            'Informationen für morgen',
            (jsonDecode(tomorrowResponse.body)["info"] as String),
            platformChannelSpecificsTomorrowInfo,
            payload: 'item x');
      }
      prefs.setString("tomorrowTimetable", tomorrowResponse.body);
    }
  }
}

Future<void> backgroundFetchArticles() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();

  String? articles = prefs.getString("articles");
  String? news = prefs.getString("news");

  http.Response fetchedArticles = await getArticles();

  http.Response fetchedNews = await getNews();

  if (fetchedArticles.statusCode == 200) {
    if (articles != fetchedArticles.body) {
      FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
          FlutterLocalNotificationsPlugin();
      const AndroidNotificationDetails androidPlatformChannelSpecificsSZ =
          AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.sz', 'Schülerzeitung',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsSZ =
          NotificationDetails(android: androidPlatformChannelSpecificsSZ);

      String subtitle;
      List listFetchedArticles = jsonDecode(fetchedArticles.body)["data"];
      if (articles != null && articles.isNotEmpty) {
        List listSavedArticles = jsonDecode(articles)["data"];
        int diff = listFetchedArticles.length - listSavedArticles.length;
        diff == 1
            ? subtitle = "1 neuer Artikel!"
            : diff > 1
                ? subtitle = "$diff neue Artikel!"
                : subtitle = "Fehler beim Ermitteln der Änderungen!";
      } else {
        int len = listFetchedArticles.length;
        len == 1
            ? subtitle = "1 neuer Artikel!"
            : len > 1
                ? subtitle = "$len neue Artikel!"
                : subtitle = "Fehler beim Ermitteln der Änderungen!";
      }

      await flutterLocalNotificationsPlugin.show(
          4,
          'Neuer Inhalt von der Schülerzeitung verfügbar!',
          subtitle,
          platformChannelSpecificsSZ,
          payload: 'item x');
      prefs.setString("articles", fetchedArticles.body);
    }
  }

  if (fetchedNews.statusCode == 200) {
    if (news != fetchedNews.body) {
      FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
          FlutterLocalNotificationsPlugin();
      const AndroidNotificationDetails androidPlatformChannelSpecificsNews =
          AndroidNotificationDetails(
              'de.cantorgymnasium.meincantor.news', 'Aktuelles',
              channelDescription: '',
              importance: Importance.max,
              priority: Priority.high,
              ticker: 'ticker');
      const NotificationDetails platformChannelSpecificsNews =
          NotificationDetails(android: androidPlatformChannelSpecificsNews);

      String subtitle;
      List listFetchedNews = jsonDecode(fetchedNews.body)["data"];
      if (news != null && news.isNotEmpty) {
        List listSavedNews = jsonDecode(news)["data"];
        int diff = listFetchedNews.length - listSavedNews.length;
        diff == 1
            ? subtitle = "1 neuer Artikel!"
            : diff > 1
                ? subtitle = "$diff neue Artikel!"
                : subtitle = "Fehler beim Ermitteln der Änderungen!";
      } else {
        int len = listFetchedNews.length;
        len == 1
            ? subtitle = "1 neuer Artikel!"
            : len > 1
                ? subtitle = "$len neue Artikel!"
                : subtitle = "Fehler beim Ermitteln der Änderungen!";
      }

      await flutterLocalNotificationsPlugin.show(
          5,
          'Neue Informationen verfügbar!',
          subtitle,
          platformChannelSpecificsNews,
          payload: 'item x');
      prefs.setString("news", fetchedNews.body);
    }
  }
}