import 'dart:convert';
import 'dart:io';

import 'package:file_picker/file_picker.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:ju_learn/learn.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() => runApp(const LearnApp());

class LearnApp extends StatelessWidget {
  const LearnApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Learn App',
      theme: ThemeData(useMaterial3: true, brightness: Brightness.light),
      darkTheme: ThemeData(useMaterial3: true, brightness: Brightness.dark),
      home: const MainPage(),
    );
  }
}

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

  @override
  MainPageState createState() => MainPageState();
}

class MainPageState extends State<MainPage> {
  List<Vault> _vaults = [];
  MainPageState() {
    loadList();
  }

  Vault? getByName(String name) {
    for (var v in _vaults) {
      if (v.name == name) return v;
    }
    return null;
  }

  loadList() async {
    final prefs = await SharedPreferences.getInstance();
    List<String>? json = prefs.getStringList("vaults");
    List<String>? jsonState = prefs.getStringList("vaultStates");
    if (json == null) return;
    setState(() {
      _vaults = json.map((e) => Vault.fromJson(jsonDecode(e))).toList();
    });
    if (jsonState == null) return;
    for (var s in jsonState) {
      var sMap = jsonDecode(s);
      Vault? v = getByName(sMap["name"]);
      if (v == null) continue;
      v.loadState(sMap);
    }
  }

  saveList() async {
    final prefs = await SharedPreferences.getInstance();
    prefs.setStringList(
        "vaults", _vaults.map((e) => jsonEncode(e.toJson())).toList());
  }

  saveStateList() async {
    final prefs = await SharedPreferences.getInstance();
    prefs.setStringList("vaultStates",
        _vaults.map((e) => jsonEncode(e.toStateJson())).toList());
  }

  _vaultMenu(Vault v) async {
    showModalBottomSheet(
        context: context,
        builder: (context) => BottomSheet(
              builder: (context) => Column(children: [
                Padding(
                    padding: const EdgeInsets.all(8),
                    child: Column(children: [
                      Text(v.name,
                          style: const TextStyle(
                            fontSize: 20.0,
                            fontWeight: FontWeight.bold,
                          )),
                      Text('Stats: ${v.txtVals()}',
                          style: const TextStyle(
                            fontSize: 10.0,
                            fontWeight: FontWeight.bold,
                          ))
                    ])),
                ListTile(
                  leading: const Icon(Icons.restore),
                  title: const Text("Reset Vault"),
                  subtitle: const Text("Reset Vault learn Data to default."),
                  trailing: const Icon(Icons.chevron_right),
                  onTap: () {
                    showDialog(
                      context: context,
                      builder: (BuildContext context) {
                        return AlertDialog(
                          title: const Text('Reset Vault'),
                          content:
                              Text('Do you want to reset „${v.name}“ Vault?'),
                          actions: [
                            TextButton(
                                onPressed: () {
                                  Navigator.of(context).pop();
                                },
                                child: const Text('Cancel')),
                            FilledButton(
                              child: const Text('Reset'),
                              onPressed: () {
                                setState(() {
                                  v.reset();
                                });
                                saveStateList();
                                Navigator.of(context).pop();
                                Navigator.of(context).pop();
                              },
                            ),
                          ],
                        );
                      },
                    );
                  },
                ),
                ListTile(
                    leading: const Icon(Icons.delete),
                    title: const Text("Vault löschen"),
                    subtitle: Text('Do you want to delete „${v.name}“ Vault?'),
                    trailing: const Icon(Icons.chevron_right),
                    onTap: () async {
                      showDialog(
                        context: context,
                        builder: (BuildContext context) {
                          return AlertDialog(
                            title: const Text('Delete Vault'),
                            content: Text(
                                'Do you want to delete „${v.name}“ Vault?'),
                            actions: [
                              TextButton(
                                  onPressed: () {
                                    Navigator.of(context).pop();
                                  },
                                  child: const Text('Cancel')),
                              FilledButton(
                                child: const Text('Delete'),
                                onPressed: () {
                                  setState(() {
                                    _vaults.remove(v);
                                  });
                                  saveList();
                                  saveStateList();
                                  Navigator.of(context).pop();
                                  Navigator.of(context).pop();
                                },
                              ),
                            ],
                          );
                        },
                      );
                    })
              ]),
              onClosing: () {},
            ));
  }

  _pickFile() async {
    FilePickerResult? result = await FilePicker.platform.pickFiles(
        type: FileType.custom,
        allowedExtensions: ['json'],
        allowMultiple: false);
    if (result != null) {
      String data = "";
      if (!kIsWeb && result.files.single.path != null) {
        File file = File(result.files.single.path ?? "");
        data = file.readAsStringSync();
      } else {
        PlatformFile pfile = result.files.first;
        data = String.fromCharCodes(pfile.bytes?.map((e) => e) ?? []);
      }
      try {
        if (data.isEmpty) throw ErrorDescription("Empty File!");
        Vault v = Vault.fromJson(jsonDecode(data));
        setState(() {
          _vaults.add(v);
        });
        saveList();
      } catch (e) {
        print(e);

        AlertDialog(
            title: const Text('Error'),
            content: const Text('An error has occurred.'),
            actions: [
              TextButton(
                child: const Text('OK'),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ]);
        return;
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Learn App'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child:
            Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: [
          ..._vaults.map((e) => Container(
              margin: const EdgeInsets.symmetric(vertical: 8.0),
              child: ElevatedButton(
                onPressed: () {
                  Navigator.push(
                    context,
                    MaterialPageRoute(
                        builder: (context) => QuizPage(e, saveStateList)),
                  );
                },
                onLongPress: () {
                  _vaultMenu(e);
                },
                child: Text(e.name),
              )))
        ]),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _pickFile,
        child: const Icon(Icons.add),
      ),
    );
  }
}

class Question {
  String quest;
  List<String> answers;
  int correct;
  String explanation;
  int drawer = 0;
  int lastInRun = 0;

  Question(this.quest, this.answers, this.correct, this.explanation);

  Map<String, dynamic> toJson() {
    return {
      "quest": quest,
      "answers": answers,
      "correct": correct,
      "explanation": explanation,
    };
  }

  factory Question.fromJson(Map<String, dynamic> json) {
    if (json["quest"] is! String) {
      throw ErrorDescription("fromJSON Error: quest");
    }
    if (json["answers"] is! List<dynamic>) {
      throw ErrorDescription("fromJSON Error: awnsers");
    }
    if (json["correct"] is! int ||
        json["correct"] < 0 ||
        json["correct"] >= json["answers"].length) {
      throw ErrorDescription("fromJSON Error: correct");
    }
    if (json["explanation"] is! String) {
      throw ErrorDescription("fromJSON Error: explanation");
    }
    return Question(
      json["quest"],
      (json["answers"] as List<dynamic>).map((d) => d.toString()).toList(),
      json["correct"],
      json["explanation"],
    );
  }
}

class Vault {
  String name;
  List<Question> questions;
  Vault(this.name, this.questions);

  Map<String, dynamic> toJson() {
    return {
      "name": name,
      "questions": questions.map((e) => e.toJson()).toList()
    };
  }

  Map<String, dynamic> toStateJson() {
    return {"name": name, "drawers": questions.map((d) => d.drawer).toList()};
  }

  void reset() {
    for (var q in questions) {
      q.drawer = 0;
      q.lastInRun = 0;
    }
  }

  void softReset() {
    for (var q in questions) {
      q.lastInRun = 0;
    }
  }

  (int, double, int) vals() {
    int min = 0xffffff;
    int total = 0;
    int max = 0;
    for (var q in questions) {
      if (q.drawer > max) max = q.drawer;
      if (q.drawer < min) min = q.drawer;
      total += q.drawer;
    }
    return (min, total.toDouble() / questions.length, max);
  }

  String txtVals() {
    var (min, avg, max) = vals();
    return '($min, ${(avg * 100).round() / 100.0}, $max)';
  }

  factory Vault.fromJson(Map<String, dynamic> json) {
    if (json["name"] is! String) {
      throw ErrorDescription("fromJSON Error: name");
    }
    if (json["questions"] is! List<dynamic>) {
      throw ErrorDescription("fromJSON Error: questions");
    }
    return Vault(
      json["name"],
      (json["questions"] as List<dynamic>)
          .map((d) => Question.fromJson(d))
          .toList(),
    );
  }
  loadState(Map<String, dynamic> json) {
    if (json["name"] != name) throw ErrorDescription("Wrong Vault Error");
    if (json["drawers"] is! List<dynamic>) {
      throw ErrorDescription("fromJSON Error: questions");
    }
    var stateList = json["drawers"];
    for (var i = 0; i < stateList.length; i++) {
      var q = questions.elementAtOrNull(i);
      if (q != null) {
        q.drawer = stateList[i] as int;
      }
    }
  }
}