import 'package:contacts_plus_plus/clients/api_client.dart';
import 'package:contacts_plus_plus/models/authentication_data.dart';
import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:contacts_plus_plus/client_holder.dart';

class LoginScreen extends StatefulWidget {
  const LoginScreen({this.onLoginSuccessful, this.cachedUsername, super.key});

  final String? cachedUsername;
  final Function(AuthenticationData)? onLoginSuccessful;

  @override
  State<StatefulWidget> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();
  final TextEditingController _totpController = TextEditingController();
  final ScrollController _scrollController = ScrollController();

  late final FocusNode _passwordFocusNode;
  late final FocusNode _totpFocusNode;

  bool _isLoading = false;
  String _error = "";
  bool _needsTotp = false;

  double get _errorOpacity => _error.isEmpty ? 0.0 : 1.0;

  @override
  void initState() {
    super.initState();
    _usernameController.text = widget.cachedUsername ?? "";
    _passwordFocusNode = FocusNode();
    _totpFocusNode = FocusNode();
  }

  @override
  void dispose() {
    _passwordFocusNode.dispose();
    _totpFocusNode.dispose();
    super.dispose();
  }

  Future<void> submit() async {
    if (_usernameController.text.isEmpty || _passwordController.text.isEmpty) {
      setState(() {
        _error = "Please enter a valid username/password combination.";
      });
      return;
    }
    setState(() {
      _error = "";
      _isLoading = true;
    });
    try {
      final authData = await ApiClient.tryLogin(
        username: _usernameController.text,
        password: _passwordController.text,
        oneTimePad: _totpController.text.isEmpty ? null : _totpController.text,
      );
      if (!authData.isAuthenticated) {
        setState(() {
          _error = "Login unsuccessful: Server sent invalid response.";
          _isLoading = false;
        });
        return;
      }
      setState(() {
        _error = "";
        _isLoading = false;
      });
      await loginSuccessful(authData);
    } catch (e) {
      setState(() {
        if (e == ApiClient.totpKey) {
          if (_needsTotp == false) {
            _error = "Please enter your 2FA-Code";
            _totpFocusNode.requestFocus();
            WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
              _scrollController.animateTo(_scrollController.position.maxScrollExtent,
                  duration: const Duration(milliseconds: 400),
                  curve: Curves.easeOutCirc
              );
            });
          } else {
            _error = "The given 2FA code is not valid.";
          }
          _needsTotp = true;
        } else {
          _error = "Login unsuccessful: $e.";
        }
        _isLoading = false;
      });
    }
  }

  Future<void> loginSuccessful(AuthenticationData authData) async {
    final settingsClient = ClientHolder
        .of(context)
        .settingsClient;
    final notificationManager = FlutterLocalNotificationsPlugin();
    if (settingsClient.currentSettings.notificationsDenied.value == null) {
      if (context.mounted) {
        await showDialog(
          context: context,
          builder: (context) {
            return AlertDialog(
              title: const Text("This app needs to ask your permission to send background notifications."),
              content: const Text("Are you okay with that?"),
              actions: [
                TextButton(
                  onPressed: () async {
                    Navigator.of(context).pop();
                    await settingsClient.changeSettings(
                        settingsClient.currentSettings.copyWith(notificationsDenied: true));
                  },
                  child: const Text("No"),
                ),
                TextButton(
                  onPressed: () async {
                    Navigator.of(context).pop();
                    final requestResult = await notificationManager.resolvePlatformSpecificImplementation<
                        AndroidFlutterLocalNotificationsPlugin>()
                        ?.requestPermission();
                    await settingsClient.changeSettings(settingsClient.currentSettings.copyWith(
                        notificationsDenied: requestResult == null ? false : !requestResult));
                  },
                  child: const Text("Yes"),
                )
              ],
            );
          },
        );
      }
    }
    await widget.onLoginSuccessful?.call(authData);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Contacts++"),
      ),
      body: Builder(
          builder: (context) {
            return ListView(
              controller: _scrollController,
              children: [
                Padding(
                  padding: const EdgeInsets.symmetric(vertical: 64),
                  child: Center(
                    child: Text("Sign In", style: Theme
                        .of(context)
                        .textTheme
                        .headlineMedium),
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 64),
                  child: TextField(
                    controller: _usernameController,
                    onEditingComplete: () => _passwordFocusNode.requestFocus(),
                    decoration: InputDecoration(
                      contentPadding: const EdgeInsets.symmetric(vertical: 20, horizontal: 24),
                      border: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(32),
                      ),
                      labelText: 'Username',
                    ),
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 64),
                  child: TextField(
                    controller: _passwordController,
                    focusNode: _passwordFocusNode,
                    onEditingComplete: submit,
                    obscureText: true,
                    decoration: InputDecoration(
                      contentPadding: const EdgeInsets.symmetric(vertical: 20, horizontal: 24),
                      border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(32)
                      ),
                      labelText: 'Password',
                    ),
                  ),
                ),
                if (_needsTotp)
                  Padding(
                    padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 64),
                    child: TextField(
                      controller: _totpController,
                      focusNode: _totpFocusNode,
                      onEditingComplete: submit,
                      obscureText: false,
                      decoration: InputDecoration(
                        contentPadding: const EdgeInsets.symmetric(vertical: 20, horizontal: 24),
                        border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(32),
                        ),
                        labelText: '2FA Code',
                      ),
                    ),
                  ),
                Padding(
                  padding: const EdgeInsets.only(top: 16),
                  child: _isLoading ?
                  const Center(child: CircularProgressIndicator()) :
                  TextButton.icon(
                    onPressed: submit,
                    icon: const Icon(Icons.login),
                    label: const Text("Login"),
                  ),
                ),
                Center(
                  child: AnimatedOpacity(
                    opacity: _errorOpacity,
                    duration: const Duration(milliseconds: 200),
                    child: Padding(
                      padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 64),
                      child: Text(_error, style: Theme
                          .of(context)
                          .textTheme
                          .labelMedium
                          ?.copyWith(color: Colors.red)),
                    ),
                  ),
                )
              ],
            );
          }
      ),
    );
  }
}