import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import '../models/language.dart';
import '../models/history_item.dart';
import '../services/settings_service.dart';
import '../services/translate_service.dart';
import '../services/history_service.dart';
import 'settings_screen.dart';
import 'history_screen.dart';

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

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  final _settingsService = SettingsService();
  late final TranslateService _translateService = TranslateService(_settingsService);
  final _historyService = HistoryService();

  final _sourceController = TextEditingController();
  Timer? _debounce;

  List<Language> _languages = [];
  Language _sourceLang = Language.auto;
  Language _targetLang = const Language(code: 'en', name: 'İngilizce');

  String _resultText = '';
  String? _detectedLangLabel;
  bool _loadingLanguages = true;
  bool _translating = false;
  String? _connectionError;

  @override
  void initState() {
    super.initState();
    _bootstrap();
    _sourceController.addListener(_onTextChanged);
  }

  @override
  void dispose() {
    _debounce?.cancel();
    _sourceController.dispose();
    super.dispose();
  }

  /// Uygulama açılışında sunucuya otomatik bağlanmayı dener.
  Future<void> _bootstrap() async {
    final hasSettings = await _settingsService.hasSettings();
    if (!hasSettings) {
      final saved = await Navigator.of(context).push<bool>(
        MaterialPageRoute(builder: (_) => const SettingsScreen(isFirstRun: true)),
      );
      if (saved != true) {
        // Kullanıcı ayarları kaydetmeden geri döndüyse yine de tekrar dene.
      }
    }
    await _loadLanguages();
  }

  Future<void> _loadLanguages() async {
    setState(() {
      _loadingLanguages = true;
      _connectionError = null;
    });
    try {
      final langs = await _translateService.fetchLanguages();
      setState(() {
        _languages = langs;
        // Hedef dil listede yoksa ilk uygun dile düş.
        if (!_languages.any((l) => l.code == _targetLang.code) && _languages.isNotEmpty) {
          _targetLang = _languages.firstWhere((l) => l.code != 'auto', orElse: () => _languages.first);
        }
      });
    } catch (e) {
      setState(() => _connectionError = e.toString());
    } finally {
      setState(() => _loadingLanguages = false);
    }
  }

  void _onTextChanged() {
    _debounce?.cancel();
    _debounce = Timer(const Duration(milliseconds: 600), _runTranslate);
  }

  Future<void> _runTranslate() async {
    final text = _sourceController.text;
    if (text.trim().isEmpty) {
      setState(() {
        _resultText = '';
        _detectedLangLabel = null;
      });
      return;
    }

    setState(() => _translating = true);
    try {
      String effectiveSource = _sourceLang.code;

      if (_sourceLang.code == 'auto') {
        final detected = await _translateService.detect(text);
        if (detected != null) {
          effectiveSource = detected.language;
          final match = _languages.firstWhere(
            (l) => l.code == detected.language,
            orElse: () => Language(code: detected.language, name: detected.language),
          );
          setState(() => _detectedLangLabel = 'Algılanan dil: ${match.name}');
        }
      } else {
        _detectedLangLabel = null;
      }

      final translated = await _translateService.translate(
        text: text,
        sourceLang: effectiveSource,
        targetLang: _targetLang.code,
      );

      if (!mounted) return;
      setState(() => _resultText = translated);

      await _historyService.add(HistoryItem(
        sourceLang: effectiveSource,
        targetLang: _targetLang.code,
        sourceText: text,
        translatedText: translated,
        timestamp: DateTime.now(),
      ));
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Çeviri hatası: $e')),
      );
    } finally {
      if (mounted) setState(() => _translating = false);
    }
  }

  void _swapLanguages() {
    if (_sourceLang.code == 'auto') return; // otomatik iken takas anlamsız
    setState(() {
      final tmp = _sourceLang;
      _sourceLang = _targetLang;
      _targetLang = tmp;
      final tmpText = _sourceController.text;
      _sourceController.text = _resultText;
      _resultText = tmpText;
    });
  }

  List<Language> get _sourceOptions => [Language.auto, ..._languages];
  List<Language> get _targetOptions => _languages;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Çeviri'),
        actions: [
          IconButton(
            tooltip: 'Geçmiş',
            icon: const Icon(Icons.history),
            onPressed: () => Navigator.of(context).push(
              MaterialPageRoute(builder: (_) => const HistoryScreen()),
            ),
          ),
          IconButton(
            tooltip: 'Ayarlar',
            icon: const Icon(Icons.settings_outlined),
            onPressed: () async {
              await Navigator.of(context).push(
                MaterialPageRoute(builder: (_) => const SettingsScreen()),
              );
              _loadLanguages();
            },
          ),
        ],
      ),
      body: _loadingLanguages
          ? const Center(child: CircularProgressIndicator())
          : _connectionError != null
              ? _buildConnectionError()
              : _buildTranslator(),
    );
  }

  Widget _buildConnectionError() {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.cloud_off, size: 48, color: Colors.grey),
            const SizedBox(height: 16),
            Text('Sunucuya bağlanılamadı', style: Theme.of(context).textTheme.titleMedium),
            const SizedBox(height: 8),
            Text(_connectionError!, textAlign: TextAlign.center),
            const SizedBox(height: 20),
            Wrap(
              spacing: 12,
              children: [
                OutlinedButton(onPressed: _loadLanguages, child: const Text('Tekrar Dene')),
                FilledButton(
                  onPressed: () async {
                    await Navigator.of(context).push(
                      MaterialPageRoute(builder: (_) => const SettingsScreen()),
                    );
                    _loadLanguages();
                  },
                  child: const Text('Ayarları Aç'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildTranslator() {
    return Padding(
      padding: const EdgeInsets.all(16),
      child: Column(
        children: [
          _buildLanguageBar(),
          const SizedBox(height: 12),
          Expanded(
            child: Column(
              children: [
                Expanded(child: _buildInputCard()),
                const SizedBox(height: 12),
                Expanded(child: _buildResultCard()),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildLanguageBar() {
    return Row(
      children: [
        Expanded(child: _buildLangDropdown(isSource: true)),
        IconButton(
          icon: const Icon(Icons.swap_horiz),
          tooltip: 'Dilleri değiştir',
          onPressed: _sourceLang.code == 'auto' ? null : _swapLanguages,
        ),
        Expanded(child: _buildLangDropdown(isSource: false)),
      ],
    );
  }

  Widget _buildLangDropdown({required bool isSource}) {
    final options = isSource ? _sourceOptions : _targetOptions;
    final value = isSource ? _sourceLang : _targetLang;
    return DropdownButtonFormField<Language>(
      isExpanded: true,
      value: options.contains(value) ? value : null,
      decoration: const InputDecoration(isDense: true),
      items: options
          .map((l) => DropdownMenuItem(value: l, child: Text(l.name, overflow: TextOverflow.ellipsis)))
          .toList(),
      onChanged: (l) {
        if (l == null) return;
        setState(() {
          if (isSource) {
            _sourceLang = l;
          } else {
            _targetLang = l;
          }
        });
        _runTranslate();
      },
    );
  }

  Widget _buildInputCard() {
    return Card(
      margin: EdgeInsets.zero,
      child: Padding(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Expanded(
              child: TextField(
                controller: _sourceController,
                maxLines: null,
                expands: true,
                textAlignVertical: TextAlignVertical.top,
                decoration: const InputDecoration(
                  border: InputBorder.none,
                  hintText: 'Çevrilecek metni yazın...',
                ),
              ),
            ),
            if (_detectedLangLabel != null)
              Padding(
                padding: const EdgeInsets.only(top: 4),
                child: Text(_detectedLangLabel!, style: Theme.of(context).textTheme.bodySmall),
              ),
            Row(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                IconButton(
                  icon: const Icon(Icons.clear, size: 20),
                  tooltip: 'Temizle',
                  onPressed: () => _sourceController.clear(),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildResultCard() {
    return Card(
      margin: EdgeInsets.zero,
      color: Theme.of(context).colorScheme.surfaceContainerHighest,
      child: Padding(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Expanded(
              child: _translating
                  ? const Center(child: CircularProgressIndicator())
                  : SingleChildScrollView(
                      child: SelectableText(
                        _resultText,
                        style: Theme.of(context).textTheme.bodyLarge,
                      ),
                    ),
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                IconButton(
                  icon: const Icon(Icons.copy, size: 20),
                  tooltip: 'Kopyala',
                  onPressed: _resultText.isEmpty
                      ? null
                      : () {
                          Clipboard.setData(ClipboardData(text: _resultText));
                          ScaffoldMessenger.of(context).showSnackBar(
                            const SnackBar(content: Text('Kopyalandı'), duration: Duration(seconds: 1)),
                          );
                        },
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}