import 'dart:math';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import '../bloc/book_bloc.dart';
import '../bloc/navigation_bloc.dart';
import '../models/models.dart';
import '../theme/app_spacing.dart';

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

  @override
  State<AddBookScreen> createState() => _AddBookScreenState();
}

class _AddBookScreenState extends State<AddBookScreen> {
  final _titleController = TextEditingController();
  final _authorController = TextEditingController();
  final _annotationController = TextEditingController();
  String _genre = 'fiction';
  bool _initialized = false;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (!_initialized) {
      _initialized = true;
      final navState = context.read<NavigationBloc>().state;
      final book = navState.selectedBook;
      final prefilled = navState.prefilledData;
      final source = book ?? prefilled;
      if (source != null) {
        _titleController.text = source.title;
        _authorController.text = source.author;
        _annotationController.text = source.annotation;
        _genre = source.genre.isNotEmpty ? source.genre : 'fiction';
      }
    }
  }

  @override
  void dispose() {
    _titleController.dispose();
    _authorController.dispose();
    _annotationController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final textTheme = Theme.of(context).textTheme;
    final navState = context.read<NavigationBloc>().state;
    final isEditing =
        navState.selectedBook != null && navState.prefilledData == null;
    final title = isEditing ? 'Редактировать' : 'Добавить книгу';

    return SafeArea(
      child: Column(
        children: [
          // Header
          Padding(
            padding: const EdgeInsets.fromLTRB(
              AppSpacing.sm,
              AppSpacing.sm,
              AppSpacing.sm,
              0,
            ),
            child: Row(
              children: [
                IconButton(
                  icon: const Icon(Icons.arrow_back),
                  onPressed: () => context.read<NavigationBloc>().add(
                    isEditing
                        ? NavigateTo(AppScreen.details)
                        : NavigateTo(AppScreen.library),
                  ),
                ),
                Text(title, style: textTheme.headlineMedium),
              ],
            ),
          ),
          Expanded(
            child: ListView(
              padding: const EdgeInsets.all(AppSpacing.lg),
              children: [
                // Cover placeholder / scanner trigger
                GestureDetector(
                  onTap: () => context.read<NavigationBloc>().add(
                    NavigateTo(AppScreen.scanner),
                  ),
                  child: Container(
                    height: 160,
                    decoration: BoxDecoration(
                      border: Border.all(color: colorScheme.outline),
                      borderRadius: BorderRadius.circular(
                        AppSpacing.radiusMedium,
                      ),
                      color: colorScheme.surfaceContainerHighest,
                    ),
                    child: Center(
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Icon(
                            Icons.camera_alt,
                            size: 40,
                            color: colorScheme.primary,
                          ),
                          const SizedBox(height: AppSpacing.sm),
                          Text(
                            'Загрузить или отсканировать',
                            style: textTheme.bodyMedium?.copyWith(
                              color: colorScheme.onSurface.withValues(
                                alpha: 0.6,
                              ),
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
                const SizedBox(height: AppSpacing.lg),
                _field('Название', _titleController, textTheme),
                const SizedBox(height: AppSpacing.md),
                _field('Автор', _authorController, textTheme),
                const SizedBox(height: AppSpacing.md),
                // Genre dropdown
                Text('Жанр', style: textTheme.labelMedium),
                const SizedBox(height: AppSpacing.xs),
                DropdownButtonFormField<String>(
                  initialValue: _genre,
                  dropdownColor: colorScheme.surface,
                  decoration: const InputDecoration(),
                  items: const [
                    DropdownMenuItem(
                      value: 'fiction',
                      child: Text('Фантастика'),
                    ),
                    DropdownMenuItem(value: 'fantasy', child: Text('Фэнтези')),
                    DropdownMenuItem(value: 'science', child: Text('Научпоп')),
                    DropdownMenuItem(
                      value: 'biography',
                      child: Text('Биография'),
                    ),
                    DropdownMenuItem(
                      value: 'detective',
                      child: Text('Детектив'),
                    ),
                    DropdownMenuItem(value: 'other', child: Text('Другое')),
                  ],
                  onChanged: (v) => setState(() => _genre = v ?? _genre),
                ),
                const SizedBox(height: AppSpacing.md),
                Text('Аннотация', style: textTheme.labelMedium),
                const SizedBox(height: AppSpacing.xs),
                TextField(controller: _annotationController, maxLines: 4),
                const SizedBox(height: 100),
              ],
            ),
          ),
          // Bottom actions
          Container(
            padding: const EdgeInsets.symmetric(
              horizontal: AppSpacing.screenPadding,
              vertical: AppSpacing.md,
            ),
            decoration: BoxDecoration(
              color: colorScheme.surface,
              border: Border(
                top: BorderSide(color: colorScheme.outlineVariant),
              ),
              boxShadow: [
                BoxShadow(
                  color: colorScheme.shadow,
                  blurRadius: 8,
                  offset: const Offset(0, -2),
                ),
              ],
            ),
            child: Row(
              children: [
                Expanded(
                  child: OutlinedButton(
                    onPressed: () => context.read<NavigationBloc>().add(
                      isEditing
                          ? NavigateTo(AppScreen.details)
                          : NavigateTo(AppScreen.library),
                    ),
                    child: const Text('Отмена'),
                  ),
                ),
                const SizedBox(width: AppSpacing.md),
                Expanded(
                  flex: 2,
                  child: ElevatedButton(
                    onPressed: _save,
                    child: const Text('Сохранить'),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _field(
    String label,
    TextEditingController controller,
    TextTheme textTheme,
  ) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(label, style: textTheme.labelMedium),
        const SizedBox(height: AppSpacing.xs),
        TextField(controller: controller),
      ],
    );
  }

  void _save() {
    final navState = context.read<NavigationBloc>().state;
    final existing = navState.selectedBook;
    final isEditing = existing != null && navState.prefilledData == null;

    final Book book = (
      id: isEditing ? existing.id : '${Random().nextInt(100000)}',
      title: _titleController.text,
      author: _authorController.text,
      genre: _genre,
      annotation: _annotationController.text,
      coverUrl: isEditing
          ? existing.coverUrl
          : 'https://picsum.photos/seed/newbook/400/600',
      pages: isEditing ? existing.pages : 0,
      language: isEditing ? existing.language : 'Russian',
      publishedYear: isEditing ? existing.publishedYear : DateTime.now().year,
      rating: isEditing ? existing.rating : 5.0,
      status: isEditing ? existing.status : 'want_to_read',
      progress: isEditing ? existing.progress : null,
      isFavorite: isEditing ? existing.isFavorite : false,
    );

    if (isEditing) {
      context.read<BookBloc>().add(UpdateBook(book));
    } else {
      context.read<BookBloc>().add(AddBook(book));
    }
    context.read<NavigationBloc>().add(NavigateTo(AppScreen.library));
  }
}