import 'package:cached_network_image/cached_network_image.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../core/theme/app_colors.dart';
import '../../shared/models/recipe.dart';
import '../../shared/models/saved_recipe.dart';
import 'recipe_provider.dart';

/// Unified detail screen for both recommendation recipes and saved recipes.
///
/// Pass a [Recipe] (from recommendations) or a [SavedRecipe] (from saved list)
/// via GoRouter's `extra` parameter.
class RecipeDetailScreen extends ConsumerStatefulWidget {
  final Recipe? recipe;
  final SavedRecipe? saved;

  const RecipeDetailScreen({super.key, this.recipe, this.saved})
      : assert(recipe != null || saved != null,
            'Provide either recipe or saved');

  @override
  ConsumerState<RecipeDetailScreen> createState() => _RecipeDetailScreenState();
}

class _RecipeDetailScreenState extends ConsumerState<RecipeDetailScreen> {
  bool _isSaving = false;

  // ── Unified accessors ────────────────────────────────────────────────────

  String get _title => widget.recipe?.title ?? widget.saved!.title;
  String? get _description =>
      widget.recipe?.description ?? widget.saved!.description;
  String? get _imageUrl =>
      widget.recipe?.imageUrl.isNotEmpty == true
          ? widget.recipe!.imageUrl
          : widget.saved?.imageUrl;
  String? get _cuisine => widget.recipe?.cuisine ?? widget.saved!.cuisine;
  String? get _difficulty =>
      widget.recipe?.difficulty ?? widget.saved!.difficulty;
  int? get _prepTimeMin =>
      widget.recipe?.prepTimeMin ?? widget.saved!.prepTimeMin;
  int? get _cookTimeMin =>
      widget.recipe?.cookTimeMin ?? widget.saved!.cookTimeMin;
  int? get _servings => widget.recipe?.servings ?? widget.saved!.servings;
  List<RecipeIngredient> get _ingredients =>
      widget.recipe?.ingredients ?? widget.saved!.ingredients;
  List<RecipeStep> get _steps =>
      widget.recipe?.steps ?? widget.saved!.steps;
  List<String> get _tags => widget.recipe?.tags ?? widget.saved!.tags;
  NutritionInfo? get _nutrition =>
      widget.recipe?.nutrition ?? widget.saved!.nutrition;

  bool get _isFromSaved => widget.saved != null;

  @override
  Widget build(BuildContext context) {
    final savedNotifier = ref.watch(savedRecipesProvider.notifier);
    final isSaved = _isFromSaved ||
        (widget.recipe != null && savedNotifier.isSaved(_title));

    return Scaffold(
      body: CustomScrollView(
        slivers: [
          _buildAppBar(context),
          SliverToBoxAdapter(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Padding(
                  padding: const EdgeInsets.fromLTRB(16, 16, 16, 0),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      // Title
                      Text(
                        _title,
                        style: Theme.of(context)
                            .textTheme
                            .headlineSmall
                            ?.copyWith(fontWeight: FontWeight.bold),
                      ),
                      if (_description != null && _description!.isNotEmpty) ...[
                        const SizedBox(height: 8),
                        Text(
                          _description!,
                          style: Theme.of(context)
                              .textTheme
                              .bodyMedium
                              ?.copyWith(color: AppColors.textSecondary),
                        ),
                      ],
                      const SizedBox(height: 16),
                      _MetaChips(
                        prepTimeMin: _prepTimeMin,
                        cookTimeMin: _cookTimeMin,
                        difficulty: _difficulty,
                        cuisine: _cuisine,
                        servings: _servings,
                      ),
                      if (_nutrition != null) ...[
                        const SizedBox(height: 16),
                        _NutritionCard(nutrition: _nutrition!),
                      ],
                      if (_tags.isNotEmpty) ...[
                        const SizedBox(height: 12),
                        _TagsRow(tags: _tags),
                      ],
                    ],
                  ),
                ),
                const Divider(height: 32),
                _IngredientsSection(ingredients: _ingredients),
                const Divider(height: 32),
                _StepsSection(steps: _steps),
                const SizedBox(height: 24),
                // Save / Unsave button
                Padding(
                  padding: const EdgeInsets.symmetric(horizontal: 16),
                  child: _SaveButton(
                    isSaved: isSaved,
                    isLoading: _isSaving,
                    onPressed: () => _toggleSave(context, isSaved),
                  ),
                ),
                const SizedBox(height: 32),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildAppBar(BuildContext context) {
    return SliverAppBar(
      expandedHeight: 280,
      pinned: true,
      flexibleSpace: FlexibleSpaceBar(
        background: _imageUrl != null && _imageUrl!.isNotEmpty
            ? CachedNetworkImage(
                imageUrl: _imageUrl!,
                fit: BoxFit.cover,
                placeholder: (_, __) => Container(color: Colors.grey[200]),
                errorWidget: (_, __, ___) => _PlaceholderImage(),
              )
            : _PlaceholderImage(),
      ),
    );
  }

  Future<void> _toggleSave(BuildContext context, bool isSaved) async {
    if (_isSaving) return;
    HapticFeedback.lightImpact();

    setState(() => _isSaving = true);
    final notifier = ref.read(savedRecipesProvider.notifier);

    try {
      if (isSaved) {
        final id = _isFromSaved
            ? widget.saved!.id
            : notifier.savedId(_title);
        if (id != null) {
          final ok = await notifier.delete(id);
          if (!ok && context.mounted) {
            _showSnack(context, 'Не удалось удалить из сохранённых');
          } else if (ok && _isFromSaved && context.mounted) {
            Navigator.of(context).pop();
          }
        }
      } else if (widget.recipe != null) {
        final saved = await notifier.save(widget.recipe!);
        if (saved == null && context.mounted) {
          _showSnack(context, 'Не удалось сохранить рецепт');
        }
      }
    } finally {
      if (mounted) setState(() => _isSaving = false);
    }
  }

  void _showSnack(BuildContext context, String message) {
    ScaffoldMessenger.of(context)
        .showSnackBar(SnackBar(content: Text(message)));
  }
}

// ---------------------------------------------------------------------------
// Sub-widgets
// ---------------------------------------------------------------------------

class _PlaceholderImage extends StatelessWidget {
  @override
  Widget build(BuildContext context) => Container(
        color: AppColors.primary.withValues(alpha: 0.15),
        child: const Center(child: Icon(Icons.restaurant, size: 64)),
      );
}

class _MetaChips extends StatelessWidget {
  final int? prepTimeMin;
  final int? cookTimeMin;
  final String? difficulty;
  final String? cuisine;
  final int? servings;

  const _MetaChips({
    this.prepTimeMin,
    this.cookTimeMin,
    this.difficulty,
    this.cuisine,
    this.servings,
  });

  @override
  Widget build(BuildContext context) {
    final totalMin = (prepTimeMin ?? 0) + (cookTimeMin ?? 0);
    return Wrap(
      spacing: 8,
      runSpacing: 4,
      children: [
        if (totalMin > 0)
          _Chip(icon: Icons.access_time, label: '$totalMin мин'),
        if (difficulty != null)
          _Chip(icon: Icons.bar_chart, label: _difficultyLabel(difficulty!)),
        if (cuisine != null)
          _Chip(icon: Icons.public, label: _cuisineLabel(cuisine!)),
        if (servings != null)
          _Chip(icon: Icons.people, label: '$servings порц.'),
      ],
    );
  }

  String _difficultyLabel(String d) => switch (d) {
        'easy' => 'Легко',
        'medium' => 'Средне',
        'hard' => 'Сложно',
        _ => d,
      };

  String _cuisineLabel(String c) => switch (c) {
        'russian' => 'Русская',
        'asian' => 'Азиатская',
        'european' => 'Европейская',
        'mediterranean' => 'Средиземноморская',
        'american' => 'Американская',
        _ => 'Другая',
      };
}

class _Chip extends StatelessWidget {
  final IconData icon;
  final String label;

  const _Chip({required this.icon, required this.label});

  @override
  Widget build(BuildContext context) => Chip(
        avatar: Icon(icon, size: 14),
        label: Text(label, style: const TextStyle(fontSize: 12)),
        padding: EdgeInsets.zero,
        visualDensity: VisualDensity.compact,
      );
}

class _NutritionCard extends StatelessWidget {
  final NutritionInfo nutrition;

  const _NutritionCard({required this.nutrition});

  @override
  Widget build(BuildContext context) {
    return Card(
      color: AppColors.primary.withValues(alpha: 0.3),
      child: Padding(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Text(
                  'КБЖУ на порцию',
                  style: Theme.of(context).textTheme.titleSmall?.copyWith(
                        fontWeight: FontWeight.bold,
                      ),
                ),
                const SizedBox(width: 4),
                Tooltip(
                  message: 'Значения рассчитаны приблизительно с помощью ИИ',
                  child: Text(
                    '≈',
                    style: TextStyle(
                      color: AppColors.primary,
                      fontSize: 16,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 10),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                _NutCell(
                    label: 'Калории', value: '${nutrition.calories.round()}'),
                _NutCell(
                    label: 'Белки', value: '${nutrition.proteinG.round()} г'),
                _NutCell(
                    label: 'Жиры', value: '${nutrition.fatG.round()} г'),
                _NutCell(
                    label: 'Углев.', value: '${nutrition.carbsG.round()} г'),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

class _NutCell extends StatelessWidget {
  final String label;
  final String value;

  const _NutCell({required this.label, required this.value});

  @override
  Widget build(BuildContext context) => Column(
        children: [
          Text(
            value,
            style: const TextStyle(
                fontWeight: FontWeight.bold, fontSize: 15),
          ),
          const SizedBox(height: 2),
          Text(
            label,
            style: const TextStyle(
                fontSize: 11, color: AppColors.textSecondary),
          ),
        ],
      );
}

class _TagsRow extends StatelessWidget {
  final List<String> tags;

  const _TagsRow({required this.tags});

  @override
  Widget build(BuildContext context) {
    return Wrap(
      spacing: 6,
      runSpacing: 4,
      children: tags
          .map(
            (t) => Chip(
              label: Text(t, style: const TextStyle(fontSize: 11)),
              backgroundColor: AppColors.primary.withValues(alpha: 0.15),
              padding: EdgeInsets.zero,
              visualDensity: VisualDensity.compact,
            ),
          )
          .toList(),
    );
  }
}

class _IngredientsSection extends StatelessWidget {
  final List<RecipeIngredient> ingredients;

  const _IngredientsSection({required this.ingredients});

  @override
  Widget build(BuildContext context) {
    if (ingredients.isEmpty) return const SizedBox.shrink();

    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Ингредиенты',
            style: Theme.of(context)
                .textTheme
                .titleMedium
                ?.copyWith(fontWeight: FontWeight.bold),
          ),
          const SizedBox(height: 10),
          ...ingredients.map(
            (ing) => Padding(
              padding: const EdgeInsets.only(bottom: 6),
              child: Row(
                children: [
                  const Icon(Icons.circle, size: 6, color: AppColors.primary),
                  const SizedBox(width: 10),
                  Expanded(child: Text(ing.name)),
                  Text(
                    '${_formatAmount(ing.amount)} ${ing.unit}',
                    style: const TextStyle(
                        color: AppColors.textSecondary, fontSize: 13),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  String _formatAmount(double amount) {
    if (amount == amount.truncate()) return amount.toInt().toString();
    return amount.toStringAsFixed(1);
  }
}

class _StepsSection extends StatelessWidget {
  final List<RecipeStep> steps;

  const _StepsSection({required this.steps});

  @override
  Widget build(BuildContext context) {
    if (steps.isEmpty) return const SizedBox.shrink();

    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Приготовление',
            style: Theme.of(context)
                .textTheme
                .titleMedium
                ?.copyWith(fontWeight: FontWeight.bold),
          ),
          const SizedBox(height: 10),
          ...steps.map((step) => _StepTile(step: step)),
        ],
      ),
    );
  }
}

class _StepTile extends StatelessWidget {
  final RecipeStep step;

  const _StepTile({required this.step});

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: 14),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          // Step number badge
          Container(
            width: 28,
            height: 28,
            decoration: const BoxDecoration(
              color: AppColors.primary,
              shape: BoxShape.circle,
            ),
            child: Center(
              child: Text(
                '${step.number}',
                style: const TextStyle(
                    color: Colors.white,
                    fontWeight: FontWeight.bold,
                    fontSize: 13),
              ),
            ),
          ),
          const SizedBox(width: 12),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(step.description),
                if (step.timerSeconds != null) ...[
                  const SizedBox(height: 4),
                  Row(
                    children: [
                      const Icon(Icons.timer_outlined,
                          size: 14, color: AppColors.primary),
                      const SizedBox(width: 4),
                      Text(
                        _formatTimer(step.timerSeconds!),
                        style: const TextStyle(
                            color: AppColors.primary, fontSize: 12),
                      ),
                    ],
                  ),
                ],
              ],
            ),
          ),
        ],
      ),
    );
  }

  String _formatTimer(int seconds) {
    if (seconds < 60) return '$seconds сек';
    final m = seconds ~/ 60;
    final s = seconds % 60;
    return s == 0 ? '$m мин' : '$m мин $s сек';
  }
}

class _SaveButton extends StatelessWidget {
  final bool isSaved;
  final bool isLoading;
  final VoidCallback onPressed;

  const _SaveButton({
    required this.isSaved,
    required this.isLoading,
    required this.onPressed,
  });

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      child: ElevatedButton.icon(
        onPressed: isLoading ? null : onPressed,
        icon: isLoading
            ? const SizedBox(
                width: 18,
                height: 18,
                child: CircularProgressIndicator(strokeWidth: 2),
              )
            : Icon(isSaved ? Icons.favorite : Icons.favorite_border),
        label: Text(isSaved ? 'Сохранено' : 'Сохранить'),
        style: ElevatedButton.styleFrom(
          backgroundColor:
              isSaved ? Colors.red[100] : AppColors.primary,
          foregroundColor: isSaved ? Colors.red[800] : Colors.white,
        ),
      ),
    );
  }
}