import 'package:flutter/material.dart';

import '../../domain/entities/recipe.dart';

/// Horizontally scrolling tray of saved recipe cards.
///
/// Each card is draggable onto the weekly calendar's meal slots and
/// carries a "+" affordance that opens the quick-assign modal.
class SavedRecipesTray extends StatelessWidget {
  const SavedRecipesTray({
    super.key,
    required this.recipes,
    this.onAssignPressed,
  });

  /// Saved recipes, newest first.
  final List<Recipe> recipes;

  /// Called when the card's quick-assign button (or the card itself) is
  /// tapped.
  final void Function(Recipe recipe)? onAssignPressed;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16),
          child: Row(
            children: [
              Text(
                'Saved Recipes',
                style: theme.textTheme.titleSmall
                    ?.copyWith(fontWeight: FontWeight.bold),
              ),
              const SizedBox(width: 8),
              Text(
                '${recipes.length}',
                style: theme.textTheme.labelMedium
                    ?.copyWith(color: theme.colorScheme.primary),
              ),
            ],
          ),
        ),
        const SizedBox(height: 8),
        SizedBox(
          height: 148,
          child: recipes.isEmpty
              ? Align(
                  alignment: Alignment.centerLeft,
                  child: Padding(
                    padding: const EdgeInsets.symmetric(horizontal: 16),
                    child: Text(
                      'Import a recipe above — it will appear here, ready to '
                      'drag onto the weekly plan.',
                      style: theme.textTheme.bodySmall?.copyWith(
                        fontStyle: FontStyle.italic,
                      ),
                    ),
                  ),
                )
              : ListView.separated(
                  scrollDirection: Axis.horizontal,
                  padding: const EdgeInsets.symmetric(horizontal: 16),
                  itemCount: recipes.length,
                  separatorBuilder: (context, index) =>
                      const SizedBox(width: 12),
                  itemBuilder: (context, index) {
                    final recipe = recipes[index];
                    return _RecipeCard(
                      recipe: recipe,
                      onAssignPressed: onAssignPressed == null
                          ? null
                          : () => onAssignPressed!(recipe),
                    );
                  },
                ),
        ),
      ],
    );
  }
}

/// Draggable card showing a recipe thumbnail, title, and protein badge.
class _RecipeCard extends StatelessWidget {
  const _RecipeCard({required this.recipe, this.onAssignPressed});

  final Recipe recipe;
  final VoidCallback? onAssignPressed;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final protein = recipe.macrosPerServing.proteinGrams;

    final card = SizedBox(
      width: 180,
      child: Card(
        clipBehavior: Clip.antiAlias,
        child: InkWell(
          onTap: onAssignPressed,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Expanded(
                child: recipe.imageUrl == null
                    ? _ThumbnailPlaceholder(theme: theme)
                    : Image.network(
                        recipe.imageUrl!,
                        width: double.infinity,
                        height: double.infinity,
                        fit: BoxFit.cover,
                        errorBuilder: (context, error, stackTrace) =>
                            _ThumbnailPlaceholder(theme: theme),
                      ),
              ),
              Padding(
                padding: const EdgeInsets.all(8),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      recipe.title,
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                      style: theme.textTheme.bodyMedium
                          ?.copyWith(fontWeight: FontWeight.w600),
                    ),
                    const SizedBox(height: 4),
                    Row(
                      children: [
                        _ProteinBadge(proteinGrams: protein),
                        const Spacer(),
                        if (onAssignPressed != null)
                          Icon(
                            Icons.add_circle_outline,
                            size: 20,
                            color: theme.colorScheme.primary,
                          ),
                      ],
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );

    return Draggable<Recipe>(
      data: recipe,
      feedback: Material(
        elevation: 6,
        borderRadius: BorderRadius.circular(12),
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 200),
          child: Padding(
            padding: const EdgeInsets.all(12),
            child: Text(
              recipe.title,
              maxLines: 2,
              overflow: TextOverflow.ellipsis,
            ),
          ),
        ),
      ),
      childWhenDragging: Opacity(opacity: 0.4, child: card),
      child: card,
    );
  }
}

/// Fallback tile when a recipe has no (loadable) thumbnail.
class _ThumbnailPlaceholder extends StatelessWidget {
  const _ThumbnailPlaceholder({required this.theme});

  final ThemeData theme;

  @override
  Widget build(BuildContext context) {
    return Container(
      color: theme.colorScheme.surfaceContainerHighest,
      child: Center(
        child: Icon(
          Icons.restaurant_menu,
          size: 28,
          color: theme.colorScheme.outline,
        ),
      ),
    );
  }
}

/// Compact green badge showing the protein contribution of a recipe.
class _ProteinBadge extends StatelessWidget {
  const _ProteinBadge({required this.proteinGrams});

  final double proteinGrams;

  @override
  Widget build(BuildContext context) {
    final rounded = proteinGrams.roundToDouble();
    final label = rounded == proteinGrams
        ? '${rounded.toStringAsFixed(0)}g P'
        : '${proteinGrams.toStringAsFixed(1)}g P';

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
      decoration: BoxDecoration(
        color: Colors.green.shade100,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Text(
        label,
        style: TextStyle(
          fontSize: 11,
          fontWeight: FontWeight.bold,
          color: Colors.green.shade800,
        ),
      ),
    );
  }
}