import 'package:flutter/material.dart';

import '../../../nutrition/domain/entities/meal_type.dart';
import '../../domain/entities/meal_plan_slot.dart';
import '../../domain/entities/recipe.dart';
import '../controllers/meal_plan_calendar_controller.dart';

/// Responsive 7-day meal-plan grid.
///
/// On wide layouts (>= 900 dp) all seven day columns are visible at once;
/// compact widths fall back to a tabbed pager with one day per tab. Each
/// column header shows the day's scheduled-protein rollup against the daily
/// target, and every meal slot is a drop target for the saved-recipe tray
/// (`Draggable`/`DragTarget`) as well as tappable for the quick-assign
/// modal.
class WeeklyCalendarView extends StatelessWidget {
  const WeeklyCalendarView({
    super.key,
    required this.state,
    required this.onRecipeDropped,
    required this.onSlotTapped,
    required this.onTogglePrepared,
    required this.onClearSlot,
  });

  final MealPlanCalendarState state;

  /// A tray recipe was dropped onto [day]'s [mealType] slot.
  final void Function(Recipe recipe, DateTime day, MealType mealType)
      onRecipeDropped;

  /// The slot was tapped — open the quick-assign modal.
  final void Function(DateTime day, MealType mealType) onSlotTapped;

  final void Function(MealPlanSlot slot) onTogglePrepared;
  final void Function(MealPlanSlot slot) onClearSlot;

  @override
  Widget build(BuildContext context) {
    final days = state.days;

    return LayoutBuilder(
      builder: (context, constraints) {
        final wide = constraints.maxWidth >= 900;
        if (wide) {
          return SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                for (final day in days)
                  SizedBox(
                    width: constraints.maxWidth / 7,
                    // Each column scrolls vertically so short windows never
                    // trigger RenderFlex overflow stripes.
                    child: SingleChildScrollView(
                      padding: const EdgeInsets.symmetric(
                        horizontal: 4,
                        vertical: 8,
                      ),
                      child: _DayColumn(
                        day: day,
                        state: state,
                        onRecipeDropped: onRecipeDropped,
                        onSlotTapped: onSlotTapped,
                        onTogglePrepared: onTogglePrepared,
                        onClearSlot: onClearSlot,
                      ),
                    ),
                  ),
              ],
            ),
          );
        }
        return _CompactWeekPager(
          days: days,
          state: state,
          onRecipeDropped: onRecipeDropped,
          onSlotTapped: onSlotTapped,
          onTogglePrepared: onTogglePrepared,
          onClearSlot: onClearSlot,
        );
      },
    );
  }
}

/// Tabbed pager used below the 900 dp breakpoint: one tab per day.
class _CompactWeekPager extends StatefulWidget {
  const _CompactWeekPager({
    required this.days,
    required this.state,
    required this.onRecipeDropped,
    required this.onSlotTapped,
    required this.onTogglePrepared,
    required this.onClearSlot,
  });

  final List<DateTime> days;
  final MealPlanCalendarState state;
  final void Function(Recipe recipe, DateTime day, MealType mealType)
      onRecipeDropped;
  final void Function(DateTime day, MealType mealType) onSlotTapped;
  final void Function(MealPlanSlot slot) onTogglePrepared;
  final void Function(MealPlanSlot slot) onClearSlot;

  @override
  State<_CompactWeekPager> createState() => _CompactWeekPagerState();
}

class _CompactWeekPagerState extends State<_CompactWeekPager>
    with SingleTickerProviderStateMixin {
  late final TabController _tabController =
      TabController(length: widget.days.length, vsync: this);

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  static const List<String> _weekdayLabels = [
    'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun',
  ];

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: widget.days.length,
      child: Column(
        children: [
          TabBar(
            controller: _tabController,
            isScrollable: true,
            tabAlignment: TabAlignment.start,
            tabs: [
              for (final day in widget.days)
                Tab(text: '${_weekdayLabels[day.weekday - 1]} ${day.day}'),
            ],
          ),
          Expanded(
            child: TabBarView(
              controller: _tabController,
              children: [
                for (final day in widget.days)
                  SingleChildScrollView(
                    padding: const EdgeInsets.all(8),
                    child: _DayColumn(
                      day: day,
                      state: widget.state,
                      onRecipeDropped: widget.onRecipeDropped,
                      onSlotTapped: widget.onSlotTapped,
                      onTogglePrepared: widget.onTogglePrepared,
                      onClearSlot: widget.onClearSlot,
                    ),
                  ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

/// One day of the weekly grid: header (date + protein rollup indicator)
/// followed by the four meal slots.
class _DayColumn extends StatelessWidget {
  const _DayColumn({
    required this.day,
    required this.state,
    required this.onRecipeDropped,
    required this.onSlotTapped,
    required this.onTogglePrepared,
    required this.onClearSlot,
  });

  final DateTime day;
  final MealPlanCalendarState state;
  final void Function(Recipe recipe, DateTime day, MealType mealType)
      onRecipeDropped;
  final void Function(DateTime day, MealType mealType) onSlotTapped;
  final void Function(MealPlanSlot slot) onTogglePrepared;
  final void Function(MealPlanSlot slot) onClearSlot;

  static const List<String> _weekdayLabels = [
    'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday',
  ];

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final protein = state.proteinForDay(day);
    final target = state.dailyProteinTargetGrams;
    final progress = state.proteinProgressForDay(day).clamp(0.0, 1.0);
    final reachedGoal = protein >= target;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 6),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '${_weekdayLabels[day.weekday - 1]} ${day.day}',
                style: theme.textTheme.titleSmall
                    ?.copyWith(fontWeight: FontWeight.bold),
              ),
              const SizedBox(height: 4),
              Row(
                children: [
                  Icon(
                    Icons.fitness_center,
                    size: 14,
                    color: reachedGoal ? Colors.green : theme.colorScheme.outline,
                  ),
                  const SizedBox(width: 4),
                  Expanded(
                    child: Text(
                      '${protein.toStringAsFixed(0)}/'
                      '${target.toStringAsFixed(0)} g',
                      style: theme.textTheme.labelSmall?.copyWith(
                        color: reachedGoal
                            ? Colors.green.shade800
                            : theme.colorScheme.outline,
                        fontWeight:
                            reachedGoal ? FontWeight.bold : FontWeight.normal,
                      ),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 4),
              ClipRRect(
                borderRadius: BorderRadius.circular(4),
                child: LinearProgressIndicator(
                  value: progress,
                  minHeight: 6,
                  backgroundColor: theme.colorScheme.surfaceContainerHighest,
                  color: reachedGoal ? Colors.green : theme.colorScheme.primary,
                ),
              ),
            ],
          ),
        ),
        const Divider(height: 12),
        for (final mealType in MealType.values) ...[
          _DaySlotCard(
            day: day,
            mealType: mealType,
            slot: state.slotFor(day, mealType),
            recipe: _recipeForSlot(state.slotFor(day, mealType)),
            onRecipeDropped: onRecipeDropped,
            onTap: () => onSlotTapped(day, mealType),
            onTogglePrepared: onTogglePrepared,
            onClearSlot: onClearSlot,
          ),
          const SizedBox(height: 8),
        ],
      ],
    );
  }

  Recipe? _recipeForSlot(MealPlanSlot? slot) =>
      slot == null ? null : state.recipeFor(slot);
}

/// A single meal slot: drop target for tray drags and tap target for the
/// quick-assign modal; shows the assigned recipe (with protein badge) or a
/// free-text note, a prepared checkbox, and a clear action.
class _DaySlotCard extends StatelessWidget {
  const _DaySlotCard({
    required this.day,
    required this.mealType,
    required this.slot,
    required this.recipe,
    required this.onRecipeDropped,
    required this.onTap,
    required this.onTogglePrepared,
    required this.onClearSlot,
  });

  final DateTime day;
  final MealType mealType;
  final MealPlanSlot? slot;
  final Recipe? recipe;
  final void Function(Recipe recipe, DateTime day, MealType mealType)
      onRecipeDropped;
  final VoidCallback onTap;
  final void Function(MealPlanSlot slot) onTogglePrepared;
  final void Function(MealPlanSlot slot) onClearSlot;

  static IconData _iconFor(MealType type) {
    switch (type) {
      case MealType.breakfast:
        return Icons.free_breakfast_outlined;
      case MealType.lunch:
        return Icons.lunch_dining_outlined;
      case MealType.dinner:
        return Icons.dinner_dining_outlined;
      case MealType.snack:
        return Icons.cookie_outlined;
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final currentSlot = slot;
    final filled = currentSlot != null && !currentSlot.isEmpty;

    return DragTarget<Recipe>(
      onAcceptWithDetails: (details) =>
          onRecipeDropped(details.data, day, mealType),
      builder: (context, candidateRecipes, rejectedRecipes) {
        final highlighted = candidateRecipes.isNotEmpty;
        return Material(
          color: highlighted
              ? theme.colorScheme.primaryContainer
              : theme.colorScheme.surfaceContainerLow,
          borderRadius: BorderRadius.circular(12),
          child: InkWell(
            borderRadius: BorderRadius.circular(12),
            onTap: onTap,
            child: Container(
              constraints: const BoxConstraints(minHeight: 64),
              padding: const EdgeInsets.all(8),
              child: _buildContent(theme, currentSlot, filled),
            ),
          ),
        );
      },
    );
  }

  Widget _buildContent(
    ThemeData theme,
    MealPlanSlot? currentSlot,
    bool filled,
  ) {
    final assignedRecipe = recipe;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Icon(_iconFor(mealType), size: 16),
            const SizedBox(width: 6),
            Expanded(
              child: Text(
                mealType.displayName,
                style: theme.textTheme.labelMedium
                    ?.copyWith(fontWeight: FontWeight.w600),
              ),
            ),
            if (currentSlot != null && filled) ...[
              Checkbox(
                value: currentSlot.isPrepared,
                onChanged: (_) => onTogglePrepared(currentSlot),
                materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                visualDensity: VisualDensity.compact,
              ),
              PopupMenuButton<String>(
                padding: EdgeInsets.zero,
                icon: const Icon(Icons.more_vert, size: 18),
                onSelected: (value) {
                  if (value == 'clear') onClearSlot(currentSlot);
                },
                itemBuilder: (context) => const [
                  PopupMenuItem(value: 'clear', child: Text('Clear slot')),
                ],
              ),
            ] else
              Icon(Icons.add, size: 18, color: theme.colorScheme.outline),
          ],
        ),
        if (currentSlot != null && filled) ...[
          const SizedBox(height: 2),
          Text(
            assignedRecipe?.title ?? currentSlot.customDescription ?? '',
            maxLines: 2,
            overflow: TextOverflow.ellipsis,
            style: theme.textTheme.bodySmall?.copyWith(
              fontWeight: FontWeight.w500,
              decoration: currentSlot.isPrepared
                  ? TextDecoration.lineThrough
                  : null,
            ),
          ),
          if (assignedRecipe != null) ...[
            const SizedBox(height: 4),
            Row(
              children: [
                _MiniProteinBadge(
                  proteinGrams: assignedRecipe.macrosPerServing.proteinGrams,
                ),
                const SizedBox(width: 6),
                Expanded(
                  child: Text(
                    '${assignedRecipe.macrosPerServing.calories} kcal',
                    style: theme.textTheme.labelSmall,
                    overflow: TextOverflow.ellipsis,
                  ),
                ),
              ],
            ),
          ],
        ] else
          Text(
            'Tap or drop a recipe',
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
            style: theme.textTheme.labelSmall?.copyWith(
              fontStyle: FontStyle.italic,
              color: theme.colorScheme.outline,
            ),
          ),
      ],
    );
  }
}

/// Tiny protein badge used inside calendar slots.
class _MiniProteinBadge extends StatelessWidget {
  const _MiniProteinBadge({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: 5, vertical: 1),
      decoration: BoxDecoration(
        color: Colors.green.shade100,
        borderRadius: BorderRadius.circular(6),
      ),
      child: Text(
        label,
        style: TextStyle(
          fontSize: 10,
          fontWeight: FontWeight.bold,
          color: Colors.green.shade800,
        ),
      ),
    );
  }
}