Eventify-frontend/lib/widgets/skeleton_loader.dart

import 'package:flutter/material.dart';
import 'package:shimmer/shimmer.dart';

/// Generic shimmer rectangle with configurable dimensions and border radius.
class SkeletonBox extends StatelessWidget {
  final double width;
  final double height;
  final double borderRadius;

  const SkeletonBox({
    Key? key,
    this.width = double.infinity,
    required this.height,
    this.borderRadius = 8,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;
    return Shimmer.fromColors(
      baseColor: isDark ? const Color(0xFF2D2D2D) : Colors.grey[300]!,
      highlightColor: isDark ? const Color(0xFF3D3D3D) : Colors.grey[100]!,
      child: Container(
        width: width,
        height: height,
        decoration: BoxDecoration(
          color: Colors.white,
          borderRadius: BorderRadius.circular(borderRadius),
        ),
      ),
    );
  }
}

/// Shimmer placeholder for a compact event card (used in horizontal lists).
class EventCardSkeleton extends StatelessWidget {
  const EventCardSkeleton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: 200,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: const [
          SkeletonBox(height: 140, borderRadius: 12),
          SizedBox(height: 8),
          SkeletonBox(height: 14, width: 160),
          SizedBox(height: 6),
          SkeletonBox(height: 12, width: 100),
        ],
      ),
    );
  }
}

/// Shimmer placeholder for a full-width event list row.
class EventListSkeleton extends StatelessWidget {
  const EventListSkeleton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6, horizontal: 16),
      child: Row(
        children: const [
          SkeletonBox(width: 64, height: 64, borderRadius: 10),
          SizedBox(width: 12),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                SkeletonBox(height: 14),
                SizedBox(height: 8),
                SkeletonBox(height: 12, width: 140),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

/// Shimmer placeholder for hero carousel area.
class HeroCarouselSkeleton extends StatelessWidget {
  const HeroCarouselSkeleton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Padding(
      padding: EdgeInsets.symmetric(horizontal: 16),
      child: SkeletonBox(height: 320, borderRadius: 24),
    );
  }
}

/// Shimmer grid for achievements tab.
class AchievementGridSkeleton extends StatelessWidget {
  const AchievementGridSkeleton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return GridView.count(
      crossAxisCount: 2,
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      mainAxisSpacing: 12,
      crossAxisSpacing: 12,
      padding: const EdgeInsets.all(16),
      children: List.generate(4, (_) => const SkeletonBox(height: 160, borderRadius: 16)),
    );
  }
}

/// Shimmer placeholder for profile stat cards row.
class ProfileStatsSkeleton extends StatelessWidget {
  const ProfileStatsSkeleton({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      child: Row(
        children: List.generate(3, (_) => const Expanded(
          child: Padding(
            padding: EdgeInsets.symmetric(horizontal: 4),
            child: SkeletonBox(height: 80, borderRadius: 12),
          ),
        )),
      ),
    );
  }
}