immich/mobile/lib/widgets/common/mesmerizing_sliver_app_bar.dart

import 'dart:async';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
import 'package:immich_mobile/domain/services/timeline.service.dart';
import 'package:immich_mobile/domain/utils/event_stream.dart';
import 'package:immich_mobile/extensions/build_context_extensions.dart';
import 'package:immich_mobile/extensions/translate_extensions.dart';
import 'package:immich_mobile/presentation/widgets/images/image_provider.dart';
import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
import 'package:immich_mobile/providers/timeline/multiselect.provider.dart';

class MesmerizingSliverAppBar extends ConsumerStatefulWidget {
  const MesmerizingSliverAppBar({
    super.key,
    required this.title,
    this.icon = Icons.camera,
  });

  final String title;
  final IconData icon;

  @override
  ConsumerState<MesmerizingSliverAppBar> createState() =>
      _MesmerizingSliverAppBarState();
}

class _MesmerizingSliverAppBarState
    extends ConsumerState<MesmerizingSliverAppBar> {
  double _scrollProgress = 0.0;

  double _calculateScrollProgress(FlexibleSpaceBarSettings? settings) {
    if (settings?.maxExtent == null || settings?.minExtent == null) {
      return 1.0;
    }

    final deltaExtent = settings!.maxExtent - settings.minExtent;
    if (deltaExtent <= 0.0) {
      return 1.0;
    }

    return (1.0 - (settings.currentExtent - settings.minExtent) / deltaExtent)
        .clamp(0.0, 1.0);
  }

  @override
  Widget build(BuildContext context) {
    final isMultiSelectEnabled =
        ref.watch(multiSelectProvider.select((s) => s.isEnabled));

    return isMultiSelectEnabled
        ? SliverToBoxAdapter(
            child: switch (_scrollProgress) {
              < 0.8 => const SizedBox(height: 120),
              _ => const SizedBox(height: 352),
            },
          )
        : SliverAppBar(
            expandedHeight: 300.0,
            floating: false,
            pinned: true,
            snap: false,
            elevation: 0,
            leading: IconButton(
              icon: Icon(
                Platform.isIOS
                    ? Icons.arrow_back_ios_new_rounded
                    : Icons.arrow_back,
                color: Color.lerp(
                  Colors.white,
                  context.primaryColor,
                  _scrollProgress,
                ),
                shadows: [
                  _scrollProgress < 0.95
                      ? Shadow(
                          offset: const Offset(0, 2),
                          blurRadius: 5,
                          color: Colors.black.withValues(alpha: 0.5),
                        )
                      : const Shadow(
                          offset: Offset(0, 2),
                          blurRadius: 0,
                          color: Colors.transparent,
                        ),
                ],
              ),
              onPressed: () {
                context.pop();
              },
            ),
            flexibleSpace: Builder(
              builder: (context) {
                final settings = context.dependOnInheritedWidgetOfExactType<
                    FlexibleSpaceBarSettings>();
                final scrollProgress = _calculateScrollProgress(settings);

                // Update scroll progress for the leading button
                WidgetsBinding.instance.addPostFrameCallback((_) {
                  if (mounted && _scrollProgress != scrollProgress) {
                    setState(() {
                      _scrollProgress = scrollProgress;
                    });
                  }
                });

                return FlexibleSpaceBar(
                  centerTitle: true,
                  title: AnimatedSwitcher(
                    duration: const Duration(milliseconds: 200),
                    child: scrollProgress > 0.95
                        ? Text(
                            widget.title,
                            style: TextStyle(
                              color: context.primaryColor,
                              fontWeight: FontWeight.w600,
                              fontSize: 18,
                            ),
                          )
                        : null,
                  ),
                  background: _ExpandedBackground(
                    scrollProgress: scrollProgress,
                    title: widget.title,
                    icon: widget.icon,
                  ),
                );
              },
            ),
          );
  }
}

class _ExpandedBackground extends ConsumerStatefulWidget {
  final double scrollProgress;
  final String title;
  final IconData icon;

  const _ExpandedBackground({
    required this.scrollProgress,
    required this.title,
    required this.icon,
  });

  @override
  ConsumerState<_ExpandedBackground> createState() =>
      _ExpandedBackgroundState();
}

class _ExpandedBackgroundState extends ConsumerState<_ExpandedBackground>
    with SingleTickerProviderStateMixin {
  late AnimationController _slideController;
  late Animation<Offset> _slideAnimation;

  @override
  void initState() {
    super.initState();

    _slideController = AnimationController(
      duration: const Duration(milliseconds: 800),
      vsync: this,
    );

    _slideAnimation = Tween<Offset>(
      begin: const Offset(0, 1.5),
      end: Offset.zero,
    ).animate(
      CurvedAnimation(
        parent: _slideController,
        curve: Curves.easeOutCubic,
      ),
    );

    Future.delayed(const Duration(milliseconds: 100), () {
      if (mounted) {
        _slideController.forward();
      }
    });
  }

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

  @override
  Widget build(BuildContext context) {
    final timelineService = ref.watch(timelineServiceProvider);

    return Stack(
      fit: StackFit.expand,
      children: [
        Transform.translate(
          offset: Offset(0, widget.scrollProgress * 50),
          child: Transform.scale(
            scale: 1.4 - (widget.scrollProgress * 0.2),
            child: _RandomAssetBackground(
              timelineService: timelineService,
              icon: widget.icon,
            ),
          ),
        ),
        Container(
          decoration: BoxDecoration(
            gradient: LinearGradient(
              begin: Alignment.topCenter,
              end: Alignment.bottomCenter,
              colors: [
                Colors.transparent,
                Colors.transparent,
                Colors.black.withValues(
                  alpha: 0.6 + (widget.scrollProgress * 0.2),
                ),
              ],
              stops: const [0.0, 0.65, 1.0],
            ),
          ),
        ),
        Positioned(
          bottom: 16,
          left: 16,
          right: 16,
          child: SlideTransition(
            position: _slideAnimation,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                SizedBox(
                  width: double.infinity,
                  child: SingleChildScrollView(
                    scrollDirection: Axis.horizontal,
                    child: Text(
                      widget.title,
                      maxLines: 1,
                      style: const TextStyle(
                        color: Colors.white,
                        fontSize: 36,
                        fontWeight: FontWeight.bold,
                        letterSpacing: 0.5,
                        shadows: [
                          Shadow(
                            offset: Offset(0, 2),
                            blurRadius: 12,
                            color: Colors.black45,
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
                AnimatedContainer(
                  duration: const Duration(milliseconds: 300),
                  child: const _ItemCountText(),
                ),
              ],
            ),
          ),
        ),
      ],
    );
  }
}

class _ItemCountText extends ConsumerStatefulWidget {
  const _ItemCountText();

  @override
  ConsumerState<_ItemCountText> createState() => _ItemCountTextState();
}

class _ItemCountTextState extends ConsumerState<_ItemCountText> {
  StreamSubscription? _reloadSubscription;

  @override
  void initState() {
    super.initState();
    _reloadSubscription =
        EventStream.shared.listen<TimelineReloadEvent>((_) => setState(() {}));
  }

  @override
  void dispose() {
    _reloadSubscription?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final assetCount = ref.watch(
      timelineServiceProvider.select((s) => s.totalAssets),
    );

    return Text(
      'items_count'.t(
        context: context,
        args: {"count": assetCount},
      ),
      style: context.textTheme.labelLarge?.copyWith(
        // letterSpacing: 0.2,
        fontWeight: FontWeight.bold,
        color: Colors.white,
        shadows: [
          const Shadow(
            offset: Offset(0, 1),
            blurRadius: 6,
            color: Colors.black45,
          ),
        ],
      ),
    );
  }
}

class _RandomAssetBackground extends StatefulWidget {
  final TimelineService timelineService;
  final IconData icon;

  const _RandomAssetBackground({
    required this.timelineService,
    required this.icon,
  });

  @override
  State<_RandomAssetBackground> createState() => _RandomAssetBackgroundState();
}

class _RandomAssetBackgroundState extends State<_RandomAssetBackground>
    with TickerProviderStateMixin {
  late AnimationController _zoomController;
  late AnimationController _crossFadeController;
  late Animation<double> _zoomAnimation;
  late Animation<Offset> _panAnimation;
  late Animation<double> _crossFadeAnimation;
  BaseAsset? _currentAsset;
  BaseAsset? _nextAsset;
  bool _isZoomingIn = true;

  @override
  void initState() {
    super.initState();

    _zoomController = AnimationController(
      duration: const Duration(seconds: 12),
      vsync: this,
    );

    _crossFadeController = AnimationController(
      duration: const Duration(milliseconds: 1200),
      vsync: this,
    );

    _zoomAnimation = Tween<double>(
      begin: 1.0,
      end: 1.2,
    ).animate(
      CurvedAnimation(
        parent: _zoomController,
        curve: Curves.easeInOut,
      ),
    );

    _panAnimation = Tween<Offset>(
      begin: Offset.zero,
      end: const Offset(0.5, -0.5),
    ).animate(
      CurvedAnimation(
        parent: _zoomController,
        curve: Curves.easeInOut,
      ),
    );

    _crossFadeAnimation = Tween<double>(
      begin: 0.0,
      end: 1.0,
    ).animate(
      CurvedAnimation(
        parent: _crossFadeController,
        curve: Curves.easeInOutCubic,
      ),
    );

    Future.delayed(
      Durations.medium1,
      () => _loadFirstAsset(),
    );
  }

  @override
  void dispose() {
    _zoomController.dispose();
    _crossFadeController.dispose();
    super.dispose();
  }

  void _startAnimationCycle() {
    if (_isZoomingIn) {
      _zoomController.forward().then((_) {
        _loadNextAsset();
      });
    } else {
      _zoomController.reverse().then((_) {
        _loadNextAsset();
      });
    }
  }

  Future<void> _loadFirstAsset() async {
    if (!mounted) {
      return;
    }

    if (widget.timelineService.totalAssets == 0) {
      setState(() {
        _currentAsset = null;
      });

      return;
    }

    setState(() {
      _currentAsset = widget.timelineService.getRandomAsset();
    });

    await _crossFadeController.forward();

    if (_zoomController.status == AnimationStatus.dismissed) {
      if (_isZoomingIn) {
        _zoomController.reset();
      } else {
        _zoomController.value = 1.0;
      }
      _startAnimationCycle();
    }
  }

  Future<void> _loadNextAsset() async {
    if (!mounted) {
      return;
    }

    try {
      if (widget.timelineService.totalAssets > 1) {
        // Load next asset while keeping current one visible
        final nextAsset = widget.timelineService.getRandomAsset();

        setState(() {
          _nextAsset = nextAsset;
        });

        await _crossFadeController.reverse();
        setState(() {
          _currentAsset = _nextAsset;
          _nextAsset = null;
        });

        _crossFadeController.value = 1.0;

        _isZoomingIn = !_isZoomingIn;

        _startAnimationCycle();
      }
    } catch (e) {
      _zoomController.reset();
      _startAnimationCycle();
    }
  }

  @override
  Widget build(BuildContext context) {
    if (widget.timelineService.totalAssets == 0) {
      return const SizedBox.shrink();
    }

    return AnimatedBuilder(
      animation: Listenable.merge(
        [_zoomAnimation, _panAnimation, _crossFadeAnimation],
      ),
      builder: (context, child) {
        return Transform.scale(
          scale: _zoomAnimation.value,
          filterQuality: FilterQuality.low,
          child: Transform.translate(
            offset: _panAnimation.value,
            filterQuality: FilterQuality.low,
            child: Stack(
              fit: StackFit.expand,
              children: [
                // Current image
                if (_currentAsset != null)
                  Opacity(
                    opacity: _crossFadeAnimation.value,
                    child: SizedBox(
                      width: double.infinity,
                      height: double.infinity,
                      child: Image(
                        alignment: Alignment.topRight,
                        image: getFullImageProvider(_currentAsset!),
                        fit: BoxFit.cover,
                        frameBuilder:
                            (context, child, frame, wasSynchronouslyLoaded) {
                          if (wasSynchronouslyLoaded || frame != null) {
                            return child;
                          }
                          return Container();
                        },
                        errorBuilder: (context, error, stackTrace) {
                          return SizedBox(
                            width: double.infinity,
                            height: double.infinity,
                            child: Icon(
                              Icons.error_outline_rounded,
                              size: 24,
                              color: Colors.red[300],
                            ),
                          );
                        },
                      ),
                    ),
                  ),

                if (_nextAsset != null)
                  Opacity(
                    opacity: 1.0 - _crossFadeAnimation.value,
                    child: SizedBox(
                      width: double.infinity,
                      height: double.infinity,
                      child: Image(
                        alignment: Alignment.topRight,
                        image: getFullImageProvider(_nextAsset!),
                        fit: BoxFit.cover,
                        frameBuilder:
                            (context, child, frame, wasSynchronouslyLoaded) {
                          if (wasSynchronouslyLoaded || frame != null) {
                            return child;
                          }
                          return const SizedBox.shrink();
                        },
                        errorBuilder: (context, error, stackTrace) {
                          return SizedBox(
                            width: double.infinity,
                            height: double.infinity,
                            child: Icon(
                              Icons.error_outline_rounded,
                              size: 24,
                              color: Colors.red[300],
                            ),
                          );
                        },
                      ),
                    ),
                  ),
              ],
            ),
          ),
        );
      },
    );
  }
}