import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_svga/flutter_svga.dart';

typedef SCSvgaMovieConfigurer =
    FutureOr<void> Function(MovieEntity movieEntity);

class SCSvgaAssetWidget extends StatefulWidget {
  static const int _maxCacheEntries = 8;
  static final Map<String, MovieEntity> _cache = <String, MovieEntity>{};
  static final Map<String, Future<MovieEntity>> _loadingTasks =
      <String, Future<MovieEntity>>{};
  static final Map<MovieEntity, int> _activeUseCounts = <MovieEntity, int>{};

  const SCSvgaAssetWidget({
    super.key,
    required this.assetPath,
    this.width,
    this.height,
    this.active = true,
    this.loop = false,
    this.fit = BoxFit.contain,
    this.filterQuality = FilterQuality.low,
    this.allowDrawingOverflow = false,
    this.fallback,
    this.clearsAfterStop = false,
    this.onPlaybackStarted,
    this.onPlaybackCompleted,
    this.dynamicIdentity,
    this.movieConfigurer,
  });

  final String assetPath;
  final double? width;
  final double? height;
  final bool active;
  final bool loop;
  final BoxFit fit;
  final FilterQuality filterQuality;
  final bool allowDrawingOverflow;
  final Widget? fallback;
  final bool clearsAfterStop;
  final VoidCallback? onPlaybackStarted;
  final VoidCallback? onPlaybackCompleted;
  final Object? dynamicIdentity;
  final SCSvgaMovieConfigurer? movieConfigurer;

  static Future<MovieEntity> preloadAsset(String assetPath) {
    return _obtainMovieEntity(assetPath);
  }

  static void clearMemoryCache({bool includeActive = false}) {
    final entries = _cache.entries.toList(growable: false);
    for (final entry in entries) {
      final entity = entry.value;
      if (!includeActive && _isActive(entity)) {
        continue;
      }
      _cache.remove(entry.key);
      _disposeMovieEntity(entity);
    }
  }

  static Future<MovieEntity> _acquireMovieEntity(String assetPath) async {
    final entity = await _obtainMovieEntity(assetPath);
    _retainMovieEntity(entity);
    return entity;
  }

  static Future<MovieEntity> _obtainMovieEntity(String assetPath) async {
    final cached = _touchCachedMovieEntity(assetPath);
    if (cached != null) {
      return cached;
    }

    final loadingTask = _loadingTasks[assetPath];
    if (loadingTask != null) {
      return loadingTask;
    }

    final future = () async {
      MovieEntity entity;
      try {
        entity = await SVGAParser.shared.decodeFromAssets(assetPath);
      } catch (_) {
        final byteData = await rootBundle.load(assetPath);
        entity = await SVGAParser.shared.decodeFromBuffer(
          byteData.buffer.asUint8List(),
        );
      }
      entity.autorelease = false;
      _cacheMovieEntity(assetPath, entity);
      return entity;
    }();

    _loadingTasks[assetPath] = future;
    try {
      return await future;
    } finally {
      _loadingTasks.remove(assetPath);
    }
  }

  static MovieEntity? _touchCachedMovieEntity(String assetPath) {
    final cached = _cache.remove(assetPath);
    if (cached != null) {
      _cache[assetPath] = cached;
    }
    return cached;
  }

  static void _cacheMovieEntity(String assetPath, MovieEntity entity) {
    final previous = _cache.remove(assetPath);
    if (previous != null && !identical(previous, entity)) {
      _disposeMovieEntityIfInactive(previous);
    }
    _cache[assetPath] = entity;
    _trimCache();
  }

  static void _trimCache() {
    while (_cache.length > _maxCacheEntries) {
      final removableEntry = _cache.entries.firstWhere(
        (entry) => !_isActive(entry.value),
        orElse: () => _cache.entries.first,
      );
      if (_isActive(removableEntry.value)) {
        _cache.remove(removableEntry.key);
        _cache[removableEntry.key] = removableEntry.value;
        break;
      }
      _cache.remove(removableEntry.key);
      _disposeMovieEntity(removableEntry.value);
    }
  }

  static void _retainMovieEntity(MovieEntity entity) {
    _activeUseCounts[entity] = (_activeUseCounts[entity] ?? 0) + 1;
  }

  static void _releaseMovieEntity(MovieEntity? entity) {
    if (entity == null) {
      return;
    }
    final count = _activeUseCounts[entity] ?? 0;
    if (count <= 1) {
      _activeUseCounts.remove(entity);
      if (!_cache.containsValue(entity)) {
        _disposeMovieEntity(entity);
      } else {
        _trimCache();
      }
      return;
    }
    _activeUseCounts[entity] = count - 1;
  }

  static bool _isActive(MovieEntity entity) =>
      (_activeUseCounts[entity] ?? 0) > 0;

  static void _disposeMovieEntityIfInactive(MovieEntity entity) {
    if (_isActive(entity)) {
      return;
    }
    _disposeMovieEntity(entity);
  }

  static void _disposeMovieEntity(MovieEntity entity) {
    try {
      _activeUseCounts.remove(entity);
      entity.dispose();
    } catch (_) {}
  }

  @override
  State<SCSvgaAssetWidget> createState() => _SCSvgaAssetWidgetState();
}

class _SCSvgaAssetWidgetState extends State<SCSvgaAssetWidget>
    with SingleTickerProviderStateMixin {
  late final SVGAAnimationController _controller;
  String? _loadedAssetPath;
  MovieEntity? _retainedMovieEntity;
  String? _retainedAssetPath;
  bool _hasError = false;

  @override
  void initState() {
    super.initState();
    _controller = SVGAAnimationController(vsync: this);
    _controller.addStatusListener(_handleAnimationStatusChanged);
    _loadAsset();
  }

  void _handleAnimationStatusChanged(AnimationStatus status) {
    if (status == AnimationStatus.forward) {
      widget.onPlaybackStarted?.call();
      return;
    }
    if (status == AnimationStatus.completed) {
      widget.onPlaybackCompleted?.call();
    }
  }

  @override
  void didUpdateWidget(covariant SCSvgaAssetWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.assetPath != widget.assetPath ||
        oldWidget.dynamicIdentity != widget.dynamicIdentity) {
      _loadAsset();
      return;
    }
    if (oldWidget.active != widget.active || oldWidget.loop != widget.loop) {
      _syncPlayback(
        restartIfActive: widget.active && oldWidget.active != widget.active,
      );
    }
  }

  Future<void> _loadAsset() async {
    final assetPath = widget.assetPath;
    setState(() {
      _hasError = false;
    });
    MovieEntity? acquiredMovieEntity;
    try {
      final movieEntity =
          _retainedAssetPath == assetPath && _retainedMovieEntity != null
              ? _retainedMovieEntity!
              : await SCSvgaAssetWidget._acquireMovieEntity(assetPath);
      final acquiredNewEntity = !identical(movieEntity, _retainedMovieEntity);
      if (acquiredNewEntity) {
        acquiredMovieEntity = movieEntity;
      }
      if (widget.movieConfigurer != null) {
        movieEntity.dynamicItem.reset();
        await widget.movieConfigurer!(movieEntity);
      }
      if (!mounted || widget.assetPath != assetPath) {
        if (acquiredNewEntity) {
          SCSvgaAssetWidget._releaseMovieEntity(movieEntity);
          acquiredMovieEntity = null;
        }
        return;
      }
      setState(() {
        _releaseRetainedMovieEntity(except: movieEntity);
        _retainedMovieEntity = movieEntity;
        _retainedAssetPath = assetPath;
        _loadedAssetPath = assetPath;
        _controller.videoItem = movieEntity;
      });
      acquiredMovieEntity = null;
      _syncPlayback(restartIfActive: true);
    } catch (error) {
      SCSvgaAssetWidget._releaseMovieEntity(acquiredMovieEntity);
      if (!mounted || widget.assetPath != assetPath) {
        return;
      }
      setState(() {
        _controller.videoItem = null;
        _releaseRetainedMovieEntity();
        _hasError = true;
      });
    }
  }

  void _syncPlayback({bool restartIfActive = false}) {
    if (_controller.videoItem == null) {
      return;
    }

    if (!widget.active) {
      _controller.stop();
      _controller.reset();
      widget.onPlaybackCompleted?.call();
      return;
    }

    if (widget.loop) {
      if (restartIfActive || !_controller.isAnimating) {
        _controller.reset();
        _controller.repeat();
      }
      return;
    }

    if (restartIfActive || !_controller.isAnimating) {
      _controller.reset();
      _controller.repeat(count: 1);
    }
  }

  @override
  void dispose() {
    _controller.removeStatusListener(_handleAnimationStatusChanged);
    _controller.dispose();
    _releaseRetainedMovieEntity();
    super.dispose();
  }

  void _releaseRetainedMovieEntity({MovieEntity? except}) {
    final entity = _retainedMovieEntity;
    if (entity == null || identical(entity, except)) {
      return;
    }
    _retainedMovieEntity = null;
    _retainedAssetPath = null;
    SCSvgaAssetWidget._releaseMovieEntity(entity);
  }

  @override
  Widget build(BuildContext context) {
    if (_hasError) {
      return _buildFallback();
    }

    final videoItem = _controller.videoItem;
    if (videoItem == null || _loadedAssetPath != widget.assetPath) {
      return _buildFallback();
    }

    return SizedBox(
      width: widget.width,
      height: widget.height,
      child: IgnorePointer(
        child: SVGAImage(
          _controller,
          fit: widget.fit,
          clearsAfterStop: widget.clearsAfterStop,
          filterQuality: widget.filterQuality,
          allowDrawingOverflow: widget.allowDrawingOverflow,
          preferredSize:
              widget.width != null && widget.height != null
                  ? Size(widget.width!, widget.height!)
                  : null,
        ),
      ),
    );
  }

  Widget _buildFallback() {
    return SizedBox(
      width: widget.width,
      height: widget.height,
      child: widget.fallback ?? const SizedBox.shrink(),
    );
  }
}