import 'package:cached_network_image/cached_network_image.dart';
import 'package:flutter/material.dart';
import 'package:photos/core/cache/thumbnail_cache.dart';
import 'package:photos/models/file.dart';
import 'package:logging/logging.dart';
import 'package:photos/core/constants.dart';
import 'package:photos/models/file_type.dart';
import 'package:photos/ui/loading_widget.dart';

class ThumbnailWidget extends StatefulWidget {
  final File photo;

  const ThumbnailWidget(
    this.photo, {
    Key key,
  }) : super(key: key);
  @override
  _ThumbnailWidgetState createState() => _ThumbnailWidgetState();
}

class _ThumbnailWidgetState extends State<ThumbnailWidget> {
  static final _logger = Logger("ThumbnailWidget");
  static final Widget loadingWidget = Container(
    alignment: Alignment.center,
    color: Colors.grey[800],
  );

  bool _hasLoadedThumbnail = false;
  bool _encounteredErrorLoadingThumbnail = false;
  ImageProvider _imageProvider;

  @override
  Widget build(BuildContext context) {
    if (widget.photo.localId == null) {
      return _getNetworkImage();
    }

    _loadLocalImage(context);
    var content;
    if (_imageProvider != null) {
      final image = Image(
        image: _imageProvider,
        fit: BoxFit.cover,
      );
      if (widget.photo.fileType == FileType.video) {
        content = Stack(
          children: [
            image,
            Icon(Icons.play_circle_outline),
          ],
          fit: StackFit.expand,
        );
      } else {
        content = image;
      }
    }
    return Stack(
      children: [
        loadingWidget,
        AnimatedOpacity(
          opacity: content == null ? 0 : 1.0,
          duration: Duration(milliseconds: 400),
          child: content,
        ),
      ],
      fit: StackFit.expand,
    );
  }

  void _loadLocalImage(BuildContext context) {
    if (!_hasLoadedThumbnail && !_encounteredErrorLoadingThumbnail) {
      final cachedSmallThumbnail =
          ThumbnailLruCache.get(widget.photo, THUMBNAIL_SMALL_SIZE);
      if (cachedSmallThumbnail != null) {
        _imageProvider = Image.memory(cachedSmallThumbnail).image;
        _hasLoadedThumbnail = true;
      } else {
        widget.photo.getAsset().then((asset) {
          asset
              .thumbDataWithSize(THUMBNAIL_SMALL_SIZE, THUMBNAIL_SMALL_SIZE)
              .then((data) {
            if (data != null && mounted) {
              final imageProvider = Image.memory(data).image;
              precacheImage(imageProvider, context).then((value) {
                if (mounted) {
                  setState(() {
                    _imageProvider = imageProvider;
                    _hasLoadedThumbnail = true;
                  });
                }
              });
            }
            ThumbnailLruCache.put(widget.photo, THUMBNAIL_SMALL_SIZE, data);
          });
        }).catchError((e) {
          _logger.warning("Could not load image: ", e);
          _encounteredErrorLoadingThumbnail = true;
        });
      }
    }
  }

  Widget _getNetworkImage() {
    final url = widget.photo.previewURL.isNotEmpty
        ? widget.photo.getThumbnailUrl()
        : widget.photo.getRemoteUrl();
    return CachedNetworkImage(
      imageUrl: url,
      placeholder: (context, url) => loadWidget,
      errorWidget: (context, url, error) => Icon(Icons.error),
      fit: BoxFit.cover,
    );
  }

  @override
  void didUpdateWidget(ThumbnailWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.photo.generatedId != oldWidget.photo.generatedId) {
      setState(() {
        _hasLoadedThumbnail = false;
        _imageProvider = null;
      });
    }
  }
}