import 'dart:math';
import 'dart:typed_data';

import 'package:aves/model/image_entry.dart';
import 'package:aves/model/image_file_service.dart';
import 'package:aves/widgets/common/icons.dart';
import 'package:flutter/material.dart';
import 'package:transparent_image/transparent_image.dart';

class Thumbnail extends StatefulWidget {
  final ImageEntry entry;
  final double extent;
  final double devicePixelRatio;

  const Thumbnail({
    Key key,
    @required this.entry,
    @required this.extent,
    @required this.devicePixelRatio,
  }) : super(key: key);

  @override
  ThumbnailState createState() => ThumbnailState();
}

class ThumbnailState extends State<Thumbnail> {
  Future<Uint8List> _byteLoader;
  Listenable _entryChangeNotifier;

  ImageEntry get entry => widget.entry;

  String get uri => widget.entry.uri;

  @override
  void initState() {
    super.initState();
    _entryChangeNotifier = Listenable.merge([entry.imageChangeNotifier, entry.metadataChangeNotifier]);
    _entryChangeNotifier.addListener(onEntryChange);
    initByteLoader();
  }

  @override
  void didUpdateWidget(Thumbnail oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.extent == oldWidget.extent && uri == oldWidget.entry.uri && widget.entry.width == oldWidget.entry.width && widget.entry.height == oldWidget.entry.height && widget.entry.orientationDegrees == oldWidget.entry.orientationDegrees) return;
    initByteLoader();
  }

  initByteLoader() {
    final dim = (widget.extent * widget.devicePixelRatio).round();
    _byteLoader = ImageFileService.getImageBytes(widget.entry, dim, dim);
  }

  onEntryChange() => setState(() => initByteLoader());

  @override
  void dispose() {
    _entryChangeNotifier.removeListener(onEntryChange);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final fontSize = min(14.0, (widget.extent / 8).roundToDouble());
    final iconSize = fontSize * 2;
    return DefaultTextStyle(
      style: TextStyle(
        color: Colors.grey[200],
        fontSize: fontSize,
      ),
      child: Container(
        decoration: BoxDecoration(
          border: Border.all(
            color: Colors.grey.shade700,
            width: 0.5,
          ),
        ),
        child: FutureBuilder(
            future: _byteLoader,
            builder: (futureContext, AsyncSnapshot<Uint8List> snapshot) {
              final bytes = (snapshot.connectionState == ConnectionState.done && !snapshot.hasError) ? snapshot.data : kTransparentImage;
              return ThumbnailImage(entry: entry, bytes: bytes, iconSize: iconSize);
            }),
      ),
    );
  }
}

class ThumbnailImage extends StatelessWidget {
  final Uint8List bytes;
  final ImageEntry entry;
  final double iconSize;

  const ThumbnailImage({
    Key key,
    @required this.bytes,
    @required this.entry,
    @required this.iconSize,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(
      alignment: AlignmentDirectional.bottomStart,
      children: [
        Hero(
          tag: entry.uri,
          child: LayoutBuilder(builder: (context, constraints) {
            // during hero animation back from a fullscreen image,
            // the image covers the whole screen (because of the 'fit' prop and the full screen hero constraints)
            // so we wrap the image to apply better constraints
            final dim = min(constraints.maxWidth, constraints.maxHeight);
            return Container(
              alignment: Alignment.center,
              constraints: BoxConstraints.tight(Size(dim, dim)),
              child: bytes.length > 0
                  ? Image.memory(
                      bytes,
                      width: dim,
                      height: dim,
                      fit: BoxFit.cover,
                    )
                  : Icon(Icons.error),
            );
          }),
        ),
        if (entry.isVideo)
          VideoIcon(
            entry: entry,
            iconSize: iconSize,
          )
        else if (entry.isGif)
          GifIcon(iconSize: iconSize)
        else if (entry.hasGps)
          GpsIcon(iconSize: iconSize)
      ],
    );
  }
}