adding missing files. Thanks for the notice, @zaprogrammer!

lib/notifiers.dart

@@ -0,0 +1,90 @@
+import 'dart:async';
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:flutter/material.dart';
+import 'package:webfeed/domain/rss_feed.dart';
+import 'package:webfeed/domain/rss_item.dart';
+
+import 'package:path_provider/path_provider.dart';
+import 'package:path/path.dart' as path;
+import 'package:webfeed/webfeed.dart';
+
+class Podcast with ChangeNotifier {
+  EpisodeFeed _feed;
+  Episode _selectedItem;
+
+  EpisodeFeed get feed => _feed;
+  void parse(String url) async {
+    final res = await http.get(url);
+    final xmlStr = res.body;
+    _feed = EpisodeFeed.parse(xmlStr);
+    notifyListeners();
+  }
+
+  Episode get selectedItem => _selectedItem;
+  set selectedItem(Episode value) {
+    _selectedItem = value;
+    notifyListeners();
+  }
+}
+
+class EpisodeFeed extends RssFeed {
+  final RssFeed _feed;
+  List<Episode> items;
+
+  EpisodeFeed(this._feed) {
+    items = _feed.items.map((i) => Episode(i)).toList();
+  }
+
+  RssImage get image => _feed.image;
+
+  static EpisodeFeed parse(xmlStr) {
+    return EpisodeFeed(RssFeed.parse(xmlStr));
+  }
+}
+
+class Episode extends RssItem with ChangeNotifier {
+  String downloadLocation;
+  RssItem _item;
+
+  Episode(this._item);
+
+  String get title => _item.title;
+  String get description => _item.description;
+  String get guid => _item.guid;
+
+  void download([Function(double) updates]) async {
+    final req = http.Request('GET', Uri.parse(_item.guid));
+    final res = await req.send();
+    if (res.statusCode != 200)
+      throw Exception('Unexpected HTTP code: ${res.statusCode}');
+
+    final contentLength = res.contentLength;
+    var downloadedLength = 0;
+
+    String filePath = await _getDownloadPath(path.split(_item.guid).last);
+    final file = File(filePath);
+    res.stream
+        .map((chunk) {
+          downloadedLength += chunk.length;
+          if (updates != null) updates(downloadedLength / contentLength);
+          return chunk;
+        })
+        .pipe(file.openWrite())
+        .whenComplete(() {
+          // TODO save this to sharedprefs or similar.
+          downloadLocation = filePath;
+          notifyListeners();
+        })
+        .catchError((e) => print('An Error has occurred!!!: $e'));
+  }
+
+  Future<String> _getDownloadPath(String filename) async {
+    final dir = await getApplicationDocumentsDirectory();
+    final prefix = dir.path;
+    final absolutePath = path.join(prefix, filename);
+    print(absolutePath);
+    return absolutePath;
+  }
+}

lib/player.dart

@@ -0,0 +1,153 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_sound/flutter_sound.dart';
+import 'package:provider/provider.dart';
+
+import 'package:dashcast/notifiers.dart';
+
+class PlayerPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(
+          Provider.of<Podcast>(context).selectedItem.title,
+        ),
+      ),
+      body: SafeArea(child: Player()),
+    );
+  }
+}
+
+class Player extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    final podcast = Provider.of<Podcast>(context);
+    return Column(
+      children: [
+        Flexible(
+            flex: 8,
+            child: SingleChildScrollView(
+              child: Column(children: [
+                Image.network(podcast.feed.image.url),
+                Padding(
+                  padding: const EdgeInsets.all(10),
+                  child: Text(
+                    podcast.selectedItem.description.trim(),
+                  ),
+                ),
+              ]),
+            )),
+        Flexible(
+          flex: 2,
+          child: Material(
+            elevation: 12,
+            child: AudioControls(),
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+class AudioControls extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      children: [
+        PlaybackButtons(),
+      ],
+    );
+  }
+}
+
+class PlaybackButtons extends StatefulWidget {
+  @override
+  _PlaybackButtonState createState() => _PlaybackButtonState();
+}
+
+class _PlaybackButtonState extends State<PlaybackButtons> {
+  bool _isPlaying = false;
+  FlutterSound _sound;
+  double _playPosition;
+  StreamSubscription<PlayStatus> _playerSubscription;
+
+  @override
+  void initState() {
+    super.initState();
+    _sound = FlutterSound();
+    _playPosition = 0;
+  }
+
+  @override
+  void dispose() {
+    _cleanup();
+    super.dispose();
+  }
+
+  void _cleanup() async {
+    if (_sound.audioState == t_AUDIO_STATE.IS_PLAYING)
+      await _sound.stopPlayer();
+    // TODO somehow this gets called from episode list and breaks everything.
+    _playerSubscription.cancel();
+  }
+
+  void _stop() async {
+    await _sound.stopPlayer();
+    setState(() => _isPlaying = false);
+  }
+
+  void _play(String url) async {
+    await _sound.startPlayer(url);
+    _playerSubscription = _sound.onPlayerStateChanged.listen((e) {
+      if (e != null) {
+        // print(e.currentPosition);
+        setState(() => _playPosition = (e.currentPosition / e.duration));
+      }
+    });
+    setState(() => _isPlaying = true);
+  }
+
+  void _fastForward() {}
+
+  void _rewind() {}
+
+  @override
+  Widget build(BuildContext context) {
+    final podcast = Provider.of<Podcast>(context);
+    final item = podcast.selectedItem;
+
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.center,
+      children: <Widget>[
+        Slider(
+          value: _playPosition,
+          onChanged: null,
+        ),
+        Row(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            IconButton(icon: Icon(Icons.fast_rewind), onPressed: null),
+            IconButton(
+              icon: _isPlaying ? Icon(Icons.stop) : Icon(Icons.play_arrow),
+              onPressed: () {
+                if (_isPlaying) {
+                  _stop();
+                } else {
+                  var url = item.downloadLocation ?? item.guid;
+                  print('Playing url: $url');
+                  _play(url);
+                }
+              },
+            ),
+            IconButton(
+              icon: Icon(Icons.fast_forward),
+              onPressed: null,
+            ),
+          ],
+        ),
+      ],
+    );
+  }
+}