Update MkvInfoReader, Add MkvNode extensions

MkvToolnixWrapper/MkvInfo/Reader/NodeUtils.cs

@@ -0,0 +1,107 @@
+using MkvPropEditWrapper.Shared;
+
+namespace MkvPropEditWrapper.MkvInfo.Reader;
+
+public static class NodeUtils
+{
+    public static IEnumerable<MkvNode> Descendants(this MkvNode root)
+    {
+        var nodes = new Stack<MkvNode>(new[] {root});
+
+        while (nodes.Any())
+        {
+            var node = nodes.Pop();
+
+            yield return node;
+
+            foreach (var newNode in node.Children)
+            {
+                nodes.Push(newNode);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Generate track info from parsed output, only works on the first root node as it uses absolute depth
+    /// </summary>
+    /// <param name="root">Node root</param>
+    /// <returns>All parseable <see cref="TrackInfo"/></returns>
+    public static IEnumerable<TrackInfo> GetTrackInfos(this MkvNodeRoot root)
+    {        
+        TrackInfo? ParseTrackInfo(MkvNode track)
+        {
+            ReadOnlySpan<char> audioType = "audio";
+            ReadOnlySpan<char> subtitleType = "subtitles";
+            
+            int number = -1;
+            var trackType = TrackType.Unknown;
+            string language = "Unknown";
+            bool defaultFlag = default;
+            bool forcedFlag = default;
+
+            foreach (var child in track.Children)
+            {
+                if (child is MkvProperty property)
+                {
+                    ReadOnlySpan<char> span;
+                    
+                    switch (property.PropertyType)
+                    {
+                        case PropertyType.TrackType:
+                            span = property.Value.Span;
+
+                            if (span.SequenceEqual(audioType))
+                            {
+                                trackType = TrackType.Audio;
+                            }
+                            else if (span.SequenceEqual(subtitleType))
+                            {
+                                trackType = TrackType.Subtitles;
+                            }
+                            else
+                            {
+                                return null;
+                            }
+                            
+                            break;
+                        case PropertyType.TrackNumber:
+                            span = property.Value.Span;
+                        
+                            number = int.Parse(span[..span.IndexOf(' ')]);
+                            break;
+                        case PropertyType.Language:
+                            language = property.Value.ToString();
+                            break;
+                        case PropertyType.FlagDefault:
+                            defaultFlag = property.Value.Span[0] == '1';
+                            break;
+                        case PropertyType.FlagForced:
+                            forcedFlag = property.Value.Span[0] == '1';
+                            break;
+                    }
+                }
+            }
+            
+            return number == -1 ? null : new TrackInfo(number, trackType, language, defaultFlag, forcedFlag);
+        }
+    
+        var tracks = root.Descendants().Where(n => n is { Depth: 2, NodeType: NodeType.Track });
+
+        foreach (var track in tracks)
+        {
+            var trackInfo = ParseTrackInfo(track);
+
+            if (trackInfo is not null)
+            {
+                yield return trackInfo;
+            }
+        }
+    }
+    
+    public static (IEnumerable<TrackInfo> audio, IEnumerable<TrackInfo> subtitles) SplitByType(this IEnumerable<TrackInfo> trackInfos)
+    {
+        var lookup = trackInfos.OrderBy(t => t.Number).ToLookup(t => t.TrackType);
+
+        return (lookup[TrackType.Audio], lookup[TrackType.Subtitles]);
+    }
+}