implemented SSA Parser

MediaBrowser.MediaEncoding/Subtitles/SsaParser.cs

@@ -1,17 +1,69 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Text.RegularExpressions;
 
 namespace MediaBrowser.MediaEncoding.Subtitles
 {
     public class SsaParser : ISubtitleParser
     {
+        private readonly CultureInfo _usCulture = new CultureInfo("en-US");
+
         public SubtitleTrackInfo Parse(Stream stream)
         {
-            throw new NotImplementedException();
+            var trackInfo = new SubtitleTrackInfo();
+            var eventIndex = 1;
+            using (var reader = new StreamReader(stream))
+            {
+                string line;
+                while (reader.ReadLine() != "[Events]")
+                {}
+                var headers = ParseFieldHeaders(reader.ReadLine());
+
+                while ((line = reader.ReadLine()) != null)
+                {
+                    if (string.IsNullOrWhiteSpace(line))
+                    {
+                        continue;
+                    }
+                    if(line.StartsWith("["))
+                        break;
+                    if(string.IsNullOrEmpty(line))
+                        continue;
+                    var subEvent = new SubtitleTrackEvent { Id = eventIndex.ToString(_usCulture) };
+                    eventIndex++;
+                    var sections = line.Substring(10).Split(',');
+
+                    subEvent.StartPositionTicks = GetTicks(sections[headers["Start"]]);
+                    subEvent.EndPositionTicks = GetTicks(sections[headers["End"]]);
+                    subEvent.Text = string.Join(",", sections.Skip(headers["Text"]));
+                    subEvent.Text = Regex.Replace(subEvent.Text, "\\{(\\\\[\\w]+\\(?([\\w\\d]+,?)+\\)?)+\\}", string.Empty, RegexOptions.IgnoreCase);
+                    subEvent.Text = Regex.Replace(subEvent.Text, @"\\N", "<br />", RegexOptions.IgnoreCase);
+
+                    trackInfo.TrackEvents.Add(subEvent);
+                }
+            }
+            return trackInfo;
+        }
+
+        long GetTicks(string time)
+        {
+            TimeSpan span;
+            return TimeSpan.TryParseExact(time, @"h\:mm\:ss\.ff", _usCulture, out span)
+                ? span.Ticks: 0;
+        }
+
+        private Dictionary<string,int> ParseFieldHeaders(string line) {
+            var fields = line.Substring(8).Split(',').Select(x=>x.Trim()).ToList();
+
+            var result = new Dictionary<string, int> {
+                                                         {"Start", fields.IndexOf("Start")},
+                                                         {"End", fields.IndexOf("End")},
+                                                         {"Text", fields.IndexOf("Text")}
+                                                     };
+            return result;
         }
     }
 }