Added StartedAt and EndsAt timespans for SpotifyGame.

They make it possible to expose track's Elapsed and Remaining properties.

src/Discord.Net.Core/Entities/Activities/SpotifyGame.cs

@@ -31,13 +31,46 @@ namespace Discord
         ///     A string containing the name of the song (e.g. <c>Lonely Together (feat. Rita Ora)</c>).
         /// </returns>
         public string TrackTitle { get; internal set; }
+
+        /// <summary>
+        ///     Gets the date the track began playing at.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="DateTimeOffset"/> containing the start timestamp of the song.
+        /// </returns>
+        public DateTimeOffset? StartedAt { get; internal set; }
+
+        /// <summary>
+        ///     Gets the date the track will stop playing at.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="DateTimeOffset"/> containing the finish timestamp of the song.
+        /// </returns>
+        public DateTimeOffset? EndsAt { get; internal set; }
+
         /// <summary>
         ///     Gets the duration of the song.
         /// </summary>
         /// <returns>
         ///     A <see cref="TimeSpan"/> containing the duration of the song.
         /// </returns>
-        public TimeSpan? Duration { get; internal set; }
+        public TimeSpan? Duration => EndsAt - StartedAt;
+
+        /// <summary>
+        ///     Gets the elapsed duration of the song.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="TimeSpan"/> containing the elapsed duration of the song.
+        /// </returns>
+        public TimeSpan? Elapsed => DateTimeOffset.UtcNow - StartedAt;
+
+        /// <summary>
+        ///     Gets the remaining duration of the song.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="TimeSpan"/> containing the remaining duration of the song.
+        /// </returns>
+        public TimeSpan? Remaining => EndsAt - DateTimeOffset.UtcNow;
 
         /// <summary>
         ///     Gets the track ID of the song.

src/Discord.Net.WebSocket/Extensions/EntityExtensions.cs

@@ -38,7 +38,8 @@ namespace Discord.WebSocket
                     AlbumTitle = albumText,
                     TrackTitle = model.Details.GetValueOrDefault(),
                     Artists = model.State.GetValueOrDefault()?.Split(';').Select(x=>x?.Trim()).ToImmutableArray(),
-                    Duration = timestamps?.End - timestamps?.Start,
+                    StartedAt = timestamps?.Start,
+                    EndsAt = timestamps?.End,
                     AlbumArtUrl = albumArtId != null ? CDN.GetSpotifyAlbumArtUrl(albumArtId) : null,
                     Type = ActivityType.Listening,
                     Flags = model.Flags.GetValueOrDefault(),