feat: keeping a history of chat messages

src/Nullinside.Api.Common/DateTimeExtensions.cs

@@ -0,0 +1,18 @@
+namespace Nullinside.Api.Common;
+
+/// <summary>
+///   Extension methods for <see cref="DateTime" />.
+/// </summary>
+public static class DateTimeExtensions {
+  /// <summary>
+  ///   Converts unix timestamp to a <see cref="DateTime" />.
+  /// </summary>
+  /// <param name="unixTimestamp">The unix timestamp.</param>
+  /// <returns>The DateTime representation of the unix timestamp.</returns>
+  public static DateTime FromUnixTimestamp(double unixTimestamp) {
+    // Unix timestamp is seconds past epoch
+    var dateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+    dateTime = dateTime.AddSeconds(unixTimestamp / 1000d).ToLocalTime();
+    return dateTime;
+  }
+}

src/Nullinside.Api.Common/Twitch/OnMessageReceivedArgsExtensions.cs

@@ -0,0 +1,21 @@
+using TwitchLib.Client.Events;
+
+namespace Nullinside.Api.Common.Twitch;
+
+/// <summary>
+///   Extensions for the <see cref="OnMessageReceivedArgs" /> class to make working with twitch chat messages easier.
+/// </summary>
+public static class OnMessageReceivedArgsExtensions {
+  /// <summary>
+  ///   Gets the timestamp of when the message was sent, in UTC.
+  /// </summary>
+  /// <param name="e">The event arguments.</param>
+  /// <returns>The <see cref="DateTime" /> if successful, null otherwise.</returns>
+  public static DateTime? GetTimestamp(this OnMessageReceivedArgs e) {
+    if (double.TryParse(e.ChatMessage.TmiSentTs, out double timestampD)) {
+      return DateTimeExtensions.FromUnixTimestamp(timestampD);
+    }
+
+    return null;
+  }
+}