Refactor reaction emojis into a separate class, add support for animations and standard emojis via twemoji

Closes #71

DiscordChatExporter.Core/Models/Emoji.cs

@@ -0,0 +1,43 @@
+using Tyrrrz.Extensions;
+
+namespace DiscordChatExporter.Core.Models
+{
+    // https://discordapp.com/developers/docs/resources/emoji#emoji-object
+
+    public class Emoji
+    {
+        public string Id { get; }
+
+        public string Name { get; }
+
+        public bool IsAnimated { get; }
+
+        public string ImageUrl
+        {
+            get
+            {
+                // Custom emoji
+                if (Id.IsNotBlank())
+                {
+                    // Animated
+                    if (IsAnimated)
+                        return $"https://cdn.discordapp.com/emojis/{Id}.gif";
+
+                    // Non-animated
+                    return $"https://cdn.discordapp.com/emojis/{Id}.png";
+                }
+
+                // Standard unicode emoji (via twemoji)
+                var codePoint = char.ConvertToUtf32(Name, 0).ToString("x");
+                return $"https://twemoji.maxcdn.com/2/72x72/{codePoint}.png";
+            }
+        }
+
+        public Emoji(string id, string name, bool isAnimated)
+        {
+            Id = id;
+            Name = name;
+            IsAnimated = isAnimated;
+        }
+    }
+}

DiscordChatExporter.Core/Models/Reaction.cs

@@ -6,15 +6,12 @@
     {
         public int Count { get; }
 
-        public string EmojiId { get; }
+        public Emoji Emoji { get; }
 
-        public string EmojiName { get; }
-
-        public Reaction(int count, string emojiId, string emojiName) 
+        public Reaction(int count, Emoji emoji)
         {
             Count = count;
-            EmojiId = emojiId;
-            EmojiName = emojiName;
+            Emoji = emoji;
         }
     }
 }