From 67a5f9777ab8e80a8aa8c8c7dd97644f7a041bb9 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Sun, 27 Aug 2023 21:24:28 +0100
Subject: [PATCH] fix: add support for unicode emojis

---
 VPLink/Services/DiscordMessageService.cs | 26 ++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/VPLink/Services/DiscordMessageService.cs b/VPLink/Services/DiscordMessageService.cs
index 8611e36..2230eaf 100644
--- a/VPLink/Services/DiscordMessageService.cs
+++ b/VPLink/Services/DiscordMessageService.cs
@@ -96,6 +96,9 @@ internal sealed class DiscordMessageService : BackgroundService, IDiscordMessage
         SanitizeContent(guild, message.Content, ref builder);
         var content = builder.ToString();
 
+        Span<byte> testSpan = stackalloc byte[Utf8Encoding.GetByteCount(content)];
+        Utf8Encoding.GetBytes(content, testSpan);
+
         _logger.LogInformation("Message by {Author}: {Content}", author, content);
 
         var messages = new List<RelayedMessage>();
@@ -141,14 +144,16 @@ internal sealed class DiscordMessageService : BackgroundService, IDiscordMessage
 
     private static void AddMessage(ICollection<RelayedMessage> messages, string displayName, string content)
     {
-        Span<byte> buffer = stackalloc byte[255]; // VP message length limit
         int byteCount = Utf8Encoding.GetByteCount(content);
+        Span<byte> buffer = stackalloc byte[byteCount];
+        Utf8Encoding.GetBytes(content, buffer);
+
         var offset = 0;
         while (offset < byteCount)
         {
-            int length = Math.Min(byteCount - offset, 255);
-            Utf8Encoding.GetBytes(content.AsSpan(offset, length), buffer);
-            messages.Add(new RelayedMessage(displayName, Utf8Encoding.GetString(buffer), false));
+            int length = Math.Min(byteCount - offset, 255); // VP message length limit
+            Span<byte> slice = buffer.Slice(offset, length);
+            messages.Add(new RelayedMessage(displayName, Utf8Encoding.GetString(slice), false));
             offset += length;
         }
     }
@@ -199,6 +204,8 @@ internal sealed class DiscordMessageService : BackgroundService, IDiscordMessage
     {
         Utf8ValueStringBuilder wordBuffer = ZString.CreateUtf8StringBuilder();
 
+        Span<char> chars = stackalloc char[2];
+        Span<byte> bytes = stackalloc byte[4];
         for (var index = 0; index < content.Length; index++)
         {
             char current = content[index];
@@ -207,6 +214,13 @@ internal sealed class DiscordMessageService : BackgroundService, IDiscordMessage
                 AddWord(guild, ref builder, ref wordBuffer, current);
                 wordBuffer.Clear();
             }
+            else if (char.IsSurrogate(current))
+            {
+                content.Slice(index++, 2).CopyTo(chars);
+                int byteCount = Utf8Encoding.GetByteCount(chars);
+                Utf8Encoding.GetBytes(chars, bytes);
+                wordBuffer.AppendLiteral(bytes[..byteCount]);
+            }
             else
             {
                 wordBuffer.Append(current);
@@ -256,6 +270,10 @@ internal sealed class DiscordMessageService : BackgroundService, IDiscordMessage
                     MentionUtility.ParseTag(guild, temp[..tagLength], ref builder, whitespace);
                     break;
 
+                case var _ when char.IsSurrogate(current):
+                    buffer.Append(chars.Slice(index++, 2));
+                    break;
+
                 default:
                     buffer.Append(current);
                     break;