Initial

MareSynchronos/Utils/ChatUtils.cs

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+using Dalamud.Game.Text.SeStringHandling.Payloads;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace MareSynchronos.Utils;
+
+public static class ChatUtils
+{
+    // Based on https://git.anna.lgbt/anna/ExtraChat/src/branch/main/client/ExtraChat/Util/PayloadUtil.cs
+    // This must store a Guid (16 bytes), as Chat 2 converts the data back to one
+
+    public static RawPayload CreateExtraChatTagPayload(Guid guid)
+    {
+        var header = (byte[])[
+            0x02,   // Payload.START_BYTE
+            0x27,   // SeStringChunkType.Interactable
+            2 + 16, // remaining length: ExtraChat sends 19 here but I think its an error
+            0x20    // Custom ExtraChat InfoType
+        ];
+
+        var footer = (byte)0x03; // Payload.END_BYTE
+
+        return new RawPayload([..header, ..guid.ToByteArray(), footer]);
+    }
+
+    // We have a unique identifier in the form of a GID, which can be consistently mapped to the same GUID
+    public static RawPayload CreateExtraChatTagPayload(string gid)
+    {
+        var gidBytes = UTF8Encoding.UTF8.GetBytes(gid);
+        var hashedBytes = MD5.HashData(gidBytes);
+        var guid = new Guid(hashedBytes);
+        return CreateExtraChatTagPayload(guid);
+    }
+}