From 578c82a932b42f556534cee4975e0bf4cda49d5b Mon Sep 17 00:00:00 2001
From: Linwenxuan <116782992+Linwenxuan05@users.noreply.github.com>
Date: Fri, 9 Feb 2024 15:52:40 +0800
Subject: [PATCH] [Core] Implemented LightAppEntity.cs

---
 .../Internal/Packets/Message/Element/Elem.cs  |  2 +-
 .../Element/Implementation/LightAppElem.cs    |  2 +-
 .../Message/Entity/LightAppEntity.cs          | 70 +++++++++++++++++++
 README.md                                     |  2 +-
 4 files changed, 73 insertions(+), 3 deletions(-)
 create mode 100644 Lagrange.Core/Message/Entity/LightAppEntity.cs

diff --git a/Lagrange.Core/Internal/Packets/Message/Element/Elem.cs b/Lagrange.Core/Internal/Packets/Message/Element/Elem.cs
index b53fbafea..0308f3b8d 100644
--- a/Lagrange.Core/Internal/Packets/Message/Element/Elem.cs
+++ b/Lagrange.Core/Internal/Packets/Message/Element/Elem.cs
@@ -42,7 +42,7 @@ internal class Elem
 	
 	[ProtoMember(45)] public SrcMsg? SrcMsg { get; set; } // Forward/ReplyEntity
 	
-	[ProtoMember(51)] public LightAppElem? LightApp { get; set; }
+	[ProtoMember(51)] public LightAppElem? LightAppElem { get; set; }
 	
 	[ProtoMember(53)] public CommonElem? CommonElem { get; set; }
 }
\ No newline at end of file
diff --git a/Lagrange.Core/Internal/Packets/Message/Element/Implementation/LightAppElem.cs b/Lagrange.Core/Internal/Packets/Message/Element/Implementation/LightAppElem.cs
index c36372693..fce6add91 100644
--- a/Lagrange.Core/Internal/Packets/Message/Element/Implementation/LightAppElem.cs
+++ b/Lagrange.Core/Internal/Packets/Message/Element/Implementation/LightAppElem.cs
@@ -8,5 +8,5 @@ internal class LightAppElem
 {
     [ProtoMember(1)] public byte[] Data { get; set; }
     
-    [ProtoMember(2)] public byte[] MsgResid { get; set; }
+    [ProtoMember(2)] public byte[]? MsgResid { get; set; }
 }
\ No newline at end of file
diff --git a/Lagrange.Core/Message/Entity/LightAppEntity.cs b/Lagrange.Core/Message/Entity/LightAppEntity.cs
new file mode 100644
index 000000000..501338c0e
--- /dev/null
+++ b/Lagrange.Core/Message/Entity/LightAppEntity.cs
@@ -0,0 +1,70 @@
+using System.Text;
+using System.Text.Json.Nodes;
+using Lagrange.Core.Internal.Packets.Message.Element;
+using Lagrange.Core.Internal.Packets.Message.Element.Implementation;
+using Lagrange.Core.Utility.Binary;
+using Lagrange.Core.Utility.Binary.Compression;
+
+namespace Lagrange.Core.Message.Entity;
+
+[MessageElement(typeof(LightAppElem))]
+public class LightAppEntity : IMessageEntity
+{
+    public string AppName { get; set; } = string.Empty;
+    
+    public string Payload { get; set; } = string.Empty;
+    
+    public LightAppEntity() { }
+
+    public LightAppEntity(string payload)
+    {
+        Payload = payload;
+        string? app = JsonNode.Parse(payload)?["app"]?.ToString();
+        if (app != null) AppName = app;
+    }
+    
+    IEnumerable<Elem> IMessageEntity.PackElement()
+    {
+        using var payload = new BinaryPacket()
+            .WriteByte(0x01)
+            .WriteBytes(ZCompression.ZDecompress(Encoding.UTF8.GetBytes(Payload)));
+
+        return new Elem[]
+        {
+            new()
+            {
+                LightAppElem = new LightAppElem
+                {
+                    Data = payload.ToArray(),
+                    MsgResid = null
+                }
+            }
+        };
+    }
+
+    IMessageEntity? IMessageEntity.UnpackElement(Elem elems)
+    {
+        if (elems.LightAppElem is { } lightApp)
+        {
+            var payload = ZCompression.ZDecompress(lightApp.Data[1..]);
+            string json = Encoding.UTF8.GetString(payload);
+            string? app = JsonNode.Parse(json)?["app"]?.ToString();
+
+            if (app != null)
+            {
+                return new LightAppEntity
+                {
+                    AppName = app,
+                    Payload = json
+                };
+            }
+        }
+        
+        return null;
+    }
+
+    public string ToPreviewString()
+    {
+        return $"[{nameof(LightAppEntity)}: {AppName}]";
+    }
+}
\ No newline at end of file
diff --git a/README.md b/README.md
index 89a7ce35e..d65af74ff 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ Please use Lagrange.Core responsibly and in accordance with the law.
 |          |         |                           |         | Reply.    |   🟢    | Group Request     |   🟢    | GroupPromoteAdmin   |   🟢    |
 |          |         |                           |         | File      |   🟡    | ~~Voice Call~~    |   🔴    | GroupInvite         |   🟢    |
 |          |         |                           |         | Poke      |   🟢    | Client Key        |   🟢    | GroupRequestJoin    |   🔴    |
-|          |         |                           |         |           |         | Cookies           |   🟢    | FriendRequest       |   🟢    |
+|          |         |                           |         | LightApp  |   🟢    | Cookies           |   🟢    | FriendRequest       |   🟢    |
 |          |         |                           |         |           |         | Send Message      |   🟢    | ~~FriendTyping~~    |   🔴    |
 |          |         |                           |         |           |         |                   |         | ~~FriendVoiceCall~~ |   🔴    |