From 6b07b916e04d0e1f81b73f6f82fce56bdf368bd9 Mon Sep 17 00:00:00 2001
From: Linwenxuan <116782992+Linwenxuan05@users.noreply.github.com>
Date: Sat, 28 Oct 2023 19:11:44 +0800
Subject: [PATCH] [Core] Parse PrivateFile in MessagePacker instead of
 FileEntity

---
 .../Service/Message/PushMessageService.cs     |  8 +++-
 Lagrange.Core/Message/Entity/FileEntity.cs    | 12 +-----
 Lagrange.Core/Message/IMessageEntity.cs       |  2 -
 Lagrange.Core/Message/MessagePacker.cs        | 40 ++++++++++---------
 4 files changed, 29 insertions(+), 33 deletions(-)

diff --git a/Lagrange.Core/Internal/Service/Message/PushMessageService.cs b/Lagrange.Core/Internal/Service/Message/PushMessageService.cs
index 5fc8efc31..fb1cfed08 100644
--- a/Lagrange.Core/Internal/Service/Message/PushMessageService.cs
+++ b/Lagrange.Core/Internal/Service/Message/PushMessageService.cs
@@ -26,12 +26,18 @@ protected override bool Parse(byte[] input, BotKeystore keystore, BotAppInfo app
         extraEvents = new List<ProtocolEvent>();
         switch (packetType)
         {
-            case PkgType.PrivateMessage or PkgType.GroupMessage or PkgType.PrivateFileMessage:
+            case PkgType.PrivateMessage or PkgType.GroupMessage:
             {
                 var chain = MessagePacker.Parse(message.Message);
                 output = PushMessageEvent.Create(chain);
                 break;
             }
+            case PkgType.PrivateFileMessage:
+            {
+                var chain = MessagePacker.ParsePrivateFile(message.Message);
+                output = PushMessageEvent.Create(chain);
+                break;
+            }
             case PkgType.GroupInviteNotice:
             {
                 if (message.Message.Body?.MsgContent == null) return false;
diff --git a/Lagrange.Core/Message/Entity/FileEntity.cs b/Lagrange.Core/Message/Entity/FileEntity.cs
index bf205eeba..99f3bd551 100644
--- a/Lagrange.Core/Message/Entity/FileEntity.cs
+++ b/Lagrange.Core/Message/Entity/FileEntity.cs
@@ -42,7 +42,7 @@ public FileEntity(string path)
         FileName = Path.GetFileName(path);
     }
 
-    private FileEntity(long fileSize, string fileName, byte[] fileMd5, string fileUuid, string fileHash)
+    internal FileEntity(long fileSize, string fileName, byte[] fileMd5, string fileUuid, string fileHash)
     {
         FileSize = fileSize;
         FileName = fileName;
@@ -82,15 +82,5 @@ private FileEntity(long fileSize, string fileName, byte[] fileMd5, string fileUu
         return null;
     }
 
-    IMessageEntity? IMessageEntity.UnpackMessageContent(ReadOnlySpan<byte> content)
-    {
-        var extra = Serializer.Deserialize<FileExtra>(content);
-        var file = extra.File;
-        
-        return file is { FileSize: not null, FileName: not null, FileMd5: not null, FileUuid: not null, FileHash: not null }
-            ? new FileEntity((long)file.FileSize, file.FileName, file.FileMd5, file.FileUuid, file.FileHash) 
-            : null;
-    }
-
     public string ToPreviewString() => $"[File] {FileName} ({FileSize}): {FileUrl ?? "failed to receive file url"}";
 }
\ No newline at end of file
diff --git a/Lagrange.Core/Message/IMessageEntity.cs b/Lagrange.Core/Message/IMessageEntity.cs
index 7d007a661..5214fd5ae 100644
--- a/Lagrange.Core/Message/IMessageEntity.cs
+++ b/Lagrange.Core/Message/IMessageEntity.cs
@@ -16,8 +16,6 @@ public interface IMessageEntity
 
     internal IMessageEntity? UnpackElement(Elem elem); // abstract method
     
-    internal IMessageEntity? UnpackMessageContent(ReadOnlySpan<byte> content) => null; // virtual method
-
     internal void SetSelfUid(string selfUid) { } // virtual method
 
     public string ToPreviewString(); // abstract method
diff --git a/Lagrange.Core/Message/MessagePacker.cs b/Lagrange.Core/Message/MessagePacker.cs
index 19d78dc71..e318eb45e 100644
--- a/Lagrange.Core/Message/MessagePacker.cs
+++ b/Lagrange.Core/Message/MessagePacker.cs
@@ -1,6 +1,7 @@
 using System.Reflection;
 using Lagrange.Core.Internal.Packets.Message.C2C;
 using Lagrange.Core.Internal.Packets.Message.Component;
+using Lagrange.Core.Internal.Packets.Message.Component.Extra;
 using Lagrange.Core.Internal.Packets.Message.Element;
 using Lagrange.Core.Internal.Packets.Message.Routing;
 using ProtoBuf;
@@ -115,35 +116,36 @@ public static MessageChain Parse(PushMsgBody message)
                 {
                     foreach (var expectElem in expectElems)
                     {
-                        var val = expectElem.GetValueByExpr(element);
-                        if (val != null)
+                        if (expectElem.GetValueByExpr(element) is not null && 
+                            Factory[entityType].UnpackElement(element) is { } entity)
                         {
-                            var entity = Factory[entityType].UnpackElement(element);
-                            if (entity != null)
-                            {
-                                chain.Add(entity);
-                                break;
-                            }
+                            chain.Add(entity);
+                            break;
                         }
                     }
                 }
             }
         }
 
-        if (message.Body is { MsgContent: not null })
+        return chain;
+    }
+
+    public static MessageChain ParsePrivateFile(PushMsgBody message)
+    {
+        if (message.Body?.MsgContent == null) throw new Exception();
+        
+        var chain = ParseChain(message);
+
+        var extra = Serializer.Deserialize<FileExtra>(message.Body.MsgContent.AsSpan());
+        var file = extra.File;
+
+        if ( file is { FileSize: not null, FileName: not null, FileMd5: not null, FileUuid: not null, FileHash: not null })
         {
-            foreach (var factory in MsgFactory)
-            {
-                var entity = factory.UnpackMessageContent(message.Body.MsgContent);
-                if (entity != null)
-                {
-                    chain.Add(entity);
-                    break;
-                }
-            }
+            chain.Add(new FileEntity((long)file.FileSize, file.FileName, file.FileMd5, file.FileUuid, file.FileHash));
+            return chain;
         }
 
-        return chain;
+        throw new Exception();
     }
 
     private static Internal.Packets.Message.Message BuildPacketBase(MessageChain chain) => new()