[Core] Split PushLogic's message processing methods

[kengwang]

Motivation

Split the big switch-case in PushLogic's Incoming method, to get better readability.

More

Make MessageBody nullable, it could be null in some cases

[Copilot]

Pull Request Overview

This PR refactors the PushLogic class by extracting its large switch-case message handling logic into separate handler classes, improving code maintainability and readability. Additionally, it makes the MessageBody property nullable to handle cases where it may not be present.

Key Changes:

• Refactored message processing from a monolithic switch-case into individual handler classes
• Implemented a handler registration system using reflection and frozen dictionaries for efficient lookup
• Made MessageBody nullable in CommonMessage to handle missing message bodies gracefully

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Lagrange.Core/Message/MessagePacker.cs	Added null checks for MessageBody and null-forgiving operator usage
Lagrange.Core/Internal/Packets/Message/NTMessageCommon.cs	Changed MessageBody property to nullable type
Lagrange.Core/Internal/Logic/PushLogic.cs	Refactored from switch-case to handler-based architecture with reflection-based handler discovery
Lagrange.Core/Internal/Logic/MsgPushHandlers/RichTextMsgHandler.cs	Extracted rich text message handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupReactionHandler.cs	Extracted group reaction handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupNudgeHandler.cs	Extracted group nudge handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupMemberIncreaseHandler.cs	Extracted group member increase handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupMemberDecreaseHandler.cs	Extracted group member decrease handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupJoinHandler.cs	Extracted group join handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/GroupInviteHandler.cs	Extracted group invite handling logic into dedicated handler
Lagrange.Core/Internal/Logic/MsgPushHandlers/FriendRequestHandler.cs	Extracted friend request handling logic into dedicated handler

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[Copilot]

Pull Request Overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

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_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}