LAN ChatBox

A premium, highly responsive Local Area Network (LAN) chat application built with .NET 10.0 Windows Presentation Foundation (WPF). It features a modern, Discord-inspired user interface, raw TCP socket communication for real-time messaging, and Entity Framework Core with PostgreSQL for persistent history storage.

Features

Modern User Interface

• Discord-style aesthetics with custom window chromes, glassmorphism title bars, and modern scrollbars.
• Dynamic custom settings panel for profile and network configuration.
• Integrated Lightbox view for full-size image previews.
• Fully restricted input fields to prevent unauthorized history manipulation (blocked Alt+Backspace, Ctrl+Z).

Messaging & File Transfer

• Real-time text messaging across the LAN via a dedicated TCP socket server (Port 9999).
• Background file transfer protocol (Port 10000) allowing seamless large file uploads and downloads.
• Drag-and-drop support: Drag files directly into the application window to instantly upload and send them to the channel.
• Automatic image preview rendering: Image attachments are downloaded and displayed in the chat feed automatically without manual user intervention.

User Configuration & Portability

• Portable Executables: The application is designed to be packaged as a single-file, self-contained executable.
• Clean Environment: User configurations, chat history caches, and downloaded files are isolated and securely stored in Windows standard %APPDATA% and %LOCALAPPDATA% directories, ensuring no test data is shipped when distributing the application.
• Customizable Avatars: Users can upload custom profile pictures which are heavily optimized and securely transmitted to peers.

Persistent Server Storage

• The Server application acts as a centralized hub, managing connected clients, broadcasting messages, and caching transferred files.
• PostgreSQL Database integration via Entity Framework Core.
• The server automatically executes schema migrations and creates the required database (ChatBoxDb) upon startup.

Asynchronous & Parallel Programming

• Non-blocking UI: Extensive use of async and await ensures the WPF UI thread never freezes during long-running network or database operations.
• Concurrent Server Handling: The server utilizes Task.Run and independent task contexts to handle multiple TCP client connections concurrently, allowing dozens of users to chat simultaneously without bottlenecking.
• Background File Processing: File transfers (uploading, downloading, and image caching) are executed in parallel on separate background threads (FileTransferService). Files are transmitted in chunks to prevent memory spikes.
• Cooperative Cancellation: Implementing CancellationTokenSource allows users to safely abort connection attempts instantly without raising unhandled exception crashes.
• Async Data Access: Entity Framework Core operations (AddAsync, SaveChangesAsync, ToListAsync) are strictly asynchronous to maximize the server's throughput capacity.

Architecture

The solution is divided into three core projects:

1. LocalChat.Core: A shared library containing data models (User, ChatMessage), database context (ChatDbContext), and core background transfer services.
2. ChatBox.Server: The backend WPF application that monitors TCP ports, relays messages, hosts the PostgreSQL connection, and stores uploaded files in %LOCALAPPDATA%.
3. ChatBox.Client: The front-end user application containing all interactive UI logic and local socket client operations.

Installation & Setup

Prerequisites

• Windows 10 or Windows 11.
• .NET 10.0 SDK.
• PostgreSQL installed and running on the server machine.

Server Configuration

By default, the server expects a local PostgreSQL instance running with the following credentials:

• Host: localhost
• Port: 5432
• Username: postgres
• Password: 12345

If your PostgreSQL credentials differ, you must update the connection string located in LocalChat.Core/Data/ChatDbContext.cs before compiling the server.

Building from Source

To build the project into clean, shareable .exe files, open a terminal in the solution directory and run the following commands:

# Build the Client
dotnet publish ChatBox.Client/ChatBox.Client.csproj -c Release -r win-x64 --self-contained true -p:PublishSingleFile=true -p:PublishReadyToRun=true -o publish/Client

# Build the Server
dotnet publish ChatBox.Server/ChatBox.Server.csproj -c Release -r win-x64 --self-contained true -p:PublishSingleFile=true -p:PublishReadyToRun=true -o publish/Server

The compiled applications will be available in the publish directory.

Usage

1. Start the Server: Run ChatBox.Server.exe on the host machine. The server will display the local IPv4 addresses it is currently listening on.
2. Start the Client: Run ChatBox.Client.exe on any computer within the same network.
3. Connect: In the client settings overlay, enter your desired Display Name and input the IP address displayed by the Server application. Click "Connect to Server".
4. Chat & Share: Once connected, use the text field to chat or drag and drop files directly into the window.

License

This project is provided for educational and internal network communication purposes.