Messaging System

This project implements a basic messaging system that supports user-to-user and user-to-group messaging.

Features

• User-to-User Messaging: Send messages between individual users.
• User-to-Group Messaging: Send messages to groups of users.
• Message Attributes: Each message includes content, timestamp, and sender information.
• Filter Messages: Messages can be filtered by sender or recipient.

Classes Overview

• User: Represents a user in the system.
• Message: Stores message content, time, and author.
• Group: Manages groups of users.
• Chat: Manages conversations between users.
• System: Handles user creation, group creation, and sending messages.

Example Usage

1. Create a user:

   System system;
   system.create_user("Alice");
   system.create_user("Bob");

2. Send a message:

   system.send_text("Alice", "Bob", "Hello, Bob!");

3. Fetch chat:

   auto chat = system.get_chat("Alice", "Bob");
   for (const auto& message : chat) {
       std::cout << message;
   }