"""
@file Message.py
@author 30hours
"""

import socket
import threading
import asyncio

class Message:

  """
  @class Message
  @brief A class for simple TCP messaging using a listener and sender.
  """

  def __init__(self, host, port):

    """
    @brief Constructor for Message.
    @param host (str): The host to bind the listener to.
    @param port (int): The port to bind the listener to.
    """
  
    self.host = host
    self.port = port
    self.server_socket = None
    self.callback_message_received = None

  def start_listener(self):

    """
    @brief Start the TCP listener to accept incoming connections.
    @details Ensure this function is run in a separate thread.
    @return None.
    """

    self.server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    self.server_socket.bind((self.host, self.port))
    self.server_socket.listen()

    print(f"Listener is waiting for connections on {self.host}:{self.port}")

    while True:
        conn, addr = self.server_socket.accept()
        thread = threading.Thread(target=self.handle_client, args=(conn, addr))
        thread.start()

  def handle_client(self, conn, addr):
    
    """
    @brief Handle communication with a connected client.
    @param conn (socket.socket): The socket object for the connected client.
    @param addr (tuple): The address (host, port) of the connected client.
    @return None.
    """
    
    with conn:
        while True:
            data = conn.recv(8096)
            if not data:
                break

            # Process data in chunks
            decoded_data = ""
            while data:
                chunk = data.decode()
                decoded_data += chunk
                data = conn.recv(8096)

            # Call the callback function if set
            if self.callback_message_received:
                reply = asyncio.run(self.callback_message_received(decoded_data))
                if reply:
                    # Send the reply in chunks
                    for i in range(0, len(reply), 8096):
                        conn.sendall(reply[i:i + 8096].encode())

  def send_message(self, message):
    
    """
    @brief Send a message to the specified host and port.
    @param message (str): The message to be sent.
    @return generator: A generator yielding chunks of the reply.
    """
    
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as client_socket:
        client_socket.settimeout(3)
        try:
            client_socket.connect((self.host, self.port))
            # Send the message in chunks
            for i in range(0, len(message), 8096):
                client_socket.sendall(message[i:i + 8096].encode())
            # Indicate the end of transmission
            client_socket.shutdown(socket.SHUT_WR)
            # Receive the reply in chunks
            while True:
                data = client_socket.recv(8096)
                if not data:
                    break
                yield data.decode()
        except ConnectionRefusedError:
            print(f"Connection to {self.host}:{self.port} refused.")

  def set_callback_message_received(self, callback):

    """
    @brief Set callback function when a message is received.
    @param callback (function): The callback function.
    @return None.
    """

    self.callback_message_received = callback

  def close_listener(self):

    """
    @brief Close the listener socket.
    @return None.
    """

    if self.server_socket:
        self.server_socket.close()