add chat application tutorial

Author: x4nth055

Diff for: README.md

@@ -110,6 +110,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Work with JSON Files in Python](https://www.thepythoncode.com/article/working-with-json-files-in-python). ([code](python-standard-library/working-with-json))
     - [How to Use Regular Expressions in Python](https://www.thepythoncode.com/article/work-with-regular-expressions-in-python). ([code](python-standard-library/regular-expressions))
     - [Logging in Python](https://www.thepythoncode.com/article/logging-in-python). ([code](python-standard-library/logging))
+    - [How to Make a Chat Application in Python](https://www.thepythoncode.com/article/make-a-chat-room-application-in-python). ([code](python-standard-library/chat-application))
 
 - ### [Using APIs](https://www.thepythoncode.com/topic/using-apis-in-python)
     - [How to Automate your VPS or Dedicated Server Management in Python](https://www.thepythoncode.com/article/automate-veesp-server-management-in-python). ([code](general/automating-server-management))

Diff for: python-standard-library/chat-application/README.md

@@ -0,0 +1,6 @@
+# [How to Make a Chat Application in Python](https://www.thepythoncode.com/article/make-a-chat-room-application-in-python)
+To run this:
+- `pip3 install -r requirements.txt`
+- Run `server.py` first to initialize the server.
+- Run one or more `client.py` instances and chat!
+- If you want to run `client.py` from another machine, make sure you change `SERVER_HOST` in `client.py` to the server's IP address.

Diff for: python-standard-library/chat-application/client.py

@@ -0,0 +1,61 @@
+import socket
+import random
+from threading import Thread
+from datetime import datetime
+from colorama import Fore, init, Back
+
+# init colors
+init()
+
+# set the available colors
+colors = [Fore.BLUE, Fore.CYAN, Fore.GREEN, Fore.LIGHTBLACK_EX, 
+    Fore.LIGHTBLUE_EX, Fore.LIGHTCYAN_EX, Fore.LIGHTGREEN_EX, 
+    Fore.LIGHTMAGENTA_EX, Fore.LIGHTRED_EX, Fore.LIGHTWHITE_EX, 
+    Fore.LIGHTYELLOW_EX, Fore.MAGENTA, Fore.RED, Fore.WHITE, Fore.YELLOW
+]
+
+# choose a random color for the client
+client_color = random.choice(colors)
+
+# server's IP address
+# if the server is not on this machine, 
+# put the private (network) IP address (e.g 192.168.1.2)
+SERVER_HOST = "127.0.0.1"
+SERVER_PORT = 5002 # server's port
+separator_token = "<SEP>" # we will use this to separate the client name & message
+
+# initialize TCP socket
+s = socket.socket()
+print(f"[*] Connecting to {SERVER_HOST}:{SERVER_PORT}...")
+# connect to the server
+s.connect((SERVER_HOST, SERVER_PORT))
+print("[+] Connected.")
+# prompt the client for a name
+name = input("Enter your name: ")
+
+def listen_for_messages():
+    while True:
+        message = s.recv(1024).decode()
+        print("\n" + message)
+
+# make a thread that listens for messages to this client & print them
+t = Thread(target=listen_for_messages)
+# make the thread daemon so it ends whenever the main thread ends
+t.daemon = True
+# start the thread
+t.start()
+
+while True:
+    # input message we want to send to the server
+    to_send =  input()
+    # a way to exit the program
+    if to_send.lower() == 'q':
+        break
+    # add the datetime, name & the color of the sender
+    date_now = datetime.now().strftime('%Y-%m-%d %H:%M:%S') 
+    to_send = f"{client_color}[{date_now}] {name}{separator_token}{to_send}{Fore.RESET}"
+    # finally, send the message
+    s.send(to_send.encode())
+
+# close the socket
+s.close()

Diff for: python-standard-library/chat-application/requirements.txt

@@ -0,0 +1 @@
+colorama

Diff for: python-standard-library/chat-application/server.py

@@ -0,0 +1,62 @@
+import socket
+from threading import Thread
+
+# server's IP address
+SERVER_HOST = "0.0.0.0"
+SERVER_PORT = 5002 # port we want to use
+separator_token = "<SEP>" # we will use this to separate the client name & message
+
+# initialize list/set of all connected client's sockets
+client_sockets = set()
+# create a TCP socket
+s = socket.socket()
+# make the port as reusable port
+s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+# bind the socket to the address we specified
+s.bind((SERVER_HOST, SERVER_PORT))
+# listen for upcoming connections
+s.listen(5)
+print(f"[*] Listening as {SERVER_HOST}:{SERVER_PORT}")
+
+def listen_for_client(cs):
+    """
+    This function keep listening for a message from `cs` socket
+    Whenever a message is received, broadcast it to all other connected clients
+    """
+    while True:
+        try:
+            # keep listening for a message from `cs` socket
+            msg = cs.recv(1024).decode()
+        except Exception as e:
+            # client no longer connected
+            # remove it from the set
+            print(f"[!] Error: {e}")
+            client_sockets.remove(cs)
+        else:
+            # if we received a message, replace the <SEP> 
+            # token with ": " for nice printing
+            msg = msg.replace(separator_token, ": ")
+        # iterate over all connected sockets
+        for client_socket in client_sockets:
+            # and send the message
+            client_socket.send(msg.encode())
+
+
+while True:
+    # we keep listening for new connections all the time
+    client_socket, client_address = s.accept()
+    print(f"[+] {client_address} connected.")
+    # add the new connected client to connected sockets
+    client_sockets.add(client_socket)
+    # start a new thread that listens for each client's messages
+    t = Thread(target=listen_for_client, args=(client_socket,))
+    # make the thread daemon so it ends whenever the main thread ends
+    t.daemon = True
+    # start the thread
+    t.start()
+
+# close client sockets
+for cs in client_sockets:
+    cs.close()
+# close server socket
+s.close()