Can you please help me in writing a simple chat website using python, HTML and javascript?

As a general description, the site should have multiple registered users and each user can send messages to each other.

The user interface of the site is extremely simple:
1. regular login using google/facebook/discord
2. on the top there is locked location textbox input that is used for the username you want to chat with - lets call it "target_username_textbox"
3. below that there is a scrollable chat history with the username in the "target_username_textbox". 
4. below that, there is another text box that can be used to enter text messages with a send button to the right, lets call it "text_message_textbox".

The functionality is such that every time you type a new name in the "target_username_textbox", the chat history is replaced with the chat history of that specific user, and everytime you press send, the message in "text_message_textbox" is sent to the target username

In the backend, the chat messages between users are stored in a MongoDB database with the following format:
{src_username: "...", dst_username: "...", date & time: "...", message: "..."}

The code should be very simple, 1 python file to the server and 1 HTML page for displaying the website

Much help will be greatly appreciated
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