This is the completed project for the reddit oauth project

reddit_complete.py

from flask import Flask, redirect, url_for, request, session
import praw
import uuid

app = Flask(__name__)

# The secret key is used to sign/secure the session data
app.secret_key = "my-secret-flask-key"

# The reddit instance, fill in your details
reddit = praw.Reddit(
    client_id="CLIENT ID",
    client_secret="CLIENT SECRET",
    redirect_uri="http://localhost:8080/callback", # Must match your Reddit App details
    user_agent="MyApp v1",
)


@app.route('/')
def main():
    if session.get("authenticated", False):
        return f"Hello, {str(reddit.user.me())} | <a href='/clear'>Clear</a>"

    return "<h1>My App</h1>" \
           "<a href='/authorize'>Authenticate</a>"


@app.route("/authorize")
def authorize():
    # Generates an authorization URL
    scopes = [
        "identity",
        "edit",
        "history"
    ]
    session["state_code"] = str(uuid.uuid4())
    return redirect(reddit.auth.url(scopes, session.get("state_code"), 'permanent'))


@app.route("/clear")
def clear():
    """ Clears the session data """
    session.clear()
    return redirect(url_for("main"))


@app.route("/callback")
def callback():
    """ After authorizing, Reddit will redirect to here with data """
    # retrieve the state and code from reddit
    state = request.args.get("state", None)
    code = request.args.get("code", None)
    error = request.args.get("error", None)

    # Handle errors
    if error is not None:
        return error

    # if the state codes do not match, the request was not by us, ...hackers :O
    if state != session.get("state_code"):
        return "Unauthorised"
    
    if code is None:
        return "No code!"

    # Use the code to authenticate the Reddit instance
    reddit.auth.authorize(code)

    # Let the server know we've authenticated
    session["authenticated"] = True

    # Now that we have the users permission, go back to the start
    return redirect(url_for("main"))


if __name__ == '__main__':
    app.run(host="localhost", port=8080)