main.py

from flask import Flask, render_template, session, redirect, url_for, request
import sqlite3
import os
from markupsafe import escape
from datetime import timedelta

app = Flask(__name__)
app.config['SECRET_KEY'] = os.urandom(16)
app.config['PERMANENT_SESSION_LIFETIME'] =  timedelta(minutes=1)
		
@app.route('/')
def home():
	return 'Hello, World!'

@app.route('/login')
def login():
	return render_template('index.html')

@app.route('/signup')
def signup():
	return render_template('signup.html')

def create():
	with sqlite3.connect('login.db') as db:
		cursor = db.cursor()
		cursor.execute(	"""	CREATE TABLE IF NOT EXISTS Users(
						Username text,
						Password text,
						Primary Key(Username))
				""")
		db.commit()
	print('CREATE')
create()

@app.route('/insert')
def insert():
	with sqlite3.connect('login.db') as db:
		cursor = db.cursor()
		cursor.execute(	"""	INSERT INTO Users (Username, Password)
						VALUES ("Bob", "123")
				""")
		db.commit()
	return 'INSERT'

@app.route('/select')
def select():
	try:
		with sqlite3.connect('login.db') as db:
			cursor = db.cursor()
			cursor.execute("SELECT * FROM Users")
			result = cursor.fetchall()
			if len(result) == 0:
				return 'no records'
			else:
				return ','.join(map(str, result))
	except Exception as e:
		return str(e)

@app.route('/table')
def table():
	con = sqlite3.connect('login.db')
	cur = con.cursor()
	cur.execute("SELECT * FROM Users")
	rows = cur.fetchall()
	return render_template('table.html', rows=rows)		

@app.route('/add', methods=['POST'])
def add():
	with sqlite3.connect('login.db') as db:
		cursor = db.cursor()
		cursor.execute(	"INSERT INTO Users (Username, Password) VALUES (?,?)",
			       		(request.form['uname'],request.form['psw']))
		db.commit()
	return request.form['uname'] + ' added'

@app.route('/verify', methods=['POST'])
def verify():
	with sqlite3.connect('login.db') as db:
		cursor = db.cursor()
		cursor.execute("SELECT * FROM Users WHERE Username=? AND Password=?",
			   (request.form['uname'],request.form['psw']))
		result = cursor.fetchall()
		if len(result) == 0:
			return 'username / password not recognised'
		else:
			session.permanent = True
			session['username'] = request.form['uname']
			return redirect(url_for('change_password'))

@app.route('/un')
def un():
	if 'username' in session:
		return 'Logged in as %s' % escape(session['username'])
	return 'You are not logged in'

@app.route('/logout')
def logout():
    session.pop('username', None)
    return redirect(url_for('un'))

@app.route('/change_password')
def change_password():
    if 'username' not in session:
        return redirect(url_for('login'))
    return render_template('change_password.html')

@app.route('/update_password', methods=['POST'])
def update_password():
    if 'username' not in session:
        return redirect(url_for('login'))
    
    current_password = request.form['current_password']
    new_password = request.form['new_password']
    confirm_password = request.form['confirm_password']
    
    if new_password != confirm_password:
        return 'New passwords do not match'
    
    with sqlite3.connect('login.db') as db:
        cursor = db.cursor()
        # Verify current password
        cursor.execute("SELECT * FROM Users WHERE Username=? AND Password=?",
                      (session['username'], current_password))
        if not cursor.fetchone():
            return 'Current password is incorrect'
        
        # Update password
        cursor.execute("UPDATE Users SET Password=? WHERE Username=?",
                      (new_password, session['username']))
        db.commit()
        
    return 'Password successfully updated'

if __name__ == "__main__":
    app.run(debug=True)