app.py

from flask import Flask, request, render_template, redirect, url_for, session, flash
from flask_bcrypt import Bcrypt
import sqlite3
import os

app = Flask(__name__)
app.secret_key = '78789898'  # Secret key for session management
bcrypt = Bcrypt(app)  # Initialize Bcrypt for password hashing

""""
 # Create database if it doesn't exist , but i have created seperate db_script.py for this purpose
if not os.path.exists('users.db'):
    conn = sqlite3.connect('users.db')
    cursor = conn.cursor()
    cursor.execute('''
        CREATE TABLE users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT UNIQUE NOT NULL,
            password_hash TEXT NOT NULL,
            status TEXT
        ) 
    ''')
    conn.commit()
    conn.close()
"""
# Function to get a database connection
def get_db_connection():
    conn = sqlite3.connect('users.db')
    conn.row_factory = sqlite3.Row  # This allows us to access columns by name
    return conn

# Main route that renders the home page
@app.route('/')
def home():
    return render_template('index.html')

# Route for registering users
@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        password_hash = bcrypt.generate_password_hash(password).decode('utf-8')  # Converts password to hash for security
        try:
            # Insert new user into the database
            conn = get_db_connection()
            cursor = conn.cursor()
            cursor.execute('INSERT INTO users (username, password_hash) VALUES (?, ?)', (username, password_hash))
            conn.commit()
            conn.close()
            flash('Registration successful! Please log in.', 'success')
            return redirect(url_for('login'))
        except sqlite3.IntegrityError: # This error occurs if the username already exists
            conn.close()
            flash('Username already exists.', 'error')
            return render_template('register.html')
    return render_template('register.html')

# Login process
@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        # Fetch user from the database
        conn = get_db_connection()
        cursor = conn.cursor()
        cursor.execute('SELECT * FROM users WHERE username = ?', (username,))
        user = cursor.fetchone() 
        conn.close()
        # Check if user exists and password matches
        if user and bcrypt.check_password_hash(user['password_hash'], password):
            session['user_id'] = user['id']  # Session used to remember user id, like cookies do
            flash('Login successful!', 'success')
            return redirect(url_for('dashboard'))
        else:
            flash('Invalid username or password.', 'error')
            return render_template('login.html')
    return render_template('login.html')

# Dashboard route
@app.route('/dashboard')
def dashboard():
    if 'user_id' not in session: # Check if user is logged in
        flash('Please log in to access the dashboard.', 'error')
        return redirect(url_for('login'))
    # Fetch user status from the database
    conn = get_db_connection()
    cursor = conn.cursor()
    cursor.execute('SELECT status FROM users WHERE id = ?', (session['user_id'],)) # Fetches the status of the logged-in user
    status = cursor.fetchone() 
    conn.close()
    status = status[0] if status else 'Not set' # Default status if not set
    return render_template('dashboard.html', status=status)

# Route to update user status , extra feature for dashboard status update
@app.route('/update_status', methods=['POST'])
def update_status():
    if 'user_id' not in session:
        flash('Please log in to update status.', 'error')
        return redirect(url_for('login'))
    # Get the new status from the form
    new_status = request.form['status']
    conn = get_db_connection()
    cursor = conn.cursor()
    cursor.execute('UPDATE users SET status = ? WHERE id = ?', (new_status, session['user_id']))
    conn.commit()
    conn.close()
    flash('Status updated successfully!', 'success')
    return redirect(url_for('dashboard'))

# Logout route
@app.route('/logout')
def logout():
    session.pop('user_id', None)  # Erases the user_id from the session
    flash('Logged out successfully.', 'success')
    return redirect(url_for('home'))

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