from flask import Flask, render_template, request, redirect, url_for, session, flash
from flask_sqlalchemy import SQLAlchemy
from werkzeug.security import generate_password_hash, check_password_hash

app = Flask(__name__)
app.secret_key = 'your_secret_key'  # Secret for session and flash
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///users.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

db = SQLAlchemy(app)

# Database model
class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    email = db.Column(db.String(80), unique=True, nullable=False)
    password = db.Column(db.String(200), nullable=False)

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

@app.route('/signup', methods=['GET', 'POST'])
def signup():
    if request.method == 'POST':
        username = request.form.get('username')
        email = request.form.get('email')
        password = request.form.get('password')

        # Check if username is already taken
        existing_user = User.query.filter_by(username=username).first()
        if existing_user:
            flash('Username already exists. Please choose another.', 'danger')
            return redirect(url_for('signup'))

        # Hash the password and save to the database
        hashed_password = generate_password_hash(password, method='pbkdf2:sha256')
        new_user = User(username=username, email=email, password=hashed_password)
        db.session.add(new_user)
        db.session.commit()
        flash('Signup successful! You can now log in.', 'success')
        return redirect(url_for('login'))

    return render_template('signup.html')

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form.get('username')
        password = request.form.get('password')

        user = User.query.filter_by(username=username).first()
        if user and check_password_hash(user.password, password):
            session['user_id'] = user.id
            flash('Login successful!', 'success')
            return redirect(url_for('welcome'))

        flash('Invalid username or password.', 'danger')

    return render_template('login.html')

@app.route('/welcome')
def welcome():
    user = User.query.get(session['user_id'])
    return render_template('welcome.html', username=user.username.upper())

@app.route('/logout')
def logout():
    session.pop('user_id', None)
    flash('You have been logged out.', 'success')
    return redirect(url_for('splash'))

if __name__ == '__main__':
    with app.app_context():
        db.create_all()  # Create database tables
    app.run(debug=True)