from flask import Flask, request, redirect, render_template, url_for, flash
from werkzeug.security import generate_password_hash, check_password_hash
from flask_session import Session

app = Flask(__name__)
app.secret_key = 'your_secret_key' # Used to sign session cookies safely

# Suppose there is a user dictionary to store username and password hash
users = {
    'admin': generate_password_hash('password')
}

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

        user_password_hash = users.get(username)

        if user_password_hash and check_password_hash(user_password_hash, password):
            # Username and password matching
            session['username'] = username # Store username in session
            return redirect(url_for('home'))
        else:
            flash('Invalid username or password')

    return render_template('login.html')

@app.route('/home')
def home():
    if 'username' in session:
        return f'Hello, {session["username"]}!'
    return redirect(url_for('login'))

@app.route('/logout')
def logout():
    session.pop('username', None) # Remove username from session
    return redirect(url_for('login'))

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

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager

app = Flask(__name__)
app.config['SECRET_KEY'] = 'your_secret_key'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
db = SQLAlchemy(app)

login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'login'

from flask_login import UserMixin

class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(100), unique=True, nullable=False)
    password = db.Column(db.String(100), nullable=False)

    def __repr__(self):
        return '<User %r>' % self.username

from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import DataRequired, Length, EqualTo, ValidationError

class RegistrationForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=4, max=25)])
    password = PasswordField('Password', validators=[DataRequired()])
    confirm_password = PasswordField('Confirm Password', validators=[DataRequired(), EqualTo('password')])
    submit = SubmitField('Sign Up')

    def validate_username(self, username):
        user = User.query.filter_by(username=username.data).first()
        if user:
            raise ValidationError('That username is taken. Please choose a different one.')

class LoginForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=4, max=25)])
    password = PasswordField('Password', validators=[DataRequired()])
    submit = SubmitField('Login')

from flask import render_template, url_for, redirect, request, flash
from werkzeug.security import generate_password_hash, check_password_hash

@app.route('/register', methods=['GET', 'POST'])
def register():
    form = RegistrationForm()
    if form.validate_on_submit():
        hashed_password = generate_password_hash(form.password.data)
        user = User(username=form.username.data, password=hashed_password)
        db.session.add(user)
        db.session.commit()
        flash('Your account has been created! You are now able to log in', 'success')
        return redirect(url_for('login'))
    return render_template('register.html', title='Register', form=form)

@app.route('/login', methods=['GET', 'POST'])
def login():
    form = LoginForm()
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.username.data).first()
        if user and check_password_hash(user.password, form.password.data):
            login_user(user)
            return redirect(url_for('dashboard'))
        else:
            flash('Login Unsuccessful. Please check username and password', 'danger')
    return render_template('login.html', title='Login', form=form)

@app.route('/dashboard')
@login_required
def dashboard():
    return 'Welcome to the Dashboard!'

@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))

with app.app_context():
    db.create_all()

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