text: from flask import render_template, redirect, request, url_for, flash
  from flask_login import login_user, logout_user, login_required, \
      current_user
  from . import auth
  from .. import db
  from ..models import User
  from ..email import send_email
  from .forms import LoginForm, RegistrationForm, ChangePasswordForm,\
      PasswordResetRequestForm, PasswordResetForm, ChangeEmailForm
  
  
  @auth.before_app_request
  def before_request():
      if current_user.is_authenticated:
          current_user.ping()
          if not current_user.confirmed \
                  and request.endpoint[:5] != 'auth.' \
                  and request.endpoint != 'static':
              return redirect(url_for('auth.unconfirmed'))
  
  
  @auth.route('/unconfirmed')
  def unconfirmed():
      if current_user.is_anonymous or current_user.confirmed:
          return redirect(url_for('main.index'))
      return render_template('auth/unconfirmed.html')
  
  
  @auth.route('/login', methods=['GET', 'POST'])
  def login():
      form = LoginForm()
      if form.validate_on_submit():
          user = User.query.filter_by(email=form.email.data).first()
          if user is not None and user.verify_password(form.password.data):
              login_user(user, form.remember_me.data)
              return redirect(request.args.get('next') or url_for('main.index'))
          flash('Invalid username or password.')
      return render_template('auth/login.html', form=form)
  
  
  @auth.route('/logout')
  @login_required
  def logout():
      logout_user()
      flash('You have been logged out.')
      return redirect(url_for('main.index'))
  
  
  @auth.route('/register', methods=['GET', 'POST'])
  def register():
      form = RegistrationForm()
      if form.validate_on_submit():
          user = User(email=form.email.data,
                      username=form.username.data,
                      password=form.password.data)
          db.session.add(user)
          db.session.commit()
          'this is a comment'
          token = user.generate_confirmation_token()
          send_email(user.email, 'Confirm Your Account',
                     'auth/email/confirm', user=user, token=token)
          flash('A confirmation email has been sent to you by email.')
          return redirect(url_for('auth.login'))
      return render_template('auth/register.html', form=form)
  
  
  @auth.route('/confirm/<token>')
  @login_required
  def confirm(token):
      if current_user.confirmed:
          return redirect(url_for('main.index'))
      if current_user.confirm(token):
          flash('You have confirmed your account. Thanks!')
      else:
          flash('The confirmation link is invalid or has expired.')
      return redirect(url_for('main.index'))
  
  
  @auth.route('/confirm')
  @login_required
  def resend_confirmation():
      token = current_user.generate_confirmation_token()
      send_email(current_user.email, 'Confirm Your Account',
                 'auth/email/confirm', user=current_user, token=token)
      flash('A new confirmation email has been sent to you by email.')
      return redirect(url_for('main.index'))
  
  
  @auth.route('/change-password', methods=['GET', 'POST'])
  @login_required
  def change_password():
      form = ChangePasswordForm()
      if form.validate_on_submit():
          if current_user.verify_password(form.old_password.data):
              current_user.password = form.password.data
              db.session.add(current_user)
              flash('Your password has been updated.')
              return redirect(url_for('main.index'))
          else:
              flash('Invalid password.')
      return render_template("auth/change_password.html", form=form)
  
  
  @auth.route('/reset', methods=['GET', 'POST'])
  def password_reset_request():
      if not current_user.is_anonymous:
          return redirect(url_for('main.index'))
      form = PasswordResetRequestForm()
      if form.validate_on_submit():
          user = User.query.filter_by(email=form.email.data).first()
          if user:
              token = user.generate_reset_token()
              send_email(user.email, 'Reset Your Password',
                         'auth/email/reset_password',
                         user=user, token=token,
                         next=request.args.get('next'))
          flash('An email with instructions to reset your password has been '
                'sent to you.')
          return redirect(url_for('auth.login'))
      return render_template('auth/reset_password.html', form=form)
  
  
  @auth.route('/reset/<token>', methods=['GET', 'POST'])
  def password_reset(token):
      if not current_user.is_anonymous:
          return redirect(url_for('main.index'))
      form = PasswordResetForm()
      if form.validate_on_submit():
          user = User.query.filter_by(email=form.email.data).first()
          if user is None:
              return redirect(url_for('main.index'))
          if user.reset_password(token, form.password.data):
              flash('Your password has been updated.')
              return redirect(url_for('auth.login'))
          else:
              return redirect(url_for('main.index'))
      return render_template('auth/reset_password.html', form=form)
  
  
  @auth.route('/change-email', methods=['GET', 'POST'])
  @login_required
  def change_email_request():
      form = ChangeEmailForm()
      if form.validate_on_submit():
          if current_user.verify_password(form.password.data):
              new_email = form.email.data
              token = current_user.generate_email_change_token(new_email)
              send_email(new_email, 'Confirm your email address',
                         'auth/email/change_email',
                         user=current_user, token=token)
              flash('An email with instructions to confirm your new email '
                    'address has been sent to you.')
              return redirect(url_for('main.index'))
          else:
              flash('Invalid email or password.')
      return render_template("auth/change_email.html", form=form)
  
  
  @auth.route('/change-email/<token>')
  @login_required
  def change_email(token):
      if current_user.change_email(token):
          flash('Your email address has been updated.')
      else:
          flash('Invalid request.')
      return redirect(url_for('main.index'))
  