text: from datetime import datetime
  from flask import render_template, flash, redirect, url_for, request
  from flask_login import login_user, logout_user, current_user, login_required
  from werkzeug.urls import url_parse
  from app import app, db
  from app.forms import LoginForm, RegistrationForm, EditProfileForm
  from app.models import User
  
  
  @app.before_request
  def before_request():
      if current_user.is_authenticated:
          current_user.last_seen = datetime.utcnow()
          db.session.commit()
  
  
  @app.route('/')
  @app.route('/index')
  @login_required
  def index():
      posts = [
          {
              'author': {'username': 'John'},
              'body': 'Beautiful day in Portland!'
          },
          {
              'author': {'username': 'Susan'},
              'body': 'The Avengers movie was so cool!'
          }
      ]
      return render_template('index.html', title='Home', posts=posts)
  
  
  @app.route('/login', methods=['GET', 'POST'])
  def login():
      if current_user.is_authenticated:
          return redirect(url_for('index'))
      form = LoginForm()
      if form.validate_on_submit():
          user = User.query.filter_by(username=form.username.data).first()
          if user is None or not user.check_password(form.password.data):
              flash('Invalid username or password')
              return redirect(url_for('login'))
          login_user(user, remember=form.remember_me.data)
          next_page = request.args.get('next')
          if not next_page or url_parse(next_page).netloc != '':
              next_page = url_for('index')
          return redirect(next_page)
      return render_template('login.html', title='Sign In', form=form)
  
  
  @app.route('/logout')
  def logout():
      logout_user()
      return redirect(url_for('index'))
  
  
  @app.route('/register', methods=['GET', 'POST'])
  def register():
      if current_user.is_authenticated:
          return redirect(url_for('index'))
      form = RegistrationForm()
      if form.validate_on_submit():
          user = User(username=form.username.data, email=form.email.data)
          user.set_password(form.password.data)
          db.session.add(user)
          db.session.commit()
          flash('Congratulations, you are now a registered user!')
          return redirect(url_for('login'))
      return render_template('register.html', title='Register', form=form)
  
  
  @app.route('/user/<username>')
  @login_required
  def user(username):
      user = User.query.filter_by(username=username).first_or_404()
      posts = [
          {'author': user, 'body': 'Test post #1'},
          {'author': user, 'body': 'Test post #2'}
      ]
      return render_template('user.html', user=user, posts=posts)
  
  
  @app.route('/edit_profile', methods=['GET', 'POST'])
  @login_required
  def edit_profile():
      form = EditProfileForm(current_user.username)
      if form.validate_on_submit():
          current_user.username = form.username.data
          current_user.about_me = form.about_me.data
          db.session.commit()
          flash('Your changes have been saved.')
          return redirect(url_for('edit_profile'))
      elif request.method == 'GET':
          form.username.data = current_user.username
          form.about_me.data = current_user.about_me
      return render_template('edit_profile.html', title='Edit Profile',
                             form=form)
  