app.py

import os
from dotenv import load_dotenv

from flask import Flask, render_template, request, flash, redirect, session, g
from flask_debugtoolbar import DebugToolbarExtension
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm.exc import StaleDataError
from werkzeug.exceptions import Unauthorized

from forms import UserAddForm, LoginForm, MessageForm, CsrfForm, UserUpdateForm
from models import db, connect_db, User, Message

load_dotenv()

CURR_USER_KEY = "curr_user"


app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = os.environ['DATABASE_URL']
app.config['SQLALCHEMY_ECHO'] = False
app.config['DEBUG_TB_INTERCEPT_REDIRECTS'] = False
app.config['SECRET_KEY'] = os.environ['SECRET_KEY']
toolbar = DebugToolbarExtension(app)

connect_db(app)

##############################################################################
# CSRF form


@app.before_request
def add_csrf_form_to_g():
    """Add csrf form to Flask global"""

    g.csrf_form = CsrfForm()

##############################################################################
# User signup/login/logout


@app.before_request
def add_user_to_g():
    """If we're logged in, add curr user to Flask global."""

    if CURR_USER_KEY in session:
        g.user = User.query.get(session[CURR_USER_KEY])

    else:
        g.user = None


def do_login(user):
    """Log in user."""

    session[CURR_USER_KEY] = user.id


def do_logout():
    """Log out user."""

    if CURR_USER_KEY in session:
        del session[CURR_USER_KEY]


@app.route('/signup', methods=["GET", "POST"])
def signup():
    """Handle user signup.

    Create new user and add to DB. Redirect to home page.

    If form not valid, present form.

    If the there already is a user with that username: flash message
    and re-present form.
    """

    if CURR_USER_KEY in session:
        del session[CURR_USER_KEY]
    form = UserAddForm()

    if form.validate_on_submit():
        try:
            user = User.signup(
                username=form.username.data,
                password=form.password.data,
                email=form.email.data,
                image_url=form.image_url.data or User.image_url.default.arg,
            )
            db.session.commit()

        except IntegrityError:
            db.session.rollback()
            flash("Username and/or email already taken", 'danger')

            return render_template('users/signup.html', form=form)

        do_login(user)

        return redirect("/")

    else:
        return render_template('users/signup.html', form=form)


@app.route('/login', methods=["GET", "POST"])
def login():
    """Handle user login and redirect to homepage on success."""

    form = LoginForm()

    if form.validate_on_submit():
        user = User.authenticate(
            form.username.data,
            form.password.data)

        if user:
            do_login(user)
            flash(f"Hello, {user.username}!", "success")
            return redirect("/")

        flash("Invalid credentials.", 'danger')

    return render_template('users/login.html', form=form)


@app.post('/logout')
def logout():
    """Handle logout of user and redirect to homepage."""

    form = g.csrf_form

    if form.validate_on_submit():
        flash(f"Goodbye, {g.user.username}", 'success')
        do_logout()
        return redirect('/')

    else:
        raise Unauthorized()


##############################################################################
# General user routes:

@app.get('/users')
def list_users():
    """Page with listing of users.

    Can take a 'q' param in querystring to search by that username.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    search = request.args.get('q')

    if not search:
        users = User.query.all()
        curr_url = '/users'
    else:
        users = User.query.filter(User.username.like(f"%{search}%")).all()
        curr_url = f'/users?q={search}'

    return render_template(
        'users/index.html',
        users=users,
        form=g.csrf_form,
        curr_url=curr_url
    )


@app.get('/users/<int:user_id>')
def show_user(user_id):
    """Show user profile."""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    user = User.query.get_or_404(user_id)

    return render_template(
        'users/show.html',
        user=user,
        form=g.csrf_form,
        curr_url=f'/users/{user_id}'
    )


@app.get('/users/<int:user_id>/following')
def show_following(user_id):
    """Show list of people this user is following."""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    user = User.query.get_or_404(user_id)
    return render_template(
        'users/following.html',
        user=user,
        form=g.csrf_form,
        curr_url=f'/users/{user_id}/following'
    )


@app.get('/users/<int:user_id>/followers')
def show_followers(user_id):
    """Show list of followers of this user."""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    user = User.query.get_or_404(user_id)
    return render_template(
        'users/followers.html',
        user=user,
        form=g.csrf_form,
        curr_url=f'/users/{user_id}/followers'
    )


@app.post('/users/follow/<int:follow_id>')
def start_following(follow_id):
    """Add a follow for the currently-logged-in user.

    Redirect to following page for the current for the current user.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    form = g.csrf_form

    if form.validate_on_submit():
        try:
            curr_url = request.form['curr-url']

            followed_user = User.query.get_or_404(follow_id)
            g.user.following.append(followed_user)
            db.session.commit()

            # return redirect(f"/users/{g.user.id}/following")
        except IntegrityError:
            db.session.rollback()

        return redirect(curr_url)

    else:
        raise Unauthorized()


@app.post('/users/stop-following/<int:follow_id>')
def stop_following(follow_id):
    """Have currently-logged-in-user stop following this user.

    Redirect to following page for the current for the current user.
    """
    form = g.csrf_form

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    if form.validate_on_submit():
        try:
            curr_url = request.form['curr-url']

            followed_user = User.query.get(follow_id)
            g.user.following.remove(followed_user)
            db.session.commit()

            # return redirect(f"/users/{g.user.id}/following")
        except ValueError:
            print("ValueError occured")
        except StaleDataError:
            print("Already deleted")

        return redirect(curr_url)

    else:
        return Unauthorized()


@app.route('/users/profile', methods=["GET", "POST"])
def profile():
    """Update profile for current user."""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    form = UserUpdateForm(obj=g.user)

    if form.validate_on_submit():
        user = User.authenticate(
            g.user.username,
            form.password.data)

        if user:
            try:
                user.username = form.username.data
                user.email = form.email.data
                user.location = form.location.data
                user.image_url = form.image_url.data or User.image_url.default.arg
                user.header_image_url = (form.header_image_url.data or
                                        User.header_image_url.default.arg)
                user.bio = form.bio.data

                db.session.commit()

                return redirect(f"/users/{g.user.id}")
            except IntegrityError:
                db.session.rollback()
                flash("Username and/or email already taken", 'danger')

        else:
            flash("Invalid username/password", 'danger')

    return render_template('users/edit.html', form=form, user=g.user)


@app.post('/users/delete')
def delete_user():
    """Delete user.

    Redirect to signup page.
    """

    form = g.csrf_form

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    if form.validate_on_submit():

        do_logout()

        try:
            Message.query.filter(Message.user_id == g.user.id).delete()
            db.session.delete(g.user)
            db.session.commit()
        except StaleDataError:
            db.session.rollback()

        return redirect("/signup")

    else:
        raise Unauthorized()


##############################################################################
# Messages routes:

@app.route('/messages/new', methods=["GET", "POST"])
def add_message():
    """Add a message:

    Show form if GET. If valid, update message and redirect to user page.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    form = MessageForm()

    if form.validate_on_submit():
        try:
            msg = Message(text=form.text.data)
            g.user.messages.append(msg)
            db.session.commit()
        except IntegrityError:
            db.session.rollback()

        return redirect(f"/users/{g.user.id}")

    return render_template('messages/create.html', form=form)


@app.get('/messages/<int:message_id>')
def show_message(message_id):
    """Show a message."""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    msg = Message.query.get_or_404(message_id)
    return render_template('messages/show.html', message=msg, form=g.csrf_form)


@app.post('/messages/<int:message_id>/delete')
def delete_message(message_id):
    """Delete a message.

    Check that this message was written by the current user.
    Redirect to user page on success.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    try:
        msg = Message.query.get_or_404(message_id)
        db.session.delete(msg)
        db.session.commit()
    except StaleDataError:
        db.session.rollback()

    return redirect(f"/users/{g.user.id}")

##############################################################################
# Likes


@app.get('/users/<int:user_id>/likes')
def show_liked_messages(user_id):
    """Display all messages user has liked"""

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    user = User.query.get_or_404(user_id)

    return render_template(
        'users/liked_messages.html',
        user=user,
        form=g.csrf_form,
        curr_url=f'/users/{user_id}/likes'
    )


@app.post('/messages/<int:message_id>/like')
def add_like_to_message(message_id):
    """Add message to user's liked messages list.
    Redirect to same page.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    form = g.csrf_form

    if form.validate_on_submit():
        msg = Message.query.get_or_404(message_id)

        # extra check against user liking own post
        if msg.user.id == g.user.id:
            raise Unauthorized()

        curr_url = request.form['curr-url']

        try:
            g.user.liked_messages.append(msg)
            db.session.commit()
        except IntegrityError:
            db.session.rollback()

        return redirect(curr_url)

    else:
        raise Unauthorized()


@app.post('/messages/<int:message_id>/unlike')
def remove_like_from_message(message_id):
    """Remove message from user's liked messages.
    Redirect to same page.
    """

    if not g.user:
        flash("Access unauthorized.", "danger")
        return redirect("/")

    form = g.csrf_form

    if form.validate_on_submit():
        msg = Message.query.get_or_404(message_id)

        # extra check against user liking own post
        if msg.user.id == g.user.id:
            raise Unauthorized()

        curr_url = request.form['curr-url']

        try:
            g.user.liked_messages.remove(msg)
            db.session.commit()
        except ValueError:
            print("ValueError occured")
        except StaleDataError:
            print("Message already deleted")

        return redirect(curr_url)

    else:
        raise Unauthorized()


##############################################################################
# Homepage and error pages


@app.get('/')
def homepage():
    """Show homepage:

    - anon users: no messages
    - logged in: 100 most recent messages of followed_users and own messages
    """

    if g.user:
        user_ids_to_include = [user.id for user in g.user.following]
        user_ids_to_include.append(g.user.id)

        messages = (Message
                    .query
                    .filter(Message.user_id.in_(user_ids_to_include))
                    .order_by(Message.timestamp.desc())
                    .limit(100)
                    .all())

        return render_template('home.html', messages=messages, form=g.csrf_form)

    else:
        return render_template('home-anon.html')


##############################################################################
# Turn off all caching in Flask
#   (useful for dev; in production, this kind of stuff is typically
#   handled elsewhere)
#
# https://stackoverflow.com/questions/34066804/disabling-caching-in-flask

@app.after_request
def add_header(response):
    """Add non-caching headers on every request."""

    # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
    response.cache_control.no_store = True
    return response