app.py

"""
The main code for server. Defines the interface and the logistics of the server.
"""

from flask import Flask, request, render_template, flash, session, redirect, url_for
from flask_sqlalchemy import SQLAlchemy
from werkzeug.security import check_password_hash, generate_password_hash
from db import Users, Books, Item
import sqlalchemy, random
from datetime import datetime, date
# import database connection and server from db file
from db import db as db_connect
from db import app

# Set the secret key to some random bytes. Keep this really secret!
app.secret_key = b'_5#y2L"F4Q8z\n\xec]/'


@app.route("/")
def getBooks():
    """
    Return all books in the database.
    """
    books = Books.query.all()
    if len(books) > 0:
        # render home page with books
        return render_template("home.html", books=books)
    # if there is no book available, render a default layout
    return render_template("layout.html")


@app.route("/index")
def index():
    """
    The main page
    """
    books = Books.query.all()
    if len(books) > 0:
        # render home page with books
        return render_template("home.html", books=books)
    # if there is no book available, render a default layout
    return render_template("layout.html")


@app.route('/register', methods=['POST', 'GET'])
def register():
    """
    Register a new user. 
    Getting username and password and repeated password from submitted form data.
    """
    if request.method == "POST":
        error = None
        # get data 
        username = request.form['username']
        password = request.form['password']
        pwd = request.form['pwd']
        # get the completeness of data 
        if not username:
            error = 'Username is required.'
        elif not password:
            error = 'Password is required.'
        elif not pwd:
            error = 'Password is required.'
        # the completeness check pass
        if error is None:
            if password == pwd:
                try:
                    # try to insert the new user 
                    customer = Users(username=username,
                                        password=generate_password_hash(password))
                    db_connect.session.add(customer)
                    db_connect.session.commit()
                except sqlalchemy.exc.IntegrityError:
                    # there is an existing user
                    error = f"User {username} is already registered."
                else:
                    # unknown error, go back to login 
                    return redirect(url_for("login"))
            else:
                # the repeated password is not the same as original password
                error = "Password is wrong."
        # flash error message to the frontend
        flash(error)
        # return the register page with error message
        return render_template('register.html', error=error)
    else:
        return render_template('register.html')


@app.route('/login', methods=['POST', 'GET'])
def login():
    """
    User login. Getting username and password from submitted form data.
    """
    if request.method == 'POST':
        error = None
        # getting data
        username = request.form['username']
        password = request.form['password']
        # check the completeness of data
        if not username:
            error = 'Username is required.'
        elif not password:
            error = 'Password is required.'
        # get users with the username
        user = Users.query.filter_by(username=username).first()
        # no such user
        if user is None:
            error = 'Incorrect username.'
        # password is invalid
        elif not check_password_hash(user.password, password):
            error = 'Incorrect password.'
        # login successfully 
        if error is None:
            # record the user information in session 
            session.clear()
            session['user_id'] = user.id
            session['username'] = user.username
            # load shopping cart
            items = Item.query.filter_by(user_id=user.id).all()
            if len(items) > 0:
                # generate data for shopping cart
                total_quantity = 0
                total_price = 0
                for item in items:
                    total_quantity += int(item.quantity)
                    total_price += int(item.quantity)*item.trade_price
                session['total_quantity'] = total_quantity
                session['total_price'] = round(total_price,2)
            else:
                session['total_quantity'] = 0
                session['total_price'] = 0
            # render main page
            return redirect(url_for('index'))
        else:
            # return the error message
            flash(error)
            return render_template('login.html', error=error)
    else:
        return render_template("login.html")


@app.route('/stock', methods=['POST', 'GET'])
def stock():
    """
    Get stock for books
    """
    if request.method == 'GET':
        # get all books and return the stock
        books = Books.query.all()
        if len(books) > 0:
            return render_template("stock.html", books=books)
        return render_template("layout.html")


@app.route('/add_stock', methods=['POST', 'GET'])
def add_stock():
    """
    Add stock to the database. 
    """
    if request.method == 'POST':
        error = None
        # get data from the form post
        ISBN = request.form['ISBN']
        bookname = request.form['bookname']
        author = request.form['author']
        public_date = request.form['public_date']
        public_date = datetime.strptime(public_date, '%Y-%m-%d')
        public_date = datetime.combine(
            public_date.today(), datetime.min.time())
        description = request.form['description']
        # getting the image file 
        picture_url = request.files.get('picture_url')
        # only allow images
        ALLOWED_EXTENSIONS = ['png', 'jpg', 'jpeg', 'gif','jfif']
        # if the image exists
        if picture_url is not None and '.' in picture_url.filename and picture_url.filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS:
                # create a random file name with time and a random number
                picpath = './static/images/'
                nowTime = datetime.now().strftime("%Y%m%d%H%M%S")  
                randomNum = random.randint(0, 100) 
                randomNum = str(randomNum).zfill(3)
                uniqueNum = nowTime + randomNum
                picurl = picpath + uniqueNum + "_" +picture_url.filename
                # actually save the file to disk
                picture_url.save(picurl)
                picture_url = uniqueNum + "_" +picture_url.filename
        # get rest data
        trade_price = request.form['trade_price']
        retail_price = request.form['retail_price']
        quantity = request.form['quantity']
        # check the completeness of data
        if ISBN and bookname and author and public_date and description and picture_url and trade_price and retail_price and quantity:
            # change the type of bookname, price, quantity
            trade_price = int(trade_price)
            retail_price = int(retail_price)
            quantity = int(quantity)
            # check whether there is a book with the same ISBN
            book = Books.query.filter_by(ISBN=ISBN).first()
            if book is None:
                # create a new book
                new_book = Books(ISBN=ISBN, bookname=bookname, author=author, public_date=public_date, description=description,
                                 picture_url=picture_url, trade_price=trade_price, retail_price=retail_price, quantity=quantity)
                db_connect.session.add(new_book)
                db_connect.session.commit()
                return redirect(url_for("stock"))
            else:
                # update the existing book data
                book.bookname = bookname
                book.author = author
                book.published_date = public_date
                book.description = description
                book.picture_url = picture_url
                book.trade_price = trade_price
                book.retail_price = retail_price
                book.quantity = quantity
                db_connect.session.commit()
                return redirect(url_for("stock"))
        else:
            error = "Something is required."
        if error is not None:
            flash(error)
            return render_template('add_stock.html', error=error)
    else:
        return render_template("add_stock.html")


@app.route('/cart', methods=['POST', 'GET'])
def cart():
    """
    Get the cart data or add a book to the cart.
    Method GET: getting data.
    Method POST: adding new book.
    """
    # get current user
    user_id = session['user_id']
    if request.method == 'POST':
        # add new book 
        error = None
        # add the book information
        ISBN = request.form['ISBN']
        quantity = request.form['quantity']
        # data is valid 
        if ISBN and quantity:
            # get all books
            book = Books.query.filter_by(ISBN=ISBN).first()
            if book is not None:
                # check the quantity of the book
                item = Item.query.filter_by(
                    ISBN=ISBN, user_id=user_id).first()
                # the book is existed in shopping cart
                if item is not None:
                    item.quantity = item.quantity + int(quantity)
                    if item.quantity > book.quantity:
                        item.quantity = book.quantity
                        if item.quantity == 0:
                            error = "The stock of the book is not enough."
                            return redirect(url_for('index'))
                    db_connect.session.commit()
                    # update the total price of the cart
                    items = Item.query.filter_by(user_id=user_id).all()
                    if len(items) > 0:
                        total_quantity = 0
                        total_price = 0
                        for item in items:
                            total_quantity += int(item.quantity)
                            total_price += int(item.quantity)*item.trade_price
                        session['total_quantity'] = total_quantity
                        session['total_price'] = round(total_price,2)
                        return render_template("cart.html", items=items)
                    return render_template("cart.html")
                else:
                    # add a new book to shopping cart
                    # check the quantity of book
                    if int(quantity) > book.quantity:
                        quantity = book.quantity
                        if quantity == 0:
                            error = "The stock of the book is not enough."
                            return redirect(url_for('index'))
                    # add a new book to the shopping cart
                    new_item = Item(
                        ISBN=ISBN, user_id=user_id, quantity=quantity, bookname=book.bookname, trade_price=book.trade_price, picture_url=book.picture_url)
                    db_connect.session.add(new_item)
                    db_connect.session.commit()
                    items = Item.query.filter_by(user_id=user_id).all()
                    # update the price
                    if len(items) > 0:
                        total_quantity = 0
                        total_price = 0
                        for item in items:
                            total_quantity += int(item.quantity)
                            total_price += int(item.quantity)*item.trade_price
                        session['total_quantity'] = total_quantity
                        session['total_price'] = round(total_price,2)
                        return render_template("cart.html", items=items)
                    return render_template("cart.html")
            else:
                error = "The book is not exist."
                return redirect(url_for('index'))
        else:
            error = "Something wrong."
            return redirect(url_for('index'))
    else:
        # getting shopping cart data
        try:
            # query all items
            items = Item.query.filter_by(user_id=user_id).all()
            # update price
            if len(items) > 0:
                total_quantity = 0
                total_price = 0
                for item in items:
                    total_quantity += int(item.quantity)
                    total_price += int(item.quantity)*item.trade_price
                session['total_quantity'] = total_quantity
                session['total_price'] = round(total_price,2)
                # render page with data
                return render_template("cart.html", items=items)
            return render_template("cart.html")
        except Exception as e:
            print(e)
            return render_template("cart.html")


@app.route('/delete_item', methods=['POST'])
def delete_item():
    """
    Delete a book from cart.
    """
    user_id = session['user_id']
    error = None
    # get the book to delete
    item_id = request.form['item_id']
    # get all books in the cart
    item = Item.query.filter_by(item_id=item_id, user_id=user_id).first()
    if item is not None:
        # find the corresponding item
        Item.query.filter_by(item_id=item_id, user_id=user_id).delete()
        db_connect.session.commit()
        items = Item.query.filter_by(user_id=user_id).all()
        # update the total price
        if len(items) > 0:
            total_quantity = 0
            total_price = 0
            for item in items:
                total_quantity += int(item.quantity)
                total_price += int(item.quantity)*item.trade_price
            session['total_quantity'] = total_quantity
            session['total_price'] = round(total_price,2)
            return render_template("cart.html", items=items)
        else:
            # delete all books, set the price and quantity to 0
            session['total_quantity'] = 0
            session['total_price'] = 0
            books = Books.query.all()
            if len(books) > 0:
                return render_template("home.html", books=books)
            return render_template("layout.html")


@app.route('/empty_cart', methods=['POST', 'GET'])
def empty_cart():
    """
    Empty the cart, would delete all books from it.
    """
    if request.method == 'GET':
        # get current user
        user_id = session['user_id']
        # get and delete all books in cart
        Item.query.filter_by(user_id=user_id).delete()
        db_connect.session.commit()
        # update the total price
        session['total_quantity'] = 0
        session['total_price'] = 0
        # render books
        books = Books.query.all()
        if len(books) > 0:
            return render_template("home.html", books=books)
        return render_template("layout.html")


@app.route('/checkout', methods=['POST', 'GET'])
def checkout():
    """
    Checkout page. Would check the cart and generate an order.
    """
    session['total'] = 0
    if request.method == 'GET':
        # get current user
        user_id = session['user_id']
        # get all items in cart
        items = Item.query.filter_by(user_id=user_id).all()
        for item in items:
            # check the quantity of each book 
            book = Books.query.filter_by(ISBN = item.ISBN).first()
            if item.quantity > book.quantity:
                item.quantity = book.quantity
            # computing postage and final price
            if item.quantity > 0:
                item.postage = 3+int(item.quantity) - 1
                item.total_price = item.postage + int(item.quantity)*item.trade_price
            else:
                item.postage = 0
                item.total_price = 0
            session['total'] += item.total_price
            session['total'] = round(session['total'],2)
        return render_template('checkout.html', items=items)

@app.route('/pay', methods=['POST','GET'])
def pay():
    """
    Make a payment
    """
    if request.method == 'POST':
        # get the payment information
        card = request.form['card']
        month = request.form['month']
        year = request.form['year']
        cvv = request.form['cvv']
        user_id = session['user_id']
        items = Item.query.filter_by(user_id = user_id).all()
        # we do not perform actual payment here
        for item in items:
            # update the quantity of each purchased book.
            book = Books.query.filter_by(ISBN=item.ISBN).first()
            if book.quantity > item.quantity:
                book.quantity -= int(item.quantity)
            else:
                book.quantity = 0
            db_connect.session.commit()
        # update the shopping cart
        Item.query.filter_by(user_id=user_id).delete()
        db_connect.session.commit()
        session['total'] = 0
        session['total_quantity'] = 0
        session['total_price'] = 0
        books = Books.query.all()
        if len(books) > 0:
            return render_template("home.html", books=books)
        return render_template("layout.html")
    else:
        return render_template('pay.html')

@app.route('/logout', methods=['POST', 'GET'])
def logout():
    """
    Logout. Clear the session.
    """
    session.clear()
    return redirect(url_for('index'))

if __name__ == '__main__':
    app.run("127.0.0.1", port=5000)