const axios = require('axios');
const express = require('express');
const https = require('https');
const fs = require('fs');
const path = require('path');
const sqlite3 = require('sqlite3').verbose();
const bodyParser = require('body-parser');
const nodemailer = require('nodemailer'); // Add nodemailer for sending emails
const rateLimit = require('express-rate-limit'); // Ensure this line is present
const basicAuth = require('express-basic-auth'); // Add express-basic-auth

const library = require('./library');
const {
    fetchBookFromLocalDatabase,
    fetchBookFromGoogleBooks,
    fetchBookFromOpenLibrary,
    fetchBookFromInternetArchive,
    searchBooksInLocalDatabase,
    searchBooksInOpenLibrary
} = require('./bookHelpers'); // Import the helper functions from the new file

require('dotenv').config();

const { Book, Location, Checkout, User } = require('./models');
const { Op } = require('sequelize'); // Import Sequelize Operators
const app = express();
const PORT = process.env.PORT || 3000;

// SSL certificate paths
const privateKey = fs.readFileSync(path.join(__dirname, 'server.key'), 'utf8');
const certificate = fs.readFileSync(path.join(__dirname, 'server.cert'), 'utf8');

const credentials = { key: privateKey, cert: certificate };

// Middleware to parse JSON bodies
app.use(express.json()); // Use built-in body-parser for JSON


// Serve static files from the 'public' directory
app.use(express.static(path.join(__dirname, 'public')));

// Basic Auth middleware
const authMiddleware = basicAuth({
    users: { 'admin': process.env.ADMIN_PASSWORD }, // Use environment variable for password
    challenge: true,
    unauthorizedResponse: (req) => 'Unauthorized'
});

// Apply auth middleware to all non-GET requests except for checkout
app.use((req, res, next) => {
    if (req.method !== 'GET' && !req.path.startsWith('/api/checkout')) {
        return authMiddleware(req, res, next);
    }
    next();
});

app.get('/book/:isbn', async (req, res) => {
    const { isbn } = req.params;
    console.log(`Fetching book data for ISBN: ${isbn}`);

    try {
        // Check if the book is in the local database
        const localBook = await fetchBookFromLocalDatabase(isbn);

        if (localBook) {
            console.log('Book found in the local database');
            return res.json({ source: 'local', data: localBook });
        }

        // If not found locally, try external sources
        const googleBooksApiKey = 'AIzaSyCQikthZ5TlkFTcKTG8n171dRafosK2Mg8';

        try {
            const googleBookData = await fetchBookFromGoogleBooks(isbn, googleBooksApiKey);
            if (googleBookData) {
                console.log('Book data found in Google Books');
                return res.json({ source: 'external', data: googleBookData });
            }
        } catch (errorStatus) {
            if (errorStatus === 429) {
                console.log('Rate limit exceeded for Google Books');
                return res.status(429).json({ error: 'Rate limit exceeded' });
            } else if (errorStatus === 408) {
                console.log('Request Timeout for Google Books');
                return res.status(408).json({ error: 'Request Timeout' });
            }
        }

        try {
            const openLibraryData = await fetchBookFromOpenLibrary(isbn);
            if (openLibraryData) {
                console.log('Book data found in Open Library');
                return res.json({ source: 'external', data: openLibraryData });
            }
        } catch (errorStatus) {
            if (errorStatus === 429) {
                console.log('Rate limit exceeded for Open Library');
                return res.status(429).json({ error: 'Rate limit exceeded' });
            } else if (errorStatus === 408) {
                console.log('Request Timeout for Open Library');
                return res.status(408).json({ error: 'Request Timeout' });
            }
        }

        const archiveData = await fetchBookFromInternetArchive(isbn);
        if (archiveData) {
            console.log('Book data found in the Internet Archive');
            return res.json({ source: 'external', data: archiveData });
        }

        console.log('Book not found in any source');
        return res.status(404).json({ error: 'Book not found' });

    } catch (error) {
        console.error(error);
        return res.status(500).json({ error: 'Failed to fetch book data' });
    }
});

// New API endpoint to fetch books with images
app.get('/api/books-with-images', async (req, res) => {
    try {
        const books = await Book.findAll({
            where: {
                [Op.or]: [
                    { cover_small: { [Op.ne]: null } },
                    { cover_medium: { [Op.ne]: null } },
                    { cover_large: { [Op.ne]: null } },
                ],
            },
            attributes: ['isbn', 'title', 'cover_small', 'cover_medium', 'cover_large', 'authors'],
        });
        // CORRECTED DEBUG LOGGING ON SERVER
        if (books && books.length > 0) {
            // Log a specific book if its ID is known, e.g., ID 207 for Artemis Fowl
            const specificBookForDebug = books.find(b => b.id === 207);
            if (specificBookForDebug) {
                console.log("Server-side specific book from /api/books (ID 207):", JSON.stringify(specificBookForDebug, null, 2));
            } else {
                console.log("Server-side book ID 207 not found in /api/books results, logging first book instead:", JSON.stringify(books[0], null, 2));
            }
        }
        res.json(books);
    } catch (error) {
        console.error('Failed to fetch books with images:', error);
        res.status(500).json({ error: 'Error fetching books with images' });
    }
});

app.post('/api/refetch-cover-images', async (req, res) => {
    try {
        await refetchCoverImages();
        res.json({ success: true, message: 'Cover images re-fetching initiated.' });
    } catch (error) {
        console.error('Failed to re-fetch cover images:', error.message);
        res.status(500).json({ error: 'Failed to re-fetch cover images' });
    }
});


async function refetchCoverImages() {
    const googleBooksApiKey = process.env.GOOGLE_BOOKS_API_KEY;
    console.log(googleBooksApiKey)

    try {
        // Fetch all books from the database
        const books = await Book.findAll();

        for (const book of books) {
            const isbn = book.isbn;

            // Fetch data from Google Books API

            const url = `https://www.googleapis.com/books/v1/volumes?q=isbn:${isbn}&key=${googleBooksApiKey}`;
            
            console.log(url)
            try {
                // Wait a second before making the next request
                await new Promise(resolve => setTimeout(resolve, 1000));
                const response = await axios.get(url);

                if (response.data.totalItems > 0) {
                    const volumeInfo = response.data.items[0].volumeInfo;

                    // Extract new cover image URLs
                    const imageLinks = volumeInfo.imageLinks || {};
                    const cover_small = imageLinks.smallThumbnail || null;
                    const cover_medium = imageLinks.thumbnail || null;
                    const cover_large = imageLinks.large || null;

                    // Update the book entry if any new image URLs are found
                    if (cover_small || cover_medium || cover_large) {
                        await book.update({
                            cover_small: cover_small || book.cover_small,
                            cover_medium: cover_medium || book.cover_medium,
                            cover_large: cover_large || book.cover_large,
                        });

                        console.log(`Updated cover images for ISBN: ${isbn}`);
                    } else {
                        console.log(`No new cover images found for ISBN: ${isbn}`);
                    }
                } else {
                    console.log(`No data found in Google Books for ISBN: ${isbn}`);
                }
            } catch (error) {
                if (error.response && error.response.status === 429) {
                    console.error('Rate limit exceeded. Pausing requests.');
                    // Implement a delay or exit the loop if necessary
                    await new Promise(resolve => setTimeout(resolve, 10000));
                    
                } else {
                    console.error(`Error fetching data for ISBN: ${isbn}`, error.message);
                }
            }
        }

        console.log('Cover image re-fetching completed.');
    } catch (error) {
        console.error('Failed to re-fetch cover images:', error.message);
    }
}



app.post('/api/refetch-book-data', async (req, res) => {
    // Handle start index for pagination, start index is in json body
    const { startIndex = 0 } = req.body;
    try {
        await refetchBookData(startIndex);
        res.json({ success: true, message: 'Book data re-fetching initiated.' });
    } catch (error) {
        console.error('Failed to re-fetch book data:', error.message);
        res.status(500).json({ error: 'Failed to re-fetch book data' });
    }
});

async function refetchBookData(startIndex = 0) {
    const googleBooksApiKey = process.env.GOOGLE_BOOKS_API_KEY;

    try {
        // Fetch all books from the database
        const books = await Book.findAll();

        console.log(`Found ${books.length} books to update.`);
        console.log(`Starting from index: ${startIndex}`);

        for (const [index, book] of books.entries()) {
            if (index < startIndex) {
                continue;
            }
            const isbn = book.isbn;

            // Fetch data from Google Books API
            const url = `https://www.googleapis.com/books/v1/volumes?q=isbn:${isbn}&key=${googleBooksApiKey}`;

            try {
                const response = await axios.get(url);

                if (response.data.totalItems > 0) {
                    const volumeInfo = response.data.items[0].volumeInfo;

                    // Extract data from the API response
                    const updatedData = {
                        title: volumeInfo.title || book.title,
                        authors: volumeInfo.authors ? volumeInfo.authors.join(', ') : book.authors,
                        publishedDate: volumeInfo.publishedDate || book.publishedDate,
                        description: volumeInfo.description || book.description,
                        number_of_pages: volumeInfo.pageCount || book.number_of_pages,
                        publishers: volumeInfo.publisher || book.publishers,
                        subjects: volumeInfo.categories ? volumeInfo.categories.join(', ') : book.subjects,
                        cover_small: volumeInfo.imageLinks ? volumeInfo.imageLinks.smallThumbnail : book.cover_small,
                        cover_medium: volumeInfo.imageLinks ? volumeInfo.imageLinks.thumbnail : book.cover_medium,
                        cover_large: volumeInfo.imageLinks ? volumeInfo.imageLinks.large : book.cover_large,
                        // Add more fields as necessary
                    };

                    // Update the book entry in the database
                    await book.update(updatedData);

                    console.log(`[${index + 1}/${books.length}] Updated data for ISBN: ${isbn}`);
                } else {
                    console.log(`[${index + 1}/${books.length}] No data found in Google Books for ISBN: ${isbn}`);
                }
            } catch (error) {
                if (error.response && error.response.status === 429) {
                    console.error('Rate limit exceeded. Pausing requests.');
                    // Implement a delay
                    await delay(10000); // Delay for 10 seconds
                    index--; // Retry the current book
                } else {
                    console.error(`Error fetching data for ISBN: ${isbn}`, error.message);
                }
            }

            // Delay between requests to respect rate limits
            await delay(1000); // Adjust the delay as needed
        }

        console.log('Book data re-fetching completed.');
    } catch (error) {
        console.error('Failed to re-fetch book data:', error.message);
    }
}

// Utility function to add delay
function delay(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

// Confirm book is in the library by ISBN
app.get('/book/confirm/:isbn', async (req, res) => {
    const { isbn } = req.params;
    console.log(`Cascade: /book/confirm/:isbn - Confirming ISBN: ${isbn}`);

    try {
        // Check if the book is in the local database
        const localBook = await fetchBookFromLocalDatabase(isbn);

        if (localBook) {
            console.log('Cascade: /book/confirm/:isbn - Book found in local database.');
            return res.json({ source: 'local', data: localBook });
        } else {
            console.log('Cascade: /book/confirm/:isbn - Book NOT found in local database.');
            return res.status(404).json({ error: 'Book not found in local library' });
        }
    } catch (error) {
        console.error('Cascade: /book/confirm/:isbn - Error during lookup:', error);
        return res.status(500).json({ error: 'Failed to confirm book in local library' });
    }
});

app.get('/search-title', async (req, res) => {
    const { title, internalOnly = false } = req.query;
    console.log(`Searching for books by title or related fields: ${title}`);

    try {
        const localBooks = await searchBooksInLocalDatabase(title);

        if (localBooks.length > 0) {
            console.log('Books found in the local database');
            return res.json({ source: 'local', results: localBooks });
        }

        if (internalOnly) {
            return res.status(404).json({ error: 'No books found with that title or related fields.' });
        }

        const externalBooks = await searchBooksInOpenLibrary(title);

        if (externalBooks.length > 0) {
            console.log('Books found by title in external sources');
            return res.json({ source: 'external', results: externalBooks });
        } else {
            return res.status(404).json({ error: 'No books found with that title or related fields.' });
        }

    } catch (error) {
        console.error(error);
        return res.status(500).json({ error: 'Failed to search for book by title or related fields' });
    }
});


// Endpoint to store book in the database
app.post('/store-book', async (req, res) => {
    try {
        const book = await Book.create(req.body);
        res.json({ success: true, book });
    } catch (error) {
        console.error('Failed to store book:', error);
        res.status(500).json({ error: 'Failed to store book in database' });
    }
});

app.put('/book/:isbn', async (req, res) => {
    try {
        const { isbn } = req.params;
        const book = await Book.findOne({ where: { isbn } });
        if (book) {
            await book.update(req.body);
            res.json({ success: true, message: 'Book updated successfully' });
        } else {
            res.status(404).json({ error: 'Book not found' });
        }
    } catch (error) {
        console.error('Failed to update book:', error);
        res.status(500).json({ error: 'Failed to update book in database' });
    }
});

app.delete('/book/:id', async (req, res) => {
    try {
        const { id } = req.params;
        const book = await Book.findByPk(id);
        if (book) {
            await book.destroy();
            res.json({ success: true, message: 'Book deleted successfully' });
        } else {
            res.status(404).json({ error: 'Book not found' });
        }
    } catch (error) {
        console.error('Failed to delete book:', error);
        res.status(500).json({ error: 'Failed to delete book from database' });
    }
});

app.get('/api/locations', async (req, res) => {
    try {
        const locations = await Location.findAll({
            order: [
                ['name', 'ASC'],
                ['shelf', 'ASC']
            ]
        });
        res.json(locations);
    } catch (error) {
        console.error('Failed to fetch locations:', error);
        res.status(500).json({ error: 'Failed to fetch locations' });
    }
});

app.post('/location', async (req, res) => {
    try {
        console.debug('Creating location:', req.body);
        const location = await Location.create(req.body);
        res.json({ success: true, location });
    } catch (error) {
        console.error('Failed to create location:', error);
        res.status(500).json({ error: 'Failed to create location' });
    }
});

app.get('/location/:id', async (req, res) => {
    try {
        const { id } = req.params;
        const location = await Location.findByPk(id);
        if (location) {
            res.json(location);
        } else {
            res.status(404).json({ error: 'Location not found' });
        }
    } catch (error) {
        console.error('Failed to fetch location:', error);
        res.status(500).json({ error: 'Failed to fetch location' });
    }
});

// Configure nodemailer with your own server
const transporter = nodemailer.createTransport({
    host: 'mail.uplink.tel', // Replace with your SMTP server
    port: 465, // Replace with your SMTP port (587 is common for TLS)
    secure: true, // Set to true if using port 465
    auth: {
        user: process.env.ADMIN_EMAIL, // Admin email
        pass: process.env.EMAIL_PASSWORD // Email password
    },
    tls: {
        rejectUnauthorized: false // Use this if you encounter certificate issues
    }
});

// Rate limiter middleware
const checkoutLimiter = rateLimit({
    windowMs: 24 * 60 * 60 * 1000, // 24 hours
    max: 5, // Limit each email to 5 requests per windowMs
    keyGenerator: (req) => req.body.email, // Use email as the key
    handler: (req, res) => {
        res.status(429).json({ error: 'Too many requests, please try again later.' });
    }
});

// New endpoint to handle checkout requests
app.post('/api/checkout/:isbn', checkoutLimiter, async (req, res) => {
    const { isbn } = req.params;
    const { email, name } = req.body; // Ensure name is also captured
    const ip = req.ip;

    try {
        const book = await Book.findOne({ where: { isbn } });
        if (book) {
            // Update book status to Pending
            await book.update({ status: 'Pending' });

            // Find or create the user in the User table
            const [user, created] = await User.findOrCreate({
                where: { email },
                defaults: { name }
            });

            // Create a new checkout record
            await Checkout.create({
                book_id: book.id,
                user_id: user.id,
                checkout_date: new Date()
            });

            // Log the requestor's email and IP
            console.log(`Checkout requested by ${email} from IP: ${ip}`);

            // Send email to admin
            const mailOptions = {
                from: process.env.ADMIN_EMAIL,
                to: process.env.ADMIN_EMAIL,
                subject: `Checkout Request for ISBN: ${isbn}`,
                html: `
                    <p>A checkout request has been made. Please review and approve.</p>
                    <table style="border: 1px solid black; border-collapse: collapse; width: 100%;">
                        <tr style="background-color: black; color: white;">
                            <th style="border: 1px solid black; padding: 8px;">Book Title</th>
                            <th style="border: 1px solid black; padding: 8px;">ISBN</th>
                            <th style="border: 1px solid black; padding: 8px;">Requestor Email</th>
                            <th style="border: 1px solid black; padding: 8px;">Requestor Name</th>
                        </tr>
                        <tr>
                            <td style="border: 1px solid black; padding: 8px;">${book.title}</td>
                            <td style="border: 1px solid black; padding: 8px;">${isbn}</td>
                            <td style="border: 1px solid black; padding: 8px;">${email}</td>
                            <td style="border: 1px solid black; padding: 8px;">${name}</td>
                        </tr>
                    </table>
                    <a href="${process.env.DOMAIN}/api/approve-checkout/${isbn}/${email}" style="margin-right: 10px; padding: 10px; background-color: green; color: white; text-decoration: none;">Approve</a>
                    <a href="${process.env.DOMAIN}/api/deny-checkout/${isbn}/${email}" style="padding: 10px; background-color: red; color: white; text-decoration: none;">Deny</a>
                `
            };

            transporter.sendMail(mailOptions, (error, info) => {
                if (error) {
                    console.error('Error sending email:', error);
                    return res.status(500).json({ error: 'Failed to send email' });
                }
                console.log('Email sent:', info.response);
                res.json({ success: true, message: 'Checkout request sent and status updated to Pending.' });
            });
        } else {
            res.status(404).json({ error: 'Book not found' });
        }
    } catch (error) {
        console.error('Failed to process checkout request:', error);
        res.status(500).json({ error: 'Failed to process checkout request' });
    }
});

// Endpoint to approve checkout request
app.get('/api/approve-checkout/:isbn/:email', async (req, res) => {
    const { isbn, email } = req.params;

    try {
        const book = await Book.findOne({ where: { isbn } });
        if (book && book.status === 'Pending') {
            // Find the checkout record
            const checkout = await Checkout.findOne({
                where: {
                    book_id: book.id,
                    user_id: (await User.findOne({ where: { email } })).id,
                    approved: false
                }
            });

            if (checkout) {
                // Set the checkout date to now and return date to one month from now
                const checkoutDate = new Date();
                const returnDate = new Date();
                returnDate.setMonth(returnDate.getMonth() + 1);

                await checkout.update({
                    approved: true,
                    checkout_date: checkoutDate,
                    return_date: returnDate
                });

                await book.update({ status: 'Checked Out' });

                // Send email to the requesting user
                const mailOptions = {
                    from: process.env.ADMIN_EMAIL,
                    to: email,
                    subject: `Checkout Approved for ISBN: ${isbn}`,
                    html: `
                        <p>Your checkout request for the book with ISBN: ${isbn} has been approved.</p>
                        <p>Checkout Date: ${checkoutDate.toDateString()}</p>
                        <p>Return Date: ${returnDate.toDateString()}</p>
                    `
                };

                transporter.sendMail(mailOptions, (error, info) => {
                    if (error) {
                        console.error('Error sending email:', error);
                        return res.status(500).json({ error: 'Failed to send approval email' });
                    }
                    console.log('Approval email sent:', info.response);
                    res.json({ success: true, message: 'Checkout approved and user notified.' });
                });
            } else {
                res.status(404).json({ error: 'Checkout record not found or already approved' });
            }
        } else {
            res.status(404).json({ error: 'Book not found or not Pending' });
        }
    } catch (error) {
        console.error('Failed to approve checkout request:', error);
        res.status(500).json({ error: 'Failed to approve checkout request' });
    }
});

// Endpoint to deny checkout request
app.get('/api/deny-checkout/:isbn/:email', async (req, res) => {
    const { isbn, email } = req.params;

    try {
        const book = await Book.findOne({ where: { isbn } });
        if (book && book.status === 'Pending') {
            await book.update({ status: null });

            // Send email to the requesting user
            const mailOptions = {
                from: process.env.ADMIN_EMAIL,
                to: email,
                subject: `Checkout Denied for ISBN: ${isbn}`,
                text: `Your checkout request for the book with ISBN: ${isbn} has been denied.`
            };

            transporter.sendMail(mailOptions, (error, info) => {
                if (error) {
                    console.error('Error sending email:', error);
                    return res.status(500).json({ error: 'Failed to send denial email' });
                }
                console.log('Denial email sent:', info.response);
                res.json({ success: true, message: 'Checkout denied and user notified.' });
            });
        } else {
            res.status(404).json({ error: 'Book not found or not Pending' });
        }
    } catch (error) {
        console.error('Failed to deny checkout request:', error);
        res.status(500).json({ error: 'Failed to deny checkout request' });
    }
});

// Utility function to get a cookie by name
function getCookie(name) {
    const value = `; ${document.cookie}`;
    const parts = value.split(`; ${name}=`);
    if (parts.length === 2) return parts.pop().split(';').shift();
}

// Utility function to set a cookie
function setCookie(name, value, days) {
    const date = new Date();
    date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
    const expires = `expires=${date.toUTCString()}`;
    document.cookie = `${name}=${value}; ${expires}; path=/`;
}

// Client-side function to request checkout
function requestCheckout(isbn) {
    fetch(`/api/checkout/${isbn}`, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json'
        }
    })
    .then(response => response.json())
    .then(data => {
        if (data.success) {
            alert('Checkout request sent successfully.');
        } else {
            alert('Failed to send checkout request.');
        }
    })
    .catch(error => {
        console.error('Error:', error);
        alert('An error occurred while sending the checkout request.');
    });
}

// API endpoint to get all books
app.get('/api/books', async (req, res) => {
    try {
        const books = await Book.findAll({
            include: [{
                model: Location,
                as: 'Location' // Corrected alias based on model definition
            }],
            order: [['title', 'ASC']]
        });
        res.json(books.map(book => ({
            id: book.id,
            title: book.title,
            authors: book.authors,
            isbn: book.isbn,
            publishedDate: book.publishedDate,
            description: book.description,
            cover_small: book.cover_small,
            number_of_pages: book.number_of_pages,
            publishers: book.publishers,
            subjects: book.subjects,
            location_id: book.location_id,
            Location: book.Location ? { id: book.Location.id, name: book.Location.name, room: book.Location.room, shelf: book.Location.shelf } : null
        })));
    } catch (error) {
        console.error('Failed to fetch books:', error);
        res.status(500).json({ error: 'Failed to fetch books' });
    }
});

// API endpoint to add a new book
app.post('/api/books', async (req, res) => {
    try {
        const {
            title,
            authors,
            publishedDate,
            description,
            isbn,
            number_of_pages,
            publishers,
            subjects,
            cover_small,
            cover_medium,
            cover_large,
            location_id
        } = req.body;

        // Basic validation (e.g., title is required)
        if (!title) {
            return res.status(400).json({ error: 'Title is required' });
        }

        const newBookData = {
            title,
            authors: Array.isArray(authors) ? authors.join(', ') : authors,
            publishedDate,
            description,
            isbn,
            number_of_pages,
            publishers: Array.isArray(publishers) ? publishers.join(', ') : publishers,
            subjects: Array.isArray(subjects) ? subjects.join(', ') : subjects,
            cover_small,
            cover_medium,
            cover_large,
            location_id: location_id === '' ? null : location_id // Handle empty string as null
        };

        const book = await Book.create(newBookData);
        
        // Fetch the newly created book with its location to send back in the response
        const createdBookWithLocation = await Book.findByPk(book.id, {
            include: [{
                model: Location,
                as: 'Location'
            }]
        });

        res.status(201).json({ success: true, book: createdBookWithLocation });
    } catch (error) {
        console.error('Failed to add new book:', error);
        if (error.name === 'SequelizeUniqueConstraintError') {
            let errorMessage = 'Failed to add new book due to a conflict.';
            // Assuming 'isbn' is a unique field in your Book model
            if (error.fields && typeof error.fields === 'object' && 'isbn' in error.fields) { 
                errorMessage = 'A book with this ISBN already exists. Please use the edit feature if you want to update it.';
            }
            return res.status(409).json({ error: errorMessage });
        }
        res.status(500).json({ error: 'Failed to add new book' });
    }
});

// API endpoint to update a book's metadata by its primary key ID
app.put('/api/books/:id', async (req, res) => {
    try {
        const bookId = req.params.id;
        const book = await Book.findByPk(bookId);

        if (!book) {
            return res.status(404).json({ error: 'Book not found' });
        }

        const {
            title,
            authors,
            publishedDate,
            description,
            isbn,
            number_of_pages,
            publishers,
            subjects,
            cover_small,
            cover_medium,
            cover_large,
            location_id // Added to handle location updates
        } = req.body;

        const updateData = {};
        if (title !== undefined) updateData.title = title;
        if (authors !== undefined) updateData.authors = Array.isArray(authors) ? authors.join(', ') : authors;
        if (publishedDate !== undefined) updateData.publishedDate = publishedDate;
        if (description !== undefined) updateData.description = description;
        if (isbn !== undefined) updateData.isbn = isbn === '' ? null : isbn;
        if (number_of_pages !== undefined) updateData.number_of_pages = number_of_pages;
        if (publishers !== undefined) updateData.publishers = Array.isArray(publishers) ? publishers.join(', ') : publishers;
        if (subjects !== undefined) updateData.subjects = Array.isArray(subjects) ? subjects.join(', ') : subjects;
        if (cover_small !== undefined) updateData.cover_small = cover_small;
        if (cover_medium !== undefined) updateData.cover_medium = cover_medium;
        if (cover_large !== undefined) updateData.cover_large = cover_large;
        if (location_id !== undefined) updateData.location_id = location_id === '' ? null : location_id; // Handle empty string as null

        await book.update(updateData);
        console.log(`Book data for ID ${bookId} updated successfully.`);
        
        // Fetch the updated book with its location to send back in the response
        const updatedBookWithLocation = await Book.findByPk(bookId, {
            include: [{
                model: Location,
                as: 'Location'
            }]
        });
        res.json({ success: true, book: updatedBookWithLocation });

    } catch (error) {
        console.error(`Failed to update book with ID ${req.params.id}:`, error);
        res.status(500).json({ error: 'Failed to update book' });
    }
});

const httpsServer = https.createServer(credentials, app);


httpsServer.listen(PORT, () => {
    console.log(`HTTPS Server running on https://localhost:${PORT}`);
});

app.get('/api/books-on-loan', async (req, res) => {
    try {
        const loans = await Checkout.findAll({
            where: {
                returned_date: null
            },
            include: [
                {
                    model: Book,
                    attributes: ['isbn', 'title']
                },
                {
                    model: User,
                    attributes: ['name']
                }
            ],
            attributes: ['checkout_date', 'return_date']
        });

        const result = loans.map(loan => ({
            isbn: loan.Book.isbn,
            title: loan.Book.title,
            name: loan.User.name,
            checkout_date: loan.checkout_date,
            return_date: loan.return_date
        }));

        res.json(result);
    } catch (error) {
        console.error('Error fetching books on loan:', error);
        res.status(500).send('Internal Server Error');
    }
});

app.post('/book/update/:isbn', authMiddleware, async (req, res) => { // Added authMiddleware for consistency
    const { isbn } = req.params;
    const googleBooksApiKey = process.env.GOOGLE_BOOKS_API_KEY;

    try {
        // Fetch data from Google Books API
        const url = `https://www.googleapis.com/books/v1/volumes?q=isbn:${isbn}&key=${googleBooksApiKey}`;
        const response = await axios.get(url);

        if (response.data.totalItems > 0) {
            const volumeInfo = response.data.items[0].volumeInfo;

            // Extract data from the API response
            const updatedData = {
                title: volumeInfo.title || null,
                authors: volumeInfo.authors ? volumeInfo.authors.join(', ') : null,
                publishedDate: volumeInfo.publishedDate || null,
                description: volumeInfo.description || null,
                number_of_pages: volumeInfo.pageCount || null,
                publishers: volumeInfo.publisher || null,
                subjects: volumeInfo.categories ? volumeInfo.categories.join(', ') : null,
                cover_small: volumeInfo.imageLinks ? volumeInfo.imageLinks.smallThumbnail : null,
                cover_medium: volumeInfo.imageLinks ? volumeInfo.imageLinks.thumbnail : null,
                cover_large: volumeInfo.imageLinks ? volumeInfo.imageLinks.large : null,
                // Add more fields as needed
            };

            // Update the book entry in the database
            const book = await Book.findOne({ where: { isbn } });

            if (book) {
                await book.update(updatedData);
                console.log(`Book data for ISBN ${isbn} updated.`);
                res.json({ success: true, book: updatedData });
            } else {
                res.status(404).json({ error: 'Book not found in local database' });
            }
        } else {
            res.status(404).json({ error: 'No data found in Google Books API' });
        }
    } catch (error) {
        console.error('Error updating book data:', error);
        res.status(500).json({ error: 'Failed to update book data' });
    }
});