let selectedDeviceId;
let isScanning = false; // Flag to prevent multiple scans at the same time

async function testCameraAccess() {
    try {
        const stream = await navigator.mediaDevices.getUserMedia({ video: true });
        console.log('Camera access granted', stream);
    } catch (error) {
        console.error('Error accessing camera:', error);
    }
}

// Get available video input devices (cameras)
async function getCameras() {
    try {
        const cameraSelect = document.getElementById('camera-select');
        const stream = await navigator.mediaDevices.getUserMedia({ video: true }); // Prompt for camera access
        const devices = await navigator.mediaDevices.enumerateDevices();
        const videoDevices = devices.filter(device => device.kind === 'videoinput');

        // Update selectedDeviceId when user selects a camera
        cameraSelect.addEventListener('change', function() {
            selectedDeviceId = this.value;
        });

        if (videoDevices.length > 0) {
            videoDevices.forEach((device, index) => {
                const option = document.createElement('option');
                option.value = device.deviceId;
                option.text = device.label || `Camera ${index + 1}`;
                cameraSelect.appendChild(option);
            });
        } else {
            console.log("No video devices found.");
            cameraSelect.innerHTML = '<option>No cameras found</option>';
        }
    } catch (error) {
        console.error("Error accessing the camera or enumerating devices:", error);
        document.getElementById('camera-select').innerHTML = '<option>' + error + '</option>';
    }
}

function startScanner() {
    if (!selectedDeviceId) {
        alert('No camera selected or available.');
        return;
    }

    Quagga.init({
        inputStream: {
            name: "Live",
            type: "LiveStream",
            target: document.querySelector('#interactive'),
            constraints: {
                deviceId: selectedDeviceId,
                facingMode: "environment", // Default to rear camera
            },
        },
        decoder: {
            readers: ["ean_reader"] // EAN is the standard format for ISBN-13 barcodes
        }
    }, function (err) {
        if (err) {
            console.log(err);
            return;
        }
        console.log("Initialization finished. Ready to start");
        Quagga.start();
    });

    Quagga.onDetected(async function (data) {
        if (isScanning) return; // Prevent further scans while a scan is being processed
        isScanning = true; // Set the scanning flag

        const isbn = data.codeResult.code;
        console.log("Detected ISBN:", isbn);
        Quagga.stop(); // Stop the scanner once an ISBN is detected

        // Fetch book details
        await fetchBookInfo(isbn);

        isScanning = false; // Reset the scanning flag once processing is done
    });
}

async function fetchBookInfo(isbn) {
    try {
        const response = await fetch(`/book/${isbn}`);
        const bookData = await response.json();

        if (bookData.title) {
            promptUserWithBook(bookData);
        } else {
            console.log("No book data found. Restarting scanner...");
            startScanner(); // Restart the scanner if no book information is found
        }
    } catch (error) {
        console.error('Error fetching book data:', error);
        startScanner(); // Restart the scanner on error as well
    }
}

function promptUserWithBook(bookData) {
    // Display book information or prompt the user for confirmation
    document.getElementById('book-info').textContent = `Title: ${bookData.title}`;
    document.getElementById('prompt').style.display = 'block';
    // Additional logic for user confirmation can be added here
}

// Start the scanner when the start button is clicked
document.getElementById('start-scanner').addEventListener('click', startScanner);

// Get cameras on page load
window.onload = getCameras;