quality_recticel/windows_print_service/chrome_extension/background.js

/**
 * Quality Label Printing Service - Background Script
 * Handles communication between web pages and Windows print service
 */

// Configuration
const PRINT_SERVICE_URL = 'http://localhost:8765';
const SERVICE_CHECK_INTERVAL = 30000; // 30 seconds

// Service status
let serviceStatus = {
    available: false,
    lastCheck: null,
    printers: []
};

// Initialize extension
chrome.runtime.onInstalled.addListener(() => {
    console.log('Quality Label Printing Service extension installed');
    checkServiceStatus();
    
    // Set up periodic service check
    setInterval(checkServiceStatus, SERVICE_CHECK_INTERVAL);
});

// Handle messages from content scripts or web pages
chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
    console.log('Background script received message:', message);
    
    switch (message.action) {
        case 'print_pdf':
            handlePrintPDF(message.data).then(sendResponse);
            return true; // Keep message channel open for async response
            
        case 'silent_print':
            handleSilentPrint(message.data).then(sendResponse);
            return true;
            
        case 'get_printers':
            handleGetPrinters().then(sendResponse);
            return true;
            
        case 'check_service':
            checkServiceStatus().then(sendResponse);
            return true;
            
        default:
            sendResponse({ error: 'Unknown action', success: false });
    }
});

// Handle external messages from web pages
chrome.runtime.onMessageExternal.addListener((message, sender, sendResponse) => {
    console.log('External message received:', message, 'from:', sender);
    
    // Verify sender origin for security
    const allowedOrigins = [
        'http://localhost:5000',
        'http://localhost:8000',
        'http://127.0.0.1:5000',
        'http://127.0.0.1:8000'
    ];
    
    if (!allowedOrigins.includes(sender.origin)) {
        sendResponse({ error: 'Unauthorized origin', success: false });
        return;
    }
    
    // Handle the message
    switch (message.action) {
        case 'print_pdf':
        case 'silent_print':
            handleSilentPrint(message.data).then(sendResponse);
            return true;
            
        case 'get_printers':
            handleGetPrinters().then(sendResponse);
            return true;
            
        case 'ping':
            sendResponse({ 
                success: true, 
                service_available: serviceStatus.available,
                extension_version: chrome.runtime.getManifest().version
            });
            break;
            
        default:
            sendResponse({ error: 'Unknown action', success: false });
    }
});

/**
 * Check if the Windows print service is available
 */
async function checkServiceStatus() {
    try {
        const response = await fetch(`${PRINT_SERVICE_URL}/health`, {
            method: 'GET',
            timeout: 5000
        });
        
        if (response.ok) {
            const data = await response.json();
            serviceStatus.available = true;
            serviceStatus.lastCheck = new Date();
            
            console.log('Print service is available:', data);
            
            // Update extension badge
            chrome.action.setBadgeText({ text: '✓' });
            chrome.action.setBadgeBackgroundColor({ color: '#28a745' });
            
            return { success: true, status: data };
        } else {
            throw new Error(`Service returned status ${response.status}`);
        }
        
    } catch (error) {
        console.warn('Print service not available:', error);
        
        serviceStatus.available = false;
        serviceStatus.lastCheck = new Date();
        
        // Update extension badge
        chrome.action.setBadgeText({ text: '✗' });
        chrome.action.setBadgeBackgroundColor({ color: '#dc3545' });
        
        return { success: false, error: error.message };
    }
}

/**
 * Handle PDF printing request
 */
async function handlePrintPDF(printData) {
    try {
        if (!serviceStatus.available) {
            await checkServiceStatus();
            
            if (!serviceStatus.available) {
                throw new Error('Print service is not available');
            }
        }
        
        const response = await fetch(`${PRINT_SERVICE_URL}/print/pdf`, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify(printData)
        });
        
        const result = await response.json();
        
        if (response.ok) {
            console.log('Print job completed:', result);
            
            // Show notification
            chrome.notifications.create({
                type: 'basic',
                iconUrl: 'icons/icon48.png',
                title: 'Quality Label Printing Service',
                message: 'PDF printed successfully'
            });
            
            return { success: true, result };
        } else {
            throw new Error(result.error || 'Print job failed');
        }
        
    } catch (error) {
        console.error('Print PDF error:', error);
        
        // Show error notification
        chrome.notifications.create({
            type: 'basic',
            iconUrl: 'icons/icon48.png',
            title: 'Quality Label Printing Service',
            message: `Print failed: ${error.message}`
        });
        
        return { success: false, error: error.message };
    }
}

/**
 * Handle silent printing request
 */
async function handleSilentPrint(printData) {
    try {
        if (!serviceStatus.available) {
            await checkServiceStatus();
            
            if (!serviceStatus.available) {
                // Try direct browser printing as fallback
                return await handleDirectPrint(printData);
            }
        }
        
        const response = await fetch(`${PRINT_SERVICE_URL}/print/silent`, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify(printData)
        });
        
        const result = await response.json();
        
        if (response.ok) {
            console.log('Silent print completed:', result);
            return { success: true, result };
        } else {
            throw new Error(result.error || 'Silent print failed');
        }
        
    } catch (error) {
        console.error('Silent print error:', error);
        
        // Fallback to direct printing
        return await handleDirectPrint(printData);
    }
}

/**
 * Handle direct browser printing (fallback)
 */
async function handleDirectPrint(printData) {
    try {
        // Create hidden iframe for printing
        const printFrame = document.createElement('iframe');
        printFrame.style.display = 'none';
        printFrame.src = printData.pdf_url || 'data:application/pdf;base64,' + printData.pdf_data;
        
        document.body.appendChild(printFrame);
        
        // Wait for load and print
        return new Promise((resolve) => {
            printFrame.onload = () => {
                setTimeout(() => {
                    printFrame.contentWindow.print();
                    document.body.removeChild(printFrame);
                    resolve({ success: true, method: 'browser_fallback' });
                }, 1000);
            };
        });
        
    } catch (error) {
        console.error('Direct print error:', error);
        return { success: false, error: error.message };
    }
}

/**
 * Get available printers
 */
async function handleGetPrinters() {
    try {
        if (!serviceStatus.available) {
            await checkServiceStatus();
            
            if (!serviceStatus.available) {
                return { 
                    success: false, 
                    error: 'Print service not available',
                    printers: []
                };
            }
        }
        
        const response = await fetch(`${PRINT_SERVICE_URL}/printers`, {
            method: 'GET'
        });
        
        const result = await response.json();
        
        if (response.ok) {
            serviceStatus.printers = result.printers || [];
            return { success: true, printers: result.printers };
        } else {
            throw new Error(result.error || 'Failed to get printers');
        }
        
    } catch (error) {
        console.error('Get printers error:', error);
        return { success: false, error: error.message, printers: [] };
    }
}

// Export for testing
if (typeof module !== 'undefined' && module.exports) {
    module.exports = {
        checkServiceStatus,
        handlePrintPDF,
        handleSilentPrint,
        handleGetPrinters
    };
}