quality_recticel/py_app/chrome_extension/background.js

// Background service worker for Chrome extension
console.log('Quality Recticel Print Helper - Background script loaded');

// Listen for messages from content script
chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  console.log('Background received message:', request);
  
  if (request.action === 'print_label') {
    handlePrintLabel(request.data, sendResponse);
    return true; // Keep message channel open for async response
  }
  
  if (request.action === 'fallback_print') {
    handleFallbackPrint(request.data, sendResponse);
    return true;
  }
  
  if (request.action === 'get_printers') {
    getPrinters(sendResponse);
    return true;
  }
  
  if (request.action === 'check_extension') {
    sendResponse({status: 'installed', version: chrome.runtime.getManifest().version});
    return true;
  }
});

// Function to handle label printing
async function handlePrintLabel(printData, sendResponse) {
  try {
    console.log('Attempting to print label with data:', printData);
    
    // Check if printing API is available
    if (!chrome.printing || !chrome.printing.getPrinters) {
      console.error('Chrome printing API not available - browser may be Brave, Edge, or older Chrome');
      sendResponse({
        success: false, 
        error: 'Direct printing API not available in this browser. The extension works best in Google Chrome 85+. Using fallback method instead.'
      });
      return;
    }
    
    // Get available printers
    const printers = await chrome.printing.getPrinters();
    console.log('Available printers:', printers);
    
    if (printers.length === 0) {
      sendResponse({success: false, error: 'No printers found. Please ensure a printer is installed and set as default.'});
      return;
    }
    
    // Find selected printer or use default/first available
    let selectedPrinter;
    if (printData.printerId && printData.printerId !== 'default') {
      selectedPrinter = printers.find(p => p.id === printData.printerId);
    }
    
    if (!selectedPrinter) {
      selectedPrinter = printers.find(p => p.isDefault) || printers[0];
    }
    
    console.log('Using printer:', selectedPrinter);
    
    // Create print job
    const printJob = {
      printerId: selectedPrinter.id,
      ticket: {
        version: '1.0',
        print: {
          color: {
            type: 'STANDARD_MONOCHROME'
          },
          duplex: {
            type: 'NO_DUPLEX'
          },
          page_orientation: {
            type: 'PORTRAIT'
          },
          copies: {
            copies: 1
          },
          dpi: {
            horizontal_dpi: 300,
            vertical_dpi: 300
          },
          media_size: {
            width_microns: 210000,  // A4 width
            height_microns: 297000  // A4 height
          },
          collate: {
            collate: false
          }
        }
      },
      documentBlob: new Blob([printData.html], {type: 'text/html'})
    };
    
    // Submit print job
    const result = await chrome.printing.submitJob(printJob);
    console.log('Print job result:', result);
    
    if (result.status === 'OK') {
      sendResponse({success: true, jobId: result.jobId});
      
      // Store successful print in extension storage
      chrome.storage.local.set({
        lastPrint: {
          timestamp: Date.now(),
          jobId: result.jobId,
          printer: selectedPrinter.displayName
        }
      });
    } else {
      sendResponse({success: false, error: result.status});
    }
    
  } catch (error) {
    console.error('Print error:', error);
    sendResponse({success: false, error: error.message});
  }
}

// Function to get available printers
async function getPrinters(sendResponse) {
  try {
    // Check if printing API is available
    if (!chrome.printing || !chrome.printing.getPrinters) {
      sendResponse({
        success: false, 
        error: 'Direct printing API not available in this browser (works in Chrome only)'
      });
      return;
    }
    
    const printers = await chrome.printing.getPrinters();
    sendResponse({success: true, printers: printers});
  } catch (error) {
    console.error('Error getting printers:', error);
    sendResponse({success: false, error: error.message});
  }
}

// Extension installation/startup
chrome.runtime.onInstalled.addListener((details) => {
  console.log('Quality Recticel Print Helper installed:', details);
  
  // Set initial storage values
  chrome.storage.local.set({
    extensionVersion: chrome.runtime.getManifest().version,
    installDate: Date.now()
  });
});

// Fallback print method using tabs API (works in Brave, Edge, Chrome)
async function handleFallbackPrint(printData, sendResponse) {
  try {
    console.log('Using fallback print method for Brave/Edge/Chrome');
    
    // Create enhanced HTML with better print styles
    const enhancedHTML = `
      <!DOCTYPE html>
      <html>
      <head>
        <title>Quality Recticel Label</title>
        <style>
          @page {
            margin: 10mm;
            size: A4;
          }
          body { 
            margin: 0; 
            padding: 0;
            font-family: Arial, sans-serif; 
            background: white;
          }
          .print-container { 
            width: 100%;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
          }
          .label-wrapper { 
            transform: scale(1.5); 
            transform-origin: center;
            page-break-inside: avoid;
          }
          @media print {
            body { padding: 0; margin: 0; }
            .print-container { min-height: auto; padding: 20px 0; }
            .no-print { display: none !important; }
          }
          .print-instructions {
            position: fixed;
            top: 10px;
            right: 10px;
            background: #007bff;
            color: white;
            padding: 10px;
            border-radius: 5px;
            font-size: 14px;
            z-index: 1000;
          }
        </style>
        <script>
          window.onload = function() {
            // Auto-print after 1 second
            setTimeout(() => {
              window.print();
              // Auto-close after printing (or after 10 seconds)
              setTimeout(() => {
                window.close();
              }, 2000);
            }, 1000);
          };
          
          // Handle print events
          window.onbeforeprint = function() {
            console.log('Print dialog opened');
          };
          
          window.onafterprint = function() {
            console.log('Print dialog closed');
            setTimeout(() => {
              window.close();
            }, 500);
          };
        </script>
      </head>
      <body>
        <div class="print-instructions no-print">
          🖨️ Printing will start automatically...<br>
          <small>If dialog doesn't appear, press Ctrl+P</small>
        </div>
        <div class="print-container">
          <div class="label-wrapper">
            ${printData.html.replace(/<!DOCTYPE html>|<html>|<\/html>|<head>.*?<\/head>|<body>|<\/body>/gi, '')}
          </div>
        </div>
      </body>
      </html>
    `;
    
    // Create a new tab with the enhanced print content
    const tab = await chrome.tabs.create({
      url: 'data:text/html;charset=utf-8,' + encodeURIComponent(enhancedHTML),
      active: true  // Make active so user can see the print dialog
    });
    
    console.log('Created print tab:', tab.id);
    sendResponse({success: true, method: 'fallback_tab', tabId: tab.id});
    
  } catch (error) {
    console.error('Fallback print error:', error);
    sendResponse({success: false, error: 'Browser print fallback failed: ' + error.message});
  }
}

// Keep service worker alive
chrome.runtime.onConnect.addListener((port) => {
  console.log('Port connected:', port.name);
});