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');
      sendResponse({
        success: false, 
        error: 'Chrome printing API not available. Please ensure you are using Chrome 85+ and the extension has proper permissions.'
      });
      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 default printer or use first available
    const defaultPrinter = printers.find(p => p.isDefault) || printers[0];
    console.log('Using printer:', defaultPrinter);
    
    // Create print job
    const printJob = {
      printerId: defaultPrinter.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: defaultPrinter.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: 'Chrome printing API not available'
      });
      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
async function handleFallbackPrint(printData, sendResponse) {
  try {
    console.log('Using fallback print method');
    
    // Create a new tab with the print content
    const tab = await chrome.tabs.create({
      url: 'data:text/html,' + encodeURIComponent(printData.html),
      active: false
    });
    
    // Wait for tab to load, then print
    setTimeout(async () => {
      try {
        await chrome.tabs.executeScript(tab.id, {
          code: 'window.print();'
        });
        
        // Close the tab after printing
        setTimeout(() => {
          chrome.tabs.remove(tab.id);
        }, 1000);
        
        sendResponse({success: true, method: 'fallback'});
      } catch (error) {
        sendResponse({success: false, error: 'Fallback print failed: ' + error.message});
      }
    }, 1000);
    
  } catch (error) {
    console.error('Fallback print error:', error);
    sendResponse({success: false, error: error.message});
  }
}

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