feat: add HTML preview pane for templates via Carbone+LibreOffice

renderer/carbone-service.js

@@ -709,6 +709,67 @@ router.post('/templates/:id/render', async (req, res) => {
   }
 });
 
+// POST /api/carbone/templates/:id/preview - Render template with data -> HTML preview
+router.post('/templates/:id/preview', async (req, res) => {
+  const templateId = req.params.id;
+  const registry = loadRegistry();
+  const template = registry.find(t => t.id === templateId);
+  
+  if (!template) return res.status(404).json({ error: 'Template not found' });
+  if (!fs.existsSync(template.path)) return res.status(404).json({ error: 'Template file missing' });
+  
+  const candidateData = req.body.candidateData || req.body;
+  const referenceDate = req.body.referenceDate || req.body.generation_date;
+  const carboneData = transformCandidateData(candidateData, referenceDate);
+  
+  try {
+    // Step 1: Merge data into DOCX with Carbone
+    const docxBuffer = await new Promise((resolve, reject) => {
+      const timer = setTimeout(() => reject(new Error('Carbone merge timed out')), 30000);
+      carbone.render(template.path, carboneData, {}, (err, result) => {
+        clearTimeout(timer);
+        if (err) reject(err); else resolve(result);
+      });
+    });
+    
+    // Step 2: Convert to HTML with LibreOffice
+    const tmpDir = path.join(__dirname, 'output');
+    fs.mkdirSync(tmpDir, { recursive: true });
+    const tmpId = uuidv4();
+    const tmpDocx = path.join(tmpDir, `${tmpId}.docx`);
+    const tmpHtml = path.join(tmpDir, `${tmpId}.html`);
+    
+    fs.writeFileSync(tmpDocx, docxBuffer);
+    
+    const { execFile } = require('child_process');
+    const htmlPath = await new Promise((resolve, reject) => {
+      const timer = setTimeout(() => reject(new Error('LibreOffice conversion timed out')), 60000);
+      execFile('soffice', [
+        '--headless', '--invisible', '--nocrashreport', '--nodefault',
+        '--nologo', '--nofirststartwizard', '--norestore',
+        '--convert-to', 'html', '--outdir', tmpDir, tmpDocx
+      ], { timeout: 60000 }, (err) => {
+        clearTimeout(timer);
+        if (err) reject(err);
+        else if (!fs.existsSync(tmpHtml)) reject(new Error('HTML was not generated'));
+        else resolve(tmpHtml);
+      });
+    });
+    
+    const htmlBuffer = fs.readFileSync(htmlPath);
+    
+    // Clean up temp files
+    try { fs.unlinkSync(tmpDocx); } catch {}
+    try { fs.unlinkSync(tmpHtml); } catch {}
+    
+    res.setHeader('Content-Type', 'text/html');
+    res.send(htmlBuffer);
+  } catch (err) {
+    console.error('Preview error:', err.message);
+    res.status(500).json({ error: 'Preview failed: ' + err.message });
+  }
+});
+
 // DELETE /api/carbone/templates/:id - Delete a template
 router.delete('/templates/:id', (req, res) => {
   const templateId = req.params.id;