feat: Use LibreOffice for DOCX to PDF conversion in board document preview

- Converts DOCX/DOC to PDF using soffice --headless
- Caches converted PDFs alongside originals
- Falls back to mammoth HTML if LibreOffice fails
- Preserves full document formatting and graphics

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

blueprints/board/routes.py

@@ -13,6 +13,9 @@ Endpoints:
 """
 
 import os
+import subprocess
+import tempfile
+import shutil
 from datetime import datetime
 from flask import (
     render_template, request, redirect, url_for, flash,
@@ -27,6 +30,48 @@ from utils.decorators import rada_member_required, office_manager_required
 from services.document_upload_service import DocumentUploadService
 
 
+def convert_docx_to_pdf(docx_path: str) -> str | None:
+    """
+    Convert DOCX to PDF using LibreOffice headless.
+    Returns path to generated PDF or None on failure.
+    PDF is stored alongside the original with .pdf extension.
+    """
+    # Generate PDF path (same location, .pdf extension)
+    pdf_path = docx_path.rsplit('.', 1)[0] + '.pdf'
+
+    # Check if PDF already exists (cached)
+    if os.path.exists(pdf_path):
+        return pdf_path
+
+    # Convert using LibreOffice
+    try:
+        output_dir = os.path.dirname(docx_path)
+        result = subprocess.run(
+            [
+                'soffice',
+                '--headless',
+                '--convert-to', 'pdf',
+                '--outdir', output_dir,
+                docx_path
+            ],
+            capture_output=True,
+            text=True,
+            timeout=60  # 60 seconds timeout
+        )
+
+        if result.returncode == 0 and os.path.exists(pdf_path):
+            # Ensure www-data can read it
+            os.chmod(pdf_path, 0o644)
+            return pdf_path
+        else:
+            return None
+
+    except subprocess.TimeoutExpired:
+        return None
+    except Exception:
+        return None
+
+
 @bp.route('/')
 @login_required
 @rada_member_required
@@ -126,30 +171,41 @@ def view(doc_id):
             )
 
         elif document.file_extension in ('docx', 'doc'):
-            # Convert DOCX to HTML using mammoth
-            try:
-                import mammoth
+            # Convert DOCX to PDF using LibreOffice (preserves formatting)
+            pdf_path = convert_docx_to_pdf(file_path)
 
-                with open(file_path, 'rb') as docx_file:
-                    result = mammoth.convert_to_html(docx_file)
-                    html_content = result.value
-
-                # Render in template with styling
-                return render_template(
-                    'board/view_document.html',
-                    document=document,
-                    html_content=html_content,
-                    conversion_messages=result.messages
+            if pdf_path and os.path.exists(pdf_path):
+                # Serve the converted PDF inline
+                pdf_filename = document.original_filename.rsplit('.', 1)[0] + '.pdf'
+                return send_file(
+                    pdf_path,
+                    as_attachment=False,
+                    download_name=pdf_filename,
+                    mimetype='application/pdf'
                 )
+            else:
+                # Fallback to mammoth HTML conversion
+                current_app.logger.warning(
+                    f"LibreOffice conversion failed for {document.title}, falling back to mammoth"
+                )
+                try:
+                    import mammoth
 
-            except ImportError:
-                current_app.logger.error("mammoth library not installed")
-                flash('Podgląd dokumentów DOCX nie jest dostępny.', 'error')
-                return redirect(url_for('board.index'))
-            except Exception as e:
-                current_app.logger.error(f"Failed to convert DOCX: {e}")
-                flash('Błąd podczas konwersji dokumentu.', 'error')
-                return redirect(url_for('board.index'))
+                    with open(file_path, 'rb') as docx_file:
+                        result = mammoth.convert_to_html(docx_file)
+                        html_content = result.value
+
+                    return render_template(
+                        'board/view_document.html',
+                        document=document,
+                        html_content=html_content,
+                        conversion_messages=result.messages
+                    )
+
+                except Exception as e:
+                    current_app.logger.error(f"Failed to convert DOCX: {e}")
+                    flash('Błąd podczas konwersji dokumentu.', 'error')
+                    return redirect(url_for('board.index'))
 
         else:
             # Unknown format - redirect to download