add utils for office xml text handling

core/utils.py

@@ -0,0 +1,50 @@
+import zipfile, xml.etree.ElementTree as ET
+
+from typing import List, Optional
+
+# -------------------------------------------------------------------------
+# Helper: pull raw text from OOXML containers (docx / xlsx / pptx)
+# -------------------------------------------------------------------------
+def extract_office_xml_text(file_bytes: bytes, mime_type: str) -> Optional[str]:
+    """
+    Very light-weight XML scraper for Word, Excel, PowerPoint files.
+    Returns plain-text if something readable is found, else None.
+    No external deps – just std-lib zipfile + ElementTree.
+    """
+    try:
+        with zipfile.ZipFile(io.BytesIO(file_bytes)) as zf:
+            # Map MIME → iterable of XML files to inspect
+            if mime_type == (
+                "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
+            ):
+                targets = ["word/document.xml"]
+            elif mime_type == (
+                "application/vnd.openxmlformats-officedocument.presentationml.presentation"
+            ):
+                targets = [n for n in zf.namelist() if n.startswith("ppt/slides/slide")]
+            elif mime_type == (
+                "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+            ):
+                targets = [n for n in zf.namelist() if n.startswith("xl/worksheets/sheet")]
+            else:
+                return None
+
+            pieces: List[str] = []
+            for member in targets:
+                try:
+                    xml_root = ET.fromstring(zf.read(member))
+                    # In both Word/PowerPoint the text is in <w:t> or <a:t>;
+                    # in Excel, cell values are in <v>.
+                    for elem in xml_root.iter():
+                        tag = elem.tag.split("}")[-1]  # strip namespace
+                        if tag in {"t", "v"} and elem.text:
+                            pieces.append(elem.text)
+                    pieces.append("\n")  # separator per part / sheet / slide
+                except Exception:
+                    continue  # ignore individual slide/sheet errors
+            text = "\n".join(pieces).strip()
+            return text or None
+    except Exception as e:
+        logger.error(f"Failed to extract file content: {e}")
+        # Any failure → quietly signal "not handled"
+        return None