fix decryption not working

pdf_sanatizer.py

@@ -40,29 +40,42 @@ This script requires the PyMuPDF (``fitz``) package.
 import sys
 import os
 import re
+import getpass
 from typing import Tuple, Optional
 
 import fitz  # type: ignore[import]
 
 
-def open_with_password(path: str) -> fitz.Document:
-    """Open a PDF file, prompting the user for a password if necessary.
+def open_with_password(path: str, max_attempts: int = 3) -> fitz.Document:
+    """Open ``path`` and prompt for a password when the PDF is encrypted.
 
-    If the file is encrypted, PyMuPDF raises a ``RuntimeError``.  In that
-    case the user is prompted to enter the password.  If authentication
-    fails, a ``ValueError`` is raised and the program aborts.
+    PyMuPDF happily opens encrypted PDFs without immediately failing, but it
+    marks them as needing authentication via ``doc.needs_pass``.  The original
+    implementation relied on ``fitz.open`` raising a ``RuntimeError`` to detect
+    encryption, which meant passwords were never requested and the caller
+    would hit authorization errors later.  We now inspect ``doc.needs_pass``
+    directly and allow up to ``max_attempts`` attempts at entering the password
+    before aborting.
     """
+
     try:
-        return fitz.open(path)
-    except RuntimeError:
-        # Document appears to be encrypted
-        print(f"The document '{path}' is encrypted.")
-        password = input("Please enter the password: ")
         doc = fitz.open(path)
-        if not doc.authenticate(password):
-            raise ValueError("Incorrect password provided. Unable to open the PDF.")
+    except RuntimeError as exc:
+        raise RuntimeError(f"Unable to open '{path}': {exc}") from exc
+
+    if not doc.needs_pass:
         return doc
 
+    print(f"The document '{path}' is encrypted.")
+    for attempt in range(1, max_attempts + 1):
+        password = getpass.getpass("Please enter the password: ")
+        if doc.authenticate(password):
+            return doc
+        print("Incorrect password. Try again." if attempt < max_attempts else "Incorrect password.")
+
+    doc.close()
+    raise ValueError("Failed to authenticate after multiple attempts. Unable to open the PDF.")
+
 
 def remove_watermark_segments(doc: fitz.Document) -> int:
     """Remove known watermark text blocks from every page of the document.
@@ -157,4 +170,4 @@ def main(argv: list[str]) -> None:
 
 
 if __name__ == "__main__":
-    main(sys.argv)
+    main(sys.argv)