Set tempfile.tempdir instead of environment variables

Use tempfile.tempdir directly instead of TEMP/TMP environment
variables. The tempfile module caches the temp directory, so setting
env vars after it's imported doesn't work. Setting tempfile.tempdir
forces it to use the video directory even if already imported.

Author: mikeSGman

fastflix/widgets/background_tasks.py

@@ -242,15 +242,15 @@ def _convert_sup_to_srt(self, sup_filepath: str) -> bool:
                 mkvtoolnix_dir = str(Path(self.app.fastflix.config.mkvmerge_path).parent)
                 os.environ["PATH"] = f"{mkvtoolnix_dir}{os.pathsep}{os.environ.get('PATH', '')}"
 
-            # CRITICAL FIX: Set TEMP/TMP to video directory before importing pgsrip
-            # This forces Python's tempfile module to use the video directory
-            original_temp = os.environ.get("TEMP")
-            original_tmp = os.environ.get("TMP")
-            os.environ["TEMP"] = video_dir
-            os.environ["TMP"] = video_dir
+            # CRITICAL FIX: Set tempfile.tempdir to video directory
+            # tempfile module caches the temp dir, so we must set tempfile.tempdir directly
+            import tempfile
+
+            original_tempdir = tempfile.tempdir
+            tempfile.tempdir = video_dir
 
             try:
-                # Import pgsrip AFTER setting TEMP/TMP
+                # Import pgsrip AFTER setting tempfile.tempdir
                 from pgsrip import pgsrip, Mkv, Options
                 from babelfish import Language as BabelLanguage
 
@@ -317,16 +317,8 @@ def _convert_sup_to_srt(self, sup_filepath: str) -> bool:
                 return True
 
             finally:
-                # Restore original TEMP/TMP
-                if original_temp is not None:
-                    os.environ["TEMP"] = original_temp
-                elif "TEMP" in os.environ:
-                    del os.environ["TEMP"]
-
-                if original_tmp is not None:
-                    os.environ["TMP"] = original_tmp
-                elif "TMP" in os.environ:
-                    del os.environ["TMP"]
+                # Restore original tempfile.tempdir
+                tempfile.tempdir = original_tempdir
 
         except Exception as err:
             self.main.thread_logging_signal.emit(f"ERROR:{t('OCR conversion failed')}: {err}")