[books] Add etag update option to webdav imports

vrobbler/apps/scrobbles/importers/webdav.py

@@ -20,7 +20,7 @@ DEFAULT_EBIRD_PATH = "var/ebird/"
 DEFAULT_SCALE_PATH = "var/scale/"
 
 
-def import_from_webdav_for_all_users(restart=False, update_retroarch_hash=False):
+def import_from_webdav_for_all_users(restart=False, update_retroarch_hash=False, update_koreader_etag=False):
     """Iterate all WebDAV-enabled users, scanning each media-type directory."""
     webdav_enabled_user_ids = UserProfile.objects.filter(
         webdav_url__isnull=False,
@@ -42,7 +42,9 @@ def import_from_webdav_for_all_users(restart=False, update_retroarch_hash=False)
         logger.info("Scanning WebDAV for user %s", user_id)
 
         logger.info("Scanning WebDAV koreader for user %s", user_id)
-        ko_count += scan_webdav_for_koreader(client, user_id, restart)
+        ko_count += scan_webdav_for_koreader(
+            client, user_id, restart, update_etag_only=update_koreader_etag
+        )
         logger.info("Scanning WebDAV gpx for user %s", user_id)
         gpx_count += scan_webdav_for_gpx(client, user_id)
         logger.info("Scanning WebDAV retroarch for user %s", user_id)
@@ -76,21 +78,26 @@ def import_from_webdav_for_all_users(restart=False, update_retroarch_hash=False)
     return ko_count, gpx_count, retro_count, bgstats_count, ebird_count, scale_count
 
 
-def scan_webdav_for_koreader(webdav_client, user_id, restart=False):
+def scan_webdav_for_koreader(webdav_client, user_id, restart=False, update_etag_only=False):
     """Check for koreader statistics.sqlite3 and queue import if changed.
 
     Uses the remote file's ETag (from a single PROPFIND) to detect changes
     without downloading the file, making the common no-change case fast.
+
+    When *update_etag_only* is True, stores the remote ETag on the last
+    completed import without re-downloading — useful when migrating to the
+    ETag-based check to avoid a one-time re-import.
     """
-    # Don't queue if one is still being processed
-    if KoReaderImport.objects.filter(
-        user_id=user_id, processed_finished__isnull=True
-    ).exists():
-        logger.info(
-            "KoReader import already pending for user",
-            extra={"user_id": user_id},
-        )
-        return 0
+    if not update_etag_only:
+        # Don't queue if one is still being processed
+        if KoReaderImport.objects.filter(
+            user_id=user_id, processed_finished__isnull=True
+        ).exists():
+            logger.info(
+                "KoReader import already pending for user",
+                extra={"user_id": user_id},
+            )
+            return 0
 
     try:
         files = webdav_client.list(DEFAULT_KOREADER_PATH, get_info=True)
@@ -122,6 +129,17 @@ def scan_webdav_for_koreader(webdav_client, user_id, restart=False):
         .last()
     )
 
+    if update_etag_only:
+        if last_import and remote_etag:
+            last_import.webdav_etag = remote_etag
+            last_import.save(update_fields=["webdav_etag"])
+            logger.info(
+                "Updated KoReader webdav_etag (%s) without re-import",
+                remote_etag[:16],
+                extra={"user_id": user_id, "last_import_id": last_import.id},
+            )
+        return 0
+
     if last_import and last_import.webdav_etag and remote_etag:
         if last_import.webdav_etag == remote_etag:
             logger.info(