Negate a condition

- removes two levels of indentation
- makes it clear that if the wrong tokens are provided nothing will happen
- remove a useless nested function

cps/gdrive.py

@@ -123,38 +123,36 @@ def revoke_watch_gdrive():
 
 @gdrive.route("/gdrive/watch/callback", methods=['GET', 'POST'])
 def on_received_watch_confirmation():
+    if request.headers.get('X-Goog-Channel-Token') != gdrive_watch_callback_token \
+            or request.headers.get('X-Goog-Resource-State') != 'change' \
+            or not request.data:
+        return redirect(url_for('admin.configuration'))
+
     log.debug('%r', request.headers)
-    if request.headers.get('X-Goog-Channel-Token') == gdrive_watch_callback_token \
-            and request.headers.get('X-Goog-Resource-State') == 'change' \
-            and request.data:
-
-        data = request.data
-
-        def updateMetaData():
-            log.info('Change received from gdrive')
-            log.debug('%r', data)
-            try:
-                j = json.loads(data)
-                log.info('Getting change details')
-                response = gdriveutils.getChangeById(gdriveutils.Gdrive.Instance().drive, j['id'])
-                log.debug('%r', response)
-                if response:
-                    if sys.version_info < (3, 0):
-                        dbpath = os.path.join(config.config_calibre_dir, "metadata.db")
-                    else:
-                        dbpath = os.path.join(config.config_calibre_dir, "metadata.db").encode()
-                    if not response['deleted'] and response['file']['title'] == 'metadata.db' \
-                       and response['file']['md5Checksum'] != hashlib.md5(dbpath):
-                        tmpDir = tempfile.gettempdir()
-                        log.info('Database file updated')
-                        copyfile(dbpath, os.path.join(tmpDir, "metadata.db_" + str(current_milli_time())))
-                        log.info('Backing up existing and downloading updated metadata.db')
-                        gdriveutils.downloadFile(None, "metadata.db", os.path.join(tmpDir, "tmp_metadata.db"))
-                        log.info('Setting up new DB')
-                        # prevent error on windows, as os.rename does on exisiting files
-                        move(os.path.join(tmpDir, "tmp_metadata.db"), dbpath)
-                        calibre_db.reconnect_db(config, ub.app_DB_path)
-            except Exception as e:
-                log.exception(e)
-        updateMetaData()
+    log.debug('%r', request.data)
+    log.info('Change received from gdrive')
+
+    try:
+        j = json.loads(request.data)
+        log.info('Getting change details')
+        response = gdriveutils.getChangeById(gdriveutils.Gdrive.Instance().drive, j['id'])
+        log.debug('%r', response)
+        if response:
+            if sys.version_info < (3, 0):
+                dbpath = os.path.join(config.config_calibre_dir, "metadata.db")
+            else:
+                dbpath = os.path.join(config.config_calibre_dir, "metadata.db").encode()
+            if not response['deleted'] and response['file']['title'] == 'metadata.db' \
+                and response['file']['md5Checksum'] != hashlib.md5(dbpath):
+                tmpDir = tempfile.gettempdir()
+                log.info('Database file updated')
+                copyfile(dbpath, os.path.join(tmpDir, "metadata.db_" + str(current_milli_time())))
+                log.info('Backing up existing and downloading updated metadata.db')
+                gdriveutils.downloadFile(None, "metadata.db", os.path.join(tmpDir, "tmp_metadata.db"))
+                log.info('Setting up new DB')
+                # prevent error on windows, as os.rename does on exisiting files
+                move(os.path.join(tmpDir, "tmp_metadata.db"), dbpath)
+                calibre_db.reconnect_db(config, ub.app_DB_path)
+    except Exception as e:
+        log.exception(e)
     return ''