translation: remove old translations

Remove translated files when the source file get removed. This includes
also renaming files.

_utils/_translation_utils/post_transifex_pull.sh

@@ -10,6 +10,8 @@ echo "============================ post processing step 1 ======================
 #read b
 bash _utils/_translation_utils/prepare_tx_config_postprocess.sh .tx/config /tmp/tx-mapping
 
+echo "============================ remove obsolete files ======================================="
+python3 _utils/_translation_utils/remove_obsolete_files.py "$1" "$2" /tmp/tx-mapping
 
 echo "============================ post processing step 2 ======================================"
 #read b

_utils/_translation_utils/remove_obsolete_files.py

@@ -0,0 +1,40 @@
+#!/usr/bin/python3
+
+import argparse
+import os
+import sys
+
+parser = argparse.ArgumentParser()
+parser.add_argument('lang')
+parser.add_argument('translation_dir')
+parser.add_argument('tx_mapping')
+
+def main():
+    args = parser.parse_args()
+
+    valid_files = set()
+    with open(args.tx_mapping) as f_mapping:
+        for line in f_mapping.readlines():
+            if line.startswith('file_filter = '):
+                valid_files.add(line.strip().split(' = ')[1].replace('<lang>', args.lang))
+
+    if not valid_files:
+        print('No files found in {}, aborting!'.format(args.tx_mapping))
+        return 1
+
+    existing_files = set()
+    for dirpath, dirs, files in os.walk(args.translation_dir):
+        existing_files.update(os.path.join(dirpath, name) for name in files)
+
+    if not existing_files:
+        print('No files found in {}, aborting!'.format(args.translation_dir))
+        return 1
+
+    for obsolete in existing_files.difference(valid_files):
+        print('Removing {}'.format(obsolete))
+        os.unlink(obsolete)
+
+
+if __name__ == '__main__':
+    sys.exit(main())
+