filter by language preference when collating

dlibrary/dlibrary.py

@@ -269,6 +269,10 @@ class Collator:
         if len(srcs) == 0:
             return True
 
+        select_language = self.try_collate_select_language(srcs)
+        if select_language is not False:
+            return select_language
+
         if len(srcs) == 2 and all(src.is_dir() for src in srcs):
             for quality in IMAGE_QUALITY_REGEXES:
                 def a_not_b(a, b, src):
@@ -417,6 +421,18 @@ class Collator:
         else:
             return False
 
+    def try_collate_select_language(self, srcs):
+        if self.locale not in LANGUAGE_REGEXES:
+            return False
+        if not all(any(lang.search(nname(src)) for lang in LANGUAGE_REGEXES.values()) for src in srcs):
+            return False
+
+        srcs_matching_language = [src for src in srcs if LANGUAGE_REGEXES[self.locale].search(nname(src))]
+        if len(srcs_matching_language) == len(srcs) or len(srcs_matching_language) == 0:
+            return False
+
+        return self.collate_from_paths(srcs_matching_language)
+
 def image_xrefs(pdf):
     images_by_page = [page.get_images() for page in pdf]
     if all(len(images) == 1 for images in images_by_page):