[mod] add 'Accept-Language' HTTP header to online processores

Most engines that support languages (and regions) use the Accept-Language from
the WEB browser to build a response that fits to the language (and region).

- add new engine option: send_accept_language_header

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/search/models.py

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 import typing
+import babel
 
 
 class EngineRef:
@@ -29,6 +30,7 @@ class SearchQuery:
         'query',
         'engineref_list',
         'lang',
+        'locale',
         'safesearch',
         'pageno',
         'time_range',
@@ -59,6 +61,13 @@ class SearchQuery:
         self.external_bang = external_bang
         self.engine_data = engine_data or {}
 
+        self.locale = None
+        if self.lang:
+            try:
+                self.locale = babel.Locale.parse(self.lang, sep='-')
+            except babel.core.UnknownLocaleError:
+                pass
+
     @property
     def categories(self):
         return list(set(map(lambda engineref: engineref.category, self.engineref_list)))

searx/search/processors/online.py

@@ -60,6 +60,17 @@ class OnlineProcessor(EngineProcessor):
         # add an user agent
         params['headers']['User-Agent'] = gen_useragent()
 
+        # add Accept-Language header
+        if self.engine.send_accept_language_header and search_query.locale:
+            ac_lang = search_query.locale.language
+            if search_query.locale.territory:
+                ac_lang = "%s-%s,%s;q=0.9,*;q=0.5" % (
+                    search_query.locale.language,
+                    search_query.locale.territory,
+                    search_query.locale.language,
+                )
+            params['headers']['Accept-Language'] = ac_lang
+
         return params
 
     def _send_http_request(self, params):