Use gettext algorithm to determine locale for activity.linfo

When activity bundles are loaded, the activity name and summary are
pulled from an activity.linfo file that is associated with
locale. However, sometimes locale, which uses $LANG has been
superceded by $LANGUAGE as set in
extensions/cpsection/languages/model.py. This patch uses the same
algorithm as gettext.py to find activity.linfo

This problem is seen on the .AU systems which use en_AU for locale and
en_GB for LANGUAGE.

src/sugar3/bundle/activitybundle.py

@@ -21,7 +21,7 @@ UNSTABLE.
 """
 
 from ConfigParser import ConfigParser
-import locale
+from locale import normalize
 import os
 import shutil
 import tempfile
@@ -34,6 +34,52 @@ from sugar3.bundle.bundleversion import NormalizedVersion
 from sugar3.bundle.bundleversion import InvalidVersionError
 
 
+def _expand_lang(locale):
+    # Private method from gettext.py
+    locale = normalize(locale)
+    COMPONENT_CODESET = 1 << 0
+    COMPONENT_TERRITORY = 1 << 1
+    COMPONENT_MODIFIER = 1 << 2
+
+    # split up the locale into its base components
+    mask = 0
+    pos = locale.find('@')
+    if pos >= 0:
+        modifier = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_MODIFIER
+    else:
+        modifier = ''
+
+    pos = locale.find('.')
+    if pos >= 0:
+        codeset = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_CODESET
+    else:
+        codeset = ''
+
+    pos = locale.find('_')
+    if pos >= 0:
+        territory = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_TERRITORY
+    else:
+        territory = ''
+
+    language = locale
+    ret = []
+    for i in range(mask + 1):
+        if not (i & ~mask):  # if all components for this combo exist ...
+            val = language
+            if i & COMPONENT_TERRITORY: val += territory
+            if i & COMPONENT_CODESET: val += codeset
+            if i & COMPONENT_MODIFIER: val += modifier
+            ret.append(val)
+    ret.reverse()
+    return ret
+
+
 class ActivityBundle(Bundle):
     """A Sugar activity bundle
 
@@ -133,20 +179,27 @@ class ActivityBundle(Bundle):
             self._summary = cp.get(section, 'summary')
 
     def _get_linfo_file(self):
-        lang = locale.getdefaultlocale()[0]
-        if not lang:
-            return None
-
-        linfo_path = os.path.join('locale', lang, 'activity.linfo')
-        linfo_file = self.get_file(linfo_path)
-        if linfo_file is not None:
-            return linfo_file
-
-        linfo_path = os.path.join('locale', lang[:2], 'activity.linfo')
-        linfo_file = self.get_file(linfo_path)
-        if linfo_file is not None:
-            return linfo_file
-
+        # Using method from gettext.py, first find languages from environ
+        languages = []
+        for envar in ('LANGUAGE', 'LC_ALL', 'LC_MESSAGES', 'LANG'):
+            val = os.environ.get(envar)
+            if val:
+                languages = val.split(':')
+                break
+
+        # Next, normalize and expand the languages
+        nelangs = []
+        for lang in languages:
+            for nelang in _expand_lang(lang):
+                if nelang not in nelangs:
+                    nelangs.append(nelang)
+
+        # Finally, select a language
+        for lang in nelangs:
+            linfo_path = os.path.join('locale', lang, 'activity.linfo')
+            linfo_file = self.get_file(linfo_path)
+            if linfo_file is not None:
+                return linfo_file
         return None
 
     def _parse_linfo(self, linfo_file):