make --alternate-language cli argument take precedence over detected language

wakatime/arguments.py

@@ -82,8 +82,8 @@ def parseArguments():
             help='optional alternate project name; auto-discovered project '+
                  'takes priority')
     parser.add_argument('--alternate-language', dest='alternate_language',
-            help='optional alternate language name; auto-detected language'+
-                 'takes priority')
+            help='optional alternate language name; if valid, takes priority '+
+                 'over auto-detected language')
     parser.add_argument('--hostname', dest='hostname', help='hostname of '+
                         'current machine.')
     parser.add_argument('--disableoffline', dest='offline',

wakatime/stats.py

@@ -18,6 +18,7 @@ from .dependencies import DependencyParser
 
 from .packages.pygments.lexers import (
     ClassNotFound,
+    find_lexer_class,
     get_lexer_by_name,
     guess_lexer_for_filename,
 )
@@ -43,11 +44,15 @@ def get_file_stats(file_name, entity_type='file', lineno=None, cursorpos=None,
             'cursorpos': cursorpos,
         }
     else:
-        language, lexer = guess_language(file_name)
+        language = standardize_language(alternate_language, plugin)
+        lexer = get_lexer(language)
+
+        if not language:
+            language, lexer = guess_language(file_name)
+
         parser = DependencyParser(file_name, lexer)
         dependencies = parser.parse()
-        if language is None and alternate_language:
-            language = standardize_language(alternate_language, plugin)
+
         stats = {
             'language': language,
             'dependencies': dependencies,
@@ -58,6 +63,19 @@ def get_file_stats(file_name, entity_type='file', lineno=None, cursorpos=None,
     return stats
 
 
+def get_lexer(language):
+    """Return a Pygments Lexer object for the given language string."""
+
+    if not language:
+        return None
+
+    lexer_cls = find_lexer_class(language)
+    if lexer_cls:
+        return lexer_cls()
+
+    return None
+
+
 def guess_language(file_name):
     """Guess lexer and language for a file.
 
@@ -188,6 +206,9 @@ def number_lines_in_file(file_name):
 def standardize_language(language, plugin):
     """Maps a string to the equivalent Pygments language."""
 
+    if not language:
+        return None
+
     # standardize language for this plugin
     if plugin:
         plugin = plugin.split(' ')[-1].split('/')[0].split('-')[0]