added transliteration before actual translation

-> e.g. if the source language is Russian, argostranslate expects a
cyrillic text

app/language.py

@@ -1,5 +1,8 @@
+import string
+
 from argostranslate import translate
 from polyglot.detect.base import Detector
+from polyglot.transliteration.base import Transliterator
 
 
 languages = translate.load_installed_languages()
@@ -68,3 +71,51 @@ def detect_languages(text):
                 }
                 for l in candidate_langs
             ]
+
+
+def __transliterate_line(transliterator, line_text):
+    new_text = []
+
+    # transliteration is done word by word
+    for orig_word in line_text.split(" "):
+        # remove any punctuation on the right side
+        r_word = orig_word.rstrip(string.punctuation)
+        r_diff = set(char for char in orig_word) - set(char for char in r_word)
+        # and on the left side
+        l_word = orig_word.lstrip(string.punctuation)
+        l_diff = set(char for char in orig_word) - set(char for char in l_word)
+
+        # the actual transliteration of the word
+        t_word = transliterator.transliterate(orig_word.strip(string.punctuation))
+
+        # if transliteration fails, default back to the original word
+        if not t_word:
+            t_word = orig_word
+        else:
+            # add back any stripped punctuation
+            if r_diff:
+                t_word = t_word + ''.join(r_diff)
+            if l_diff:
+                t_word = ''.join(l_diff) + t_word
+
+        new_text.append(t_word)
+
+    # rebuild the text
+    return " ".join(new_text)
+
+
+def transliterate(text, target_lang="en"):
+    # initialize the transliterator from polyglot
+    transliterator = Transliterator(target_lang=target_lang)
+
+    # check for multiline string
+    if "\n" in text:
+        lines = []
+        # process each line separate
+        for line in text.split("\n"):
+            lines.append(__transliterate_line(transliterator, line))
+
+        # rejoin multiline string
+        return "\n".join(lines)
+    else:
+        return __transliterate_line(transliterator, text)