Include the third-party wiki app into the i18n toolchain

We use pybabel to extract strings from third-party apps, put them on
Transifex, then merge them into django.po.

[LMS-1681]

.tx/config

@@ -42,3 +42,9 @@ file_filter = conf/locale/<lang>/LC_MESSAGES/messages.po
 source_file = conf/locale/en/LC_MESSAGES/messages.po
 source_lang = en
 type = PO
+
+[edx-platform.wiki]
+file_filter = conf/locale/<lang>/LC_MESSAGES/wiki.po
+source_file = conf/locale/en/LC_MESSAGES/wiki.po
+source_lang = en
+type = PO

conf/locale/babel.cfg

@@ -1,23 +0,0 @@
-# Extraction from Python source files
-#[python: cms/**.py]
-#[python: lms/**.py]
-#[python: common/**.py]
-
-# Extraction from Javscript source files
-#[javascript: cms/**.js]
-#[javascript: lms/**.js]
-#[javascript: common/static/js/capa/**.js]
-#[javascript: common/static/js/course_groups/**.js]
-# do not extract from common/static/js/vendor/**
-
-# Extraction from Mako templates
-[mako: cms/templates/**.html]
-input_encoding = utf-8
-[mako: lms/templates/**.html]
-input_encoding = utf-8
-[mako: lms/templates/**.mustache]
-input_encoding = utf-8
-[mako: common/templates/**.html]
-input_encoding = utf-8
-[mako: cms/templates/emails/**.txt]
-input_encoding = utf-8

conf/locale/babel_mako.cfg

@@ -0,0 +1,11 @@
+# Extraction from Mako templates
+[mako: cms/templates/**.html]
+input_encoding = utf-8
+[mako: lms/templates/**.html]
+input_encoding = utf-8
+[mako: lms/templates/**.mustache]
+input_encoding = utf-8
+[mako: common/templates/**.html]
+input_encoding = utf-8
+[mako: cms/templates/emails/**.txt]
+input_encoding = utf-8

conf/locale/babel_third_party.cfg

@@ -0,0 +1,6 @@
+# Use this configuration file for third-party app source trees.
+[python: **.py]
+input_encoding = utf-8
+
+[django: **/template/**.html]
+input_encoding = utf-8

conf/locale/config.yaml

@@ -66,6 +66,14 @@ ignore_dirs:
     - common/static/xmodule/modules
     - common/static/xmodule/descriptors
 
+
+# Third-party installed apps that we also extract strings from.  When adding a
+# file here, also add it to the django.po merge files below, and to the
+# .tx/config file so that it will be pushed to and pulled from transifex.
+third_party:
+    - wiki
+
+
 # How should .po files be segmented?  See i18n/segment.py for details. Strings
 # that are only found in a particular segment are segregated into that .po file
 # so that translators can focus on separate parts of the product.
@@ -93,6 +101,7 @@ generate_merge:
         - mako.po
         - mako-studio.po
         - messages.po
+        - wiki.po
     djangojs.po:
         - djangojs-partial.po
         - djangojs-studio.po

i18n/config.py

@@ -23,6 +23,7 @@ class Configuration(object):
         'locales': ['en'],
         'segment': {},
         'source_locale': 'en',
+        'third_party': [],
     }
 
     def __init__(self, filename):

i18n/extract.py

@@ -15,8 +15,14 @@ and it cannot be overridden.
 
 """
 
-import os, sys, logging
 from datetime import datetime
+import importlib
+import os
+import os.path
+import logging
+import sys
+
+from path import path
 from polib import pofile
 
 from i18n.config import BASE_DIR, LOCALE_DIR, CONFIGURATION
@@ -24,18 +30,14 @@ from i18n.execute import execute, create_dir_if_necessary, remove_file
 from i18n.segment import segment_pofiles
 
 
-# BABEL_CONFIG contains declarations for Babel to extract strings from mako template files
-# Use relpath to reduce noise in logs
-BABEL_CONFIG = BASE_DIR.relpathto(LOCALE_DIR.joinpath('babel.cfg'))
-
-# Strings from mako template files are written to BABEL_OUT
-# Use relpath to reduce noise in logs
-BABEL_OUT = BASE_DIR.relpathto(CONFIGURATION.source_messages_dir.joinpath('mako.po'))
-
 EDX_MARKER = "edX translation file"
 
 LOG = logging.getLogger(__name__)
 
+def base(path1, *paths):
+    """Return a relative path from BASE_DIR to path1 / paths[0] / ... """
+    return BASE_DIR.relpathto(path1.joinpath(*paths))
+
 def main():
     logging.basicConfig(stream=sys.stdout, level=logging.INFO)
     create_dir_if_necessary(LOCALE_DIR)
@@ -43,7 +45,11 @@ def main():
     remove_file(source_msgs_dir.joinpath('django.po'))
 
     # Extract strings from mako templates.
-    babel_mako_cmd = 'pybabel extract -F %s -c "Translators:" . -o %s' % (BABEL_CONFIG, BABEL_OUT)
+    babel_mako_cmd = 'pybabel extract -F {config} -c "Translators:" . -o {output}'
+    babel_mako_cmd = babel_mako_cmd.format(
+        config=base(LOCALE_DIR, 'babel_mako.cfg'),
+        output=base(CONFIGURATION.source_messages_dir, 'mako.po'),
+    )
     execute(babel_mako_cmd, working_directory=BASE_DIR)
 
     makemessages = "django-admin.py makemessages -l en"
@@ -73,6 +79,20 @@ def main():
         source_msgs_dir.joinpath('djangojs-partial.po')
     )
 
+    # Extract strings from third-party applications.
+    for app_name in CONFIGURATION.third_party:
+        # Import the app to find out where it is.  Then use pybabel to extract
+        # from that directory.
+        app_module = importlib.import_module(app_name)
+        app_dir = path(app_module.__file__).dirname().dirname()
+        babel_cmd = 'pybabel extract -F {config} -c "Translators:" {app} -o {output}'
+        babel_cmd = babel_cmd.format(
+            config=LOCALE_DIR / 'babel_third_party.cfg',
+            app=app_name,
+            output=source_msgs_dir / (app_name + ".po"),
+        )
+        execute(babel_cmd, working_directory=app_dir)
+
     # Segment the generated files.
     segmented_files = segment_pofiles("en")