docs/dev/i18n.rst

.. _translations:

============
Translations
============

Translations are available on Hosted Weblate at the following URL:

    https://hosted.weblate.org/projects/kallithea/kallithea/

Registered users may contribute to the existing languages, or request a new
language translation.


Translating using Weblate
-------------------------

Weblate_ offers a simple and easy to use interface featuring glossary, machine
translation, suggestions based on similar translations in other projects,
automatic checks etc. Weblate imports the source code tree directly from
the version control system, and commits edits back from time to time.

When registering at Weblate, make sure you use the name and email address you
prefer to be used when your changes are committed. We can and probably will
amend changesets coming from Weblate, but having things right from the beginning
makes things easier.

Weblate performs sanity checks all the time and tries to prevent you from ignoring
them. Most common mistakes are inconsistent punctuation, whitespace, missing or extra
format parameters, untranslated strings copied into the translation. Please perform
necessary corrections when they're needed, or override the false positives.


Merging translations from Weblate (admin-only)
----------------------------------------------

Weblate rebases its changes every time it pulls from our repository. Pulls are triggered
by a web hook from Our Own Kallithea every time it receives new commits. Usually merging
the new translations is a straightforward process consisting of a pull from the Weblate-hosted
repository which is available under the Data Exports tab in the Weblate interface.

Weblate tries to minimise the number of commits, but that doesn't always work, especially
when two translators work with different languages at more or less the same time.
It makes sense sometimes to re-order or fold commits by the same author when they touch
just the same language translation. That, however, may confuse Weblate sometimes, in
which case it should be manually convinced it has to discard the commits it created by
using its administrative interface.


Regenerating translations after source code changes (admin-only)
----------------------------------------------------------------

When the Kallithea source code changes, both the location as the content of
translation strings can change. It is therefore necessary to regularly
regenerate the `kallithea.pot` file containing these strings, as well as aligning
the translation files (`*.po`).

First update the translation strings::

    python3 setup.py extract_messages

Then regenerate the translation files. This could either be done with `python3
setup.py update_catalog` or with `msgmerge` from the `gettext` package. As
Weblate is also touching these translation files, it is preferred to use the
same tools (`msgmerge`) and settings as Weblate to minimize the diff::

    find kallithea/i18n -name kallithea.po | xargs -I '{}' \
        msgmerge --width=76 --backup=none --previous --update '{}' \
        kallithea/i18n/kallithea.pot


Manual creation of a new language translation
---------------------------------------------

In the prepared development environment, run the following to ensure
all translation strings are extracted and up-to-date::

    python3 setup.py extract_messages

Create new language by executing following command::

    python3 setup.py init_catalog -l <new_language_code>

This creates a new translation under directory `kallithea/i18n/<new_language_code>`
based on the translation template file, `kallithea/i18n/kallithea.pot`.

Edit the new PO file located in `LC_MESSAGES` directory with poedit or your
favorite PO files editor. After you finished with the translations, check the
translation file for errors by executing::

    msgfmt -f -c kallithea/i18n/<new_language_code>/LC_MESSAGES/<updated_file.po>

Finally, compile the translations::

    python3 setup.py compile_catalog -l <new_language_code>


Manually updating translations
------------------------------

Extract the latest versions of strings for translation by running::

    python3 setup.py extract_messages

Update the PO file by doing::

    python3 setup.py update_catalog -l <new_language_code>

Edit the newly updated translation file. Repeat all steps after the
`init_catalog` step from the 'new translation' instructions above.


Testing translations
--------------------

Edit `kallithea/tests/conftest.py` and set `i18n.lang` to `<new_language_code>`
and run Kallithea tests by executing::

    py.test


Managing translations with scripts/i18n tooling
-----------------------------------------------

The general idea with the ``scripts/i18n`` tooling is to keep changes in the
main repository focussed on actual and reviewable changes with minimal noise.
Noisy generated or redundant localization changes (that are useful when
translations) are contained in the ``kallithea-i18n`` repo on the ``i18n``
branch. The translation files in the main repository have no line numbers, no
untranslated entries, no fuzzy entries, no unused entries, and no constantly
changing records of "latest" this and that (name, date, version, etc).

The branches in the main repo (``default`` and ``stable``) will thus only have
stripped ``.pot`` and ``.po`` files: an (almost) empty
``kallithea/i18n/kallithea.pot`` file, and minimal ``.po`` files. There are no
binary ``.mo`` files in any repo - these are only generated when packaging for
release (or locally if installing from source).

Generally, ``kallithea/i18n/`` should not be changed on the ``default`` and
``stable`` branches at all. The ``i18n`` branch should *only* change
``kallithea/i18n/`` . If there are changesets with exceptions from that, these
changesets should probably be grafted/redone in the "right" place.

The basic flow is thus:

0. All weblate translation is done on the ``i18n`` branch which generally is
   based on the ``stable`` branch.
1. Graft the essential part of all new changes on the ``i18n`` branch to
   ``stable`` (while normalizing to current stripped state of stable).
2. Merge from ``stable`` to ``i18n`` (while normalizing to the resulting
   unstripped and fully ``msgmerge``'d state and ``.pot``-updating state).
3. Verify that the content of the ``i18n`` branch will give exactly the content
   of the ``stable`` branch after stripping. If there is a diff, something has
   to be fixed in one way or the other ... and the whole process should
   probably be redone.

Translate
^^^^^^^^^

First land full translation changes in the ``kallithea-i18n`` repo on the
``i18n`` branch. That can be done in pretty much any way you want. If changes
for some reason have to be grafted or merged, there might be odd conflicts due
to all the noise. Conflicts on the full ``i18n`` branch can perhaps be resolved
more easily using non-stripping normalization before merging::

  python3 setup.py extract_messages && cp kallithea/i18n/kallithea.pot full.pot && hg revert kallithea/i18n/kallithea.pot -r .
  hg resolve kallithea/i18n/ --tool X --config merge-tools.X.executable=python3 --config merge-tools.X.args='scripts/i18n normalized-merge --merge-pot-file full.pot $local $base $other $output'

Land in main repository - stripped
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When the full i18n changes have landed on the ``i18n`` branch, prepare to land
them on ``stable``::

  hg up -cr stable
  python3 setup.py extract_messages && cp kallithea/i18n/kallithea.pot full.pot && hg revert kallithea/i18n/kallithea.pot

Consider all new ``i18n`` changes since last merge from ``stable``::

  hg log -G --style compact -r 'only("i18n", children(::stable))'

Graft them one by one (or in collapsed chunks) while normalizing.

If the graft has conflicts, use the ``scripts/i18n`` normalization tool to
apply ``msgmerge`` and strip before doing 3-way merge and resolving conflicts::

  hg resolve kallithea/i18n/ --tool X --config merge-tools.X.executable=python3 --config merge-tools.X.args='scripts/i18n normalized-merge --merge-pot-file full.pot --strip $local $base $other $output'

When all conflicts have been resolved, continue the graft::

  hg graft --continue

Then make sure any non-conflicting files are normalized and stripped too::

  scripts/i18n normalize-po-files --strip --merge-pot-file full.pot kallithea/i18n/*/LC_MESSAGES/kallithea.po
  hg ci --amend --config ui.editor=true

When things have been grafted to the ``stable`` branch, clean up history if
necessary: clean up the author and commit message when necessary, and perhaps
merge multiple changesets from same contributor.

Merge back to ``i18n``
^^^^^^^^^^^^^^^^^^^^^^

For any i18n changes that for some reason have been done on the ``stable``
branch, apply them manually on the ``i18n`` branch too - perhaps by grafting
and editing manually. The merge done in this step will `not` take care of it.
If the verification step done a bit later points out that something has been
missed, strip and go back to this point.

Then merge back to the ``i18n`` branch using normalization while keeping the
full ``.po`` files, and updating the full ``.pot`` and ``.po`` to current
state::

  hg up -cr i18n
  hg merge stable --tool internal:fail
  hg revert kallithea/i18n/*/LC_MESSAGES/*.po -r .
  hg resolve -m kallithea/i18n/*/LC_MESSAGES/*.po
  hg resolve -l  # verify all conflicts have been resolved
  python3 setup.py extract_messages && cp kallithea/i18n/kallithea.pot full.pot
  scripts/i18n normalize-po-files --merge-pot-file full.pot kallithea/i18n/*/LC_MESSAGES/kallithea.po
  hg commit  # "Merge from stable"

Note: ``normalize-po-files`` can also pretty much be done manually with::

  for po in kallithea/i18n/*/LC_MESSAGES/kallithea.po; do msgmerge --width=76 --backup=none --previous --update $po full.pot ; done

Note: Additional merges from ``stable`` to ``i18n`` can be done any time.

Verify
^^^^^^

Verify things are in sync between the full ``i18n`` branch and the stripped
``stable`` branch::

  hg up -cr stable
  hg revert -a -r i18n
  python3 setup.py extract_messages && cp kallithea/i18n/kallithea.pot full.pot && hg revert kallithea/i18n/kallithea.pot
  scripts/i18n normalize-po-files --strip --merge-pot-file full.pot kallithea/i18n/*/LC_MESSAGES/kallithea.po
  hg diff

If there is a diff, figure out where it came from, go back and fix the root
cause, and redo the graft/merge.

Push
^^^^

The changes on the ``stable`` branch should now be ready for pushing - verify
the actual changes with a thorough review of::

  hg out -pvr stable

When ``stable`` changes have been pushed, also push the ``i18n`` branch to the
``kallithea-i18n`` repo so Weblate can see it.


.. _Weblate: http://weblate.org/