libretube/plugins/i18n_subsites

=======================
I18N Sub-sites Plugin
=======================

This plugin extends the translations functionality by creating
internationalized sub-sites for the default site.

This plugin is designed for Pelican 3.4 and later.

What it does
============

1. When the content of the main site is being generated, the settings
are saved and the generation stops when content is ready to be
written. While reading source files and generating content objects,
the output queue is modified in certain ways:

- translations that will appear as native in a different (sub-)site
will be removed
- untranslated articles will be transformed to drafts if
``I18N_UNTRANSLATED_ARTICLES`` is ``'hide'`` (default), removed if
``'remove'`` or kept as they are if ``'keep'``.
- untranslated pages will be transformed into hidden pages if
``I18N_UNTRANSLATED_PAGES`` is ``'hide'`` (default), removed if
``'remove'`` or kept as they are if ``'keep'``.''
- additional content manipulation similar to articles and pages can
be specified for custom generators in the ``I18N_GENERATOR_INFO``
setting.

2. For each language specified in the ``I18N_SUBSITES`` dictionary the
settings overrides are applied to the settings from the main site
and a new sub-site is generated in the same way as with the main
site until content is ready to be written.
3. When all (sub-)sites are waiting for content writing, all removed
contents, translations and static files are interlinked across the
(sub-)sites.
4. Finally, all the output is written.

Setting it up
=============

For each extra used language code, a language-specific settings overrides
dictionary must be given (but can be empty) in the ``I18N_SUBSITES`` dictionary

.. code-block:: python

PLUGINS = ['i18n_subsites', ...]

# mapping: language_code -> settings_overrides_dict
I18N_SUBSITES = {
'cz': {
'SITENAME': 'Hezkej blog',
}
}

You must also have the following in your pelican configuration

.. code-block:: python
JINJA_ENVIRONMENT = {
'extensions': ['jinja2.ext.i18n'],
}



Default and special overrides
-----------------------------
The settings overrides may contain arbitrary settings, however, there
are some that are handled in a special way:

``SITEURL``
Any overrides to this setting should ensure that there is some level
of hierarchy between all (sub-)sites, because Pelican makes all URLs
relative to ``SITEURL`` and the plugin can only cross-link between
the sites using this hierarchy. For instance, with the main site
``http://example.com`` a sub-site ``http://example.com/de`` will
work, but ``http://de.example.com`` will not. If not overridden, the
language code (the language identifier used in the ``lang``
metadata) is appended to the main ``SITEURL`` for each sub-site.
``OUTPUT_PATH``, ``CACHE_PATH``
If not overridden, the language code is appended as with ``SITEURL``.
Separate cache paths are required as parser results depend on the locale.
``STATIC_PATHS``, ``THEME_STATIC_PATHS``
If not overridden, they are set to ``[]`` and all links to static
files are cross-linked to the main site.
``THEME``, ``THEME_STATIC_DIR``
If overridden, the logic with ``THEME_STATIC_PATHS`` does not apply.
``DEFAULT_LANG``
This should not be overridden as the plugin changes it to the
language code of each sub-site to change what is perceived as translations.

Localizing templates
--------------------

Most importantly, this plugin can use localized templates for each
sub-site. There are two approaches to having the templates localized:

- You can set a different ``THEME`` override for each language in
``I18N_SUBSITES``, e.g. by making a copy of a theme ``my_theme`` to
``my_theme_lang`` and then editing the templates in the new
localized theme. This approach means you don't have to deal with
gettext ``*.po`` files, but it is harder to maintain over time.
- You use only one theme and localize the templates using the
`jinja2.ext.i18n Jinja2 extension
`_. For a kickstart
read this `guide <./localizing_using_jinja2.rst>`_.

Additional context variables
............................

It may be convenient to add language buttons to your theme in addition
to the translation links of articles and pages. These buttons could,
for example, point to the ``SITEURL`` of each (sub-)site. For this
reason the plugin adds these variables to the template context:

``main_lang``
The language of the main site — the original ``DEFAULT_LANG``
``main_siteurl``
The ``SITEURL`` of the main site — the original ``SITEURL``
``lang_siteurls``
An ordered dictionary, mapping all used languages to their
``SITEURL``. The ``main_lang`` is the first key with ``main_siteurl``
as the value. This dictionary is useful for implementing global
language buttons that show the language of the currently viewed
(sub-)site too.
``extra_siteurls``
An ordered dictionary, subset of ``lang_siteurls``, the current
``DEFAULT_LANG`` of the rendered (sub-)site is not included, so for
each (sub-)site ``set(extra_siteurls) == set(lang_siteurls) -
set([DEFAULT_LANG])``. This dictionary is useful for implementing
global language buttons that do not show the current language.
``relpath_to_site``
A function that returns a relative path from the first (sub-)site to
the second (sub-)site where the (sub-)sites are identified by the
language codes given as two arguments.

If you don't like the default ordering of the ordered dictionaries,
use a Jinja2 filter to alter the ordering.

All the siteurls above are always absolute even in the case of
``RELATIVE_URLS == True`` (it would be to complicated to replicate the
Pelican internals for local siteurls), so you may rather use something
like ``{{ SITEURL }}/{{ relpath_to_site(DEFAULT_LANG, main_lang }}``
to link to the main site.

This short `howto <./implementing_language_buttons.rst>`_ shows two
example implementations of language buttons.

Usage notes
===========
- It is **mandatory** to specify ``lang`` metadata for each article
and page as ``DEFAULT_LANG`` is later changed for each sub-site, so
content without ``lang`` metadata would be rendered in every
(sub-)site.
- As with the original translations functionality, ``slug`` metadata
is used to group translations. It is therefore often convenient to
compensate for this by overriding the content URL (which defaults to
slug) using the ``url`` and ``save_as`` metadata. You could also
give articles e.g. ``name`` metadata and use it in ``ARTICLE_URL =
'{name}.html'``.

Development
===========

- A demo and a test site is in the ``gh-pages`` branch and can be seen
at http://smartass101.github.io/pelican-plugins/