Note that, for everything to work consistently, we need to make sure
that the default locale is one of the available locales.
Also note that we aren't overwriting the `#save ` method set by
globalize. I didn't feel too comfortable changing a monkey-patch which
ideally shouldn't be there in the first place, I haven't found a case
where `Globalize.locale` is `nil` (since it defaults to `I18n.locale`,
which should never be `nil`), so using `I18n.default_locale` probably
doesn't affect us.
Note that, currently, we take these settings from the database but we
don't provide a way to edit them through the admin interface, so the
locales must be manually introduced through a Rails console.
While we did consider using a comma-separated list, we're using spaces
in order to be consistent with the way we store the allowed content
types settings.
The `enabled_locales` nomenclature, which contrasts with
`available_locales`, is probably subconsciously based on similar
patterns like the one Nginx uses to enable sites.
Note that we aren't using `Setting.enabled_locales` in the globalize
initializer when setting the fallbacks. This means the following test
(which we could add to the shared globalizable examples) would fail:
```
it "Falls back to an enabled locale if the fallback is not enabled" do
Setting["locales.default"] = "en"
Setting["locales.enabled"] = "fr en"
allow(I18n.fallbacks).to receive(:[]).and_return([:fr, :es])
Globalize.set_fallbacks_to_all_available_locales
I18n.with_locale(:fr) do
expect(record.send(attribute)).to eq "In English"
end
end
```
The reason is that the code making this test pass could be:
```
def Globalize.set_fallbacks_to_all_available_locales
Globalize.fallbacks = I18n.available_locales.index_with do |locale|
((I18n.fallbacks[locale] & Setting.enabled_locales) + Setting.enabled_locales).uniq
end
end
```
However, this would make it impossible to run `rake db:migrate` on new
applications because the initializer would try to load the `Setting`
model but the `settings` table wouldn't exist at that point.
Besides, this is a really rare case that IMHO we don't need to support.
For this scenario, an installation would have to enable a locale, create
records with contents in that locale, then disable that locale and have
that locale as a fallback for a language where content for that record
wasn't created. If that happened, it would be solved by creating content
for that record in every enabled language.
