Helpers for translating hstore fields in Django

i18n.py

# vim: fileencoding=utf-8 tw=100 expandtab ts=4 sw=4 :
#
# gmc_api
# (c) 2015 ActivKonnect

from django.core.exceptions import ValidationError
from django.utils.six import string_types
from django.utils.translation import get_language
from django.conf import settings


def get_short_language():
    """
    Guess the language (without the country code) based on what Django says.
    """

    l = get_language()

    if not l:
        l = settings.LANGUAGE_CODE

    return normalize_language(l)


def normalize_language(lang):
    """
    Returns a normalized version of a language, and drop the country code if needed
    """

    try:
        lang, _ = lang.split('-', 1)
    except ValueError:
        pass

    return lang.lower()


def choose_language(choices):
    """
    Choose a language from the choices. Preferably one that the user speaks.

    If no language is provided as choice, None will be returned.
    """

    l = get_short_language()
    raw = None

    for choice, raw in ((normalize_language(x), x) for x in choices):
        if choice == l:
            return raw

    return raw


def localize(translations):
    """
    From a {lang: translation} dict, return the most fitting translation string for the user.
    """

    l = choose_language(translations.keys())

    if not l:
        return None

    return translations[l]


def validate_translation_dict(translations):
    """
    Validates that a translation dict has valid keys/values
    """

    for k, v in translations.items():
        if normalize_language(k) != k:
            raise ValidationError('"{}" is not a valid language name'.format(k))

        if not isinstance(v, string_types):
            raise ValidationError('"{}" is not a string'.format(v))