import gettext
import typing

from collections import OrderedDict

from fastapi import Request
from jinja2 import contextfilter

import aurweb.config

SUPPORTED_LANGUAGES = OrderedDict({
    "ar": "العربية",
    "ast": "Asturianu",
    "ca": "Català",
    "cs": "Český",
    "da": "Dansk",
    "de": "Deutsch",
    "el": "Ελληνικά",
    "en": "English",
    "es": "Español",
    "es_419": "Español (Latinoamérica)",
    "fi": "Suomi",
    "fr": "Français",
    "he": "עברית",
    "hr": "Hrvatski",
    "hu": "Magyar",
    "it": "Italiano",
    "ja": "日本語",
    "nb": "Norsk",
    "nl": "Nederlands",
    "pl": "Polski",
    "pt_BR": "Português (Brasil)",
    "pt_PT": "Português (Portugal)",
    "ro": "Română",
    "ru": "Русский",
    "sk": "Slovenčina",
    "sr": "Srpski",
    "tr": "Türkçe",
    "uk": "Українська",
    "zh_CN": "简体中文",
    "zh_TW": "正體中文"
})


class Translator:
    def __init__(self):
        self._localedir = aurweb.config.get('options', 'localedir')
        self._translator = {}

    def get_translator(self, lang: str):
        if lang not in self._translator:
            self._translator[lang] = gettext.translation("aurweb",
                                                         self._localedir,
                                                         languages=[lang],
                                                         fallback=True)
        return self._translator.get(lang)

    def translate(self, s: str, lang: str):
        return self.get_translator(lang).gettext(s)


# Global translator object.
translator = Translator()


def get_request_language(request: Request):
    return request.cookies.get("AURLANG",
                               aurweb.config.get("options", "default_lang"))


def get_raw_translator_for_request(request: Request):
    lang = get_request_language(request)
    return translator.get_translator(lang)


def get_translator_for_request(request: Request):
    """
    Determine the preferred language from a FastAPI request object and build a
    translator function for it.

    Example:
    ```python
    _ = get_translator_for_request(request)
    print(_("Hello"))
    ```
    """
    lang = get_request_language(request)

    def translate(message):
        return translator.translate(message, lang)

    return translate


@contextfilter
def tr(context: typing.Any, value: str):
    """ A translation filter; example: {{ "Hello" | tr("de") }}. """
    _ = get_translator_for_request(context.get("request"))
    return _(value)