# See https://zulip.readthedocs.io/en/latest/translating/internationalization.html

import logging
import operator
import os
from functools import lru_cache
from itertools import zip_longest
from typing import Any, Dict, List, Optional

import orjson
from django.conf import settings
from django.http import HttpRequest
from django.utils import translation


@lru_cache()
def get_language_list() -> List[Dict[str, Any]]:
    path = os.path.join(settings.DEPLOY_ROOT, "locale", "language_name_map.json")
    with open(path, "rb") as reader:
        languages = orjson.loads(reader.read())
        return languages["name_map"]


def get_language_list_for_templates(default_language: str) -> List[Dict[str, Dict[str, str]]]:
    language_list = [
        lang
        for lang in get_language_list()
        if "percent_translated" not in lang or lang["percent_translated"] >= 5.0
    ]

    formatted_list = []
    lang_len = len(language_list)
    firsts_end = (lang_len // 2) + operator.mod(lang_len, 2)
    firsts = list(range(0, firsts_end))
    seconds = list(range(firsts_end, lang_len))
    assert len(firsts) + len(seconds) == lang_len
    for row in zip_longest(firsts, seconds):
        item = {}
        for position, ind in zip(["first", "second"], row):
            if ind is None:
                continue

            lang = language_list[ind]
            percent = name = lang["name"]
            if "percent_translated" in lang:
                percent = "{} ({}%)".format(name, lang["percent_translated"])

            selected = False
            if default_language in (lang["code"], lang["locale"]):
                selected = True

            item[position] = {
                "name": name,
                "code": lang["code"],
                "percent": percent,
                "selected": selected,
            }

        formatted_list.append(item)

    return formatted_list


def get_language_name(code: str) -> str:
    for lang in get_language_list():
        if code in (lang["code"], lang["locale"]):
            return lang["name"]
    # Log problem, but still return a name
    logging.error("Unknown language code '%s'", code)
    return "Unknown"


def get_available_language_codes() -> List[str]:
    language_list = get_language_list()
    codes = [language["code"] for language in language_list]
    return codes


def get_language_translation_data(language: str) -> Dict[str, str]:
    if language == "en":
        return {}
    locale = translation.to_locale(language)
    path = os.path.join(settings.DEPLOY_ROOT, "locale", locale, "translations.json")
    try:
        with open(path, "rb") as reader:
            return orjson.loads(reader.read())
    except FileNotFoundError:
        print(f"Translation for {language} not found at {path}")
        return {}


def get_and_set_request_language(
    request: HttpRequest, user_configured_language: str, testing_url_language: Optional[str] = None
) -> str:
    # We pick a language for the user as follows:
    # * First priority is the language in the URL, for debugging.
    # * If not in the URL, we use the language from the user's settings.
    request_language = testing_url_language
    if request_language is None:
        request_language = user_configured_language
    translation.activate(request_language)

    # We also want to save the language to the user's cookies, so that
    # something reasonable will happen in logged-in portico pages.
    # We accomplish that by setting a flag on the request which signals
    # to LocaleMiddleware to set the cookie on the response.
    request._set_language = translation.get_language()

    return request_language