# 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.]

    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 {}
    elif language == 'zh-hans':
        language = 'zh_Hans'
    elif language == 'zh-hant':
        language = 'zh_Hant'
    elif language == 'id-id':
        language = 'id_ID'
    path = os.path.join(settings.DEPLOY_ROOT, 'locale', language, '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 save the language to the user's session, so that
    # something reasonable will happen in logged-in portico pages.
    request.session[translation.LANGUAGE_SESSION_KEY] = translation.get_language()

    return request_language