# -*- coding: utf-8 -*-

# This script generates languages.py from intersecting each engine's supported languages.
#
# Output files (engines_languages.json and languages.py)
# are written in current directory to avoid overwriting in case something goes wrong.

import json
from pprint import pformat
from sys import path
from babel import Locale, UnknownLocaleError
from babel.languages import get_global

path.append('../searx')  # noqa
from searx import settings
from searx.engines import initialize_engines, engines

# Output files.
engines_languages_file = 'engines_languages.json'
languages_file = 'languages.py'


# Fetchs supported languages for each engine and writes json file with those.
def fetch_supported_languages():

    engines_languages = dict()
    names = list(engines)
    names.sort()

    for engine_name in names:
        if hasattr(engines[engine_name], 'fetch_supported_languages'):
            engines_languages[engine_name] = engines[engine_name].fetch_supported_languages()
            print("fetched %s languages from engine %s" % (
                len(engines_languages[engine_name]), engine_name))
            if type(engines_languages[engine_name]) == list:
                engines_languages[engine_name] = sorted(engines_languages[engine_name])

    # write json file
    with open(engines_languages_file, 'w', encoding='utf-8') as f:
        json.dump(engines_languages, f, indent=2, sort_keys=True)

    return engines_languages


# Get babel Locale object from lang_code if possible.
def get_locale(lang_code):
    try:
        locale = Locale.parse(lang_code, sep='-')
        return locale
    except (UnknownLocaleError, ValueError):
        return None


# Join all language lists.
def join_language_lists(engines_languages):
    language_list = dict()
    for engine_name in engines_languages:
        for lang_code in engines_languages[engine_name]:

            # apply custom fixes if necessary
            if lang_code in getattr(engines[engine_name], 'language_aliases', {}).values():
                lang_code = next(lc for lc, alias in engines[engine_name].language_aliases.items()
                                 if lang_code == alias)

            locale = get_locale(lang_code)

            # ensure that lang_code uses standard language and country codes
            if locale and locale.territory:
                lang_code = "{lang}-{country}".format(lang=locale.language, country=locale.territory)
            short_code = lang_code.split('-')[0]

            # add language without country if not in list
            if short_code not in language_list:
                if locale:
                    # get language's data from babel's Locale object
                    language_name = locale.get_language_name().title()
                    english_name = locale.english_name.split(' (')[0]
                elif short_code in engines_languages['wikipedia']:
                    # get language's data from wikipedia if not known by babel
                    language_name = engines_languages['wikipedia'][short_code]['name']
                    english_name = engines_languages['wikipedia'][short_code]['english_name']
                else:
                    language_name = None
                    english_name = None

                # add language to list
                language_list[short_code] = {'name': language_name,
                                             'english_name': english_name,
                                             'counter': set(),
                                             'countries': dict()}

            # add language with country if not in list
            if lang_code != short_code and lang_code not in language_list[short_code]['countries']:
                country_name = ''
                if locale:
                    # get country name from babel's Locale object
                    country_name = locale.get_territory_name()

                language_list[short_code]['countries'][lang_code] = {'country_name': country_name,
                                                                     'counter': set()}

            # count engine for both language_country combination and language alone
            language_list[short_code]['counter'].add(engine_name)
            if lang_code != short_code:
                language_list[short_code]['countries'][lang_code]['counter'].add(engine_name)

    return language_list


# Filter language list so it only includes the most supported languages and countries
def filter_language_list(all_languages):
    min_engines_per_lang = 15
    min_engines_per_country = 10
    main_engines = [engine_name for engine_name in engines.keys()
                    if 'general' in engines[engine_name].categories and
                       engines[engine_name].supported_languages and
                       not engines[engine_name].disabled]

    # filter list to include only languages supported by most engines or all default general engines
    filtered_languages = {code: lang for code, lang
                          in all_languages.items()
                          if (len(lang['counter']) >= min_engines_per_lang or
                              all(main_engine in lang['counter']
                                  for main_engine in main_engines))}

    def _copy_lang_data(lang, country_name=None):
        new_dict = dict()
        new_dict['name'] = all_languages[lang]['name']
        new_dict['english_name'] = all_languages[lang]['english_name']
        if country_name:
            new_dict['country_name'] = country_name
        return new_dict

    def _country_count(i):
        return len(countries[sorted_countries[i]]['counter'])

    # for each language get country codes supported by most engines or at least one country code
    filtered_languages_with_countries = dict()
    for lang, lang_data in filtered_languages.items():
        countries = lang_data['countries']
        filtered_countries = dict()

        # get language's country codes with enough supported engines
        for lang_country, country_data in countries.items():
            if len(country_data['counter']) >= min_engines_per_country:
                filtered_countries[lang_country] = _copy_lang_data(lang, country_data['country_name'])

        # add language without countries too if there's more than one country to choose from
        if len(filtered_countries) > 1:
            filtered_countries[lang] = _copy_lang_data(lang)
        elif len(filtered_countries) == 1:
            # if there's only one country per language, it's not necessary to show country name
            lang_country = next(iter(filtered_countries))
            filtered_countries[lang_country]['country_name'] = None

        # if no country has enough engines try to get most likely country code from babel
        if not filtered_countries:
            lang_country = None
            subtags = get_global('likely_subtags').get(lang)
            if subtags:
                country_code = subtags.split('_')[-1]
                if len(country_code) == 2:
                    lang_country = "{lang}-{country}".format(lang=lang, country=country_code)

            if lang_country:
                filtered_countries[lang_country] = _copy_lang_data(lang)
            else:
                filtered_countries[lang] = _copy_lang_data(lang)

        filtered_languages_with_countries.update(filtered_countries)

    return filtered_languages_with_countries


# Write languages.py.
def write_languages_file(languages):
    file_headers = (
        "# -*- coding: utf-8 -*-",
        "# list of language codes",
        "# this file is generated automatically by utils/fetch_languages.py",
        "language_codes ="
    )

    language_codes = tuple([
        (
            code,
            languages[code]['name'].split(' (')[0],
            languages[code].get('country_name') or '',
            languages[code].get('english_name') or ''
        ) for code in sorted(languages)
    ])

    with open(languages_file, 'w') as new_file:
        file_content = "{file_headers} \\\n{language_codes}".format(
            file_headers='\n'.join(file_headers),
            language_codes=pformat(language_codes, indent=4)
        )
        new_file.write(file_content)
        new_file.close()


if __name__ == "__main__":
    initialize_engines(settings['engines'])
    engines_languages = fetch_supported_languages()
    all_languages = join_language_lists(engines_languages)
    filtered_languages = filter_language_list(all_languages)
    write_languages_file(filtered_languages)
