#!/usr/bin/env python
# lint: pylint
# SPDX-License-Identifier: AGPL-3.0-or-later
"""This script generates :origin:`searx/languages.py` from intersecting each
engine's supported properites. The script checks all engines about a function::

  def _fetch_engine_properties(resp, engine_properties):
      ...

and a variable named ``supported_properties_url``.  The HTTP get response of
``supported_properties_url`` is passed to the ``_fetch_engine_properties``
function including a template of ``engine_properties`` (see
:py:obj:`searx.engines.engine_properties_template`).

Output files: :origin:`searx/data/engines_languages.json` and
:origin:`searx/languages.py` (:origin:`CI Update data ...
<.github/workflows/data-update.yml>`).

.. hint::

  This implementation is backward compatible and supports the (depricated)
  ``_fetch_supported_languages`` interface.

  On the long term the depricated implementations in the engines will be
  replaced by ``_fetch_engine_properties``.

"""

# pylint: disable=invalid-name
from unicodedata import lookup
import json
from pathlib import Path
from pprint import pformat
from babel import Locale, UnknownLocaleError
from babel.languages import get_global
from babel.core import parse_locale

from searx import settings, searx_dir
from searx import network
from searx.engines import load_engines, engines, engine_properties_template
from searx.utils import gen_useragent

# Output files.
engines_languages_file = Path(searx_dir) / 'data' / 'engines_languages.json'
languages_file = Path(searx_dir) / 'languages.py'


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

    """
    network.set_timeout_for_thread(10.0)
    engines_languages = {}
    names = list(engines)
    names.sort()

    # The headers has been moved here from commit 9b6ffed06: Some engines (at
    # least bing and startpage) return a different result list of supported
    # languages depending on the IP location where the HTTP request comes from.
    # The IP based results (from bing) can be avoided by setting a
    # 'Accept-Language' in the HTTP request.

    headers = {
        'User-Agent': gen_useragent(),
        'Accept-Language': "en-US,en;q=0.5",  # bing needs to set the English language
    }

    for engine_name in names:
        engine = engines[engine_name]
        fetch_languages = getattr(engine, '_fetch_supported_languages', None)
        fetch_properties = getattr(engine, '_fetch_engine_properties', None)

        if fetch_properties is not None:
            resp = network.get(engine.supported_properties_url, headers=headers)
            engine_properties = engine_properties_template()
            fetch_properties(resp, engine_properties)
            print("%s: %s languages" % (engine_name, len(engine_properties['languages'])))
            print("%s: %s regions" % (engine_name, len(engine_properties['regions'])))

        elif fetch_languages is not None:
            # print("%s: using deepricated _fetch_fetch_languages()" % engine_name)
            resp = network.get(engine.supported_languages_url, headers=headers)
            engine_properties = fetch_languages(resp)
            if isinstance(engine_properties, list):
                engine_properties.sort()

            print("%s: fetched language %s containing %s items" % (
                engine_name,
                engine_properties.__class__.__name__,
                len(engine_properties)
            ))
        else:
            continue

        engines_languages[engine_name] = engine_properties

    print("fetched properties from %s engines" % len(engines_languages))
    print("write json file: %s" % (engines_languages_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


lang2emoji = {
    'ha': '\U0001F1F3\U0001F1EA',  # Hausa / Niger
    'bs': '\U0001F1E7\U0001F1E6',  # Bosnian / Bosnia & Herzegovina
    'jp': '\U0001F1EF\U0001F1F5',  # Japanese
    'ua': '\U0001F1FA\U0001F1E6',  # Ukrainian
    'he': '\U0001F1EE\U0001F1F7',  # Hebrew
}


def get_unicode_flag(lang_code):
    """Determine a unicode flag (emoji) that fits to the ``lang_code``"""

    emoji = lang2emoji.get(lang_code.lower())
    if emoji:
        return emoji

    if len(lang_code) == 2:
        return '\U0001F310'

    language = territory = script = variant = ''
    try:
        language, territory, script, variant = parse_locale(lang_code, '-')
    except ValueError as exc:
        print(exc)

    # https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
    if not territory:
        # https://www.unicode.org/emoji/charts/emoji-list.html#country-flag
        emoji = lang2emoji.get(language)
        if not emoji:
            print(
                "%s --> language: %s / territory: %s / script: %s / variant: %s"
                % (lang_code, language, territory, script, variant)
            )
        return emoji

    emoji = lang2emoji.get(territory.lower())
    if emoji:
        return emoji

    try:
        c1 = lookup('REGIONAL INDICATOR SYMBOL LETTER ' + territory[0])
        c2 = lookup('REGIONAL INDICATOR SYMBOL LETTER ' + territory[1])
        # print("%s --> territory: %s --> %s%s" %(lang_code, territory, c1, c2 ))
    except KeyError as exc:
        print("%s --> territory: %s --> %s" % (lang_code, territory, exc))
        return None

    return c1 + c2


def get_territory_name(lang_code):
    country_name = None
    locale = get_locale(lang_code)
    try:
        country_name = locale.get_territory_name()
    except FileNotFoundError as exc:
        print("ERROR: %s --> %s" % (locale, exc))
    return country_name

def join_language_lists(engines_languages):
    """Join all languages of the engines into one list.  The returned language list
    contains language codes (``zh``) and region codes (``zh-TW``).  The codes can
    be parsed by babel::

      babel.Locale.parse(language_list[n])

    """
    # pylint: disable=too-many-branches
    language_list = {}

    for engine_name in engines_languages:
        engine = engines[engine_name]
        engine_codes = languages = engines_languages[engine_name]

        if isinstance(languages, dict):
            engine_codes = languages.get('regions', engine_codes)

        if isinstance(engine_codes, dict):
            engine_codes = engine_codes.keys()

        for lang_code in engine_codes:

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

            # 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
                    try:
                        country_name = locale.get_territory_name()
                    except FileNotFoundError as exc:
                        print("ERROR: %s --> %s" % (locale, exc))
                        locale = None

                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 = 13
    min_engines_per_country = 7
    # pylint: disable=consider-using-dict-items, consider-iterating-dictionary
    main_engines = [
        engine_name
        for engine_name in engines.keys()
        if 'general' in engines[engine_name].categories
        and hasattr(engines[engine_name], 'supported_languages')
        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 = {}
        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

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

        # 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, None)
        elif len(filtered_countries) == 1:
            lang_country = next(iter(filtered_countries))

        # 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, None)
            else:
                filtered_countries[lang] = _copy_lang_data(lang, None)

        filtered_languages_with_countries.update(filtered_countries)

    return filtered_languages_with_countries


class UnicodeEscape(str):
    """Escape unicode string in :py:obj:`pprint.pformat`"""

    def __repr__(self):
        return "'" + "".join([chr(c) for c in self.encode('unicode-escape')]) + "'"


# 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 = (\n",
    )

    language_codes = []

    for code in sorted(languages):

        name = languages[code]['name']
        if name is None:
            print("ERROR: languages['%s'] --> %s" % (code, languages[code]))
            continue

        flag = get_unicode_flag(code) or ''
        item = (
            code,
            languages[code]['name'].split(' (')[0],
            get_territory_name(code) or '',
            languages[code].get('english_name') or '',
            UnicodeEscape(flag),
        )

        language_codes.append(item)

    language_codes = tuple(language_codes)

    with open(languages_file, 'w', encoding='utf-8') as new_file:
        file_content = "{file_headers} {language_codes},\n)\n".format(
            # fmt: off
            file_headers = '\n'.join(file_headers),
            language_codes = pformat(language_codes, indent=4)[1:-1]
            # fmt: on
        )
        new_file.write(file_content)
        new_file.close()


if __name__ == "__main__":
    load_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)