# SPDX-License-Identifier: GPL-2.0-only
#
# This file is part of Nominatim. (https://nominatim.org)
#
# Copyright (C) 2022 by the Nominatim developer community.
# For a full list of authors see the git log.
"""
Functions for importing and managing static country information.
"""
import psycopg2.extras

from nominatim.db import utils as db_utils
from nominatim.db.connection import connect
from nominatim.errors import UsageError

def _flatten_name_list(names):
    if names is None:
        return {}

    if not isinstance(names, dict):
        raise UsageError("Expected key-value list for names in country_settings.py")

    flat = {}
    for prefix, remain in names.items():
        if isinstance(remain, str):
            flat[prefix] = remain
        elif not isinstance(remain, dict):
            raise UsageError("Entries in names must be key-value lists.")
        else:
            for suffix, name in remain.items():
                if suffix == 'default':
                    flat[prefix] = name
                else:
                    flat[f'{prefix}:{suffix}'] = name

    return flat



class _CountryInfo:
    """ Caches country-specific properties from the configuration file.
    """

    def __init__(self):
        self._info = {}


    def load(self, config):
        """ Load the country properties from the configuration files,
            if they are not loaded yet.
        """
        if not self._info:
            self._info = config.load_sub_configuration('country_settings.yaml')
            for prop in self._info.values():
                # Convert languages into a list for simpler handling.
                if 'languages' not in prop:
                    prop['languages'] = []
                elif not isinstance(prop['languages'], list):
                    prop['languages'] = [x.strip()
                                         for x in prop['languages'].split(',')]
                prop['names'] = _flatten_name_list(prop.get('names'))


    def items(self):
        """ Return tuples of (country_code, property dict) as iterable.
        """
        return self._info.items()

    def get(self, country_code):
        """ Get country information for the country with the given country code.
        """
        return self._info.get(country_code, {})



_COUNTRY_INFO = _CountryInfo()


def setup_country_config(config):
    """ Load country properties from the configuration file.
        Needs to be called before using any other functions in this
        file.
    """
    _COUNTRY_INFO.load(config)


def iterate():
    """ Iterate over country code and properties.
    """
    return _COUNTRY_INFO.items()


def setup_country_tables(dsn, sql_dir, ignore_partitions=False):
    """ Create and populate the tables with basic static data that provides
        the background for geocoding. Data is assumed to not yet exist.
    """
    db_utils.execute_file(dsn, sql_dir / 'country_osm_grid.sql.gz')

    params = []
    for ccode, props in _COUNTRY_INFO.items():
        if ccode is not None and props is not None:
            if ignore_partitions:
                partition = 0
            else:
                partition = props.get('partition')
            lang = props['languages'][0] if len(
                props['languages']) == 1 else None

            params.append((ccode, props['names'], lang, partition))
    with connect(dsn) as conn:
        with conn.cursor() as cur:
            psycopg2.extras.register_hstore(cur)
            cur.execute(
                """ CREATE TABLE public.country_name (
                        country_code character varying(2),
                        name public.hstore,
                        derived_name public.hstore,
                        country_default_language_code text,
                        partition integer
                    ); """)
            cur.execute_values(
                """ INSERT INTO public.country_name
                    (country_code, name, country_default_language_code, partition) VALUES %s
                """, params)
        conn.commit()


def create_country_names(conn, tokenizer, languages=None):
    """ Add default country names to search index. `languages` is a comma-
        separated list of language codes as used in OSM. If `languages` is not
        empty then only name translations for the given languages are added
        to the index.
    """
    if languages:
        languages = languages.split(',')

    def _include_key(key):
        return ':' not in key or not languages or \
               key[key.index(':') + 1:] in languages

    with conn.cursor() as cur:
        psycopg2.extras.register_hstore(cur)
        cur.execute("""SELECT country_code, name FROM country_name
                       WHERE country_code is not null""")

        with tokenizer.name_analyzer() as analyzer:
            for code, name in cur:
                names = {'countrycode': code}

                # country names (only in languages as provided)
                if name:
                    names.update({k : v for k, v in name.items() if _include_key(k)})

                analyzer.add_country_names(code, names)

    conn.commit()