"""Static countries data."""

import json

import pkg_resources


COUNTRIES_FILE_NAME = pkg_resources.resource_filename(
    'iso_standards', 'data/json/countries_and_regions.json'
)


class Country:
    """Class that represents a country object."""

    _country_list = []
    _indexes = {}

    def __init__(self, country_code):
        """Get Country instance by code

        Args:
            country_code (str): either of ISO-3166 alpha2|alpha3|numeric codes
        Raises:
            KeyError if not found
        """
        Country._init_countries_data()
        self._country = self._get_country_by_code(country_code)

    @classmethod
    def _init_countries_data(cls):
        if cls._country_list:
            return
        with open(COUNTRIES_FILE_NAME, encoding='utf-8') as countries_file:
            cls._country_list = json.load(countries_file)
        cls._build_indexes(fields=[
            'alpha-2', 'alpha-3', 'country-code', 'region'])

    @classmethod
    def _build_indexes(cls, fields):
        """We need to index our countries to search quicker."""
        for country in cls._country_list:
            for key in fields:
                value = country[key]
                # e.g. _indexes['alpha-2'] = {}
                values_storage = cls._indexes.setdefault(key, {})
                # e.g _indexes['alpha-2']['US'] = []
                index_storage = values_storage.setdefault(value, [])
                # e.g. _indexes['alpha-2']['US'] = [Country]
                index_storage.append(country)

    @classmethod
    def get_countries_by_region_name(cls, region_name):
        """Get ISO 3166 countries of the region."""
        cls._init_countries_data()
        if region_name not in cls._indexes['region']:
            raise KeyError(
                'Region with name {} was not found'.format(region_name))
        return [
            cls(item['alpha-3'])
            for item in cls._indexes['region'][region_name]
        ]

    @classmethod
    def get_list(cls):
        """Get all countries list."""
        cls._init_countries_data()
        return [
            cls(item['alpha-3']) for item in cls._country_list
        ]

    def _get_country_by_code(self, code):
        if code in self._indexes.get('alpha-2', {}):
            return self._indexes['alpha-2'][code][0]
        if code in self._indexes.get('alpha-3', {}):
            return self._indexes['alpha-3'][code][0]
        if code in self._indexes.get('country-code', {}):
            return self._indexes['country-code'][code][0]
        raise KeyError('Country with code {} was not found'.format(code))

    @property
    def alpha2(self):
        """Get ISO 3166-1 alpha-2 code."""
        return self._country['alpha-2']

    @property
    def alpha3(self):
        """Get ISO 3166-1 alpha-2 code."""
        return self._country['alpha-3']

    @property
    def numeric(self):
        """Get ISO 3166-1 numeric code."""
        return self._country['country-code']

    @property
    def name(self):
        """Get ISO 3166-1 country name."""
        return self._country['name']

    @property
    def region(self):
        """Get ISO 3166-2 region name."""
        return self._country['region']

    def to_dict(self):
        """Serialize country into a dictionary."""
        return {
            'alpha2': self._country['alpha-2'],
            'alpha3': self._country['alpha-3'],
            'numeric': self._country['country-code'],
            'name': self._country['name'],
            'region': self._country['region']
        }