import deprecation
import collections

from typing import Optional
from django.conf import settings
from django.utils import translation


class LocalizedValue(dict):
    """Represents the value of a :see:LocalizedField."""
    default_value = None

    def __init__(self, keys: dict=None):
        """Initializes a new instance of :see:LocalizedValue.

        Arguments:
            keys:
                The keys to initialize this value with. Every
                key contains the value of this field in a
                different language.
        """

        super().__init__({})
        self._interpret_value(keys)

    def get(self, language: str=None, default: str=None) -> str:
        """Gets the underlying value in the specified or
        primary language.

        Arguments:
            language:
                The language to get the value in.

        Returns:
            The value in the current language, or
            the primary language in case no language
            was specified.
        """

        language = language or settings.LANGUAGE_CODE
        value = super().get(language, default)
        return value if value is not None else default

    def set(self, language: str, value: str):
        """Sets the value in the specified language.

        Arguments:
            language:
                The language to set the value in.

            value:
                The value to set.
        """

        self[language] = value
        self.__dict__.update(self)
        return self

    def deconstruct(self) -> dict:
        """Deconstructs this value into a primitive type.

        Returns:
            A dictionary with all the localized values
            contained in this instance.
        """

        path = 'localized_fields.value.%s' % self.__class__.__name__
        return path, [self.__dict__], {}

    def _interpret_value(self, value):
        """Interprets a value passed in the constructor as
        a :see:LocalizedValue.

        If string:
            Assumes it's the default language.

        If dict:
            Each key is a language and the value a string
            in that language.

        If list:
            Recurse into to apply rules above.

        Arguments:
            value:
                The value to interpret.
        """

        for lang_code, _ in settings.LANGUAGES:
            self.set(lang_code, self.default_value)

        if isinstance(value, str):
            self.set(settings.LANGUAGE_CODE, value)

        elif isinstance(value, dict):
            for lang_code, _ in settings.LANGUAGES:
                lang_value = value.get(lang_code, self.default_value)
                self.set(lang_code, lang_value)

        elif isinstance(value, collections.Iterable):
            for val in value:
                self._interpret_value(val)

    def translate(self) -> Optional[str]:
        """Gets the value in the current language or falls
        back to the next language if there's no value in the
        current language."""

        fallbacks = getattr(settings, 'LOCALIZED_FIELDS_FALLBACKS', {})

        language = translation.get_language() or settings.LANGUAGE_CODE
        languages = fallbacks.get(language, [settings.LANGUAGE_CODE])[:]
        languages.insert(0, language)

        for lang_code in languages:
            value = self.get(lang_code)
            if value:
                return value or None

        return None

    def __str__(self) -> str:
        """Gets the value in the current language or falls
        back to the next language if there's no value in the
        current language."""

        return self.translate() or ''

    def __eq__(self, other):
        """Compares :paramref:self to :paramref:other for
        equality.

        Returns:
            True when :paramref:self is equal to :paramref:other.
            And False when they are not.
        """

        if not isinstance(other, type(self)):
            if isinstance(other, str):
                return self.__str__() == other
            return False

        for lang_code, _ in settings.LANGUAGES:
            if self.get(lang_code) != other.get(lang_code):
                return False

        return True

    def __ne__(self, other):
        """Compares :paramref:self to :paramerf:other for
        in-equality.

        Returns:
            True when :paramref:self is not equal to :paramref:other.
            And False when they are.
        """

        return not self.__eq__(other)

    def __setattr__(self, language: str, value: str):
        """Sets the value for a language with the specified name.

        Arguments:
            language:
                The language to set the value in.

            value:
                The value to set.
        """

        self.set(language, value)

    def __repr__(self):  # pragma: no cover
        """Gets a textual representation of this object."""

        return '%s<%s> 0x%s' % (self.__class__.__name__,
                                self.__dict__, id(self))


class LocalizedStringValue(LocalizedValue):
    default_value = ''


class LocalizedFileValue(LocalizedValue):
    def __getattr__(self, name: str):
        """Proxies access to attributes to attributes of LocalizedFile"""

        value = self.get(translation.get_language())
        if hasattr(value, name):
            return getattr(value, name)
        raise AttributeError("'{}' object has no attribute '{}'".
                             format(self.__class__.__name__, name))

    def __str__(self) -> str:
        """Returns string representation of value"""

        return str(super().__str__())

    @deprecation.deprecated(deprecated_in='4.6', removed_in='5.0',
                            current_version='4.6',
                            details='Use the translate() function instead.')
    def localized(self):
        """Returns value for current language"""

        return self.get(translation.get_language())


class LocalizedIntegerValue(LocalizedValue):
    """All values are integers."""

    default_value = None

    def translate(self):
        """Gets the value in the current language, or
        in the configured fallbck language."""

        value = super().translate()
        if value is None or (isinstance(value, str) and value.strip() == ''):
            return None

        return int(value)

    def __int__(self):
        """Gets the value in the current language as an integer."""

        value = self.translate()
        if value is None:
            return self.default_value

        return int(value)