from rest_framework import serializers

from dynamic_preferences.signals import preference_updated


class PreferenceValueField(serializers.Field):
    def get_attribute(self, o):
        return o

    def to_representation(self, o):
        return o.preference.api_repr(o.value)

    def to_internal_value(self, data):
        return data


class PreferenceSerializer(serializers.Serializer):

    section = serializers.CharField(read_only=True)
    name = serializers.CharField(read_only=True)
    identifier = serializers.SerializerMethodField()
    default = serializers.SerializerMethodField()
    value = PreferenceValueField()
    verbose_name = serializers.SerializerMethodField()
    help_text = serializers.SerializerMethodField()
    additional_data = serializers.SerializerMethodField()
    field = serializers.SerializerMethodField()

    class Meta:
        fields = [
            "default",
            "value",
            "verbose_name",
            "help_text",
        ]

    def get_default(self, o):
        return o.preference.api_repr(o.preference.get("default"))

    def get_verbose_name(self, o):
        return o.preference.get("verbose_name")

    def get_identifier(self, o):
        return o.preference.identifier()

    def get_help_text(self, o):
        return o.preference.get("help_text")

    def get_additional_data(self, o):
        return o.preference.get_api_additional_data()

    def get_field(self, o):
        return o.preference.get_api_field_data()

    def validate_value(self, value):
        """
        We call validation from the underlying form field
        """
        field = self.instance.preference.setup_field()
        value = field.to_python(value)
        field.validate(value)
        field.run_validators(value)
        return value

    def update(self, instance, validated_data):
        old_value = instance.value
        instance.value = validated_data["value"]
        instance.save()
        preference_updated.send(
            sender=self.__class__,
            section=instance.section,
            name=instance.name,
            old_value=old_value,
            new_value=validated_data["value"],
            instance=instance
        )
        return instance


class GlobalPreferenceSerializer(PreferenceSerializer):
    pass