"""Schemas for filtering on get_<type>_conflicts endpoints."""
import marshmallow

from conflict_manager.constants import error as error_consts
from conflict_manager.constants import query_parameters as query_consts


class FilterSchema(marshmallow.Schema):
    """Validation schema for filter parameters of get_conflicts endpoints."""

    class Meta:
        """Schema options."""

        unknown = marshmallow.EXCLUDE

    def __init__(self, *args, **kwargs):
        """Constructor.

        Args:
            filter_fields (list<str>): Optional list of eligible filter fields.
        """
        self.filter_fields = kwargs.pop('filter_fields', [])

        super().__init__(*args, **kwargs)

    query = marshmallow.fields.String(load_default=None, required=False)

    fields = marshmallow.fields.List(
        marshmallow.fields.String(), load_default=None, required=False)

    @marshmallow.validates(query_consts.FILTER_FIELDS)
    def validate_fields(self, value, **kwargs):
        """Validate filter fields parameter.

        Args:
            value (str): Value to validate. Can also be None.

        Raises:
            ValidationError
        """
        if value is None or value == '':
            value = None

        for val in value:
            if val is not None and val not in self.filter_fields:
                raise marshmallow.ValidationError(
                    error_consts.INVALID_FILTER_FIELD_MSG.format(value))

    @marshmallow.post_load
    def finalize_output(self, data, **kwargs):
        """Finalize output.

        Args:
            data (dict): Deserialized dict

        Return:
            dict
        """
        if self.filter_fields and not data[query_consts.FILTER_FIELDS]:
            data[query_consts.FILTER_FIELDS] = []
        return data