from slugify import slugify
from wtforms_alchemy.validators import Unique, ValidationError


class UniqueSlug(Unique):
    """
    Validates slug field related for the specified field.

    Use `slug` column to point validator to the specific slug field in model.
    User `limiter_column` to add etra scope limitation.
    """

    def __init__(
        self,
        column,
        slug_column,
        limiter_column=None,
        get_session=None,
        message=None,
        slug_repr=None,
    ):
        super().__init__(column, get_session, message)
        self.slug_column = slug_column
        self.limiter_column = limiter_column
        self.slug_repr = slug_repr or self.get_default_slug_repr()

    def __call__(self, form, field):
        query = None
        if self.limiter_column:
            columns = self._syntaxes_as_tuples(
                form, field, self.limiter_column
            )
            self.model = columns[0][1].class_
            query = self.query
            for field_name, column in columns:
                query = query.filter(column == form[field_name].data)

        columns = self._syntaxes_as_tuples(form, field, self.column)
        self.model = columns[0][1].class_
        if not query:
            query = self.query
        for field_name, column in columns:
            slug = slugify(str(form[field_name].data))
            query = query.filter(self.slug_column == slug)

        obj = query.first()

        if not hasattr(form, "_obj"):
            raise Exception(
                "Couldn't access Form._obj attribute. Either make your form "
                "inherit WTForms-Alchemy ModelForm or WTForms-Components "
                "ModelForm or make this attribute available in your form."
            )

        if obj and not form._obj == obj:
            if self.message is None:
                self.message = field.gettext(
                    f"{self.slug_repr} already exists."
                )
            raise ValidationError(self.message)

    def get_default_slug_repr(self):
        name = self.slug_column.name
        slug_repr = " ".join(name.split("_")).capitalize()
        return slug_repr