from django.core import validators
from django.core.exceptions import ValidationError
from django.forms.widgets import Textarea

EMPTY_VALUES = (*validators.EMPTY_VALUES, "[]")


class CSVWidget(Textarea):
    is_hidden = False

    def prep_value(self, value):
        """Prepare value before effectively render widget"""
        if value in EMPTY_VALUES:
            return ""
        if isinstance(value, str):
            return value
        if isinstance(value, list):
            return ";".join(value)
        raise ValidationError("Invalid format.")

    def render(self, name, value, **kwargs):
        value = self.prep_value(value)
        return super().render(name, value, **kwargs)

    def value_from_datadict(self, data, files, name):
        """
        Return the value of this widget or None.

        Since we're only given the value of the entity name and the data dict
        contains the '_eav_config_cls' (which we don't have access to) as the
        key, we need to loop through each field checking if the eav attribute
        exists with the given 'name'.
        """
        for data_value in data.values():
            widget_value = getattr(data_value, name, None)
            if widget_value is not None:
                return widget_value

        return None