from typing import Optional
import tdw_catalog.metadata_template.field as field

from tdw_catalog.errors import CatalogUnimplementedException
from tdw_catalog.utils import MetadataFieldType


class Field(field.MetadataTemplateField[None]):
    """
    Attach files as metadata directly to a :class:`.Dataset`. Default attachment values are not currently supported.

    Attributes
    ----------
    None
    """

    def __init__(self, key: str, optional: Optional[bool]) -> None:
        super().__init__(key, default_value=None, optional=optional)

    @field.MetadataTemplateField.default_value.getter
    def default_value(self):
        raise CatalogUnimplementedException(
            message=
            "Default values are not currently supported for attachment fields")

    @field.MetadataTemplateField.default_value.setter
    def default_value(self, value: Optional['field.T']):
        if value != None:
            raise CatalogUnimplementedException(
                message=
                "Default values are not currently supported for attachment fields"
            )

    def serialize(self) -> dict:
        res = super().serialize()
        res["default_value"] = None
        res["field_type"] = MetadataFieldType.FT_ATTACHMENT
        return res