from typing import List, Union

from baserow.contrib.builder.data_sources.builder_dispatch_context import (
    BuilderDispatchContext,
)
from baserow.core.formula.registries import DataProviderType


class HumanReadableFieldsDataProviderType(DataProviderType):
    """
    This data provider type is used to read the human readable values for the row
    fields. This is used for example in the AI field to be able to reference other
    fields in the same row to generate a different prompt for each row based on the
    values of the other fields.
    """

    type = "fields"

    def get_data_chunk(
        self, dispatch_context: BuilderDispatchContext, path: List[str]
    ) -> Union[int, str]:
        """
        When a page parameter is read, returns the value previously saved from the
        request object.
        """

        if len(path) != 1:
            return None

        first_part = path[0]

        return dispatch_context.human_readable_row_values.get(first_part, "")