"""Feature store for GraphBolt."""

import torch

__all__ = ["Feature", "FeatureStore"]


class Feature:
    r"""A wrapper of feature data for access."""

    def __init__(self):
        pass

    def read(self, ids: torch.Tensor = None):
        """Read from the feature.

        Parameters
        ----------
        ids : torch.Tensor, optional
            The index of the feature. If specified, only the specified indices
            of the feature are read. If None, the entire feature is returned.
        Returns
        -------
        torch.Tensor
            The read feature.
        """
        raise NotImplementedError

    def size(self):
        """Get the size of the feature.

        Returns
        -------
        torch.Size
            The size of the feature.
        """
        raise NotImplementedError

    def update(self, value: torch.Tensor, ids: torch.Tensor = None):
        """Update the feature.

        Parameters
        ----------
        value : torch.Tensor
            The updated value of the feature.
        ids : torch.Tensor, optional
            The indices of the feature to update. If specified, only the
            specified indices of the feature will be updated. For the feature,
            the `ids[i]` row is updated to `value[i]`. So the indices and value
            must have the same length. If None, the entire feature will be
            updated.
        """
        raise NotImplementedError

    def metadata(self):
        """Get the metadata of the feature.

        Returns
        -------
        Dict
            The metadata of the feature.
        """
        return {}


class FeatureStore:
    r"""A store to manage multiple features for access."""

    def __init__(self):
        pass

    def read(
        self,
        domain: str,
        type_name: str,
        feature_name: str,
        ids: torch.Tensor = None,
    ):
        """Read from the feature store.

        Parameters
        ----------
        domain : str
            The domain of the feature such as "node", "edge" or "graph".
        type_name : str
            The node or edge type name.
        feature_name : str
            The feature name.
        ids : torch.Tensor, optional
            The index of the feature. If specified, only the specified indices
            of the feature are read. If None, the entire feature is returned.

        Returns
        -------
        torch.Tensor
            The read feature.
        """
        raise NotImplementedError

    def size(
        self,
        domain: str,
        type_name: str,
        feature_name: str,
    ):
        """Get the size of the specified feature in the feature store.

        Parameters
        ----------
        domain : str
            The domain of the feature such as "node", "edge" or "graph".
        type_name : str
            The node or edge type name.
        feature_name : str
            The feature name.
        Returns
        -------
        torch.Size
            The size of the specified feature in the feature store.
        """
        raise NotImplementedError

    def metadata(
        self,
        domain: str,
        type_name: str,
        feature_name: str,
    ):
        """Get the metadata of the specified feature in the feature store.

        Parameters
        ----------
        domain : str
            The domain of the feature such as "node", "edge" or "graph".
        type_name : str
            The node or edge type name.
        feature_name : str
            The feature name.
        Returns
        -------
        Dict
            The metadata of the feature.
        """
        raise NotImplementedError

    def update(
        self,
        domain: str,
        type_name: str,
        feature_name: str,
        value: torch.Tensor,
        ids: torch.Tensor = None,
    ):
        """Update the feature store.

        Parameters
        ----------
        domain : str
            The domain of the feature such as "node", "edge" or "graph".
        type_name : str
            The node or edge type name.
        feature_name : str
            The feature name.
        value : torch.Tensor
            The updated value of the feature.
        ids : torch.Tensor, optional
            The indices of the feature to update. If specified, only the
            specified indices of the feature will be updated. For the feature,
            the `ids[i]` row is updated to `value[i]`. So the indices and value
            must have the same length. If None, the entire feature will be
            updated.
        """
        raise NotImplementedError
