"""
Attribute loading, saving, and table-like operations.

This module provides AttrOps for working with node and edge attributes.
"""

from typing import TYPE_CHECKING, Any

if TYPE_CHECKING:
    from groggy.builder.algorithm_builder import AlgorithmBuilder

from groggy.builder.varhandle import VarHandle


class AttrOps:
    """Attribute loading, saving, and table-like operations."""

    def __init__(self, builder: "AlgorithmBuilder"):
        """
        Initialize attribute operations.

        Args:
            builder: Parent algorithm builder
        """
        self.builder = builder

    def load(self, name: str, default: Any = 0.0) -> VarHandle:
        """
        Load node attribute.

        Args:
            name: Attribute name
            default: Default value for missing attributes

        Returns:
            VarHandle with attribute values

        Example:
            >>> # Load existing node weights
            >>> weights = builder.attr.load("weight", default=1.0)
            >>> scaled = weights * 2.0
        """
        var = self.builder._new_var(f"attr_{name}")
        self.builder.steps.append(
            {
                "type": "load_attr",
                "attr_name": name,
                "default": default,
                "output": var.name,
            }
        )
        return var

    def load_edge(self, name: str, default: Any = 0.0) -> VarHandle:
        """
        Load edge attribute.

        Args:
            name: Edge attribute name
            default: Default value for missing attributes

        Returns:
            VarHandle with edge attribute values

        Example:
            >>> # Load edge weights for weighted aggregation
            >>> edge_weights = builder.attr.load_edge("weight", default=1.0)
            >>> weighted_sum = builder.graph.neighbor_agg(values, weights=edge_weights)
        """
        var = self.builder._new_var(f"edge_attr_{name}")
        self.builder.steps.append(
            {
                "type": "load_edge_attr",
                "attr_name": name,
                "default": default,
                "output": var.name,
            }
        )
        return var

    def save(self, name: str, values: VarHandle):
        """
        Save values as node attribute.

        Args:
            name: Attribute name to save to
            values: VarHandle to save

        Example:
            >>> # Compute and save PageRank
            >>> ranks = compute_pagerank(...)
            >>> builder.attr.save("pagerank", ranks)
        """
        self.builder.steps.append(
            {"type": "attach_attr", "input": values.name, "attr_name": name}
        )

    def save_edge(self, name: str, values: VarHandle):
        """
        Save values as edge attribute (future feature).

        Args:
            name: Edge attribute name
            values: VarHandle to save

        Example:
            >>> # Save edge weights
            >>> builder.attr.save_edge("new_weight", weights)
        """
        # This is a placeholder for future implementation
        raise NotImplementedError("save_edge() not yet implemented")

    def groupby(self, labels: VarHandle):
        """
        Group nodes by labels (future feature).

        Args:
            labels: Grouping labels

        Returns:
            GroupBy handle for aggregation operations

        Example:
            >>> # Group by community, compute avg degree per community
            >>> communities = builder.attr.load("community")
            >>> degrees = builder.graph.degree()
            >>> avg_deg = builder.attr.groupby(communities).mean(degrees)
        """
        # This is a placeholder for future table-like operations
        raise NotImplementedError("groupby() not yet implemented")
