"""``REDACT_SOLID_V1`` — remove an observed value while keeping node identity.

The node's identity/position remains available to the renderer as a stable
redaction anchor, but its value is removed from the transformed epistemic world.
Consequently an executor cannot read hidden evidence through a privileged
structured-state side channel.  Alternative completion worlds restore different
values under the same visibility marker and must render byte-identically.
"""

from __future__ import annotations

from typing import Any

from ..sources.base import World
from ..sources.world_ops import node_kind, world_sha256
from .base import (
    InterventionError,
    OperatorName,
    TransformedWorld,
    remove_observed_value,
    set_hidden,
    transformed_hash,
)

_NAME: OperatorName = "REDACT_SOLID_V1"


class RedactSolidOperator:
    """Hide ``target_node``'s pixels without removing it from the world."""

    name = _NAME

    def apply(
        self,
        world: World,
        target_node: str,
        *,
        seed: int,
        **_kwargs: Any,
    ) -> TransformedWorld:
        if node_kind(world, target_node) is None:
            raise InterventionError(f"REDACT_SOLID_V1: target {target_node!r} is not a world node")
        hidden = frozenset({target_node})
        new_world = set_hidden(remove_observed_value(world, target_node), hidden)
        return TransformedWorld(
            world=new_world,
            operator=_NAME,
            target_node=target_node,
            seed=seed,
            transformed_world_sha256=transformed_hash(
                operator=_NAME,
                target_node=target_node,
                seed=seed,
                source_world_sha256=world_sha256(world),
                transformed_world_sha256=world_sha256(new_world),
                hidden_nodes=hidden,
                substitute_value=None,
            ),
            hidden_nodes=hidden,
            substitute_value=None,
            description=f"redact-solid {target_node}",
        )


__all__ = ["RedactSolidOperator"]