"""Read model provider registry — K-Ext-1."""

from __future__ import annotations

from dataclasses import dataclass
from typing import Any, Callable

from steering.eval_context import SteeringEvalContext

ReadModelCompute = Callable[[SteeringEvalContext], Any]


@dataclass(frozen=True)
class ReadModelProvider:
    key: str
    requires_elements: frozenset[str]
    requires_data_slices: frozenset[str]
    compute: ReadModelCompute
    requires_any_element: frozenset[str] = frozenset()


_PROVIDERS: list[ReadModelProvider] = []


def register_read_model(provider: ReadModelProvider) -> None:
    _PROVIDERS.append(provider)


def compute_read_models(ctx: SteeringEvalContext) -> dict[str, Any]:
    """Run all matching read model providers for the initiative context."""
    elements = ctx.steering_elements
    slices = frozenset(ctx.data_slices)
    result: dict[str, Any] = {}

    for provider in _PROVIDERS:
        if provider.requires_elements and not provider.requires_elements <= elements:
            continue
        if provider.requires_any_element and not (
            provider.requires_any_element & elements
        ):
            continue
        if provider.requires_data_slices and not provider.requires_data_slices <= slices:
            continue
        result[provider.key] = provider.compute(ctx)

    return result


def _register_builtin_read_models() -> None:
    from steering.read_models.epic_rollup import compute_epic_rollup
    from steering.read_models.execution_graph import compute_execution_graph_read_model
    from steering.read_models.planning_debt import compute_planning_debt_read_model
    from steering.read_models.tech_debt import compute_tech_debt_summary

    register_read_model(
        ReadModelProvider(
            key="epic_rollup",
            requires_elements=frozenset({"backlog_epic_hierarchy"}),
            requires_data_slices=frozenset({"backlog"}),
            compute=lambda ctx: compute_epic_rollup(
                backlog_items=ctx.backlog_items,
                actions=ctx.actions,
            ),
        )
    )
    register_read_model(
        ReadModelProvider(
            key="planning_debt",
            requires_elements=frozenset({"gate_fulfillment"}),
            requires_data_slices=frozenset({"roadmap", "actions"}),
            compute=compute_planning_debt_read_model,
        )
    )
    register_read_model(
        ReadModelProvider(
            key="execution_graph",
            requires_elements=frozenset(),
            requires_any_element=frozenset({"critical_path", "gate_fulfillment"}),
            requires_data_slices=frozenset({"actions"}),
            compute=compute_execution_graph_read_model,
        )
    )
    register_read_model(
        ReadModelProvider(
            key="tech_debt_summary",
            requires_elements=frozenset(),
            requires_data_slices=frozenset({"backlog", "actions"}),
            compute=compute_tech_debt_summary,
        )
    )


_register_builtin_read_models()