from __future__ import annotations

from abc import ABC, abstractmethod
from typing import Literal

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from domain.property_baseline.performance import Performance

RebaselineReason = Literal["none", "pre_sap10", "physical_state_changed", "both"]

# The SAP spec version below which a cert's recorded scores reflect a superseded
# methodology and must be ML-rebaselined (CONTEXT.md: Rebaselining).
_SAP10_FLOOR = 10.0


class RebaselineNotImplemented(Exception):
    """A Property needs Rebaselining, but the ML adapter is not wired yet.

    Raised rather than silently recording ``reason="none"`` for a property that
    genuinely needs rebaselining — a plausible-but-wrong baseline is expensive to
    discover downstream. Surfaces how much of a First Run cohort the pipeline can
    handle today (#1135).
    """


class Rebaseliner(ABC):
    """Produces a Property's Effective Performance from its Effective EPC.

    Rebaselining (CONTEXT.md) re-predicts the rated quantities via ML when the
    EPC was lodged pre-SAP10 or its physical state diverged from the lodged EPC;
    otherwise Effective Performance equals Lodged. Injected into the
    PropertyBaselineOrchestrator (ADR-0011) so the ML adapter can swap in without
    touching the orchestrator, and so the single-property re-score-on-override
    flow reuses the same port.
    """

    @abstractmethod
    def rebaseline(
        self, property_id: int, effective_epc: EpcPropertyData, lodged: Performance
    ) -> tuple[Performance, RebaselineReason]: ...


class StubRebaseliner(Rebaseliner):
    """A no-calculator stub for tests that don't want the real calculator.

    SAP10 certs pass through untouched — Effective Performance equals Lodged,
    reason ``"none"``. A pre-SAP10 cert genuinely needs rebaselining, which this
    stub does not do, so it raises rather than fabricating a "none". Production
    uses ``CalculatorRebaseliner`` (the calculator is load-bearing — ADR-0013
    amendment); this stub stays for orchestrator/repo unit tests.
    """

    def rebaseline(
        self, property_id: int, effective_epc: EpcPropertyData, lodged: Performance
    ) -> tuple[Performance, RebaselineReason]:
        sap_version = effective_epc.sap_version
        if sap_version is not None and sap_version < _SAP10_FLOOR:
            raise RebaselineNotImplemented(
                f"Property needs rebaselining (pre-SAP10 cert, sap_version="
                f"{sap_version}); ML rebaselining is not implemented yet"
            )
        return lodged, "none"