from __future__ import annotations

from collections import Counter

import pytest

from k1link.compute.e37_acceptance_contract import (
    E37AcceptanceContractError,
    assign_split,
    derive_reference_labels,
)


def _decision(
    *,
    detector: str,
    ownership: str,
    cause: str | None = None,
    effective_stratum: str | None = "agree",
) -> dict[str, object]:
    return {
        "detector_assessment": detector,
        "point_ownership": ownership,
        "cause_code": cause,
        "effective_stratum": effective_stratum,
    }


def test_r0_reference_projection_keeps_dimensions_independent() -> None:
    assert derive_reference_labels(
        _decision(detector="valid", ownership="object"),
        None,
    ) == ("object-present", "object-associated", "current")
    assert derive_reference_labels(
        _decision(
            detector="false-positive",
            ownership="surface-or-background",
            cause="time_mismatch",
        ),
        None,
    ) == ("background-or-noise", "rejected-nonobject", "stale")
    assert derive_reference_labels(
        _decision(
            detector="not-applicable",
            ownership="insufficient-support",
            effective_stratum="camera-only",
        ),
        None,
    ) == ("unknown", "insufficient-support", "unavailable")


def test_human_exception_only_overrides_the_ambiguous_reference() -> None:
    ambiguous = _decision(
        detector="insufficient-evidence",
        ownership="insufficient-evidence",
        effective_stratum=None,
    )
    assert derive_reference_labels(ambiguous, "object-present") == (
        "occupied-environment",
        "independent-occupied",
        "unavailable",
    )
    assert derive_reference_labels(ambiguous, "background-or-noise") == (
        "background-or-noise",
        "rejected-nonobject",
        "unavailable",
    )


def test_split_is_deterministic_balanced_and_complete() -> None:
    rows = [
        {
            "item_id": f"item-{index:03d}",
            "source_stratum": "agree" if index % 2 else "conflict",
            "range_bucket": "near" if index % 3 else "far",
        }
        for index in range(60)
    ]
    first = assign_split(
        rows,
        seed="frozen-seed",
        validation_fraction=0.3,
    )
    second = assign_split(
        list(reversed(rows)),
        seed="frozen-seed",
        validation_fraction=0.3,
    )
    assert first == second
    assert set(first) == {row["item_id"] for row in rows}
    assert Counter(first.values())["validation"] == 18


def test_split_rejects_mutable_or_invalid_fraction() -> None:
    with pytest.raises(E37AcceptanceContractError):
        assign_split([], seed="", validation_fraction=0.3)
    with pytest.raises(E37AcceptanceContractError):
        assign_split([], seed="seed", validation_fraction=0.9)