"""Liability firewall: the rules that stop a false accusation."""

from text_detection import guard as tg
from text_detection.schema import DetectionResult, EnsembleResult, Verdict


def _enable_zeroshot_guard(monkeypatch):
    monkeypatch.setattr(tg, "_ZEROSHOT_AI_OK", False)


def _mk_ensemble(verdict, p_fake, confidence):
    return EnsembleResult(
        verdict=verdict, p_fake=p_fake, confidence=confidence,
        primary_evidence="x", detector_results=[],
    )


def _mk_det(name, verdict, p_fake, confidence=0.9):
    return DetectionResult(
        detector=name, p_fake=p_fake, verdict=verdict, confidence=confidence,
    )


def test_word_count_counts_words():
    assert tg.word_count("hello world foo") == 3
    assert tg.word_count("") == 0


def test_is_too_short_boundary_at_50():
    assert tg.is_too_short(" ".join(["w"] * 49)) is True
    assert tg.is_too_short(" ".join(["w"] * 50)) is False


def test_short_text_forced_uncertain_and_capped():
    res = _mk_ensemble(Verdict.AI_GENERATED, 0.92, 0.90)
    out = tg.apply_liability_firewall(res, "too short here", [])
    assert out.verdict == Verdict.UNCERTAIN
    assert out.confidence <= tg.SHORT_TEXT_CONF_CAP
    # original untouched (immutability)
    assert res.verdict == Verdict.AI_GENERATED
    assert res.confidence == 0.90


def test_ai_verdict_withheld_when_only_zeroshot_agrees(monkeypatch):
    _enable_zeroshot_guard(monkeypatch)
    text = " ".join(["word"] * 80)
    res = _mk_ensemble(Verdict.AI_GENERATED, 0.80, 0.60)
    dets = [_mk_det("text_fastdetectgpt", Verdict.AI_GENERATED, 0.80)]
    out = tg.apply_liability_firewall(res, text, dets)
    assert out.verdict == Verdict.UNCERTAIN


def test_ai_verdict_kept_when_non_zeroshot_supports():
    text = " ".join(["word"] * 80)
    res = _mk_ensemble(Verdict.AI_GENERATED, 0.80, 0.60)
    dets = [
        _mk_det("text_fastdetectgpt", Verdict.AI_GENERATED, 0.80),
        _mk_det("text_watermark", Verdict.AI_GENERATED, 0.98),
    ]
    out = tg.apply_liability_firewall(res, text, dets)
    assert out.verdict == Verdict.AI_GENERATED


def test_errored_zeroshot_vote_does_not_count_as_support(monkeypatch):
    _enable_zeroshot_guard(monkeypatch)
    text = " ".join(["word"] * 80)
    res = _mk_ensemble(Verdict.AI_GENERATED, 0.80, 0.60)
    dets = [
        _mk_det("text_fastdetectgpt", Verdict.AI_GENERATED, 0.80),
        DetectionResult(
            detector="text_watermark", p_fake=0.9, verdict=Verdict.AI_GENERATED,
            confidence=0.0, error="boom",
        ),
    ]
    out = tg.apply_liability_firewall(res, text, dets)
    assert out.verdict == Verdict.UNCERTAIN


def test_real_verdict_on_long_text_is_left_alone():
    text = " ".join(["word"] * 80)
    res = _mk_ensemble(Verdict.REAL, 0.10, 0.80)
    dets = [_mk_det("text_fastdetectgpt", Verdict.REAL, 0.10)]
    out = tg.apply_liability_firewall(res, text, dets)
    assert out.verdict == Verdict.REAL
    assert out.confidence == 0.80