from __future__ import annotations

from datetime import datetime, timedelta, timezone

import pytest

from maturity_engine.compute import compute_level
from maturity_engine.errors import UnevaluableCriterion
from maturity_engine.models import Criterion, Evidence, Ladder, Level
from conftest import INSTANT, evidence


def test_floor_level_with_no_evidence(engine):
    assessment = engine.assess("estate", "asm", at=INSTANT)
    assert assessment.level == 0
    assert assessment.level_id == "ASM-0"
    assert assessment.next_level_id == "ASM-1"
    assert assessment.unmet


def test_determinism_same_inputs_same_assessment(engine):
    kinds = ["central-secret-manager", "secret-rbac", "basic-secret-scanning", "basic-rotation"]
    for kind in kinds:
        engine.submit_evidence(evidence(engine, "estate", kind))
    first = engine.assess("estate", "asm", at=INSTANT)
    second = engine.assess("estate", "asm", at=INSTANT)
    assert first.id == second.id
    assert first.level == second.level == 1
    assert first.as_explanation() == second.as_explanation()


def test_explainability_lists_met_and_next(engine):
    engine.submit_evidence(evidence(engine, "estate", "central-secret-manager"))
    assessment = engine.assess("estate", "asm", at=INSTANT)
    assert assessment.level == 0
    kinds_unmet = {item.evidence_kind for item in assessment.unmet}
    assert "secret-rbac" in kinds_unmet
    explanation = assessment.as_explanation()
    assert explanation["met"] == []
    assert explanation["next_level_id"] == "ASM-1"


def test_expiry_demotes_a_subject(engine):
    until = INSTANT + timedelta(hours=1)
    kinds = ["central-secret-manager", "secret-rbac", "basic-secret-scanning", "basic-rotation"]
    for kind in kinds:
        engine.submit_evidence(evidence(engine, "estate", kind, until=until))
    high = engine.assess("estate", "asm", at=INSTANT)
    assert high.level == 1
    later = INSTANT + timedelta(hours=2)
    low = engine.assess("estate", "asm", at=later)
    assert low.level == 0
    assert low.level_id == "ASM-0"
    assert low.expired_evidence_ids
    history = engine.history("estate", "asm")
    assert [item.level for item in history] == [1, 0]


def test_unevaluable_criterion_rejected():
    ladder = Ladder(
        id="bad",
        version="1",
        owner="nobody",
        name="bad",
        levels=(
            Level(0, "L0", "floor", ()),
            Level(
                1,
                "L1",
                "judged",
                (Criterion("c1", "judgment", "a human decides"),),
            ),
        ),
    )
    with pytest.raises(UnevaluableCriterion):
        ladder.validate()


def test_compute_is_pure(engine):
    item = Evidence(
        id="e1",
        subject="s",
        kind="central-secret-manager",
        submitted_by="t",
        submitted_at=INSTANT,
        valid_from=INSTANT,
        valid_until=None,
    )
    ladder = engine.store.get_ladder("asm")
    a = compute_level(ladder, (item,), subject="s", instant=INSTANT)
    b = compute_level(ladder, (item,), subject="s", instant=INSTANT)
    assert a == b
    other = compute_level(
        ladder, (item,), subject="s", instant=datetime(2026, 8, 30, tzinfo=timezone.utc)
    )
    assert other.id != a.id