from central.app.ai.cache_policy import CONFLICT, NEEDS_REVALIDATION, VALID, cache_key, classify_knowledge_freshness
from central.app.ai.provider import BudgetGuard


def test_cache_key_changes_for_each_input_dimension():
    base = ("input", "candidates", "model", "prompt", {"ncm": "n1", "tipi": "t1"})
    key = cache_key(*base)
    assert key != cache_key("changed", *base[1:])
    assert key != cache_key(base[0], "changed", *base[2:])
    assert key != cache_key(base[0], base[1], "changed", *base[3:])
    assert key != cache_key(base[0], base[1], base[2], "changed", base[4])
    assert key != cache_key(*base[:4], {"ncm": "n2", "tipi": "t1"})
    assert key == cache_key(*base)


def test_dataset_freshness_is_fail_closed():
    assert classify_knowledge_freshness({"ncm": "v1"}, {"ncm": "v1"}) == VALID
    assert classify_knowledge_freshness({"ncm": "v1"}, {"ncm": "v2"}) == CONFLICT
    assert classify_knowledge_freshness({"ncm": "v1"}, {"ncm": "v1", "tipi": "v2"}) == NEEDS_REVALIDATION
    assert classify_knowledge_freshness({}, {"ncm": "v1"}) == NEEDS_REVALIDATION


def test_budget_blocks_before_call_and_actual_usage_cannot_exceed_limit():
    guard = BudgetGuard(1.0, 1.0, 2.0)
    assert guard.authorize(guard.estimate(600_000, 300_000)) is False
    assert guard.authorize(guard.estimate(100_000, 50_000)) is True
    assert guard.authorize_usage(100_000, 50_000, prior_cost_usd=0.9) is False


def test_unknown_cost_requires_explicit_limited_run():
    guard = BudgetGuard(5.0, None, None)
    assert guard.authorize_usage(1000, 100) is False
    assert guard.authorize_usage(1000, 100, allow_unknown_cost=True) is True