import pytest

from llm_connect.costs import CostEstimate, CostModel, estimate_cost
from llm_connect.rates import ModelRate, ModelRateRegistry


def test_known_model_cost_matches_lefevre_smoke_budget():
    estimate = estimate_cost("openai/gpt-4o-mini", 28_000, 7_500)

    assert estimate.cost_source == "rate_table:openai/gpt-4o-mini"
    assert estimate.cost_usd == pytest.approx(0.0087)
    assert estimate.cost_usd == pytest.approx(0.009, rel=0.2)


def test_unknown_model_returns_unknown_without_zeroing_cost():
    estimate = estimate_cost("unknown/model", 100, 50)

    assert estimate == CostEstimate(cost_usd=None, cost_source="unknown")


def test_registry_override_controls_estimate():
    registry = ModelRateRegistry(
        {
            "vendor/model": ModelRate(
                "vendor/model",
                prompt_per_1k=1.0,
                completion_per_1k=2.0,
            )
        }
    )

    estimate = estimate_cost("vendor/model", 1_000, 500, registry=registry)

    assert estimate.cost_usd == pytest.approx(2.0)
    assert estimate.prompt_cost_usd == pytest.approx(1.0)
    assert estimate.completion_cost_usd == pytest.approx(1.0)


def test_zero_tokens_are_valid_and_cost_zero_for_known_model():
    estimate = CostModel().estimate_cost("openai/gpt-4o-mini", 0, 0)

    assert estimate.cost_usd == 0
    assert estimate.prompt_cost_usd == 0
    assert estimate.completion_cost_usd == 0


def test_negative_tokens_are_rejected():
    with pytest.raises(ValueError, match="prompt_tokens"):
        estimate_cost("openai/gpt-4o-mini", -1, 0)