import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
SRC_DIR = ROOT / "src"
if str(SRC_DIR) not in sys.path:
    sys.path.insert(0, str(SRC_DIR))

import renunney.track1_reference as ref


def test_fecundity_matches_r_definition():
    params = ref.Track1Parameters(K=5000, N0=50, n=1, u=5e-6, R=10.0, T=40)
    r = params.intrinsic_growth_rate()
    assert ref.female_fecundity(r, N=0, K=params.K) == pytest_approx(10.0)


def test_initialize_population_shapes_and_allele_zero_fixation():
    params = ref.Track1Parameters(K=5000, N0=12, n=3, u=5e-6, R=10.0, T=40)
    state = ref.initialize_population(params, ref.np.random.default_rng(1))
    assert state.genomes.shape == (12, 2, 3)
    assert state.sexes.shape == (12,)
    assert int(state.genomes.sum()) == 0


def test_simulate_run_returns_generation_summaries():
    params = ref.Track1Parameters(K=5000, N0=20, n=1, u=5e-6, R=10.0, T=20)
    out = ref.simulate_run(params, seed=2)
    assert out
    assert out[0].N == 20
    assert out[0].t == -(params.T // 2)


def test_generation_summary_reports_tracking_fields_for_initial_population():
    params = ref.Track1Parameters(K=5000, N0=20, n=2, u=5e-6, R=10.0, T=20)
    out = ref.simulate_run(params, seed=2)
    first = out[0]
    assert first.mean_allele_value == pytest_approx(0.0)
    assert first.mean_genotype_value == pytest_approx(0.0)
    assert first.target_value == pytest_approx(-0.5)
    assert first.mean_tracking_gap == pytest_approx(0.5)
    assert first.paper_M == pytest_approx(0.05)
    assert first.expected_mutations_current_N == pytest_approx(0.0004)


def test_generation_summary_reports_realized_mutations_for_high_u():
    params = ref.Track1Parameters(K=5000, N0=20, n=1, u=0.5, R=10.0, T=20)
    out = ref.simulate_run(params, seed=2)
    first = out[0]
    assert first.realized_mutation_count >= 0
    assert 0.0 <= first.realized_mutation_rate_per_allele <= 1.0


def pytest_approx(value: float, tol: float = 1e-9):
    class Approx:
        def __eq__(self, other):
            return abs(other - value) <= tol

    return Approx()