from reactor_sim.atomic import AtomicPhysics, make_atom


def test_alpha_decay_reduces_mass_and_charge():
    physics = AtomicPhysics(seed=1)
    parent = make_atom(92, 143)
    event = physics.alpha_decay(parent)
    daughter, alpha = event.products
    assert daughter.protons == 90
    assert daughter.neutrons == 141
    assert alpha.protons == 2 and alpha.neutrons == 2
    assert "alpha" in event.emitted_particles
    assert event.energy_mev > 0


def test_beta_minus_conserves_mass_number():
    physics = AtomicPhysics(seed=2)
    parent = make_atom(26, 30)
    event = physics.beta_minus_decay(parent)
    (daughter,) = event.products
    assert daughter.mass_number == parent.mass_number
    assert daughter.protons == parent.protons + 1
    assert "beta-" in event.emitted_particles


def test_beta_plus_and_electron_capture_lower_proton_count():
    physics = AtomicPhysics(seed=3)
    parent = make_atom(15, 16)
    beta_plus = physics.beta_plus_decay(parent)
    capture = physics.electron_capture(parent)
    assert beta_plus.products[0].protons == parent.protons - 1
    assert capture.products[0].protons == parent.protons - 1
    assert "beta+" in beta_plus.emitted_particles
    assert "gamma" in capture.emitted_particles


def test_gamma_emission_keeps_nuclide_same():
    physics = AtomicPhysics(seed=4)
    parent = make_atom(8, 8)
    event = physics.gamma_emission(parent, energy_mev=0.3)
    (product,) = event.products
    assert product == parent
    assert "gamma" in event.emitted_particles
    assert event.energy_mev == 0.3


def test_spontaneous_fission_creates_two_fragments():
    physics = AtomicPhysics(seed=5)
    parent = make_atom(92, 143)
    event = physics.spontaneous_fission(parent)
    assert len(event.products) == 2
    total_mass = sum(atom.mass_number for atom in event.products)
    assert total_mass <= parent.mass_number
    assert event.energy_mev > 0