import numpy as np
import pytest

from pg_rad.inputparser.parser import ConfigParser
from pg_rad.landscape.director import LandscapeDirector
from pg_rad.physics import calculate_fluence_at


@pytest.fixture
def phi_ref(test_landscape):
    source = test_landscape.point_sources[0]

    r = np.linalg.norm(np.array([10, 10, 0]) - np.array(source.pos))

    A = source.activity * 1E6
    b = source.isotope.b
    mu_air = source.isotope.mu_mass_air * test_landscape.air_density
    mu_air *= 0.1

    return A * b * np.exp(-mu_air * r) / (4 * np.pi * r**2)


@pytest.fixture
def test_landscape():

    test_yaml = """
    name: Test landscape
    speed: 8.33
    acquisition_time: 1

    path:
        length: 1000
        segments:
            - straight

    sources:
        test_source:
            activity_MBq: 100
            position: [0, 0, 0]
            isotope: CS137
    """

    cp = ConfigParser(test_yaml).parse()
    landscape = LandscapeDirector.build_from_config(cp)
    return landscape


def test_single_source_fluence(phi_ref, test_landscape):
    phi = calculate_fluence_at(
        test_landscape,
        np.array([10, 10, 0]),
        )
    assert pytest.approx(phi[0], rel=1E-3) == phi_ref