#!/usr/bin/env python3
"""
Cosine ripple on a 2D lattice
"""
import bornagain as ba
from bornagain import deg, nm


def get_sample():
    """
    Returns a sample with cosine ripples on a substrate.
    The structure is modelled as a 2D Lattice.
    """

    # Define materials
    material_Particle = ba.HomogeneousMaterial("Particle", 0.0006, 2e-08)
    material_Substrate = ba.HomogeneousMaterial("Substrate", 6e-06, 2e-08)
    material_Vacuum = ba.HomogeneousMaterial("Vacuum", 0, 0)

    # Define form factors
    ff = ba.FormFactorCosineRippleBox(100*nm, 20*nm, 4*nm)

    # Define particles
    particle = ba.Particle(material_Particle, ff)

    # Define 2D lattices
    lattice = ba.BasicLattice2D(200*nm, 50*nm, 90*deg, 0)

    # Define interference functions
    iff = ba.InterferenceFunction2DLattice(lattice)
    iff_pdf = ba.FTDecayFunction2DCauchy(160*nm, 16*nm, 0)
    iff.setDecayFunction(iff_pdf)

    # Define particle layouts
    layout = ba.ParticleLayout()
    layout.addParticle(particle)
    layout.setInterferenceFunction(iff)
    layout.setTotalParticleSurfaceDensity(0.0001)

    # Define layers
    layer_1 = ba.Layer(material_Vacuum)
    layer_1.addLayout(layout)
    layer_2 = ba.Layer(material_Substrate)

    # Define sample
    sample = ba.MultiLayer()
    sample.addLayer(layer_1)
    sample.addLayer(layer_2)

    return sample


def get_simulation(sample):
    beam = ba.Beam(1, 0.16*nm, ba.Direction(0.3*deg, 0))
    detector = ba.SphericalDetector(100, -1.5*deg, 1.5*deg, 100, 0,
                                    2.5*deg)
    simulation = ba.GISASSimulation(beam, sample, detector)
    return simulation


if __name__ == '__main__':
    import ba_plot
    sample = get_sample()
    simulation = get_simulation(sample)
    ba_plot.run_and_plot(simulation)