"""
Library for this simulation
"""
import numpy as np

from earsim import Antenna

def sine_beacon(f, t, t0=0, amplitude=1):
    return amplitude * np.sin(2*np.pi*f*(t-t0))


def distance(x1, x2):
    """
    Calculate the Euclidean distance between two locations x1 and x2
    """

    assert type(x1) in [Antenna]
    x1 = np.array([x1.x, x1.y, x1.z])

    assert type(x2) in [Antenna]
    x2 = np.array([x2.x, x2.y, x2.z])

    return np.sqrt( np.sum( (x1-x2)**2 ) )

def beacon_from(tx, rx, f, t=0, t0=0, c_light=3e8, **kwargs):
    dist = distance(tx,rx)/c_light
    t0 = t0 + dist/c_light

    return sine_beacon(f, t, t0=t0, **kwargs)