import spiceypy as cspice
import numpy as np
import matplotlib.pyplot as plt


def main(mk, utc0, utcf, steps, target, observer, frame):

    # load MK
    cspice.furnsh(mk)

    # define time stamp
    et0 = cspice.utc2et(utc0)
    etf = cspice.utc2et(utcf)
    times = np.linspace(et0, etf, steps)

    cartesian_juice = []
    radec_juice = []
    cartesian_juice_ecliptj2000 = []
    source_ang_separation = []
    for t in times:

        # compute target position
        r = cspice.spkpos(target, t, frame, 'NONE', observer)[0]
        cartesian_juice.append(r)

        # convert cartesian coordinates to Range [km], Right Ascension [rad] and Declination [rad]
        radec = cspice.recrad(r)
        radec_juice.append([radec[0], np.rad2deg(radec[1]), np.rad2deg(radec[2])])

        # compute rotation matrix to transform from "frame" to "ECLIPTJ2000" (or any other ref frame)
        M_rot = cspice.pxform(frame, 'ECLIPJ2000', t)

        # multiply the rotation matrix by the position vector to transform it to the ECLIPJ2000 frame
        cartesian_juice_ecliptj2000.append(cspice.mxv(M_rot, r))

        # transform Range [km], Right Ascension [rad] and Declination [rad] to Cartesian coordinates
        source_ra = np.deg2rad(30)
        source_dec = np.deg2rad(5)
        r_source = cspice.radrec(1, source_ra, source_dec)

        # compute angular separation between two vectors
        source_ang_separation.append(np.rad2deg(cspice.vsep(r, r_source)))


    cartesian_juice = np.asarray(cartesian_juice)
    plt.plot(cartesian_juice[:, 0], cartesian_juice[:, 1], color='green')
    plt.xlabel('X [km]')
    plt.ylabel('Y [km]')
    plt.grid()
    plt.show()

    cartesian_juice_ecliptj2000 = np.asarray(cartesian_juice_ecliptj2000)
    plt.plot(cartesian_juice_ecliptj2000[:, 0], cartesian_juice_ecliptj2000[:, 1], color='green')
    plt.xlabel('X [km]')
    plt.ylabel('Y [km]')
    plt.grid()
    plt.show()

    radec_juice = np.asarray(radec_juice)
    plt.plot(radec_juice[:, 1], radec_juice[:, 2], color='green')
    plt.xlabel('RA [deg]')
    plt.ylabel('Dec [deg]')
    plt.grid()
    plt.show()

    plt.plot(times, source_ang_separation, color='green')
    plt.xlabel('Times [s]')
    plt.ylabel('JUICE to source angular separation [deg]')
    plt.grid()
    plt.show()

    return


main(mk='/Users/aescalante/spice/missions/juice/juice/kernels/mk/juice_crema_5_0_local.tm',
     utc0='2026-01-01', utcf='2026-01-07', steps=10000,
     target='JUICE', observer='EARTH', frame='J2000')