
# -*- coding: utf-8 -*-
from amuse.support.testing.amusetest import TestWithMPI
import os
import sys
import numpy
import time
import math

from amuse_bhtree.interface import BHTreeInterface, BHTree
from amuse.support.exceptions import AmuseException
from amuse.units import constants
from amuse.units import nbody_system
from amuse.units import units
from amuse.units import quantities
from amuse import datamodel
from amuse.datamodel import particle_attributes
from amuse.ic import plummer
try:
    from matplotlib import pyplot
    HAS_MATPLOTLIB = True
except ImportError:
    HAS_MATPLOTLIB = False


class TestBHTreeInterface(TestWithMPI):

    def test0(self):
        instance = BHTreeInterface()
        self.assertTrue("Barnes" in instance.all_literature_references_string())
        instance.stop()

    def test1(self):
        instance = BHTreeInterface()
        instance.initialize_code()
        instance.commit_parameters()
        res1 = instance.new_particle(mass=11.0, radius=2.0, x=0.0, y=0.0, z=0.0, vx=0.0, vy=0.0, vz=0.0)
        res2 = instance.new_particle(mass=21.0, radius=5.0, x=10.0, y=0.0, z=0.0, vx=10.0, vy=0.0, vz=0.0)

        instance.commit_particles()
        self.assertEqual(1, res1['index_of_the_particle'])
        self.assertEqual(2, res2['index_of_the_particle'])

        retrieved_state1 = instance.get_state(1)
        retrieved_state2 = instance.get_state(2)

        self.assertEqual(11.0,  retrieved_state1['mass'])
        self.assertEqual(21.0,  retrieved_state2['mass'])
        self.assertEqual(0.0,  retrieved_state1['x'])
        self.assertEqual(10.0,  retrieved_state2['x'])

        self.assertEqual(1, instance.get_index_of_first_particle()['index_of_the_particle'])
        self.assertEqual(2, instance.get_index_of_next_particle(1)['index_of_the_next_particle'])

        instance.cleanup_code()
        instance.stop()

    def test2(self):
        instance = BHTreeInterface()
        instance.initialize_code()

        instance.commit_parameters()
        for i in [1, 2, 3]:
            temp_particle = instance.new_particle(mass=i, radius=1.0, x=0.0, y=0.0, z=0.0, vx=0.0, vy=0.0, vz=0.0)
            self.assertEqual(i, temp_particle['index_of_the_particle'])

        instance.commit_particles()
        self.assertEqual(1, instance.get_index_of_first_particle()['index_of_the_particle'])
        self.assertEqual(2, instance.get_index_of_next_particle(1)['index_of_the_next_particle'])
        self.assertEqual(3, instance.get_index_of_next_particle(2)['index_of_the_next_particle'])

        instance.delete_particle(1)

        self.assertEqual(2, instance.get_number_of_particles()['number_of_particles'])

        # the deletion does a swap, so 3 is copied to 1, (overwriting old 1 and treesize -> treesize-1
        self.assertEqual(3, instance.get_index_of_first_particle()['index_of_the_particle'])

        self.assertEqual(1, instance.get_index_of_next_particle(2)['__result'])

        instance.cleanup_code()
        instance.stop()

    def test5(self):
        interface = BHTreeInterface()
        interface.initialize_code()

        interface.commit_parameters()
        interface.new_particle([10, 20], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [1, 1])
        interface.commit_particles()
        retrieved_state = interface.get_state(1)

        self.assertEqual(10.0,  retrieved_state['mass'])
        self.assertEqual(1, retrieved_state['radius'])

        retrieved_state = interface.get_state([1, 2])
        self.assertEqual(20.0,  retrieved_state['mass'][1])
        self.assertEqual(interface.get_number_of_particles()['number_of_particles'], 2)
        interface.cleanup_code()
        interface.stop()

    def test6(self):
        instance = BHTreeInterface()
        instance.initialize_code()
        instance.commit_parameters()

        ids = []
        for i in [1, 2, 3]:
            id, error = instance.new_particle(mass=i, radius=1.0, x=0.0, y=0.0, z=0.0, vx=0.0, vy=0.0, vz=0.0)
            ids.append(id)

        print(ids)

        instance.commit_particles()

        instance.delete_particle(ids[0])
        id, error = instance.new_particle(mass=4, radius=1.0, x=0.0, y=0.0, z=0.0, vx=0.0, vy=0.0, vz=0.0)
        self.assertNotEqual(id, ids[-1])

        instance.cleanup_code()
        instance.stop()

    def test7(self):
        interface = BHTreeInterface()  # channel_type="remote") #, debugger="xterm")
        interface.initialize_code()

        interface.commit_parameters()
        interface.new_particle([10, 20], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [1, 1])
        interface.commit_particles()
        retrieved_state = interface.get_state(1)

        self.assertEqual(10.0,  retrieved_state['mass'])
        self.assertEqual(1, retrieved_state['radius'])

        retrieved_state = interface.get_state([1, 2])
        self.assertEqual(20.0,  retrieved_state['mass'][1])
        self.assertEqual(interface.get_number_of_particles()['number_of_particles'], 2)
        interface.cleanup_code()
        interface.stop()

    def test8(self):
        instance = BHTreeInterface()
        instance.initialize_code()
        instance.set_epsilon_squared(0.1 * 0.1)
        instance.commit_parameters()
        id1, errorcode = instance.new_particle(mass=10.0, radius=1.0, x=0.0, y=0.0, z=0.0, vx=0.0, vy=0.0, vz=0.0)
        id2, errorcode = instance.new_particle(mass=10.0, radius=1.0, x=2.0, y=0.0, z=0.0, vx=10.0, vy=0.0, vz=0.0)

        instance.commit_particles()
        potential, errorcode = instance.get_potential(id1)
        self.assertEqual(errorcode, 0)
        self.assertAlmostRelativeEquals(potential,  -10.0 / numpy.sqrt(2.0**2 + 0.1**2), 8)
        instance.cleanup_code()
        instance.stop()


class TestBHTree(TestWithMPI):
    def new_system_of_sun_and_earth(self):
        stars = datamodel.Stars(2)
        sun = stars[0]
        sun.mass = units.MSun(1.0)
        sun.position = units.m(numpy.array((0.0, 0.0, 0.0)))
        sun.velocity = units.ms(numpy.array((0.0, 0.0, 0.0)))
        sun.radius = units.RSun(1.0)

        earth = stars[1]
        earth.mass = units.kg(5.9736e24)
        earth.radius = units.km(6371)
        earth.position = units.km(numpy.array((149.5e6, 0.0, 0.0)))
        earth.velocity = units.ms(numpy.array((0.0, 29800, 0.0)))

        return stars

    def test1(self):
        convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 149.5e6 | units.km)

        instance = BHTree(convert_nbody)
        instance.parameters.epsilon_squared = 0.001 | units.AU**2

        stars = datamodel.Stars(2)

        sun = stars[0]
        sun.mass = units.MSun(1.0)
        sun.position = [0.0, 0.0, 0.0] | units.m
        sun.velocity = [0.0, 0.0, 0.0] | units.ms
        sun.radius = units.RSun(1.0)

        earth = stars[1]
        earth.mass = units.kg(5.9736e24)
        earth.radius = units.km(6371)
        earth.position = [149.5e6, 0.0, 0.0] | units.km
        earth.velocity = [0.0, 29800, 0.0] | units.ms

        # instance.particles.add_particles(stars)
        instance.particles.add_particles(stars)

        postion_at_start = earth.position.value_in(units.AU)[0]

        instance.evolve_model(365.0 | units.day)
        instance.particles.copy_values_of_all_attributes_to(stars)

        postion_after_full_rotation = earth.position.value_in(units.AU)[0]

        self.assertAlmostEqual(postion_at_start, postion_after_full_rotation, 3)

        instance.evolve_model(365.0 + (365.0 / 2) | units.day)

        instance.particles.copy_values_of_all_attributes_to(stars)

        postion_after_half_a_rotation = earth.position.value_in(units.AU)[0]
        self.assertAlmostEqual(-postion_at_start, postion_after_half_a_rotation, 2)

        instance.evolve_model(365.0 + (365.0 / 2) + (365.0 / 4) | units.day)

        instance.particles.copy_values_of_all_attributes_to(stars)

        postion_after_half_a_rotation = earth.position.value_in(units.AU)[1]

        self.assertAlmostEqual(-postion_at_start, postion_after_half_a_rotation, 1)
        instance.cleanup_code()
        instance.stop()

    def test2(self):
        # not completed
        convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 149.5e6 | units.km)

        instance = BHTree(convert_nbody)
        # instance.dt_dia = 1
        instance.parameters.epsilon_squared = 0.001 | units.AU**2
        # instance.timestep = 0.0001
        # instance.use_self_gravity = 0
        instance.commit_parameters()

        stars = datamodel.Stars(2)
        sun = stars[0]
        sun.mass = units.MSun(1.0)
        sun.position = units.m(numpy.array((0.0, 0.0, 0.0)))
        sun.velocity = units.ms(numpy.array((0.0, 0.0, 0.0)))
        sun.radius = units.RSun(1.0)

        earth = stars[1]
        earth.mass = units.kg(5.9736e24)
        earth.radius = units.km(6371)
        earth.position = units.km(numpy.array((149.5e6, 0.0, 0.0)))
        earth.velocity = units.ms(numpy.array((0.0, 29800, 0.0)))

        instance.particles.add_particles(stars)
        instance.commit_particles()
        self.assertAlmostRelativeEquals(sun.radius, instance.particles[0].radius)

        for x in range(1, 2000, 10):
            instance.evolve_model(x | units.day)
            instance.particles.copy_values_of_all_attributes_to(stars)
            stars.savepoint()

        if HAS_MATPLOTLIB:
            figure = pyplot.figure()
            plot = figure.add_subplot(1, 1, 1)

            x_points = earth.get_timeline_of_attribute("x")
            y_points = earth.get_timeline_of_attribute("y")

            x_points_in_AU = [t_x[1].value_in(units.AU) for t_x in x_points]
            y_points_in_AU = [t_x1[1].value_in(units.AU) for t_x1 in y_points]

            plot.scatter(x_points_in_AU, y_points_in_AU, color="b", marker='o')

            plot.set_xlim(-1.5, 1.5)
            plot.set_ylim(-1.5, 1.5)

            test_results_path = self.get_path_to_results()
            output_file = os.path.join(test_results_path, "bhtree-earth-sun.svg")
            figure.savefig(output_file)

        instance.cleanup_code()
        instance.stop()

    def test3(self):
        convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 149.5e6 | units.km)

        instance = BHTree(convert_nbody)
        # instance.dt_dia = 1
        instance.parameters.epsilon_squared = 0.001 | units.AU**2
        # instance.timestep = 0.0001
        # instance.use_self_gravity = 0
        instance.commit_parameters()

        stars = datamodel.Stars(2)
        star1 = stars[0]
        star2 = stars[1]

        star1.mass = units.MSun(1.0)
        star1.position = units.AU(numpy.array((-.10, 0.0, 0.0)))
        star1.velocity = units.AUd(numpy.array((0.0, 0.0, 0.0)))
        star1.radius = units.RSun(1.0)

        star2.mass = units.MSun(1.0)
        star2.position = units.AU(numpy.array((.10, 0.0, 0.0)))
        star2.velocity = units.AUd(numpy.array((0.0, 0.0, 0.0)))
        star2.radius = units.RSun(100.0)

        instance.particles.add_particles(stars)
        instance.commit_particles()

        for x in range(1, 200, 1):
            instance.evolve_model(x | units.day)
            instance.particles.copy_values_of_all_attributes_to(stars)
            # instance.get_indices_of_colliding_particles()
            # print stars[0].position-stars[1].position
            stars.savepoint()

        instance.cleanup_code()
        instance.stop()

    def test4(self):
        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)

        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        index = instance.new_particle(
            15.0 | units.kg,
            10.0 | units.m, 20.0 | units.m, 30.0 | units.m,
            # 1.0 | units.m/units.s, 1.0 | units.m/units.s, 3.0 | units.m/units.s
            0.0 | units.m/units.s, 0.0 | units.m/units.s, 0.0 | units.m/units.s,
            10.0 | units.m
        )
        instance.commit_particles()
        self.assertEqual(instance.get_mass(index), 15.0 | units.kg)
        self.assertEqual(instance.get_radius(index), 10.0 | units.m)
        instance.cleanup_code()
        instance.stop()

    def test5(self):

        instance = BHTree()
        instance.commit_parameters()

        index = instance.new_particle(
            15.0 | nbody_system.mass,
            10.0 | nbody_system.length, 20.0 | nbody_system.length, 30.0 | nbody_system.length,
            1.0 | nbody_system.speed, 1.0 | nbody_system.speed, 3.0 | nbody_system.speed,
            10.0 | nbody_system.length
        )
        instance.commit_particles()
        self.assertEqual(instance.get_mass(index), 15.0 | nbody_system.mass)
        self.assertEqual(instance.get_radius(index), 10.0 | nbody_system.length)

        instance.cleanup_code()
        instance.stop()

    def test6(self):
        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)
        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        indices = instance.new_particle(
            [15.0, 30.0] | units.kg,
            [10.0, 20.0] | units.m, [20.0, 40.0] | units.m, [30.0, 50.0] | units.m,
            # 1.0 | units.m/units.s, 1.0 | units.m/units.s, 3.0 | units.m/units.s
            [0.0, 0.01] | units.m/units.s, [0.0, 0.01] | units.m/units.s, [0.0, 0.01] | units.m/units.s,
            [10.0, 20.0] | units.m
        )
        instance.commit_particles()

        self.assertEqual(instance.get_mass(indices[0]), 15.0 | units.kg)
        self.assertEqual(instance.get_mass(indices)[0], 15.0 | units.kg)

        self.assertRaises(AmuseException, instance.get_mass, [4, 5],
            expected_message="Error when calling 'get_mass' of a 'BHTree', errorcode is -1")

        instance.cleanup_code()
        instance.stop()

    def test7(self):
        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)

        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        particles = datamodel.Particles(2)
        self.assertEqual(len(instance.particles), 0)

        particles.mass = [15.0, 30.0] | units.kg
        particles.radius = [10.0, 20.0] | units.m
        particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s

        instance.particles.add_particles(particles)
        instance.commit_particles()

        self.assertEqual(instance.get_mass(1), 15.0 | units.kg)
        self.assertAlmostRelativeEquals(instance.get_position(1)[2], 30.0 | units.m)

        self.assertEqual(len(instance.particles), 2)

        self.assertAlmostRelativeEquals(instance.particles.mass[1], 30.0 | units.kg)
        self.assertAlmostRelativeEquals(instance.particles.position[1][2], 60.0 | units.m)
        instance.cleanup_code()
        instance.stop()

    def test8(self):
        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)

        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        particles = datamodel.Particles(2)
        self.assertEqual(len(instance.particles), 0)

        particles.mass = [15.0, 30.0] | units.kg
        particles.radius = [10.0, 20.0] | units.m
        particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s

        instance.particles.add_particles(particles)
        instance.commit_particles()

        instance.particles.mass = [17.0, 33.0] | units.kg

        self.assertEqual(instance.get_mass(1), 17.0 | units.kg)
        instance.cleanup_code()
        instance.stop()

    def test9(self):
        instance = BHTree()
        instance.initialize_code()
        instance.parameters.epsilon_squared = 0.00001 | nbody_system.length**2

        particles = datamodel.Particles(2)
        particles.mass = [1.0, 1.0] | nbody_system.mass
        particles.radius = [0.0001, 0.0001] | nbody_system.length
        particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]] | nbody_system.length
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | nbody_system.speed
        instance.particles.add_particles(particles)

        zero = 0.0 | nbody_system.length
        fx, fy, fz = instance.get_gravity_at_point(zero, 1.0 | nbody_system.length, zero, zero)
        self.assertAlmostEqual(fx, 0.0 | nbody_system.acceleration, 3)
        self.assertAlmostEqual(fy, 0.0 | nbody_system.acceleration, 3)
        self.assertAlmostEqual(fz, 0.0 | nbody_system.acceleration, 3)

        for x in (0.25, 0.5, 0.75):
            x0 = x | nbody_system.length
            x1 = (2.0 - x) | nbody_system.length
            potential0 = instance.get_potential_at_point(zero, x0, zero, zero)
            potential1 = instance.get_potential_at_point(zero, x1, zero, zero)
            fx0, fy0, fz0 = instance.get_gravity_at_point(zero, x0, zero, zero)
            fx1, fy1, fz1 = instance.get_gravity_at_point(zero, x1, zero, zero)

            self.assertAlmostEqual(fy0, 0.0 | nbody_system.acceleration, 3)
            self.assertAlmostEqual(fz0, 0.0 | nbody_system.acceleration, 3)
            self.assertAlmostEqual(fy1, 0.0 | nbody_system.acceleration, 3)
            self.assertAlmostEqual(fz1, 0.0 | nbody_system.acceleration, 3)

            self.assertAlmostEqual(fx0, -1.0 * fx1, 5)
            fx = (-1.0 / (x0**2) + 1.0 / (x1**2)) * (1.0 | nbody_system.length ** 3 / nbody_system.time ** 2)
            self.assertAlmostEqual(fx, fx0, 2)
            self.assertAlmostEqual(potential0, potential1, 5)
        instance.cleanup_code()
        instance.stop()

    def test10(self):
        instance = BHTree()
        instance.initialize_code()
        instance.parameters.epsilon_squared = 0.00001 | nbody_system.length**2
        instance.commit_parameters()

        particles = datamodel.Particles(6)
        particles.mass = 1.0 | nbody_system.mass
        particles.radius = 0.00001 | nbody_system.length
        particles.position = [[-1.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, -1.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, -1.0], [0.0, 0.0, 1.0]] | nbody_system.length
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | nbody_system.speed
        instance.particles.add_particles(particles)
        instance.commit_particles()

        zero = 0.0 | nbody_system.length
        fx, fy, fz = instance.get_gravity_at_point(zero, zero, zero, zero)
        self.assertAlmostEqual(fx, 0.0 | nbody_system.acceleration, 3)
        self.assertAlmostEqual(fy, 0.0 | nbody_system.acceleration, 3)
        self.assertAlmostEqual(fz, 0.0 | nbody_system.acceleration, 3)

        for position in (0.25, 0.5, 0.75):
            p0 = position | nbody_system.length
            p1 = -position | nbody_system.length
            for i in range(3):
                args0 = [zero] * 4
                args1 = [zero] * 4
                args0[1 + i] = p0
                args1[1 + i] = p1
                f0 = instance.get_gravity_at_point(*args0)
                f1 = instance.get_gravity_at_point(*args1)

                for j in range(3):
                    if j != i:
                        self.assertAlmostEqual(f0[j], 0.0 | nbody_system.acceleration, 3)
                        self.assertAlmostEqual(f1[j], 0.0 | nbody_system.acceleration, 3)
                    else:
                        self.assertAlmostEqual(f0[j], -1.0 * f1[j], 5)

        instance.stop()

    def test11(self):

        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)

        instance = BHTree(convert_nbody)

        particles = datamodel.Particles(2)
        self.assertEqual(len(instance.particles), 0)

        particles.mass = [15.0, 30.0] | units.kg
        particles.radius = [10.0, 20.0] | units.m
        particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s

        instance.particles.add_particles(particles)

        copyof = instance.particles.copy()

        self.assertAlmostEqual(30 | units.kg, copyof[1].mass, 6)

        copyof[1].mass = 35 | units.kg

        copyof.copy_values_of_all_attributes_to(instance.particles)

        self.assertAlmostEqual(35 | units.kg, instance.particles[1].mass, 6)
        instance.stop()

    def test12(self):

        convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)

        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        particles = datamodel.Particles(2)
        self.assertEqual(len(instance.particles), 0)

        particles.mass = [15.0, 30.0] | units.kg
        particles.radius = [10.0, 20.0] | units.m
        particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s

        instance.particles.add_particles(particles)
        instance.commit_particles()

        copyof = instance.particles.copy()

        instance.set_state(1, 16 | units.kg, 20.0 | units.m, 40.0 | units.m, 60.0 | units.m,
                                 1.0 | units.ms, 1.0 | units.ms, 1.0 | units.ms)

        curr_state = instance.get_state(1)
        for expected, actual in zip((16 | units.kg, 20.0 | units.m, 40.0 | units.m, 60.0 | units.m,
                                 1.0 | units.ms, 1.0 | units.ms, 1.0 | units.ms, 0 | units.m), curr_state):
            self.assertAlmostRelativeEquals(actual, expected)

        instance.set_state(1, 16 | units.kg, 20.0 | units.m, 40.0 | units.m, 60.0 | units.m,
                                 1.0 | units.ms, 1.0 | units.ms, 1.0 | units.ms, 20.0 | units.m)

        curr_state = instance.get_state(1)
        for expected, actual in zip((16 | units.kg, 20.0 | units.m, 40.0 | units.m, 60.0 | units.m,
                                 1.0 | units.ms, 1.0 | units.ms, 1.0 | units.ms, 20 | units.m), curr_state):
            self.assertAlmostRelativeEquals(actual, expected)

        instance.stop()

    def test13(self):

        convert_nbody = nbody_system.nbody_to_si(1.0 | units.kg, 1.0 | units.m)

        instance = BHTree(convert_nbody)
        instance.commit_parameters()

        particles = datamodel.Particles(2)
        self.assertEqual(len(instance.particles), 0)

        particles.mass = [30.0, 30.0] | units.kg
        particles.radius = [1.0, 1.0] | units.m
        particles.position = [[-10.0, 0.0, 0.0], [10.0, 0.0, 0.0]] | units.m
        particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s

        instance.particles.add_particles(particles)
        instance.commit_particles()

        copyof = instance.particles.copy()

        com = instance.center_of_mass_position
        self.assertAlmostEqual(com[0], quantities.new_quantity(0.0, units.m), constants.precision)
        instance.stop()

    def test14(self):
        print("Test14: Testing BHTree parameters (I)")
        convert_nbody = nbody_system.nbody_to_si(1.0 | units.yr, 1.0 | units.AU)
        instance = BHTree(convert_nbody)

        value, error = instance.legacy_interface.get_epsilon_squared()
        self.assertEqual(0, error)
        self.assertEqual(0.125, value)
        self.assertAlmostEqual(0.125 | units.AU**2, instance.parameters.epsilon_squared, in_units=units.AU**2)
        for x in [0.01, 0.1, 0.2]:
            instance.parameters.epsilon_squared = x | units.AU**2
            self.assertAlmostEqual(x | units.AU**2, instance.parameters.epsilon_squared, in_units=units.AU**2)

        (value, error) = instance.legacy_interface.get_time_step()
        self.assertEqual(0, error)
        self.assertEqual(0.015625, value)
        self.assertAlmostEqual(0.015625 | units.yr, instance.parameters.timestep, in_units=units.yr)
        for x in [0.001, 0.01, 0.1]:
            instance.parameters.timestep = x | units.yr
            self.assertAlmostEqual(x | units.yr, instance.parameters.timestep, in_units=units.yr)

        (value, error) = instance.legacy_interface.get_theta_for_tree()
        self.assertEqual(0, error)
        self.assertEqual(0.75, value)
        self.assertEqual(0.75, instance.parameters.opening_angle)
        for x in [0.2, 0.5, 0.7]:
            instance.parameters.opening_angle = x
            self.assertEqual(x, instance.parameters.opening_angle)

        (value, error) = instance.legacy_interface.get_use_self_gravity()
        self.assertEqual(0, error)
        self.assertEqual(1, value)
        self.assertEqual(1, instance.parameters.use_self_gravity)
        for x in [0, 1]:
            instance.parameters.use_self_gravity = x
            self.assertEqual(x, instance.parameters.use_self_gravity)

        (value, error) = instance.legacy_interface.get_ncrit_for_tree()
        self.assertEqual(0, error)
        self.assertEqual(12, value)
        self.assertEqual(12, instance.parameters.ncrit_for_tree)
        for x in [512, 2048, 4096]:
            instance.parameters.ncrit_for_tree = x
            self.assertEqual(x, instance.parameters.ncrit_for_tree)

        (value, error) = instance.legacy_interface.get_dt_dia()
        self.assertEqual(0, error)
        self.assertEqual(1.0, value)
        self.assertAlmostEqual(1.0 | units.yr, instance.parameters.dt_dia, in_units=units.yr)
        for x in [0.1, 10.0, 100.0]:
            instance.parameters.dt_dia = x | units.yr
            self.assertAlmostEqual(x | units.yr, instance.parameters.dt_dia, in_units=units.yr)
        instance.stop()

    def test15(self):
        print("Test15: Testing effect of BHTree parameter epsilon_squared")
        convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU)

        particles = datamodel.Particles(2)
        sun = particles[0]
        sun.mass = 1.0 | units.MSun
        sun.position = [0.0, 0.0, 0.0] | units.AU
        sun.velocity = [0.0, 0.0, 0.0] | units.AU / units.yr
        sun.radius = 1.0 | units.RSun

        earth = particles[1]
        earth.mass = 5.9736e24 | units.kg
        earth.radius = 6371.0 | units.km
        earth.position = [0.0, 1.0, 0.0] | units.AU
        earth.velocity = [2.0*numpy.pi, -0.0001, 0.0] | units.AU / units.yr

        initial_direction = math.atan((earth.velocity[0]/earth.velocity[1]))
        final_direction = []
        for log_eps2 in range(-9, 10, 2):
            instance = BHTree(convert_nbody)
            instance.initialize_code()
            instance.parameters.epsilon_squared = 10.0**log_eps2 | units.AU ** 2
            instance.particles.add_particles(particles)
            instance.commit_particles()
            instance.evolve_model(0.25 | units.yr)
            final_direction.append(math.atan((instance.particles[1].velocity[0] /
                instance.particles[1].velocity[1])))
            instance.stop()
        # Small values of epsilon_squared should result in normal earth-sun dynamics: rotation of 90 degrees
        self.assertAlmostEqual(abs(final_direction[0]), abs(initial_direction+math.pi/2.0), 2)
        # Large values of epsilon_squared should result in ~ no interaction
        self.assertAlmostEqual(final_direction[-1], initial_direction, 2)
        # Outcome is most sensitive to epsilon_squared when epsilon_squared = d(earth, sun)^2
        delta = [abs(final_direction[i+1]-final_direction[i]) for i in range(len(final_direction)-1)]
        self.assertEqual(delta[len(final_direction)//2 - 1], max(delta))

    def test16(self):
        numpy.random.seed(0)
        number_of_stars = 2
        stars = plummer.new_plummer_model(number_of_stars)
        stars.radius = 0.00001 | nbody_system.length
        stars.scale_to_standard()

        instance = BHTree()
        instance.initialize_code()
        instance.parameters.epsilon_squared = (1.0 / 20.0 / (number_of_stars**0.33333) | nbody_system.length)**2
        instance.parameters.timestep = 0.004 | nbody_system.time
        instance.parameters.timestep = 0.00001 | nbody_system.time
        instance.commit_parameters()
        print(instance.parameters.timestep)
        instance.particles.add_particles(stars)
        instance.commit_particles()
        energy_total_t0 = instance.potential_energy + instance.kinetic_energy
        request = instance.evolve_model.asynchronous(1.0 | nbody_system.time)
        request.result()
        energy_total_t1 = instance.potential_energy + instance.kinetic_energy

        self.assertAlmostRelativeEqual(energy_total_t0, energy_total_t1, 3)
        instance.stop()
        numpy.random.seed()

    def test17(self):
        print("Testing BHTree collision_detection")
        particles = datamodel.Particles(7)
        particles.mass = 0.001 | nbody_system.mass
        particles.radius = 0.01 | nbody_system.length
        particles.x = [-101.0, -100.0, -0.5, 0.5, 100.0, 101.0, 104.0] | nbody_system.length
        particles.y = 0 | nbody_system.length
        particles.z = 0 | nbody_system.length
        particles.velocity = [[2, 0, 0], [-2, 0, 0]]*3 + [[-4, 0, 0]] | nbody_system.speed

        instance = BHTree(redirection='none')
        instance.initialize_code()
        instance.parameters.set_defaults()

        # Uncommenting any of the following two lines will suppress collision detection
# ~        instance.parameters.use_self_gravity = 0
# ~        instance.parameters.epsilon_squared = 0.0 | nbody_system.length**2

        instance.parameters.opening_angle = 0.1
        instance.particles.add_particles(particles)
        collisions = instance.stopping_conditions.collision_detection
        collisions.enable()
        instance.evolve_model(1.0 | nbody_system.time)

        self.assertTrue(collisions.is_set())
        self.assertTrue(instance.model_time < 0.5 | nbody_system.time)
        self.assertEqual(len(collisions.particles(0)), 3)
        self.assertEqual(len(collisions.particles(1)), 3)
        self.assertEqual(len(particles - collisions.particles(0) - collisions.particles(1)), 1)
        self.assertEqual(abs(collisions.particles(0).x - collisions.particles(1).x) <
                (collisions.particles(0).radius + collisions.particles(1).radius),
                [True, True, True])

        sticky_merged = datamodel.Particles(len(collisions.particles(0)))
        sticky_merged.mass = collisions.particles(0).mass + collisions.particles(1).mass
        sticky_merged.radius = collisions.particles(0).radius
        for p1, p2, merged in zip(collisions.particles(0), collisions.particles(1), sticky_merged):
            merged.position = (p1 + p2).center_of_mass()
            merged.velocity = (p1 + p2).center_of_mass_velocity()

        print(instance.model_time)
        print(instance.particles)
        instance.particles.remove_particles(collisions.particles(0) + collisions.particles(1))
        instance.particles.add_particles(sticky_merged)

        instance.evolve_model(1.0 | nbody_system.time)
        print()
        print(instance.model_time)
        print(instance.particles)
        self.assertTrue(collisions.is_set())
        self.assertTrue(instance.model_time < 1.0 | nbody_system.time)
        self.assertEqual(len(collisions.particles(0)), 1)
        self.assertEqual(len(collisions.particles(1)), 1)
        self.assertEqual(len(instance.particles - collisions.particles(0) - collisions.particles(1)), 2)
        self.assertEqual(abs(collisions.particles(0).x - collisions.particles(1).x) <
                (collisions.particles(0).radius + collisions.particles(1).radius),
                [True])
        instance.stop()

    def test18(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0 | nbody_system.length
        particles.z = 0 | nbody_system.length
        particles.radius = 0.005 | nbody_system.length
        particles.vx = 0 | nbody_system.speed
        particles.vy = 0 | nbody_system.speed
        particles.vz = 0 | nbody_system.speed
        particles.mass = 1.0 | nbody_system.mass

        instance = BHTree()
        instance.initialize_code()
        instance.parameters.stopping_conditions_number_of_steps = 2
        self.assertEqual(instance.parameters.stopping_conditions_number_of_steps, 2)
        instance.parameters.epsilon_squared = (0.01 | nbody_system.length)**2
        instance.particles.add_particles(particles)
        instance.stopping_conditions.number_of_steps_detection.enable()
        instance.evolve_model(10 | nbody_system.time)
        self.assertTrue(instance.stopping_conditions.number_of_steps_detection.is_set())
        self.assertTrue(instance.model_time < 10 | nbody_system.time)
        instance.stop()

    def test19(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0.0 | nbody_system.length
        particles.z = 0.0 | nbody_system.length
        particles.radius = 0.005 | nbody_system.length
        particles.vx = 0.0 | nbody_system.speed
        particles.vy = 0.0 | nbody_system.speed
        particles.vz = 0.0 | nbody_system.speed
        particles.mass = 1.0 | nbody_system.mass

        very_short_time_to_evolve = 1 | units.s
        very_long_time_to_evolve = 1e9 | nbody_system.time

        instance = BHTree()
        instance.initialize_code()
        instance.parameters.stopping_conditions_timeout = very_short_time_to_evolve
        self.assertEqual(instance.parameters.stopping_conditions_timeout, very_short_time_to_evolve)
        instance.parameters.epsilon_squared = (0.01 | nbody_system.length)**2
        instance.particles.add_particles(particles)
        instance.stopping_conditions.timeout_detection.enable()
        start = time.time()
        instance.evolve_model(very_long_time_to_evolve)
        end = time.time()
        self.assertTrue(instance.stopping_conditions.timeout_detection.is_set())
        self.assertTrue((end-start) < very_short_time_to_evolve.value_in(units.s) + 2)  # 2 = some overhead compensation
        instance.stop()

    def test20(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0.0 | nbody_system.length
        particles.z = 0.0 | nbody_system.length
        particles.radius = 0.005 | nbody_system.length
        particles.vx = 0.0 | nbody_system.speed
        particles.vy = 0.0 | nbody_system.speed
        particles.vz = 0.0 | nbody_system.speed
        particles.mass = 1.0 | nbody_system.mass

        very_short_time_to_evolve = 1 | units.s
        very_long_time_to_evolve = 1e9 | nbody_system.time

        instance = BHTree()
        instance.initialize_code()
        instance.parameters.stopping_conditions_timeout = very_short_time_to_evolve
        self.assertEqual(instance.parameters.stopping_conditions_timeout, very_short_time_to_evolve)
        instance.parameters.epsilon_squared = (0.01 | nbody_system.length)**2
        instance.particles.add_particles(particles)
        codeparticles1 = instance.particles
        instance.particles.add_particle(datamodel.Particle(
            position=[0, 1, 2] | nbody_system.length,
            velocity=[0, 0, 0] | nbody_system.speed,
            radius=0.005 | nbody_system.length,
            mass=1 | nbody_system.mass
        ))
        codeparticles2 = instance.particles
        self.assertTrue(codeparticles1 is codeparticles2)
        instance.cleanup_code()
        codeparticles3 = instance.particles
        self.assertFalse(codeparticles1 is codeparticles3)

        instance.stop()

    def test21(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0.0 | nbody_system.length
        particles.z = 0.0 | nbody_system.length
        particles.radius = 0.005 | nbody_system.length
        particles.vx = 0.0 | nbody_system.speed
        particles.vy = 0.0 | nbody_system.speed
        particles.vz = 0.0 | nbody_system.speed
        particles.mass = 1.0 | nbody_system.mass

        very_short_time_to_evolve = 1 | units.s
        very_long_time_to_evolve = 1e9 | nbody_system.time

        instance = BHTree()
        instance.initialize_code()
        instance.parameters.epsilon_squared = (1e-5 | nbody_system.length)**2
        instance.particles.add_particles(particles)
        instance.commit_particles()
        self.assertAlmostRelativeEquals(instance.potential_energy, -0.1 | nbody_system.energy, 5)
        instance.stop()

    def test22(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0.0 | nbody_system.length
        particles.z = 0.0 | nbody_system.length
        particles.vx = 0.0 | nbody_system.speed
        particles.vy = 0.0 | nbody_system.speed
        particles.vz = 0.0 | nbody_system.speed
        particles.mass = 1.0 | nbody_system.mass

        instance = BHTree()
        instance.particles.add_particles(particles)
        instance.commit_particles()
        self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length)
        p = datamodel.Particle(
            x=1.0 | nbody_system.length,
            y=2.0 | nbody_system.length,
            z=3.0 | nbody_system.length,
            vx=1.0 | nbody_system.speed,
            vy=2.0 | nbody_system.speed,
            vz=3.0 | nbody_system.speed,
            mass=1.0 | nbody_system.mass,
            radius=4.0 | nbody_system.length,
        )
        instance.particles.add_particle(p)
        self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length)
        self.assertEqual(instance.particles[1].radius, 0.0 | nbody_system.length)
        self.assertEqual(instance.particles[2].radius, 4.0 | nbody_system.length)

        instance.stop()

    def test23(self):
        particles = datamodel.Particles(2)
        particles.x = [0.0, 10.0] | nbody_system.length
        particles.y = 0.0 | nbody_system.length
        particles.z = 0.0 | nbody_system.length
        particles.vx = 1.0 | nbody_system.speed
        particles.vy = 0.0 | nbody_system.speed
        particles.vz = 0.0 | nbody_system.speed
        particles.mass = 0.1 | nbody_system.mass

        instance = BHTree(redirection="none")
        instance.particles.add_particles(particles)
        instance.commit_particles()
        instance.evolve_model(0.1 | nbody_system.time)
        self.assertFalse(instance.particles[0].vy > 0 | nbody_system.speed)
        self.assertAlmostRelativeEquals(instance.particles[0].x, 0.1 | nbody_system.length, 4)
        instance.particles.new_channel_to(particles).copy()
        particles.vy = 1 | nbody_system.speed
        particles.new_channel_to(instance.particles).copy()

        instance.evolve_model(0.2 | nbody_system.time)
        self.assertTrue(instance.particles[0].vy > 0 | nbody_system.speed)
        self.assertAlmostRelativeEquals(instance.particles[0].y, 0.1 | nbody_system.length, 4)
        instance.stop()
