# Test functions for poppy multiprocessing

from .. import poppy_core
from .. import optics
from .. import conf
from .. import utils

import numpy as np
import astropy
import astropy.io.fits as fits
import sys
from distutils.version import LooseVersion

try:
    import pytest
    _HAVE_PYTEST = True
except:
    _HAVE_PYTEST = False


if _HAVE_PYTEST:

    @pytest.mark.xfail
    # Just skip this test entirely for right now because sometimes it hangs the
    # entire Python process...

    @pytest.mark.skipif( sys.platform=='win32',
            reason='Multiprocessing forkserver context not supported on Windows')
    @pytest.mark.skipif( (sys.version_info < (3,4,0) ),
            reason="Python 3.4 required for reliable forkserver start method")
    @pytest.mark.skipif(LooseVersion(astropy.__version__) <  LooseVersion('1.0.3'),
            reason="astropy >=1.0.3 required for tests of multiprocessing")
    def test_basic_multiprocessing():
        """For a simple optical system, test that single process and
        multiprocess calculation give the same results"""
        osys = poppy_core.OpticalSystem("test")
        pupil = optics.CircularAperture(radius=1)
        osys.add_pupil(pupil)
        osys.add_detector(pixelscale=0.1, fov_arcsec=5.0)

        source={'wavelengths': [1.0e-6, 1.1e-6, 1.2e-6, 1.3e-6], 'weights':[0.25, 0.25, 0.25, 0.25]}
        conf.use_fftw=False

        conf.use_multiprocessing=False
        psf_single = osys.calc_psf(source=source)

        conf.use_multiprocessing=True
        psf_multi = osys.calc_psf(source=source)

        assert np.allclose(psf_single[0].data, psf_multi[0].data), \
            "PSF from multiprocessing does not match PSF from single process"

        return psf_single, psf_multi


    @pytest.mark.skipif( sys.platform=='win32',
            reason='Multiprocessing forkserver context not supported on Windows')
    @pytest.mark.skipif( (sys.version_info < (3,4,0) ),
            reason="Python 3.4 required for reliable forkserver start method")
    @pytest.mark.skipif(LooseVersion(astropy.__version__) <  LooseVersion('1.0.3'),
            reason="astropy >=1.0.3 required for tests of multiprocessing")
    def test_multiprocessing_intermediate_planes():
        """ Test that using multiprocessing you can retrieve the intermediate planes,
        and they are consistent with the intermediate planes from a
        single process calculation"""
        osys = poppy_core.OpticalSystem("test")
        osys.add_pupil(optics.CircularAperture(radius=1))
        osys.add_pupil(optics.CircularAperture(radius=0.5))
        osys.add_detector(pixelscale=0.1, fov_arcsec=2.0)

        source={'wavelengths': [1.0e-6, 1.1e-6, 1.2e-6, 1.3e-6], 'weights':[0.25, 0.25, 0.25, 0.25]}
        conf.use_fftw=False

        conf.use_multiprocessing=False
        psf_single, planes_single = osys.calc_psf(source=source, return_intermediates=True)

        conf.use_multiprocessing=True
        psf_multi, planes_multi = osys.calc_psf(source=source, return_intermediates=True)

        assert np.allclose(psf_single[0].data, psf_multi[0].data), \
            "PSF from multiprocessing does not match PSF from single process"


        assert len(planes_multi) == len(planes_single), \
            "Intermediate calculation planes from multiprocessing has wrong number of planes."

        for i in range(len(planes_single)):
            assert (np.allclose(planes_single[i].intensity, planes_multi[i].intensity)), \
                "Intermediate plane {} from multiprocessing does not match same plane from single process.".format(i)

        return psf_single, psf_multi


def test_estimate_nprocesses():
    """ Apply some basic functionality tests to the
    estimate nprocesses function.
    """
    osys = poppy_core.OpticalSystem("test")
    osys.add_pupil(optics.CircularAperture(radius=1))
    osys.add_pupil(optics.CircularAperture(radius=0.5))
    osys.add_detector(pixelscale=0.1, fov_arcsec=2.0)

    answer = utils.estimate_optimal_nprocesses(osys)

    #see if it's an int with a reasonable value
    assert type(answer) is int

    assert answer > 0, "Estimated optimal nprocesses must be positive integer"
    assert answer < 100, "Estimated optimal nprocesses is unreasonably large"

