# This file is part of meas_base.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

import unittest

import numpy as np

import lsst.geom
import lsst.afw.geom as afwGeom
import lsst.utils.tests as utilsTests

# Rename the class on import so it does not confuse the test scanner
from lsst.meas.base.tests import TestDataset as DatasetTester


class TestDatasetTestCase(utilsTests.TestCase):

    def setUp(self):
        # Construct an arbitrary WCS for testing.
        crval = lsst.geom.SpherePoint(45.0, 45.0, lsst.geom.degrees)
        scale = 0.2*lsst.geom.arcseconds
        crpix = lsst.geom.PointD(100, 100)
        self.wcs = afwGeom.makeSkyWcs(crpix=crpix, crval=crval,
                                      cdMatrix=afwGeom.makeCdMatrix(scale=scale))

    def tearDown(self):
        del self.wcs

    def test_perturb(self):
        """Test that perturbing a WCS gives us back something different.
        """
        # We should always get something different from our starting point.
        self.assertNotEqual(self.wcs, DatasetTester.makePerturbedWcs(self.wcs))

        # If we use the same random seed, the results should be reproducible.
        self.assertEqual(DatasetTester.makePerturbedWcs(self.wcs, randomSeed=0),
                         DatasetTester.makePerturbedWcs(self.wcs, randomSeed=0))

        # If we specify different seeds, we should always get something
        # different.
        self.assertNotEqual(DatasetTester.makePerturbedWcs(self.wcs, randomSeed=1),
                            DatasetTester.makePerturbedWcs(self.wcs, randomSeed=2))

    def test_randomState(self):
        """Test that we do not alter global state when perturbing the WCS.

        Notes
        -----
        This checks that global state doesn't change while the test is
        executing. This isn't perfectly robust: the test will fail if another
        thread manipulates the RNG state while this is executing. However,
        since pytest doesn't using multi-threading, it should be safe in
        practice.
        """
        init_state = np.random.get_state()
        DatasetTester.makePerturbedWcs(self.wcs)
        for init, final in zip(init_state, np.random.get_state()):
            self.assertTrue(np.array_equal(init, final))


class TestMemory(utilsTests.MemoryTestCase):
    pass


def setup_module(module):
    utilsTests.init()


if __name__ == "__main__":
    utilsTests.init()
    unittest.main()