# 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 <http://www.gnu.org/licenses/>.
#
# Copyright(C) 2013-2018 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.

import unittest
import nifty5 as ift
import numpy as np
from itertools import product
from test.common import expand


def _flat_PS(k):
    return np.ones_like(k)


class Energy_Tests(unittest.TestCase):
    @expand(product([ift.GLSpace(15),
                     ift.RGSpace(64, distances=.789),
                     ift.RGSpace([32, 32], distances=.789)],
                    [4, 78, 23]))
    def testLinearMap(self, space, seed):
        np.random.seed(seed)
        dim = len(space.shape)
        hspace = space.get_default_codomain()
        ht = ift.HarmonicTransformOperator(hspace, target=space)
        binbounds = ift.PowerSpace.useful_binbounds(hspace, logarithmic=False)
        pspace = ift.PowerSpace(hspace, binbounds=binbounds)
        Dist = ift.PowerDistributor(target=hspace, power_space=pspace)
        xi0 = ift.Field.from_random(domain=hspace, random_type='normal')

        def pspec(k): return 1 / (1 + k**2)**dim
        pspec = ift.PS_field(pspace, pspec)
        A = Dist(ift.sqrt(pspec))
        n = ift.Field.from_random(domain=space, random_type='normal')
        s0 = xi0 * A
        Instrument = ift.ScalingOperator(10., space)
        R = Instrument * ht
        N = ift.ScalingOperator(1., space)
        d = R(s0) + n

        IC = ift.GradientNormController(
            iteration_limit=100,
            tol_abs_gradnorm=1e-5)

        S = ift.create_power_operator(hspace, power_spectrum=_flat_PS)
        energy = ift.WienerFilterEnergy(
            position=s0, d=d, R=R, N=N, S=S, iteration_controller=IC)
        ift.extra.check_value_gradient_curvature_consistency(
            energy, ntries=10)

    @expand(product([ift.GLSpace(15),
                     ift.RGSpace(64, distances=.789),
                     ift.RGSpace([32, 32], distances=.789)],
                    [ift.Tanh, ift.Exponential, ift.Linear],
                    [4, 78, 23]))
    def testGaussianEnergy(self, space, nonlinearity, seed):
        np.random.seed(seed)
        f = nonlinearity()
        dim = len(space.shape)
        hspace = space.get_default_codomain()
        ht = ift.HarmonicTransformOperator(hspace, target=space)
        binbounds = ift.PowerSpace.useful_binbounds(hspace, logarithmic=False)
        pspace = ift.PowerSpace(hspace, binbounds=binbounds)
        Dist = ift.PowerDistributor(target=hspace, power_space=pspace)
        xi0 = ift.Field.from_random(domain=hspace, random_type='normal')
        xi0_var = ift.Variable(ift.MultiField({'xi':xi0}))['xi']

        def pspec(k): return 1 / (1 + k**2)**dim
        pspec = ift.PS_field(pspace, pspec)
        A = Dist(ift.sqrt(pspec))
        n = ift.Field.from_random(domain=space, random_type='normal')
        s = ht(ift.makeOp(A)(xi0_var))
        R = ift.ScalingOperator(10., space)
        N = ift.ScalingOperator(1., space)
        d_model = R(ift.LocalModel(s, nonlinearity()))
        d = d_model.value + n

        energy = ift.GaussianEnergy(d_model, d, N)
        if isinstance(nonlinearity, ift.Linear):
            ift.extra.check_value_gradient_curvature_consistency(
                energy, ntries=10)
        else:
            ift.extra.check_value_gradient_consistency(
                energy, ntries=10)