/* ******************************************************************************
 *
 *
 * This program and the accompanying materials are made available under the
 * terms of the Apache License, Version 2.0 which is available at
 * https://www.apache.org/licenses/LICENSE-2.0.
 *
 *  See the NOTICE file distributed with this work for additional
 *  information regarding copyright ownership.
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/

//
//  @author GS <sgazeos@gmail.com>
//

#include <ops/declarable/helpers/legacy_helpers.h>
#include <array/NDArrayFactory.h>
#include <system/op_boilerplate.h>
#include <ops/ops.h>

namespace sd {
namespace ops {
namespace helpers {

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    template <typename T>
    linkage void cubeDerivative_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            return y * (3 * x * x);
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void cubeDerivative(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), cubeDerivative_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    //return (x >= X(0.f) ? y: -y);
    template <typename T>
    linkage void reduceNorm1_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            return x > T(0.f)? y : -y;
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void reduceNorm1(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), reduceNorm1_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////
    template <typename T>
    linkage void sigmCrossEntropy_(NDArray* logits, NDArray* labels, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            return sd::math::nd4j_max<T>(x, (T)0.f) - x * y + sd::math::nd4j_log<T,T>((T)1.f + sd::math::nd4j_exp<T,T>(-sd::math::nd4j_abs(x)));
        };

        logits->applyPairwiseLambda(*labels, functor, *output);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void sigmCrossEntropy(sd::LaunchContext * context, NDArray* logits, NDArray* labels, NDArray* output) {
        BUILD_SINGLE_SELECTOR(logits->dataType(), sigmCrossEntropy_, (logits, labels, output), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////
    template <typename T>
    linkage void sigmCrossEntropyGrad_(NDArray* logits, NDArray* labels, NDArray* output) {
        // 1 - labels - 1 / (1 + exp(logits))
        auto functor = LAMBDA_TT(x, y) {
            if(x <= 0)
                return static_cast<T>(1.) - y - static_cast<T>(1.) / (static_cast<T>(1.) + sd::math::nd4j_exp<T,T>(x));
            auto e = sd::math::nd4j_exp<T,T>(-x);
            return static_cast<T>(1.) - y - e / (static_cast<T>(1.) + e);
        };

        logits->applyPairwiseLambda(*labels, functor, *output);
    }
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void sigmCrossEntropyGrad(sd::LaunchContext * context, NDArray* logits, NDArray* labels, NDArray* output) {
        BUILD_SINGLE_SELECTOR(logits->dataType(), sigmCrossEntropyGrad_, (logits, labels, output), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    //            X f = (X) 1.0f + sd::math::nd4j_abs<X>(d1);
    //            return (X) d2 * ((X) 1.0f / (f * f));
    //
    template <typename T>
    linkage void softSignDerivative_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            T ss = (T)1.f + sd::math::nd4j_abs<T>(x);
            return y * ((T) 1.0f  / (ss * ss));
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void softSignDerivative(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), softSignDerivative_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    template <typename T>
    linkage void softPlusDerivative_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            T p = sd::math::nd4j_pow<T, T, T>(static_cast<T>(M_E), x);
            return y * (p / (p + 1.));
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

    void softPlusDerivative(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), softPlusDerivative_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///
/// \param input
/// \param epsilon
/// \param output
    template <typename T>
    linkage void sigmoidDerivative_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            T s = sd::math::nd4j_sigmoid<T,T>(x);
            return y * (s * ((T) 1.0f - s));
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

    void sigmoidDerivative(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), sigmoidDerivative_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }

    template <typename T>
    linkage void hardSigmoidDerivative_(NDArray* input, NDArray* epsilon, NDArray* output) {
        auto functor = LAMBDA_TT(x, y){
            return y * simdOps::HardSigmoidDerivative<T>::op(x, nullptr);
        };

        input->applyPairwiseLambda(*epsilon, functor, *output);
    }

    void hardSigmoidDerivative(sd::LaunchContext * context, NDArray* theFirst, NDArray* theSecond, NDArray* theOutput) {
        BUILD_SINGLE_SELECTOR(theFirst->dataType(), hardSigmoidDerivative_, (theFirst, theSecond, theOutput), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    template <typename T>
    linkage void logSumExp_(NDArray* input, NDArray* axis, NDArray* output) {
        // reduce along axis with
        NDArray tempInput = input->dup();
        input->applyTransform(transform::Exp, tempInput);
        std::vector<int> axisVector;
        if (axis != nullptr) {
            axisVector.resize(axis->lengthOf());
            for (size_t i = 0; i < axisVector.size(); ++i)
                axisVector[i] = axis->e<int>(i);
        }
        tempInput.reduceAlongDimension(reduce::Sum, *output, axisVector);
        output->applyTransform(transform::Log, *output);
    }

    template <typename T>
    linkage void logSumExp_(NDArray* input, NDArray* subtrah, NDArray* axis, NDArray* output) {
        // reduce along axis with
        NDArray tempInput = input->dup();
        input->applyPairwiseTransform(pairwise::Subtract, *subtrah, tempInput);
        tempInput.applyTransform(transform::Exp, tempInput);

        std::vector<int> axisVector;
        if (axis != nullptr) {
            axisVector.resize(axis->lengthOf());
            for (size_t i = 0; i < axisVector.size(); ++i)
                axisVector[i] = axis->e<int>(i);
        }
        tempInput.reduceAlongDimension(reduce::Sum, *output, axisVector);
        output->applyTransform(transform::Log, *output);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void logSumExp(sd::LaunchContext * context, NDArray* input, NDArray* axis, NDArray* output) {
        BUILD_SINGLE_SELECTOR(input->dataType(), logSumExp_, (input, axis, output), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void logSumExp(sd::LaunchContext * context, NDArray* input, NDArray* subtrah, NDArray* axis, NDArray* output) {
        BUILD_SINGLE_SELECTOR(input->dataType(), logSumExp_, (input, subtrah, axis, output), FLOAT_TYPES);
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    template <typename T>
    void weightedCrossEntropyWithLogitsFunctor_(NDArray const* targets, NDArray const* input, NDArray const* weights, NDArray* output) {

        T posWeight = weights->e<T>(0);

        auto mainRoutineT1 = LAMBDA_TT(_x, _z, posWeight) {
            T targetWeight = (1. + (posWeight - (T)1.f) * _z);
            return (1. - _z) * _x +
                   targetWeight * (sd::math::nd4j_log<T,T>((T)1.f + sd::math::nd4j_exp<T,T>(-sd::math::nd4j_abs(_x))) +
                                   sd::math::nd4j_max(-_x, T(0.f))
                   );
        };

        auto mainRoutineT2 = LAMBDA_TTT(_x, _z, _w) {
            return (((T)1.0 - _z) * _x) +
                   _w * (sd::math::nd4j_log<T,T>(T(1.) + sd::math::nd4j_exp<T,T>(-sd::math::nd4j_abs(_x))) +
                         sd::math::nd4j_max(-_x, T(0.f)));
        };


        if (weights->isScalar()) {
            const_cast<NDArray*>(input)->applyPairwiseLambda(const_cast<NDArray&>(*targets), mainRoutineT1, *output);
        }
        else
        {
            std::unique_ptr<NDArray> targetVector(new NDArray(*weights));
            targetVector->applyScalar(scalar::Add, -1.f, *targetVector);

            std::unique_ptr<NDArray> targetTensor(new NDArray(*targets));
            *targetTensor = (*targetVector * *targetTensor) + T(1.f);
            const_cast<NDArray*>(input)->applyTriplewiseLambda(const_cast<NDArray&>(*targets), *targetTensor.get(), mainRoutineT2, *output);
        }
    }
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    void weightedCrossEntropyWithLogitsFunctor(sd::LaunchContext * context, NDArray const* targets, NDArray const* input, NDArray const* weights, NDArray* output) {
        NDArray::prepareSpecialUse({output}, {targets, input, weights});

        BUILD_SINGLE_SELECTOR(targets->dataType(), weightedCrossEntropyWithLogitsFunctor_, (targets, input, weights, output), FLOAT_TYPES);

        NDArray::registerSpecialUse({output}, {targets, input, weights});
    }

}
}
}