/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 * Copyright (c) 2019 Konduit K.K.
 *
 * 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.
 *
 * 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 Yurii Shyrma (iuriish@yahoo.com)
//

#include <ops/declarable/helpers/convolutions.h>
#include <helpers/PointersManager.h>
#include <math/templatemath.h>

namespace sd {
namespace ops  {

//////////////////////////////////////////////////////////////////////////
template <typename T>
__global__ static void pooling3dBPCuda(const void* vx, const Nd4jLong* xShapeInfo, const void* vy, const Nd4jLong* yShapeInfo, void* vz, const Nd4jLong* zShapeInfo, const int kD, const int kH, const int kW, const int sD, const int sH, const int sW, const int pD, const int pH, const int pW, const int dD, const int dH, const int dW, const int poolingMode, const int extraParam0) {

    // x: input [bS, iC, iD, iH, iW]
    // y: gradO [bS, iC, oD, oH, oW]
    // z: gradI [bS, iC, iD, iH, iW] -> gradI is output in this function


    const T* x = reinterpret_cast<const T*>(vx);
    const T* y = reinterpret_cast<const T*>(vy);
          T* z = reinterpret_cast<T*>(vz);

    Nd4jLong coord2, coord3, coord4;
    __shared__ int rank, kDeff, kHeff, kWeff, iD, iH, iW, kProd;
    __shared__ Nd4jLong yLen, *sharedMem;

    if (threadIdx.x == 0) {
        extern __shared__ unsigned char shmem[];
        sharedMem = reinterpret_cast<Nd4jLong*>(shmem);

        yLen = shape::length(yShapeInfo);
        rank = 5;

        kDeff = kD + (kD - 1) * (dD - 1);
        kHeff = kH + (kH - 1) * (dH - 1);
        kWeff = kW + (kW - 1) * (dW - 1);

        iD = xShapeInfo[3];
        iH = xShapeInfo[4];
        iW = xShapeInfo[5];

        kProd = kD * kH * kW;
    }
    __syncthreads();

    const auto yInd = threadIdx.x + blockIdx.x * blockDim.x;

    if(yInd >= yLen)
        return;

    auto coords = sharedMem + threadIdx.x * rank;

    shape::index2coords(yInd, yShapeInfo, coords);

    const auto yOffset = shape::getOffset(yShapeInfo, coords);

    int dstart = coords[2] * sD - pD;
    int hstart = coords[3] * sH - pH;
    int wstart = coords[4] * sW - pW;
    int dend = dstart + kDeff;
    int hend = hstart + kHeff;
    int wend = wstart + kWeff;

    if(dstart < 0)
        dstart += dD * ((-dstart + dD - 1) / dD);
    if(hstart < 0)
        hstart += dH * ((-hstart + dH - 1) / dH);
    if(wstart < 0)
        wstart += dW * ((-wstart + dW - 1) / dW);
    if(dend > iD)
        dend -= dD * ((dend - iD + dD - 1) / dD);
    if(hend > iH)
        hend -= dH * ((hend - iH + dH - 1) / dH);
    if(wend > iW)
        wend -= dW * ((wend - iW + dW - 1) / dW);


    switch (poolingMode) {

        /*** max ***/
        case 0: {

            T max = -DataTypeUtils::max<T>();
            for (coords[2] = dstart; coords[2] < dend; coords[2] += dD) {
                for (coords[3] = hstart; coords[3] < hend; coords[3] += dH){
                    for (coords[4] = wstart; coords[4] < wend; coords[4] += dW) {
                        T val = x[shape::getOffset(xShapeInfo, coords)];
                        if (val > max) {
                            max = val;
                            coord2 = coords[2];
                            coord3 = coords[3];
                            coord4 = coords[4];
                        }
                    }
                }
            }
            coords[2] = coord2;
            coords[3] = coord3;
            coords[4] = coord4;
            sd::math::atomics::nd4j_atomicAdd<T>(&z[shape::getOffset(zShapeInfo, coords)], y[yOffset]);
        }
        break;

        /*** avg ***/
        case 1: {

            T val = y[yOffset];

            if (extraParam0 == 0)         //Exclude padding
                val /= sd::math::nd4j_ceil<double,T>(static_cast<double>(dend - dstart) / static_cast<double>(dD))  * sd::math::nd4j_ceil<double,T>(static_cast<double>(hend - hstart) / static_cast<double>(dH))     * sd::math::nd4j_ceil<double,T>(static_cast<double>(wend - wstart)    / static_cast<double>(dW));   //Accounts for dilation
            else if (extraParam0 == 1)    //Include padding
                val /= kProd;

            for (coords[2] = dstart; coords[2] < dend; coords[2] += dD)
                for (coords[3] = hstart; coords[3] < hend; coords[3] += dH)
                    for (coords[4] = wstart; coords[4] < wend; coords[4] += dW)
                        sd::math::atomics::nd4j_atomicAdd<T>(&z[shape::getOffset(zShapeInfo, coords)], val);
        }
        break;

        /*** pnorm ***/
        case 2: {

            T sum = static_cast<T>(0.);
            T val = y[yOffset];

            for (coords[2] = dstart; coords[2] < dend; coords[2] += dD)
                for (coords[3] = hstart; coords[3] < hend; coords[3] += dH)
                    for (coords[4] = wstart; coords[4] < wend; coords[4] += dW)
                        sum += sd::math::nd4j_pow<T,T,T>(sd::math::nd4j_abs<T>(x[shape::getOffset(xShapeInfo, coords)]), extraParam0);

            val *= sd::math::nd4j_pow<T,T,T>(sum, ((T)1.f - extraParam0) / extraParam0);

            for (coords[2] = dstart; coords[2] < dend; coords[2] += dD) {
                for (coords[3] = hstart; coords[3] < hend; coords[3] += dH) {
                    for (coords[4] = wstart; coords[4] < wend; coords[4] += dW) {
                        const auto xOffset = shape::getOffset(xShapeInfo, coords);
                        const auto zOffset = shape::getOffset(zShapeInfo, coords);
                        sd::math::atomics::nd4j_atomicAdd<T>(&z[zOffset], val * sd::math::nd4j_pow<T,T,T>(sd::math::nd4j_abs<T>(x[xOffset]), extraParam0 - 1.f) * sd::math::nd4j_sgn<T,T>(x[xOffset]));
                    }
                }
            }
        }
        break;
    }
}

//////////////////////////////////////////////////////////////////////////
template <typename T>
static void pooling3dBPCudaLauncher(const int blocksPerGrid, const int threadsPerBlock, const int sharedMem, const cudaStream_t *stream,
                                    const void* vx, const Nd4jLong* xShapeInfo,
                                    const void* vy, const Nd4jLong* yShapeInfo,
                                          void* vz, const Nd4jLong* zShapeInfo,
                                    const int kD, const int kH, const int kW,
                                    const int sD, const int sH, const int sW,
                                    const int pD, const int pH, const int pW,
                                    const int dD, const int dH, const int dW,
                                    const int poolingMode, const int extraParam0) {

    pooling3dBPCuda<T><<<blocksPerGrid, threadsPerBlock, sharedMem, *stream>>>(vx, xShapeInfo, vy, yShapeInfo, vz, zShapeInfo, kD, kH, kW, sD, sH, sW, pD, pH, pW, dD, dH, dW, poolingMode, extraParam0);
}

//////////////////////////////////////////////////////////////////////////
void ConvolutionUtils::pooling3dBP(sd::graph::Context& block, const NDArray& input, const NDArray& gradO, NDArray& gradI, const int kD, const int kH, const int kW, const int sD, const int sH, const int sW, const int pD, const int pH, const int pW, const int dD, const int dH, const int dW, const int poolingMode, const int extraParam0) {

    // initial zeroing of gradI
    gradI.nullify();

    PointersManager manager(block.launchContext(), "pooling3dBP");

    const int threadsPerBlock = MAX_NUM_THREADS / 2;
    const int blocksPerGrid = (gradO.lengthOf() + threadsPerBlock - 1) / threadsPerBlock;
    const int sharedMem = gradO.rankOf() * sizeof(Nd4jLong) * threadsPerBlock + 128;

    NDArray::prepareSpecialUse({&gradI}, {&input, &gradO});
    BUILD_SINGLE_SELECTOR(input.dataType(), pooling3dBPCudaLauncher, (blocksPerGrid, threadsPerBlock, sharedMem, block.launchContext()->getCudaStream(), input.specialBuffer(), input.specialShapeInfo(), gradO.specialBuffer(), gradO.specialShapeInfo(), gradI.specialBuffer(), gradI.specialShapeInfo(), kD, kH, kW, sD, sH, sW, pD, pH, pW, dD, dH, dW, poolingMode, extraParam0), FLOAT_TYPES);
    NDArray::registerSpecialUse({&gradI}, {&input, &gradO});

    manager.synchronize();
}

}
}