// Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://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.

#include "lite/backends/arm/math/sequence_pool.h"
#include <algorithm>
#include <cmath>
#include <limits>
#include <vector>
#include "lite/backends/arm/math/funcs.h"
#include "lite/core/op_registry.h"
#include "lite/core/tensor.h"
#include "lite/core/type_system.h"

namespace paddle {
namespace lite {
namespace arm {
namespace math {

template <>
void seq_pool_sum<float>(const float* din,
                         const float* din_grad,
                         float* dout,
                         const std::vector<uint64_t> lod,
                         int64_t width) {
  for (int i = 0; i < static_cast<int>(lod.size()) - 1; ++i) {
    int64_t height = static_cast<int64_t>(lod[i + 1] - lod[i]);
    const float* din_ptr = din + lod[i] * width;
    const float* din_grad_ptr = din + i * width;
    float* dout_ptr = dout + lod[i] * width;
    if (width == 1) {
      for (int h = 0; h < height; ++h) {
          dout_ptr[h] = din_grad_ptr[h];
      }
    } else {
      for (int w = 0; w < width; w++) {
        for (int h = 0; h < height; h++) {
            dout_ptr[h] = *din_grad_ptr;
            dout_ptr += width;
        }
        din_grad_ptr++;
      }
    }
  }
}

template <>
void seq_pool_average<float>(const float* din,
                             const float* din_grad,
                             float* dout,
                             const std::vector<uint64_t> lod,
                             int64_t width) {
  for (int i = 0; i < static_cast<int>(lod.size()) - 1; ++i) {
    int64_t height = static_cast<int64_t>(lod[i + 1] - lod[i]);
    const float* din_ptr = din + lod[i] * width;
    const float* din_grad_ptr = din + i * width;
    float* dout_ptr = dout + lod[i] * width;
    float alpha = 1.0 / height;
    if (height > 0) {
      if (width == 1) {
        float sum = 0.f;
        for (int h = 0; h < height; ++h) {
          dout_ptr[h] = alpha * din_grad_ptr[h];
        }
      } else {
        for (int w = 0; w < width; w++) {
          for (int h = 0; h < height; h++) {
            dout_ptr[h] = alpha * din_grad_ptr[w];
            dout_ptr += width;
          }
        }
      }
    }
  }
}

template <>
void seq_pool_sqrt<float>(const float* din,
                          const float* din_grad,
                          float* dout,
                          const std::vector<uint64_t> lod,
                          int64_t width) {
  for (int i = 0; i < static_cast<int>(lod.size()) - 1; ++i) {
    int64_t height = static_cast<int64_t>(lod[i + 1] - lod[i]);
    const float* din_ptr = din + lod[i] * width;
    const float* din_grad_ptr = din + i * width;
    float* dout_ptr = dout + lod[i] * width;
    float alpha = 1.0 / sqrtf(height);
    if (height > 0) {
      if (width == 1) {
        float sum = 0.f;
        for (int h = 0; h < height; ++h) {
          dout_ptr[h] = alpha * din_grad_ptr[h];
        }
      } else {
        for (int w = 0; w < width; w++) {
          for (int h = 0; h < height; h++) {
            dout_ptr[h] = alpha * din_grad_ptr[w];
            dout_ptr += width;
          }
        }
      }
    }
  }
}

template <>
void seq_pool_first<float>(const float* din,
                           const float* din_grad,
                           float* dout,
                           const std::vector<uint64_t> lod,
                           int64_t width) {
  for (int i = 0; i < static_cast<int>(lod.size()) - 1; ++i) {
    int64_t height = lod[i + 1] - lod[i];
    const float* din_ptr = din + width * lod[i];
    const float* din_grad_ptr = din + i * width;
    float* dout_ptr = dout + lod[i] * width;
    if (height > 0) {
      for (int w = 0; w < width; w++) {
          dout_ptr[w] = din_grad_ptr[w];
      }
    }
  }
}

}  // namespace math
}  // namespace arm
}  // namespace lite
}  // namespace paddle