// Copyright 2018 The MACE 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 <vector>

#include "mace/core/operator.h"
#include "mace/utils/math.h"

#ifdef MACE_ENABLE_OPENCL
#include "mace/ops/opencl/buffer/reshape.h"
#include "mace/ops/opencl/image/reshape.h"
#endif

namespace mace {
namespace ops {

namespace {

MaceStatus GetOutputShape(const Tensor *input,
                          const int32_t *shape_data,
                          const index_t num_dims,
                          std::vector<index_t> *out_shape) {
  MACE_CHECK(input != nullptr && shape_data != nullptr && out_shape != nullptr);
  int unknown_idx = -1;
  index_t product = 1;
  index_t n = 0;

  out_shape->resize(num_dims);
  for (int i = 0; i < num_dims; ++i) {
    if (shape_data[i] == -1) {
      MACE_CHECK(unknown_idx == -1, "Only one input size may be -1");
      unknown_idx = i;
      (*out_shape)[i] = 1;
    } else {
      MACE_CHECK(shape_data[i] >= 0, "Shape must be non-negative: ",
                 shape_data[i]);
      if (shape_data[i] == 0) {
        MACE_CHECK(i < input->dim_size(), "dims:0 out of input dims' range.");
        n = input->dim(i);
      } else {
        n = shape_data[i];
      }
      (*out_shape)[i] = n;
      product *= n;
    }
  }

  if (unknown_idx != -1) {
    MACE_CHECK(product != 0)
        << "Cannot infer shape if there is zero shape size.";
    const index_t missing = input->size() / product;
    MACE_CHECK(missing * product == input->size())
        << "Input size not match reshaped tensor size";
    (*out_shape)[unknown_idx] = missing;
  }

  return MaceStatus::MACE_SUCCESS;
}

}  // namespace

template <DeviceType D, class T>
class ReshapeOp : public Operation {
 public:
  explicit ReshapeOp(OpConstructContext *context)
      : Operation(context), dim_(Operation::GetRepeatedArgs<int>("dim")),
        has_df_(Operation::GetOptionalArg<int>("has_data_format", 0)) {}

  MaceStatus Run(OpContext *context) override {
    MACE_UNUSED(context);
    const Tensor *input = this->Input(INPUT);
    const Tensor *shape = this->Input(SHAPE);
    Tensor::MappingGuard shape_guard(shape);
    const int32_t *shape_data = shape->data<int32_t>();
    const index_t num_dims = shape->dim_size() == 0 ? 0 : shape->dim(0);
    std::vector<index_t> out_shape;

    // NHWC -> NCHW
    std::vector<int32_t> trans_shape_data(shape_data,
                                          shape_data + shape->size());
    if (has_df_ && D == DeviceType::CPU && shape->dim_size() == 4 &&
        out_shape.size() == 4 && dim_.size() == 4) {
      std::vector<int> dst_dims = {0, 3, 1, 2};
      std::vector<int32_t> tmp_shape =
          TransposeShape<int32_t , int32_t>(trans_shape_data, dst_dims);
      trans_shape_data = tmp_shape;
    }

    MACE_RETURN_IF_ERROR(
        GetOutputShape(input, trans_shape_data.data(), num_dims, &out_shape));

    Tensor *output = this->Output(OUTPUT);
    output->ReuseTensorBuffer(*input);
    output->Reshape(out_shape);

    return MaceStatus::MACE_SUCCESS;
  }

 private:
  std::vector<int> dim_;
  bool has_df_;

 private:
  MACE_OP_INPUT_TAGS(INPUT, SHAPE);
  MACE_OP_OUTPUT_TAGS(OUTPUT);
};

#ifdef MACE_ENABLE_OPENCL
template <>
class ReshapeOp<GPU, float> : public Operation {
 public:
  explicit ReshapeOp(OpConstructContext *context)
      : Operation(context), dim_(Operation::GetRepeatedArgs<int>("dim")) {
    if (context->GetOpMemoryType() == MemoryType::GPU_IMAGE) {
      kernel_ = make_unique<opencl::image::ReshapeKernel>(context);
    } else {
      kernel_ = make_unique<opencl::buffer::ReshapeKernel>();
    }
  }

  MaceStatus Run(OpContext *context) override {
    const Tensor *input = this->Input(INPUT);
    const int32_t *shape_data = dim_.data();
    const index_t num_dims = dim_.size();
    std::vector<index_t> out_shape;
    MACE_RETURN_IF_ERROR(
        GetOutputShape(input, shape_data, num_dims, &out_shape));

    Tensor *output = this->Output(OUTPUT);
    return kernel_->Compute(context, input, out_shape, output);
  }

 private:
  std::vector<int> dim_;
  std::unique_ptr<OpenCLReshapeKernel> kernel_;
  MACE_OP_INPUT_TAGS(INPUT, SHAPE);
  MACE_OP_OUTPUT_TAGS(OUTPUT);
};
#endif

void RegisterReshape(OpRegistryBase *op_registry) {
  MACE_REGISTER_OP(op_registry, "Reshape", ReshapeOp, DeviceType::CPU, float);
  MACE_REGISTER_OP(op_registry, "Reshape", ReshapeOp, DeviceType::CPU, int32_t);
  MACE_REGISTER_GPU_OP(op_registry, "Reshape", ReshapeOp);
  MACE_REGISTER_OP_CONDITION(
      op_registry, OpConditionBuilder("Reshape").SetDevicePlacerFunc(
                       [](OpConditionContext *context) -> std::set<DeviceType> {
                         auto op = context->operator_def();
                         if (op->output_shape_size() != op->output_size()) {
                           return {DeviceType::CPU, DeviceType::GPU};
                         }

                         auto tensor_shape_info = context->tensor_shape_info();
                         const std::string &input_0 = op->input(0);
                         const auto out_dims_size =
                             op->output_shape(0).dims_size();
                         if (4 == tensor_shape_info->at(input_0).size()
                             && (out_dims_size == 4 || out_dims_size == 2)) {
                           return {DeviceType::CPU, DeviceType::GPU};
                         }
                         return {DeviceType::CPU};
                       }));
}

}  // namespace ops
}  // namespace mace
