/* ******************************************************************************
 *
 *
 * 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
 ******************************************************************************/

//
// Created by raver119 on 29/10/17.
//

#include <system/op_boilerplate.h>
#if NOT_EXCLUDED(OP_flatten2d)

#include <ops/declarable/CustomOperations.h>

namespace sd {
namespace ops {

//////////////////////////////////////////////////////////////////////////
// here iArgs is a vector with (optional) negative of order as first element:
// ({-order, dim1, dim2, dim3, ...})
CUSTOM_OP_IMPL(flatten_2d, 1, 1, false, 0, -2) {
  auto x = INPUT_VARIABLE(0);
  auto z = OUTPUT_VARIABLE(0);

  // Special case: empty.reshape(<other empty shape>) -> return empty
  if (x->isEmpty()) {
    REQUIRE_TRUE(z->isEmpty(), 0, "Reshape: when input is empty, output must also be empty");
    return Status::OK;  // No op
  }

  REQUIRE_TRUE(x->lengthOf() == z->lengthOf(), 0,
               "Reshape: lengths before and after reshape should match, but got %i vs %i", x->lengthOf(),
               z->lengthOf());

  auto* zShapeVec = z->getShapeAsVector();
  if (Environment::getInstance().isDebugAndVerbose()) sd_printv("Reshape: new shape", *zShapeVec);

  auto xReshaped = x->reshape(z->ordering(), *zShapeVec);
  delete zShapeVec;
  z->assign(xReshaped);
  delete xReshaped;
  return Status::OK;
}

DECLARE_TYPES(flatten_2d) {
  getOpDescriptor()->setAllowedInputTypes(0, ANY)->setAllowedInputTypes(1, {ALL_INTS})->setSameMode(true);
}

DECLARE_SHAPE_FN(flatten_2d) {
  const auto x = INPUT_VARIABLE(0);
  const auto shape = x->shapeOf();
  auto axis = INT_ARG(0);
  if (axis < 0) {
    axis += x->rankOf();
  }
  std::vector<int> reshapeArgs;
  std::vector<LongType> shapeNew;
  auto firstDim = 1;
  auto lastDim = 1;
  for (int i = 0; i < axis; i++) {
    firstDim *= shape[i];
  }

  for (int i = axis; i < x->rankOf(); i++) {
    lastDim *= shape[i];
  }

  shapeNew.push_back(firstDim);
  shapeNew.push_back(lastDim);
  auto len = shape::prodLong(shapeNew.data(), shapeNew.size());
  REQUIRE_TRUE(x->lengthOf() == len, 0, "Reshape: lengths before and after reshape should match, but got %i vs %i",
               x->lengthOf(), len);

  return SHAPELIST(ConstantShapeHelper::getInstance().createShapeInfo(x->dataType(), x->ordering(), shapeNew));
}
}  // namespace ops
}  // namespace sd

#endif