/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

/*!
 * \brief Dilate op constructions
 * \file nn/dilate.h
 */
#ifndef TVM_TOPI_NN_DILATE_H_
#define TVM_TOPI_NN_DILATE_H_

#include <tvm/arith/analyzer.h>
#include <tvm/te/operation.h>
#include <tvm/topi/tags.h>

#include <string>

namespace tvm {
namespace topi {
namespace nn {

using namespace tvm::te;

/*!
 * \brief Create a new expression of the logical and of all
 * conditions in the arguments.
 *
 * \param args The arguments to find the logical conjunction of
 *
 * \return The logical conjunction expression
 */
PrimExpr all(Array<PrimExpr> args) {
  ICHECK_GT(args.size(), 0) << "all requires at least one argument";

  PrimExpr ret = args[0];
  for (size_t i = 1; i < args.size(); ++i) {
    ret = ret && args[i];
  }
  return ret;
}

/*!
 * \brief Dilate data with given dilation value (0 by default).
 *
 * \param x The input tensor, this can have any number of
 * dimensions and any layout.
 * \param strides Dilation stride for each dimension. Stride 1
 * means no dilation.
 * \param dilation_value Value used to dilate the input.
 * \param name The name of the operation
 * \param tag The tag to mark the operation
 *
 * \return The output tensor.
 */
inline Tensor dilate(const Tensor& x, Array<PrimExpr> strides, double dilation_value,
                     std::string name = "tensor", std::string tag = kInjective) {
  auto n = x->shape.size();
  ICHECK_EQ(n, strides.size()) << "strides size (" << strides.size()
                               << ") must match dimension of x (" << n << ")";

  Array<PrimExpr> out_shape;
  arith::Analyzer analyzer;
  for (size_t i = 0; i < n; ++i) {
    out_shape.push_back(analyzer.Simplify((x->shape[i] - 1) * (strides[i] + 1)));
  }

  return tvm::te::compute(
      out_shape,
      [&](const Array<Var>& indices) {
        Array<PrimExpr> not_zero;
        Array<PrimExpr> index_tuple;
        for (size_t i = 0; i < n; ++i) {
          if (IsConstInt(strides[i]) && GetConstInt(strides[i]) == 1) {
            index_tuple.push_back(indices[i]);
          } else {
            index_tuple.push_back(indexdiv(indices[i], strides[i]));
            not_zero.push_back((indexmod(indices[i], strides[i])) == 0);
          }
        }
        if (not_zero.size() > 0) {
          auto all_not_zero = all(not_zero);
          return tvm::if_then_else(all_not_zero, x(index_tuple),
                                   make_const(x->dtype, dilation_value));
        }
        return x(index_tuple);
      },
      name, tag);
}

}  // namespace nn
}  // namespace topi
}  // namespace tvm
#endif  // TVM_TOPI_NN_DILATE_H_