// Copyright (c) 2019 Intel Corporation
//
// 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.

///////////////////////////////////////////////////////////////////////////////////////////////////
#pragma once

#include "primitive.hpp"
#include <vector>

namespace cldnn {
/// @addtogroup cpp_api C++ API
/// @{
/// @addtogroup cpp_topology Network Topology
/// @{
/// @addtogroup cpp_primitives Primitives
/// @{

/// @brief Broadcasts input to defined by @p broadcast_sizes output. @p broadcast_axes are used to
///        reinterpret input (reshape) inside algorithm.
///
/// @details Takes input, reinterpret it according to @p broadcast_axes
///          and copies it to output once or multiple times.
/// @n
/// @n Simple example with empty @p broadcast_axes. Lets assume that:
/// @n      <tt>input_sizes = (in_b, in_f, in_y, in_x)</tt>
/// @n      <tt>broadcast_sizes = (bs_b, bs_f, bs_y, bs_x)</tt>
/// @n      <tt>broadcast_axes = () - empty</tt>
/// @n The input is broadcasted on each dimension where <tt>bs_{dim} > in_{dim}</tt> and <tt>bs_{dim}</tt>
///    is dividable by <tt>in_{dim}</tt> (input is copied <tt>bs_{dim} / in_{dim}</tt> times).
///    The dimensions where <tt>bs_{dim}</tt> is equal to <tt>in_{dim}</tt> remain unchanged.
/// @n The resulting output will have sizes equal to @p broadcast_sizes and contains values from
///    input that meet following criteria:
/// @n      <tt>output[(b, f, y, x)] = input[(b % in_b, f % in_f, y % in_y, x % in_x)]</tt>
/// @n where <tt>(b, f, y, x)</tt> is a position of value in a primitive output.
/// @n
/// @n More complicated example with non empty @p broadcast_axes. Lets assume that:
/// @n      <tt>broadcast_sizes = (bs_b, bs_f, bs_y, bs_x)</tt>
/// @n      <tt>broadcast_axes = (2)</tt>
/// @n Taking into account broadcast_axes size (=1) primitive's input must be (4 - 1 = 3):
/// @n      <tt>primitive input = (1, in_b, in_f, in_x)</tt>
/// @n Due to broadcast_axes = (2) primitive will interpret input as:
/// @n      <tt>primitive input(internal representation) = (in_b, in_f, 1, in_x)</tt>
/// @n Now, you can apply broadcast rules from previous example to modified (reinterpreted)
///    input and output:
/// @n      <tt>input_sizes = (in_b, in_f, 1, in_x)</tt>
/// @n      <tt>output_shape = (bs_b, bs_f, bs_y, bs_x)</tt>
/// @n      <tt>broadcast_axes = () - empty</tt>
/// @n
/// @n@b Requirements:
/// @n - @p broadcast_sizes must be positive on all dimensions.
/// @n - @p broadcast_axes size (dimensions count) must be within (inclusive) range
///      0 - 4.
/// @n - @p broadcast_axes mustn't have duplicate values.
/// @n - Values of @p broadcast_axes must be within (inclusive) range 0 - 3
/// @n - @p output_shape must be greater (dividable) than or equal to reinterpreted
///      input on all dimensions.
/// @n Breaking any of these conditions will raise an exception.
struct broadcast : public primitive_base<broadcast> {
    CLDNN_DECLARE_PRIMITIVE(broadcast)

    /// @brief Constructs broadcast primitive / layer.
    ///
    /// @param id              An identifier of new primitive.
    /// @param input           An identifier of primitive which is an input for newly created
    ///                        broadcast primitive.
    /// @param broadcast_sizes Sizes of broadcast. Output size of current primitive
    ///                        will match broadcast sizes (layout type will not change).
    /// @param broadcast_axes  Axes positions (0-based, from left to right) in output_shape
    ///                        that are being broadcast. Values of broadcast_axes on remaining
    ///                        axes must be greater (dividable) or equal to corresponding input
    ///                        dimension values.
    /// @param output_padding  Optional padding for output from primitive.
    broadcast(const primitive_id& id,
              const primitive_id& input,
              const tensor& broadcast_sizes,
              const std::vector<uint16_t>& broadcast_axes = {},
              const padding& output_padding = padding())
        : primitive_base(id, {input}, output_padding),
          broadcast_sizes(broadcast_sizes),
          broadcast_axes(broadcast_axes) {}

    /// @brief Expected sizes of output from broadcast primitive.
    tensor broadcast_sizes;
    /// @brief Array of axes positions from output shape (0-based, from left to right)
    ///        along which broadcast should happen.
    std::vector<uint16_t> broadcast_axes;
};
/// @}
/// @}
/// @}
}  // namespace cldnn
