#pragma once

#include <boost/variant.hpp>
#include <initializer_list>
#include <stdexcept>
#include <vector>

#include "paddle/framework/dim.h"

namespace paddle {
namespace framework {

namespace {
typedef boost::variant<Dim<1>, Dim<2>, Dim<3>, Dim<4>, Dim<5>, Dim<6>, Dim<7>,
                       Dim<8>, Dim<9>>
    DDimVar;
}

/**
 * \brief A dynamically sized dimension.
 *
 * The number of dimensions must be between [1, 9].
 */
struct DDim {
  DDimVar var;

  DDim() : var(Dim<1>()) {}

  template <int D>
  explicit DDim(const Dim<D>& in) : var(in) {}

  template <int D>
  DDim& operator=(const Dim<D>& in) {
    var = in;
    return *this;
  }

  int& operator[](int idx);
  int operator[](int idx) const;

  template <typename Visitor>
  typename Visitor::result_type apply_visitor(Visitor& visitor) {
    return var.apply_visitor(visitor);
  }

  template <typename Visitor>
  typename Visitor::result_type apply_visitor(Visitor& visitor) const {
    return var.apply_visitor(visitor);
  }

  DDimVar getVar() { return var; }

  bool operator==(DDim d) const;

  bool operator!=(DDim d) const;

  DDim operator+(DDim d) const;

  DDim operator*(DDim d) const;
};

/**
 * \brief Make a DDim from std::vector<int>
 *
 * \param dims An vector of ints. Must be sized between [1, 9]
 */
DDim make_ddim(const std::vector<int>& dims);

/**
 * \brief Make a DDim from an initializer list
 *
 * \param dims An initializer list of ints. Must be sized between [1, 9]
 *
 */
DDim make_ddim(std::initializer_list<int> dims);

int get(const DDim& dim, int idx);
void set(DDim& dim, int idx, int val);

std::vector<int> vectorize(const DDim& ddim);

ssize_t product(const DDim& ddim);

/**
 * \brief Slice a ddim
 *
 * Slice dim with [begin, end).
 * e.g.  DDim d = make_ddim({1,2,3,4,5});
 *       slice_ddim(d, 1, 3); ====> {2,3}
 */
DDim slice_ddim(const DDim& dim, int begin, int end);

/**
 * \brief What is the length of this dimension?
 *
 * \param Dynamic dimension to inspect
 */

int arity(const DDim& ddim);

std::ostream& operator<<(std::ostream&, const DDim&);

}  // namespace framework
}  // namespace paddle

namespace boost {

template <typename T>
T get(const paddle::framework::DDim& in) {
  return boost::get<T>(in.var);
}

}  // namespace boost