/*
  Copyright (C) 2018 David Robillard <d@drobilla.net>
  Copyright (C) 2006-2007 Chris Hamilton <chamilton@cs.dal.ca>

  This program is free software: you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation, either version 2 of the License, or (at your option) any later
  version.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  details.

  You should have received a copy of the GNU General Public License along with
  this program.  If not, see <https://www.gnu.org/licenses/>.
*/

#ifndef CHILBERT_BOUNDEDBITVEC_HPP
#define CHILBERT_BOUNDEDBITVEC_HPP

#include "chilbert/detail/BitVecIndex.hpp"
#include "chilbert/detail/BitVecIterator.hpp"
#include "chilbert/detail/BitVecMask.hpp"
#include "chilbert/detail/MultiBitVec.hpp"
#include "chilbert/detail/operations.hpp"

#include <algorithm>
#include <array>
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <cstring>

namespace chilbert {

/** A statically allocated bit vector with a dynamic size.
 *
 * This can be used to have bit vectors of an arbitrary dynamic size, under
 * some static bound, without using dynamic allocation.
 *
 * @tparam MaxN Maximum number of bits.
 */
template<size_t MaxN>
class BoundedBitVec : public detail::MultiBitVec<BoundedBitVec<MaxN>>
{
public:
  using Rack = typename detail::MultiBitVec<BoundedBitVec<MaxN>>::Rack;

  using detail::MultiBitVec<BoundedBitVec<MaxN>>::bits_per_rack;

  BoundedBitVec() = default;

  explicit BoundedBitVec(const size_t bits)
    : m_size{bits}
  {
    assert(bits <= MaxN);
  }

  BoundedBitVec(const size_t bits, const Rack value)
    : BoundedBitVec{bits}
  {
    m_racks[0] = value;
  }

  /// Return the size in bits
  size_t size() const { return m_size; }

  /// Return a reference to the `index`th rack
#ifndef NDEBUG
  const auto& rack(const size_t index) const
  {
    return m_racks.at(index);
  }
  auto& rack(const size_t index)
  {
    return m_racks.at(index);
  }
#else
  const auto& rack(const size_t index) const
  {
    return m_racks[index];
  }
  auto& rack(const size_t index)
  {
    return m_racks[index];
  }
#endif

  /// Return a raw pointer to the racks
  Rack* data()
  {
    return m_racks.data();
  }
  const Rack* data() const
  {
    return m_racks.data();
  }

  /// Return the total size of all racks in bytes
  size_t data_size() const
  {
    return num_racks() * sizeof(Rack);
  }

  /// Return the number of racks
  size_t num_racks() const
  {
    return calculate_num_racks(m_size);
  }

private:
  static constexpr size_t calculate_num_racks(const size_t bits)
  {
    return (std::max(bits, size_t{1}) + bits_per_rack - 1U) / bits_per_rack;
  }

  std::array<Rack, calculate_num_racks(MaxN)> m_racks{};
  size_t                                      m_size{};
};

namespace detail {

template<size_t MaxN>
struct is_bitvec<BoundedBitVec<MaxN>> {
  constexpr static bool value = true;
};

template<size_t MaxN>
void
gray_code(BoundedBitVec<MaxN>& value)
{
  gray_code(static_cast<detail::MultiBitVec<BoundedBitVec<MaxN>>&>(value));
}

template<size_t MaxN>
void
gray_code_inv(BoundedBitVec<MaxN>& value)
{
  gray_code_inv(static_cast<detail::MultiBitVec<BoundedBitVec<MaxN>>&>(value));
}

} // namespace detail

} // namespace chilbert

#endif