/*
 * Frozen
 * Copyright 2016 QuarksLab
 *
 * 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.
 */

#ifndef FROZEN_SET_H
#define FROZEN_SET_H

#include "frozen/bits/algorithms.h"
#include "frozen/bits/basic_types.h"
#include "frozen/bits/constexpr_assert.h"
#include "frozen/bits/version.h"
#include "frozen/bits/defines.h"

#include <iterator>
#include <utility>

namespace frozen {

template <class Key, std::size_t N, class Compare = std::less<Key>> class set : private Compare {
  using container_type = bits::carray<Key, N>;
  container_type keys_;

public:
  /* container typedefs*/
  using key_type = Key;
  using value_type = Key;
  using size_type = typename container_type::size_type;
  using difference_type = typename container_type::size_type;
  using key_compare = Compare;
  using value_compare = Compare;
  using reference = typename container_type::const_reference;
  using const_reference = reference;
  using pointer = typename container_type::const_pointer;
  using const_pointer = pointer;
  using iterator = typename container_type::const_iterator;
  using reverse_iterator = std::reverse_iterator<iterator>;
  using const_iterator = iterator;
  using const_reverse_iterator = std::reverse_iterator<const_iterator>;

public:
  /* constructors */
  constexpr set(const set &other) = default;

  constexpr set(container_type keys, Compare const & comp)
      : Compare{comp}
      , keys_(bits::quicksort(keys, value_comp())) {
      }

  explicit constexpr set(container_type keys)
      : set{keys, Compare{}} {}

  constexpr set(std::initializer_list<Key> keys, Compare const & comp)
      : set{container_type{keys}, comp} {
        constexpr_assert(keys.size() == N, "Inconsistent initializer_list size and type size argument");
      }

  constexpr set(std::initializer_list<Key> keys)
      : set{keys, Compare{}} {}

  constexpr set& operator=(const set &other) = default;

  /* capacity */
  constexpr bool empty() const { return !N; }
  constexpr size_type size() const { return N; }
  constexpr size_type max_size() const { return N; }

  /* lookup */
  template <class KeyType>
  constexpr std::size_t count(KeyType const &key) const {
    return bits::binary_search<N>(keys_.begin(), key, value_comp());
  }

  template <class KeyType>
  constexpr const_iterator find(KeyType const &key) const {
    const_iterator where = lower_bound(key);
    if ((where != end()) && !value_comp()(key, *where))
      return where;
    else
      return end();
  }
  
  template <class KeyType>
  constexpr bool contains(KeyType const &key) const {
    return this->find(key) != keys_.end();
  }

  template <class KeyType>
  constexpr std::pair<const_iterator, const_iterator> equal_range(KeyType const &key) const {
    auto const lower = lower_bound(key);
    if (lower == end())
      return {lower, lower};
    else
      return {lower, lower + 1};
  }

  template <class KeyType>
  constexpr const_iterator lower_bound(KeyType const &key) const {
    auto const where = bits::lower_bound<N>(keys_.begin(), key, value_comp());
    if ((where != end()) && !value_comp()(key, *where))
      return where;
    else
      return end();
  }

  template <class KeyType>
  constexpr const_iterator upper_bound(KeyType const &key) const {
    auto const where = bits::lower_bound<N>(keys_.begin(), key, value_comp());
    if ((where != end()) && !value_comp()(key, *where))
      return where + 1;
    else
      return end();
  }

  /* observers */
  constexpr const key_compare& key_comp() const { return value_comp(); }
  constexpr const key_compare& value_comp() const { return static_cast<const Compare&>(*this); }

  /* iterators */
  constexpr const_iterator begin() const { return keys_.begin(); }
  constexpr const_iterator cbegin() const { return keys_.begin(); }
  constexpr const_iterator end() const { return keys_.end(); }
  constexpr const_iterator cend() const { return keys_.end(); }

  constexpr const_reverse_iterator rbegin() const { return const_reverse_iterator{keys_.end()}; }
  constexpr const_reverse_iterator crbegin() const { return const_reverse_iterator{keys_.end()}; }
  constexpr const_reverse_iterator rend() const { return const_reverse_iterator{keys_.begin()}; }
  constexpr const_reverse_iterator crend() const { return const_reverse_iterator{keys_.begin()}; }

  /* comparison */
  constexpr bool operator==(set const& rhs) const { return bits::equal(begin(), end(), rhs.begin()); }
  constexpr bool operator!=(set const& rhs) const { return !(*this == rhs); }
  constexpr bool operator<(set const& rhs) const { return bits::lexicographical_compare(begin(), end(), rhs.begin(), rhs.end()); }
  constexpr bool operator<=(set const& rhs) const { return (*this < rhs) || (*this == rhs); }
  constexpr bool operator>(set const& rhs) const { return bits::lexicographical_compare(rhs.begin(), rhs.end(), begin(), end()); }
  constexpr bool operator>=(set const& rhs) const { return (*this > rhs) || (*this == rhs); }
};

template <class Key, class Compare> class set<Key, 0, Compare> : private Compare {
  using container_type = bits::carray<Key, 0>; // just for the type definitions

public:
  /* container typedefs*/
  using key_type = Key;
  using value_type = Key;
  using size_type = typename container_type::size_type;
  using difference_type = typename container_type::size_type;
  using key_compare = Compare;
  using value_compare = Compare;
  using reference = typename container_type::const_reference;
  using const_reference = reference;
  using pointer = typename container_type::const_pointer;
  using const_pointer = pointer;
  using iterator = pointer;
  using reverse_iterator = pointer;
  using const_iterator = const_pointer;
  using const_reverse_iterator = const_pointer;

public:
  /* constructors */
  constexpr set(const set &other) = default;
  constexpr set(bits::carray<Key, 0>, Compare const &) {}
  explicit constexpr set(bits::carray<Key, 0>) {}

  constexpr set(std::initializer_list<Key>, Compare const &comp)
      : Compare{comp} {}
  constexpr set(std::initializer_list<Key> keys) : set{keys, Compare{}} {}

  constexpr set& operator=(const set &other) = default;

  /* capacity */
  constexpr bool empty() const { return true; }
  constexpr size_type size() const { return 0; }
  constexpr size_type max_size() const { return 0; }

  /* lookup */
  template <class KeyType>
  constexpr std::size_t count(KeyType const &) const { return 0; }

  template <class KeyType>
  constexpr const_iterator find(KeyType const &) const { return end(); }

  template <class KeyType>
  constexpr std::pair<const_iterator, const_iterator>
  equal_range(KeyType const &) const { return {end(), end()}; }

  template <class KeyType>
  constexpr const_iterator lower_bound(KeyType const &) const { return end(); }

  template <class KeyType>
  constexpr const_iterator upper_bound(KeyType const &) const { return end(); }

  /* observers */
  constexpr const key_compare& key_comp() const { return value_comp(); }
  constexpr const key_compare& value_comp() const { return static_cast<Compare const&>(*this); }

  /* iterators */
  constexpr const_iterator begin() const { return nullptr; }
  constexpr const_iterator cbegin() const { return nullptr; }
  constexpr const_iterator end() const { return nullptr; }
  constexpr const_iterator cend() const { return nullptr; }

  constexpr const_reverse_iterator rbegin() const { return nullptr; }
  constexpr const_reverse_iterator crbegin() const { return nullptr; }
  constexpr const_reverse_iterator rend() const { return nullptr; }
  constexpr const_reverse_iterator crend() const { return nullptr; }
};

template <typename T>
constexpr auto make_set(bits::ignored_arg = {}/* for consistency with the initializer below for N = 0*/) {
  return set<T, 0>{};
}

template <typename T, std::size_t N>
constexpr auto make_set(const T (&args)[N]) {
  return set<T, N>(args);
}

template <typename T, std::size_t N>
constexpr auto make_set(std::array<T, N> const &args) {
  return set<T, N>(args);
}

template <typename T, typename Compare, std::size_t N>
constexpr auto make_set(const T (&args)[N], Compare const& compare = Compare{}) {
  return set<T, N, Compare>(args, compare);
}

template <typename T, typename Compare, std::size_t N>
constexpr auto make_set(std::array<T, N> const &args, Compare const& compare = Compare{}) {
  return set<T, N, Compare>(args, compare);
}

#ifdef FROZEN_LETITGO_HAS_DEDUCTION_GUIDES

template<class T, class... Args>
set(T, Args...) -> set<T, sizeof...(Args) + 1>;

#endif // FROZEN_LETITGO_HAS_DEDUCTION_GUIDES

} // namespace frozen

#endif