/**
 * MIT License
 *
 * Copyright (c) 2017 Thibaut Goetghebuer-Planchon <tessil@gmx.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#ifndef TSL_BHOPSCOTCH_SET_H
#define TSL_BHOPSCOTCH_SET_H

#include <algorithm>
#include <cstddef>
#include <functional>
#include <initializer_list>
#include <memory>
#include <set>
#include <type_traits>
#include <utility>

#include "hopscotch_hash.h"

namespace tsl {

/**
 * Similar to tsl::hopscotch_set but instead of using a list for overflowing
 * elements it uses a binary search tree. It thus needs an additional template
 * parameter Compare. Compare should be arithmetically coherent with KeyEqual.
 *
 * The binary search tree allows the set to have a worst-case scenario of O(log
 * n) for search and delete, even if the hash function maps all the elements to
 * the same bucket. For insert, the amortized worst case is O(log n), but the
 * worst case is O(n) in case of rehash.
 *
 * This makes the set resistant to DoS attacks (but doesn't preclude you to have
 * a good hash function, as an element in the bucket array is faster to retrieve
 * than in the tree).
 *
 * @copydoc hopscotch_set
 */
template <class Key, class Hash = std::hash<Key>,
          class KeyEqual = std::equal_to<Key>, class Compare = std::less<Key>,
          class Allocator = std::allocator<Key>,
          unsigned int NeighborhoodSize = 62, bool StoreHash = false,
          class GrowthPolicy = tsl::hh::power_of_two_growth_policy<2>>
class bhopscotch_set {
 private:
  template <typename U>
  using has_is_transparent = tsl::detail_hopscotch_hash::has_is_transparent<U>;

  class KeySelect {
   public:
    using key_type = Key;

    const key_type& operator()(const Key& key) const { return key; }

    key_type& operator()(Key& key) { return key; }
  };

  using overflow_container_type = std::set<Key, Compare, Allocator>;
  using ht = tsl::detail_hopscotch_hash::hopscotch_hash<
      Key, KeySelect, void, Hash, KeyEqual, Allocator, NeighborhoodSize,
      StoreHash, GrowthPolicy, overflow_container_type>;

 public:
  using key_type = typename ht::key_type;
  using value_type = typename ht::value_type;
  using size_type = typename ht::size_type;
  using difference_type = typename ht::difference_type;
  using hasher = typename ht::hasher;
  using key_equal = typename ht::key_equal;
  using key_compare = Compare;
  using allocator_type = typename ht::allocator_type;
  using reference = typename ht::reference;
  using const_reference = typename ht::const_reference;
  using pointer = typename ht::pointer;
  using const_pointer = typename ht::const_pointer;
  using iterator = typename ht::iterator;
  using const_iterator = typename ht::const_iterator;

  /*
   * Constructors
   */
  bhopscotch_set() : bhopscotch_set(ht::DEFAULT_INIT_BUCKETS_SIZE) {}

  explicit bhopscotch_set(size_type bucket_count, const Hash& hash = Hash(),
                          const KeyEqual& equal = KeyEqual(),
                          const Allocator& alloc = Allocator(),
                          const Compare& comp = Compare())
      : m_ht(bucket_count, hash, equal, alloc, ht::DEFAULT_MAX_LOAD_FACTOR,
             comp) {}

  bhopscotch_set(size_type bucket_count, const Allocator& alloc)
      : bhopscotch_set(bucket_count, Hash(), KeyEqual(), alloc) {}

  bhopscotch_set(size_type bucket_count, const Hash& hash,
                 const Allocator& alloc)
      : bhopscotch_set(bucket_count, hash, KeyEqual(), alloc) {}

  explicit bhopscotch_set(const Allocator& alloc)
      : bhopscotch_set(ht::DEFAULT_INIT_BUCKETS_SIZE, alloc) {}

  template <class InputIt>
  bhopscotch_set(InputIt first, InputIt last,
                 size_type bucket_count = ht::DEFAULT_INIT_BUCKETS_SIZE,
                 const Hash& hash = Hash(), const KeyEqual& equal = KeyEqual(),
                 const Allocator& alloc = Allocator())
      : bhopscotch_set(bucket_count, hash, equal, alloc) {
    insert(first, last);
  }

  template <class InputIt>
  bhopscotch_set(InputIt first, InputIt last, size_type bucket_count,
                 const Allocator& alloc)
      : bhopscotch_set(first, last, bucket_count, Hash(), KeyEqual(), alloc) {}

  template <class InputIt>
  bhopscotch_set(InputIt first, InputIt last, size_type bucket_count,
                 const Hash& hash, const Allocator& alloc)
      : bhopscotch_set(first, last, bucket_count, hash, KeyEqual(), alloc) {}

  bhopscotch_set(std::initializer_list<value_type> init,
                 size_type bucket_count = ht::DEFAULT_INIT_BUCKETS_SIZE,
                 const Hash& hash = Hash(), const KeyEqual& equal = KeyEqual(),
                 const Allocator& alloc = Allocator())
      : bhopscotch_set(init.begin(), init.end(), bucket_count, hash, equal,
                       alloc) {}

  bhopscotch_set(std::initializer_list<value_type> init, size_type bucket_count,
                 const Allocator& alloc)
      : bhopscotch_set(init.begin(), init.end(), bucket_count, Hash(),
                       KeyEqual(), alloc) {}

  bhopscotch_set(std::initializer_list<value_type> init, size_type bucket_count,
                 const Hash& hash, const Allocator& alloc)
      : bhopscotch_set(init.begin(), init.end(), bucket_count, hash, KeyEqual(),
                       alloc) {}

  bhopscotch_set& operator=(std::initializer_list<value_type> ilist) {
    m_ht.clear();

    m_ht.reserve(ilist.size());
    m_ht.insert(ilist.begin(), ilist.end());

    return *this;
  }

  allocator_type get_allocator() const { return m_ht.get_allocator(); }

  /*
   * Iterators
   */
  iterator begin() noexcept { return m_ht.begin(); }
  const_iterator begin() const noexcept { return m_ht.begin(); }
  const_iterator cbegin() const noexcept { return m_ht.cbegin(); }

  iterator end() noexcept { return m_ht.end(); }
  const_iterator end() const noexcept { return m_ht.end(); }
  const_iterator cend() const noexcept { return m_ht.cend(); }

  /*
   * Capacity
   */
  bool empty() const noexcept { return m_ht.empty(); }
  size_type size() const noexcept { return m_ht.size(); }
  size_type max_size() const noexcept { return m_ht.max_size(); }

  /*
   * Modifiers
   */
  void clear() noexcept { m_ht.clear(); }

  std::pair<iterator, bool> insert(const value_type& value) {
    return m_ht.insert(value);
  }
  std::pair<iterator, bool> insert(value_type&& value) {
    return m_ht.insert(std::move(value));
  }

  iterator insert(const_iterator hint, const value_type& value) {
    return m_ht.insert(hint, value);
  }
  iterator insert(const_iterator hint, value_type&& value) {
    return m_ht.insert(hint, std::move(value));
  }

  template <class InputIt>
  void insert(InputIt first, InputIt last) {
    m_ht.insert(first, last);
  }
  void insert(std::initializer_list<value_type> ilist) {
    m_ht.insert(ilist.begin(), ilist.end());
  }

  /**
   * Due to the way elements are stored, emplace will need to move or copy the
   * key-value once. The method is equivalent to
   * insert(value_type(std::forward<Args>(args)...));
   *
   * Mainly here for compatibility with the std::unordered_map interface.
   */
  template <class... Args>
  std::pair<iterator, bool> emplace(Args&&... args) {
    return m_ht.emplace(std::forward<Args>(args)...);
  }

  /**
   * Due to the way elements are stored, emplace_hint will need to move or copy
   * the key-value once. The method is equivalent to insert(hint,
   * value_type(std::forward<Args>(args)...));
   *
   * Mainly here for compatibility with the std::unordered_map interface.
   */
  template <class... Args>
  iterator emplace_hint(const_iterator hint, Args&&... args) {
    return m_ht.emplace_hint(hint, std::forward<Args>(args)...);
  }

  iterator erase(iterator pos) { return m_ht.erase(pos); }
  iterator erase(const_iterator pos) { return m_ht.erase(pos); }
  iterator erase(const_iterator first, const_iterator last) {
    return m_ht.erase(first, last);
  }
  size_type erase(const key_type& key) { return m_ht.erase(key); }

  /**
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup to the value if you already have the hash.
   */
  size_type erase(const key_type& key, std::size_t precalculated_hash) {
    return m_ht.erase(key, precalculated_hash);
  }

  /**
   * This overload only participates in the overload resolution if the typedef
   * KeyEqual::is_transparent and Compare::is_transparent exist. If so, K must
   * be hashable and comparable to Key.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  size_type erase(const K& key) {
    return m_ht.erase(key);
  }

  /**
   * @copydoc erase(const K& key)
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup to the value if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  size_type erase(const K& key, std::size_t precalculated_hash) {
    return m_ht.erase(key, precalculated_hash);
  }

  void swap(bhopscotch_set& other) { other.m_ht.swap(m_ht); }

  /*
   * Lookup
   */
  size_type count(const Key& key) const { return m_ht.count(key); }

  /**
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  size_type count(const Key& key, std::size_t precalculated_hash) const {
    return m_ht.count(key, precalculated_hash);
  }

  /**
   * This overload only participates in the overload resolution if the typedef
   * KeyEqual::is_transparent and Compare::is_transparent exist. If so, K must
   * be hashable and comparable to Key.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  size_type count(const K& key) const {
    return m_ht.count(key);
  }

  /**
   * @copydoc count(const K& key) const
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  size_type count(const K& key, std::size_t precalculated_hash) const {
    return m_ht.count(key, precalculated_hash);
  }

  iterator find(const Key& key) { return m_ht.find(key); }

  /**
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  iterator find(const Key& key, std::size_t precalculated_hash) {
    return m_ht.find(key, precalculated_hash);
  }

  const_iterator find(const Key& key) const { return m_ht.find(key); }

  /**
   * @copydoc find(const Key& key, std::size_t precalculated_hash)
   */
  const_iterator find(const Key& key, std::size_t precalculated_hash) const {
    return m_ht.find(key, precalculated_hash);
  }

  /**
   * This overload only participates in the overload resolution if the typedef
   * KeyEqual::is_transparent and Compare::is_transparent exist. If so, K must
   * be hashable and comparable to Key.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  iterator find(const K& key) {
    return m_ht.find(key);
  }

  /**
   * @copydoc find(const K& key)
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  iterator find(const K& key, std::size_t precalculated_hash) {
    return m_ht.find(key, precalculated_hash);
  }

  /**
   * @copydoc find(const K& key)
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  const_iterator find(const K& key) const {
    return m_ht.find(key);
  }

  /**
   * @copydoc find(const K& key)
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  const_iterator find(const K& key, std::size_t precalculated_hash) const {
    return m_ht.find(key, precalculated_hash);
  }

  bool contains(const Key& key) const { return m_ht.contains(key); }

  /**
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  bool contains(const Key& key, std::size_t precalculated_hash) const {
    return m_ht.contains(key, precalculated_hash);
  }

  /**
   * This overload only participates in the overload resolution if the typedef
   * KeyEqual::is_transparent exists. If so, K must be hashable and comparable
   * to Key.
   */
  template <
      class K, class KE = KeyEqual,
      typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
  bool contains(const K& key) const {
    return m_ht.contains(key);
  }

  /**
   * @copydoc contains(const K& key) const
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual,
      typename std::enable_if<has_is_transparent<KE>::value>::type* = nullptr>
  bool contains(const K& key, std::size_t precalculated_hash) const {
    return m_ht.contains(key, precalculated_hash);
  }

  std::pair<iterator, iterator> equal_range(const Key& key) {
    return m_ht.equal_range(key);
  }

  /**
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  std::pair<iterator, iterator> equal_range(const Key& key,
                                            std::size_t precalculated_hash) {
    return m_ht.equal_range(key, precalculated_hash);
  }

  std::pair<const_iterator, const_iterator> equal_range(const Key& key) const {
    return m_ht.equal_range(key);
  }

  /**
   * @copydoc equal_range(const Key& key, std::size_t precalculated_hash)
   */
  std::pair<const_iterator, const_iterator> equal_range(
      const Key& key, std::size_t precalculated_hash) const {
    return m_ht.equal_range(key, precalculated_hash);
  }

  /**
   * This overload only participates in the overload resolution if the typedef
   * KeyEqual::is_transparent and Compare::is_transparent exist. If so, K must
   * be hashable and comparable to Key.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  std::pair<iterator, iterator> equal_range(const K& key) {
    return m_ht.equal_range(key);
  }

  /**
   * @copydoc equal_range(const K& key)
   *
   * Use the hash value 'precalculated_hash' instead of hashing the key. The
   * hash value should be the same as hash_function()(key). Useful to speed-up
   * the lookup if you already have the hash.
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  std::pair<iterator, iterator> equal_range(const K& key,
                                            std::size_t precalculated_hash) {
    return m_ht.equal_range(key, precalculated_hash);
  }

  /**
   * @copydoc equal_range(const K& key)
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  std::pair<const_iterator, const_iterator> equal_range(const K& key) const {
    return m_ht.equal_range(key);
  }

  /**
   * @copydoc equal_range(const K& key, std::size_t precalculated_hash)
   */
  template <
      class K, class KE = KeyEqual, class CP = Compare,
      typename std::enable_if<has_is_transparent<KE>::value &&
                              has_is_transparent<CP>::value>::type* = nullptr>
  std::pair<const_iterator, const_iterator> equal_range(
      const K& key, std::size_t precalculated_hash) const {
    return m_ht.equal_range(key, precalculated_hash);
  }

  /*
   * Bucket interface
   */
  size_type bucket_count() const { return m_ht.bucket_count(); }
  size_type max_bucket_count() const { return m_ht.max_bucket_count(); }

  /*
   *  Hash policy
   */
  float load_factor() const { return m_ht.load_factor(); }
  float max_load_factor() const { return m_ht.max_load_factor(); }
  void max_load_factor(float ml) { m_ht.max_load_factor(ml); }

  void rehash(size_type count_) { m_ht.rehash(count_); }
  void reserve(size_type count_) { m_ht.reserve(count_); }

  /*
   * Observers
   */
  hasher hash_function() const { return m_ht.hash_function(); }
  key_equal key_eq() const { return m_ht.key_eq(); }
  key_compare key_comp() const { return m_ht.key_comp(); }

  /*
   * Other
   */

  /**
   * Convert a const_iterator to an iterator.
   */
  iterator mutable_iterator(const_iterator pos) {
    return m_ht.mutable_iterator(pos);
  }

  size_type overflow_size() const noexcept { return m_ht.overflow_size(); }

  friend bool operator==(const bhopscotch_set& lhs, const bhopscotch_set& rhs) {
    if (lhs.size() != rhs.size()) {
      return false;
    }

    for (const auto& element_lhs : lhs) {
      const auto it_element_rhs = rhs.find(element_lhs);
      if (it_element_rhs == rhs.cend()) {
        return false;
      }
    }

    return true;
  }

  friend bool operator!=(const bhopscotch_set& lhs, const bhopscotch_set& rhs) {
    return !operator==(lhs, rhs);
  }

  friend void swap(bhopscotch_set& lhs, bhopscotch_set& rhs) { lhs.swap(rhs); }

 private:
  ht m_ht;
};

/**
 * Same as `tsl::bhopscotch_set<Key, Hash, KeyEqual, Compare, Allocator,
 * NeighborhoodSize, StoreHash, tsl::hh::prime_growth_policy>`.
 */
template <class Key, class Hash = std::hash<Key>,
          class KeyEqual = std::equal_to<Key>, class Compare = std::less<Key>,
          class Allocator = std::allocator<Key>,
          unsigned int NeighborhoodSize = 62, bool StoreHash = false>
using bhopscotch_pg_set =
    bhopscotch_set<Key, Hash, KeyEqual, Compare, Allocator, NeighborhoodSize,
                   StoreHash, tsl::hh::prime_growth_policy>;

}  // end namespace tsl

#endif
