// commenting everything out when I commit so all commits my code technically
// compiles
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <initializer_list>
#include <stdexcept>
#include <utility>
#include <vector>

// everything is super interconnected so some forward declarations are needed at
// various points
namespace cs440 {

template <typename Key_T, typename Mapped_T> class Map;

namespace {
enum class Color { Red, Black };
enum class Direction { Left, Right };
Direction operator!(Direction dir) {
  switch (dir) {
  case Direction::Left:
    return Direction::Right;
  case Direction::Right:
    return Direction::Left;
  default:
    // unreachable the only directions are left and right
    assert(false);
  }
}
template <typename Key_T, typename Mapped_T> struct BookKeeping {
  using Self = BookKeeping<Key_T, Mapped_T>;
  using ValueType = std::pair<Key_T, Mapped_T>;
  using Ptr = typename std::vector<Self>::iterator;
  friend class Map<Key_T, Mapped_T>;
  Map<Key_T, Mapped_T> &container;
  ValueType value;
  Ptr self;
  Color color;
  // nullptr indicates empty
  Self *parent;
  Self *left;
  Self *right;
  Self *prev;
  Self *next;
  BookKeeping(Map<Key_T, Mapped_T> &container) : container{container} {}
  BookKeeping(BookKeeping const &rhs)
      : container{rhs.container}, value{rhs.value}, self{rhs.self},
        color{rhs.color}, parent{rhs.parent}, left{rhs.left}, right{rhs.right},
        prev{rhs.prev}, next{rhs.next} {}
  // if pointing to different containers throws
  BookKeeping &operator=(BookKeeping const &rhs) {
    if (&this->container != &rhs.container) {
      throw std::invalid_argument{"can only reassign Bookkeeping "
                                  "values/iterators from the same map object"};
    }
    this->value = rhs.value;
    this->self = rhs.self;
    this->color = rhs.color;
    this->parent = rhs.parent;
    this->left = rhs.left;
    this->right = rhs.right;
    this->prev = rhs.prev;
    this->next = rhs.next;
    return *this;
  }
  // reference to a pointer because the alternatives were worse
  inline Self *&child(Direction dir) {
    switch (dir) {
    case Direction::Left:
      return left;
      break;
    case Direction::Right:
      return right;
      break;
    default:
      assert(false);
    }
  }
  // this is root/P for this method
  // copying from wikipedia RotateDirRoot with translation into my own idioms
  // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Operations
  inline void rotate(Direction dir) {
    // wikipedia version uses alphabet soup, might fix later
    Self *P = this;
    auto &T = container;
    Self *G = P->parent;
    Self *S = P->child(!dir);
    Self *C;

    // this method shouldn't be called in cases where this assert will trip
    assert(S != nullptr);

    //
    C = S->child(dir);
    P->child(!dir) = C;

    if (C != nullptr) {
      C->parent = P;
    }
    S->child(dir) = P;
    P->parent = S;
    S->parent = G;
    if (G != nullptr) {
      if (P == G->right) {
        G->right = S;
      } else {
        G->left = S;
      }
    } else {
      T.root = S;
    }
  }
};
} // namespace
// https://en.wikipedia.org/wiki/Red%E2%80%93black_tree
template <typename Key_T, typename Mapped_T> class Map {
private:
  using ValueType = std::pair<Key_T, Mapped_T>;
  using Node = BookKeeping<Key_T, Mapped_T>;
  using Map_T = Map<Key_T, Mapped_T>;

public:
  class Iterator;
  class ConstIterator;
  class ReverseIterator;

  friend class Iterator;
  friend class ConstIterator;
  friend class ReverseIterator;
  friend Node;
  class Iterator {
    friend Map_T;
    friend Node;

  private:
    // pointer needed so we can replace as needed
    Node *ref;
    Node *escape;
    Iterator(Node *ref, Node *escape = nullptr) : ref{ref}, escape{escape} {}

  public:
    Iterator() = delete;
    Iterator &operator++() {
      if (ref == nullptr) {
        ref = escape;
        return *this;
      }
      if (ref->next == nullptr) {
        escape = ref;
      }
      ref = ref->next;
      return *this;
    }
    Iterator operator++(int) {
      Iterator tmp = *this;
      ++(*this);
      return tmp;
    }
    Iterator &operator--() {
      if (ref == nullptr) {
        ref = escape;
        return *this;
      }
      if (ref->prev == nullptr) {
        escape = ref;
      }
      ref = ref->prev;
      return *this;
    }
    Iterator operator--(int) {
      Iterator tmp = *this;
      --(*this);
      return tmp;
    }
    ValueType &operator*() const { return this->ref->value; }
    ValueType *operator->() const { return &this->ref->value; }
    friend bool operator==(Iterator const &lhs, Iterator const &rhs) {
      return lhs.ref == rhs.ref;
    }
    friend bool operator!=(Iterator const &lhs, Iterator const &rhs) {
      return lhs.ref != rhs.ref;
    }
    friend bool operator==(ConstIterator const &lhs, Iterator const &rhs) {
      return lhs.store_iter.ref == rhs.ref;
    }
    friend bool operator!=(ConstIterator const &lhs, Iterator const &rhs) {
      return lhs.store_iter.ref != rhs.ref;
    }
    friend bool operator==(Iterator const &lhs, ConstIterator const &rhs) {
      return lhs.ref == rhs.store_iter.ref;
    }
    friend bool operator!=(Iterator const &lhs, ConstIterator const &rhs) {
      return lhs.ref != rhs.store_iter.ref;
    }
  };
  class ConstIterator {
  public:
    friend class Map<Key_T, Mapped_T>;
    friend class Iterator;
    using underlying = Iterator;

  private:
    underlying store_iter;
    ConstIterator(underlying iter) : store_iter{iter} {}

  public:
    ConstIterator() = delete;
    friend bool operator==(ConstIterator const &lhs, ConstIterator const &rhs) {
      return lhs.store_iter == rhs.store_iter;
    }
    ConstIterator &operator++() {
      ++this->store_iter;
      return *this;
    }
    ConstIterator operator++(int) {
      ConstIterator tmp = *this;
      this->store_iter++;
      return tmp;
    }
    ConstIterator &operator--() {
      --this->store_iter;
      return *this;
    }
    ConstIterator operator--(int) {
      ConstIterator tmp = *this;
      this->store_iter--;
      return tmp;
    }
    const ValueType &operator*() const { return *this->store_iter; }
    const ValueType *operator->() const {
      return this->store_iter.operator->();
    }
    friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
      return lhs.store_iter != rhs.store_iter;
    }
  };
  class ReverseIterator {
  public:
    friend class Map<Key_T, Mapped_T>;
    friend class Iterator;
    using underlying = Iterator;

  private:
    underlying store_iter;

  public:
    ReverseIterator() = delete;
    ReverseIterator(underlying store_iter) : store_iter{store_iter} {}
    ReverseIterator &operator++() {
      --store_iter;
      return *this;
    }
    ReverseIterator operator++(int) {
      ReverseIterator ret = *this;
      ++(*this);
      return ret;
    }
    ReverseIterator &operator--() {
      ++store_iter;
      return *this;
    }
    ReverseIterator operator--(int) {
      ReverseIterator ret = *this;
      --(*this);
      return ret;
    }
    ValueType &operator*() const { return this->store_iter.ref->value; }
    ValueType *operator->() const { return &this->store_iter.ref->value; }
    friend bool operator==(ReverseIterator const &lhs,
                           ReverseIterator const &rhs) {
      return lhs.store_iter == rhs.store_iter;
    }
    friend bool operator!=(ConstIterator const &lhs, ConstIterator const &rhs) {
      return lhs.store_iter != rhs.store_iter;
    }
  };

private:
  Node *root;
  Node *min;
  Node *max;
  std::vector<Node> nodes;

public:
  Map() : root{nullptr}, min{nullptr}, max{nullptr}, nodes{} {}
  Map(const Map &rhs)
      : root{rhs.root}, min{nullptr}, max{nullptr}, nodes{rhs.nodes} {}
  Map &operator=(const Map &rhs) {
    this->root = rhs.root;
    this->min = rhs.min;
    this->max = rhs.max;
    this->nodes = rhs.nodes;
  }
  Map(std::initializer_list<ValueType> elems) : root{nullptr}, nodes{} {
    this->insert(elems.begin(), elems.end());
  }

  ~Map() {}

  size_t size() const {
    root = nullptr;
    return this->nodes.size();
  }
  bool empty() const { return this->size() == 0; }
  Iterator begin() { return Iterator{min}; }
  Iterator end() { return Iterator{nullptr, max}; }
  ConstIterator begin() const { return ConstIterator{this->begin()}; }
  ConstIterator end() const { return ConstIterator{this->end()}; }
  ConstIterator cbegin() const { return this->begin(); }
  ConstIterator cend() const { return this->end(); }
  ReverseIterator rbegin() { return ReverseIterator{Iterator{this->max}}; }
  ReverseIterator rend() { return ReverseIterator{Iterator{nullptr, min}}; }
  Iterator find(const Key_T &key) {
    // we need a locate slot function for insert regardless so might as well use
    // it here
    auto [parent, dir] = this->locate_slot(key);
    if (parent == nullptr) {
      if (this->root->value.first == key) {
        return Iterator{root};
      } else {
        return this->end();
      }
    }
    if (parent->child(dir) == nullptr) {
      return this->end();
    }
    return Iterator{parent->child(dir)};
  }
  // implicit cast to ConstIterator from Iterator
  ConstIterator find(const Key_T &key) const { return this->find(key); }

  Mapped_T &at(const Key_T &key) { return (this->find(key))->second; }
  const Mapped_T &at(const Key_T &key) const { return this->at(key); }
  Mapped_T &operator[](const Key_T &key) { return this->at(key); }

private:
  void handle_root_rotation(Node *grandparent, Node *parent, Node *inserting,
                            Direction dir) {
    // making inner grandchild into outer grandchild
    if (inserting == parent->child(!dir)) {
      parent->rotate(dir);
      inserting = parent;
      parent = grandparent->child(dir);
    }
    // RotateDirRoot(T,G,1-dir);
    Node *gr_grandparent = grandparent->parent;
    Node *sibling = grandparent->child(!dir);
    assert(sibling != nullptr);
    Node *child = sibling->child(dir);
    grandparent->child(!dir) = child;
    sibling->child(dir) = grandparent;
    grandparent->parent = sibling;
    sibling->parent = gr_grandparent;
    if (gr_grandparent != nullptr) {
      Direction grandparent_direction;
      if (gr_grandparent->left == grandparent) {
        grandparent_direction = Direction::Left;
      } else {
        grandparent_direction = Direction::Right;
      }
      gr_grandparent->child(grandparent_direction) = sibling;
    } else {
      this->root = sibling;
    }

    parent->color = Color::Black;
    grandparent->color = Color::Red;
  }
  // heavily referencing the wikipedia implementation for this
  // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Insertion
  void insert_helper(Node *to_insert, Node *parent, Direction dir) {
    // initialize the element we're inserting
    to_insert->color = Color::Red;
    to_insert->left = nullptr;
    to_insert->right = nullptr;
    to_insert->parent = parent;
    switch (dir) {
    case Direction::Left:
      to_insert->next = parent;
      to_insert->prev = parent->prev;
      parent->prev = to_insert;
      break;
    case Direction::Right:
      to_insert->prev = parent;
      to_insert->next = parent->next;
      parent->next = to_insert;
      break;
    }

    // if this is the first element to be inserted it's root
    if (to_insert->parent == nullptr) {
      this->root = to_insert;
      return;
    }

    switch (dir) {
    case Direction::Left:
      parent->left = to_insert;
      break;
    case Direction::Right:
      parent->right = to_insert;
      break;
    }

    do {
      // don't need to keep track of these in between loops they get
      // recalculated
      Node *grandparent;
      Node *uncle;
      if (parent->color == Color::Black) {
        // black parent means invariants definitely hold
        return;
      }

      grandparent = parent->parent;

      if (grandparent == nullptr) {
        // parent is root, just need to recolor it to black
        parent->color = Color::Black;
        return;
      }

      Direction parent_direction;
      if (grandparent->left == parent) {
        parent_direction = Direction::Left;
        uncle = grandparent->right;
      } else {
        parent_direction = Direction::Right;
        uncle = grandparent->left;
      }

      if (uncle == nullptr || uncle->color == Color::Black) {
        // case 5 and 6
        this->handle_root_rotation(grandparent, parent, to_insert,
                                   parent_direction);
        return;
      }

      // now we know parent and uncle are both red so red-black coloring can be
      // pushed down from grandparent
      parent->color = Color::Black;
      uncle->color = Color::Black;
      grandparent->color = Color::Red;

      to_insert = grandparent;
      parent = to_insert->parent;
    } while (parent != nullptr);

    // case 3: current node is red root so we're done
  }
  // returns nullptr iff map is empty
  std::pair<Node *, Direction> locate_slot(const Key_T &key) {
    Node *current = this->root;
    Node *parent = nullptr;
    Direction dir;
    while (current != nullptr && current->value.first != key) {
      parent = current;
      if (current->value.first < key) {
        dir = Direction::Left;
        current = current->left;
      } else {
        dir = Direction::Right;
        current = current->right;
      }
    }
    return std::make_pair(parent, dir);
  }

public:
  // If the key does not already exist in the map, it returns an iterator
  // pointing to the new element, and true. If the key already exists, no
  // insertion is performed nor is the mapped object changed, and it returns
  // an iterator pointing to the element with the same key, and false.
  std::pair<Iterator, bool> insert(const ValueType &val) {
    auto [parent, dir] = locate_slot(val.first);
    bool ret = parent == nullptr || parent->child(dir) == nullptr;
    if (!ret) {
      return std::make_pair(Iterator{parent->child(dir)}, ret);
    }
    Node to_insert{*this};
    to_insert.value = val;
    this->nodes.push_back(std::move(to_insert));
    this->nodes.back().self = (--this->nodes.end());
    insert_helper(&nodes.back(), parent, dir);

    if (min == nullptr || val.first < min->value.first) {
      min = &nodes.back();
    }
    if (max == nullptr || val.first > max->value.first) {
      max = &nodes.back();
    }

    return std::make_pair(Iterator(&nodes.back()), ret);
  }
  template <typename IT_T> void insert(IT_T range_beg, IT_T range_end) {
    std::for_each(range_beg, range_end,
                  [&](ValueType &val) { this->insert(val); });
  }

private:
  void case5(Node *parent, Node *sibling, Node *close_nephew,
             Node *distant_nephew, Direction dir) {
    sibling->rotate(!dir);
    sibling->color = Color::Red;
    close_nephew->color = Color::Black;
    distant_nephew = sibling;
    sibling = close_nephew;
    case6(parent, sibling, distant_nephew, dir);
  }
  void case6(Node *parent, Node *sibling, Node *distant_nephew, Direction dir) {
    parent->rotate(dir);
    sibling->color = parent->color;
    parent->color = Color::Black;
    distant_nephew->color = Color::Black;
  }
  // heavily referring to
  // https://en.wikipedia.org/wiki/Red%E2%80%93black_tree#Removal_of_a_black_non-root_leaf
  void complex_erase(Iterator pos) {

    Node *to_delete = pos.ref;
    Node *parent = to_delete->parent;
    assert(parent != nullptr);

    Direction dir =
        parent->right == to_delete ? Direction::Right : Direction::Left;

    Node *sibling;
    ;
    Node *close_nephew;
    Node *distant_nephew;

    parent->child(dir) = nullptr;

    do {
      dir = parent->right == to_delete ? Direction::Right : Direction::Left;

      sibling = parent->child(!dir);
      distant_nephew = sibling->child(!dir);
      close_nephew = sibling->child(dir);

      if (sibling->color == Color::Red) {
        // case 3
        parent->rotate(dir);
        parent->color = Color::Red;
        sibling->color = Color::Black;
        sibling = close_nephew;
        // redundant?
        distant_nephew = sibling->child(!dir);
        if (distant_nephew != nullptr && distant_nephew->color == Color::Red) {
          case6(parent, sibling, distant_nephew, dir);
          return;
        }
        close_nephew = sibling->child(dir);
        if (close_nephew != nullptr && close_nephew->color == Color::Red) {
          case5(parent, sibling, close_nephew, distant_nephew, dir);
          return;
        }
        sibling->color = Color::Red;
        parent->color = Color::Black;
        return;
      }

      if (distant_nephew != nullptr && distant_nephew->color == Color::Red) {
        case6(parent, sibling, distant_nephew, dir);
        return;
      }

      if (close_nephew != nullptr && close_nephew->color == Color::Red) {
        case5(parent, sibling, close_nephew, distant_nephew, dir);
        return;
      }

      if (parent->color == Color::Red) {
        // case 4
        sibling->color = Color::Red;
        parent->color = Color::Black;
        return;
      }

      // case 2
      sibling->color = Color::Red;
      to_delete = parent;
      parent = to_delete->parent;
    } while (parent != nullptr);
  }

public:
  // TODO: check that the way of reconnecting next and prev works
  void erase(Iterator pos) {
    // simple cases
    Node *ref = pos.ref;
    // 2 children
    if (ref->left != nullptr && ref->right != nullptr) {
      Node *next = ref->next;
      Node *prev = ref->prev;
      *ref = *next;
      prev->next = next;
      next->prev = prev;
      this->erase(Iterator{next});
    }
    // single child which is left
    else if (ref->left != nullptr && ref->right == nullptr) {
      Node *next = ref->next;
      Node *prev = ref->prev;
      *ref = *ref->left;
      prev->next = next;
      next->prev = prev;
    }
    // single child which is right
    else if (ref->left == nullptr && ref->right != nullptr) {
      Node *next = ref->next;
      Node *prev = ref->prev;
      *ref = *ref->right;
      prev->next = next;
      next->prev = prev;
    }
    // no children and root
    else if (ref->left == nullptr && ref->right == nullptr) {
      this->root = nullptr;
    }
    // no children and red
    else if (ref->left == nullptr && ref->right == nullptr) {
      Node *next = ref->next;
      Node *prev = ref->prev;
      prev->next = next;
      next->prev = prev;
    }
    // complicated case of black node with no kids
    else {
      this->complex_erase(pos);
    }
  }
  void erase(const Key_T &key) { this->erase(this->find(key)); }
  void clear() {
    this->root = nullptr;
    this->nodes.clear();
  }
  friend bool operator==(const Map &lhs, const Map &rhs) {
    if (lhs.nodes.size() != rhs.nodes.size()) {
      return false;
    }
    auto liter = lhs.cbegin();
    auto riter = rhs.cbegin();
    // both must be the same length so this is fine
    while (liter != lhs.cend()) {
      if (*liter != *riter) {
        return false;
      }
      liter++;
      riter++;
    }
    return true;
  }
  friend bool operator!=(const Map &lhs, const Map &rhs) {
    return !(lhs == rhs);
  }
  friend bool operator<(const Map &lhs, const Map &rhs) {
    auto l_iter = lhs.cbegin();
    auto r_iter = rhs.cbegin();
    for (; l_iter != lhs.cend() && r_iter != rhs.cend(); l_iter++, r_iter++) {
      if (*l_iter < *r_iter) {
        return true;
      }
    }
    return lhs.size() < rhs.size();
  }
};
} // namespace cs440