#ifndef KING_H_
#define KING_H_

#include "algorithm/dynamic_reachability.h"
#include "algorithm/italiano.h"

using namespace graph;

namespace algo {

template<typename T>
class King : public DynamicReachability<T> {
public:
  King() = default;

  King(Digraph<T> G) { this->G = G; }

  // Initialize decremental maintenance data structures for DAGs for each
  // vertex's in and out reachability trees
  void init() override;

  // Execute reachability query q(u, v) from vertex u to vertex v
  // in O(n) using the stored decremental maintenance data structure for DAGs
  bool query(const T& u, const T& v) override;

  // Delete edge e(u, v) from all reachability trees and update each one of
  // them using the decremental reachability algorithm for DAGs
  void remove(const T& u, const T& v) override;

  // Insert edge e(u, v) by reconstructing all reachability trees
  void insert(const T& u, const T& v) override;
private:
  // Connect each reachabiliy tree with decremental maintenance data structure
  std::map<T, Italiano<T>> In;
  std::map<T, Italiano<T>> Out;
};

template<typename T>
void King<T>::init() {
  for (const auto& u : this->G.vertices()) {
    In[u] = Italiano<T>(BreadthFirstTree<T>(this->G.reverse(), u));
    In[u].init();
    Out[u] = Italiano<T>(BreadthFirstTree<T>(this->G, u));
    Out[u].init();
  }
}

template<typename T>
bool King<T>::query(const T& u, const T& v) {
  return std::any_of(this->G.vertices().begin(), this->G.vertices().end(),
                     [&](const T& w) {
                       return In[w].query(w, u) && Out[w].query(w, v);
                     });
}

template<typename T>
void King<T>::remove(const T& u, const T& v) {
  this->G.remove(u, v);
  for (const auto& w : this->G.vertices()) {
    In[w].remove(v, u);
    Out[w].remove(u, v);
  }
}

template<typename T>
void King<T>::insert(const T& u, const T& v) {
  this->G.insert(u, v);
  init();
}

} // namespace algo

#endif