#pragma once

#include <map>

template<typename Vertex>
class BfsVisitor {
 public:
     BfsVisitor() {
         is_start = true;
         parent.clear();
         distance.clear();
     }

    void ExamineVertex(const Vertex& vertex) {
        if (is_start) {
            is_start = false;
            parent[vertex] = vertex;
            distance[vertex] = 0;
        }
        current_v = vertex;
    }

    void DiscoverVertex(const Vertex& vertex) {
        parent[vertex] = current_v;
        distance[vertex] = distance[current_v] + 1;
    }

    size_t DistanceTo(const Vertex& target) const {
        return distance[target];
    }

    Vertex Parent(const Vertex& vertex) const {
        return parent[vertex];
    }

 private:
    static bool is_start;
    static Vertex current_v;
    static std::map<Vertex, Vertex> parent;
    static std::map<Vertex, size_t> distance;
};