/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   Licensed 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.txt

   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.

=========================================================================*/

#pragma once

#include "imstkImageData.h"

#include <unordered_set>
#include <queue>

namespace imstk
{
///
/// \class FastMarch
///
/// \brief
///
class FastMarch
{
protected:
    // Setup Node struct for priority queue
    struct Node
    {
        int m_nodeId;
        double m_cost;
        Vec3i m_coord;

        Node(int nodeId, double cost, Vec3i coord) :
            m_nodeId(nodeId), m_cost(cost), m_coord(coord)
        {
        }
    };
    struct NodeComparator
    {
        bool operator()(const Node& a, const Node& b)
        {
            return a.m_cost > b.m_cost;
        }
    };

public:
    bool isVisited(int nodeId) { return m_visited.count(nodeId) == 0 ? false : true; }
    double getDistance(int nodeId) { return m_distances.count(nodeId) == 0 ? IMSTK_DOUBLE_MAX : m_distances.at(nodeId); }

    void solve();

    void solveNode(Vec3i coord, int index);

    void setSeeds(std::vector<Vec3i> seedVoxels) { m_seedVoxels = seedVoxels; }
    void setVisited(std::unordered_set<int> visited) { m_visited = visited; }
    void setDistnaces(std::unordered_map<int, double> distances) { m_distances = distances; }
    void setImage(std::shared_ptr<ImageData> image) { m_imageData = image; }
    void setDistThreshold(double distThreshold) { m_distThreshold = distThreshold; }

protected:
    // The image to operate on
    std::shared_ptr<ImageData> m_imageData;
    Vec3i m_dim;
    Vec3d m_spacing;
    int   m_indexShift;

    std::unordered_set<int> m_visited;
    std::unordered_map<int, double> m_distances;

    // The starting voxels
    std::vector<Vec3i> m_seedVoxels;

    // Distance to go too
    double m_distThreshold;

    std::priority_queue<Node, std::vector<Node>, NodeComparator> m_queue;
};
} // namespace imstk