/*
 * © Copyright 2014 – Urheberrechtshinweis
 * Alle Rechte vorbehalten / All Rights Reserved
 *
 * Programmcode ist urheberrechtlich geschuetzt.
 * Das Urheberrecht liegt, soweit nicht ausdruecklich anders gekennzeichnet, bei Frank Ebner.
 * Keine Verwendung ohne explizite Genehmigung.
 * (vgl. § 106 ff UrhG / § 97 UrhG)
 */

#ifndef INDOOR_GW3_WALKEVALUATOR_H
#define INDOOR_GW3_WALKEVALUATOR_H

#include "Structs.h"
#include "Helper.h"

#include "../../../math/Distributions.h"
#include "../../../grid/Grid.h"

namespace GW3 {

	/** describes a potential walk, which can be evaluated */
	struct PotentialWalk {

		/** initial parameters (requested walk) */
		const WalkParams& params;

		/** walk started here */
		Point3 pStart;

		/** walk ended here */
		Point3 pEnd;

		/** usually the euclidean distance start<->end but not necessarily! */
		float walkDist_m;

		/** ctor */
		PotentialWalk(const WalkParams& params, const Point3 pStart, const Point3 pEnd, const float walkedDistance_m) :
			params(params), pStart(pStart), pEnd(pEnd), walkDist_m(walkedDistance_m) {
			;
		}

	};

	/** interface for all evaluators that return a probability for a given walk */
	template <typename Node> class WalkEvaluator {

	public:

		/** get the probability for the given walk */
		//virtual double getProbability(const Walk<Node>& walk) const = 0;

		virtual double getProbability(const PotentialWalk& walk) const = 0;

	};


	/** evaluate the grid-node-importance importance(end) */
	template <typename Node> class WalkEvalEndNodeProbability : public WalkEvaluator<Node> {

		Grid<Node>* grid;

	public:

		WalkEvalEndNodeProbability(Grid<Node>* grid) : grid(grid) {;}

		virtual double getProbability(const PotentialWalk& walk) const override {

			const GridPoint gp = Helper<Node>::p3ToGp(walk.pEnd);
			const Node& node = grid->getNodeFor(gp);
			const double p = node.getWalkImportance();
			return p;
			//return std::pow(p,10);

		}

	};



	/** evaluate the difference between head(start,end) and the requested heading */
	template <typename Node> class WalkEvalHeadingStartEnd : public WalkEvaluator<Node> {

		const double sigma_rad;
		const double kappa;
		Distribution::VonMises<double> _dist;
		Distribution::LUT<double> dist;

	public:

		// kappa = 1/var = 1/sigma^2
		// https://en.wikipedia.org/wiki/Von_Mises_distribution
		WalkEvalHeadingStartEnd(const double sigma_rad = 0.04) :
			sigma_rad(sigma_rad), kappa(1.0/(sigma_rad*sigma_rad)), _dist(0, kappa), dist(_dist.getLUT()) {
			;
		}

		virtual double getProbability(const PotentialWalk& walk) const override {

			if (walk.pStart == walk.pEnd) {
				std::cout << "warn! start-position == end-positon" << std::endl;
				return 0;
			}

			const Heading head(walk.pStart.xy(), walk.pEnd.xy());
			const float diff = head.getDiffHalfRAD(walk.params.heading);
			//const float diff = Heading::getSignedDiff(params.heading, head);
			//return Distribution::Normal<double>::getProbability(0, sigma, diff);
			return dist.getProbability(diff);

		}

	};

	/** evaluate the difference between distance(start, end) and the requested distance */
	template <typename Node> class WalkEvalDistance : public WalkEvaluator<Node> {

		const Grid<Node>& grid;

		const double sigma;

		const Distribution::Normal<double> dist;

	public:

		WalkEvalDistance(const Grid<Node>& grid, const double sigma = 0.1) : grid(grid), sigma(sigma), dist(0, sigma) {
			Assert::isFalse(grid.isEmpty(), "empty grid given");
		}

		virtual double getProbability(const PotentialWalk& walk) const override {

			const float requestedDistance_m = walk.params.getDistanceInMeter(grid);
			const float walkedDistance_m = walk.walkDist_m;//pStart.getDistance(pEnd);
			const float diff = walkedDistance_m - requestedDistance_m;
			return dist.getProbability(diff);
			//return Distribution::Normal<double>::getProbability(params.distance_m, sigma, walkedDistance_m);

		}

	};

}

#endif // INDOOR_GW3_WALKEVALUATOR_H