/*
 * © 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 GRIDWALKSIMPLECONTROL_H
#define GRIDWALKSIMPLECONTROL_H



#include "../../geo/Heading.h"
#include "../Grid.h"

#include "../../math/Distributions.h"
#include "../../math/DrawList.h"
#include "../../math/Random.h"

#include "GridWalkState.h"
#include "GridWalkHelper.h"
#include "GridWalk.h"

template <typename T> class GridWalkSimpleControl : public GridWalk<T> {

	friend class GridWalkHelper;

private:

	/** per-edge: change heading with this sigma */
	static constexpr float HEADING_CHANGE_SIGMA = Angle::degToRad(10);

	/** fast random-number-generator */
	Random::RandomGenerator gen;

	/** 0-mean normal distribution */
	std::normal_distribution<float> headingChangeDist = std::normal_distribution<float>(0.0, HEADING_CHANGE_SIGMA);



	DrawList<T&> drawer;

public:

	/** ctor */
	GridWalkSimpleControl() {
		gen.seed(1234);
	}

	Distribution::Normal<float> dHead = Distribution::Normal<float>(1, 0.01);
	Distribution::Normal<float> dWalk = Distribution::Normal<float>(1, 0.10);
	Distribution::Normal<float> sWalk = Distribution::Normal<float>(0, 0.10);

	GridWalkState<T> getDestination(Grid<T>& grid, const GridWalkState<T>& start, float distance_m, float headChange_rad, Activity act) {

		// proportional change of the heading


		// proportional change of the to-be-walked distance
		//static 	Distribution::Normal<float> dWalk(1, 0.10);

		distance_m = distance_m*dWalk.draw()*1.4;		// TODO: why * X?
		headChange_rad = headChange_rad*dHead.draw();

		//static 	Distribution::Normal<float> sWalk(0, 0.10);
		if (distance_m == 0) { distance_m = std::abs( sWalk.draw() ); }

		return walk(grid, start, distance_m, headChange_rad);

	}

private:

	double getProbability(const T& start, const T& possible, const Heading head) const {

		// TODO: WHY?! not only when going back to the start?
		if (start.x_cm == possible.x_cm && start.y_cm == possible.y_cm) {
			if (start.z_cm == possible.z_cm) {return 0;} // back to the start
			//throw 1;
			return 0.5;// stair start/end TODO: fix
		}

		// get the angle between START and the possible next node
		const Heading possibleHead = GridWalkHelper::getHeading(start, possible);

		// calculate the difference
		const float diff = possibleHead.getDiffHalfRAD(head);

//		// compare this heading with the requested one
		const double angleProb = Distribution::Normal<float>::getProbability(0, Angle::degToRad(15), diff);
//		const double angleProb = (diff <= Angle::degToRad(15)) ? 1 : 0.1;		// favor best 3 angles equally

		// nodes own importance
		const double nodeProb = Distribution::Logistic<float>::getCDF(possible.imp, 1, 0.9);
		//const double nodeProb = std::pow(possible.imp, 2);
		//const double nodeProb = 1.0;

		// bring it together
		return angleProb * nodeProb;

	}

	Distribution::Uniform<float> dChange = Distribution::Uniform<float>(Angle::degToRad(0), +Angle::degToRad(359));

	GridWalkState<T> walk(Grid<T>& grid, const GridWalkState<T>& start, const float distance_m, const float headChange_rad) {

		// try-again distribution
		//static 	Distribution::Normal<float> dHead(0, Angle::degToRad(10));
		//static 	Distribution::Normal<float> dUpdate(0, Angle::degToRad(3));
		//	static	Distribution::Uniform<float> dChange(Angle::degToRad(0), +Angle::degToRad(359));

		int retries = 5;
		float walked_m = 0;
		GridWalkState<T> cur = start;

		// the desired heading
		Heading reqHeading = start.heading + (headChange_rad);

		// walk until done
		while(walked_m < distance_m) {

			// evaluate all neighbors
			drawer.reset();
			for (T& neighbor : grid.neighbors(*cur.node)) {

				const double prob = getProbability(*start.node, neighbor, reqHeading);
				drawer.add(neighbor, prob);

			}

			// too bad? start over!
			if (drawer.getCumProbability() < 0.1 && (--retries) >= 0) {
				walked_m = 0;
				cur = start;
				//WHAT THE HELL
				if (retries == 0) { reqHeading = dChange.draw(); }
				continue;
			}

			// get the neighbor
			const T& neighbor = drawer.get();

			// update
			walked_m += neighbor.getDistanceInMeter(*cur.node);
			cur.node = &neighbor;

		}

		cur.distanceWalked_m = NAN;
		cur.headingChange_rad = NAN;
		cur.heading = reqHeading;

		return cur;

	}

};

#endif // GRIDWALKSIMPLECONTROL_H