#ifndef WALKMODULESPREAD_H
#define WALKMODULESPREAD_H

#include "WalkModule.h"
#include "WalkStateHeading.h"

#include "../../../../Assertions.h"

/** state-parameter needed for WalkModuleSpread */
struct WalkStateSpread {

	/** nested struct to prevent name-clashes */
	struct {

		/** keep something like a moving-average-position we want to strictly depart from */
		GridPoint departFrom;

	} spread;

};


/**
 * simply try to move away from the starting node as much as possible
 */
template <typename Node, typename WalkState> class WalkModuleSpread : public WalkModule<Node, WalkState> {

private:

	/**
	 * how fast to adjust the average-position to depart from
	 * values between 3% and 10% seem fine
	 */
	const float kappa = 0.10;

public:


	/** ctor */
	WalkModuleSpread() {

		/** ensure the templated WalkState inherits from WalkStateSpread */
		StaticAssert::AinheritsB<WalkState, WalkStateSpread>();

	}


	virtual void updateBefore(WalkState& state, const Node& startNode) override {
		(void) state;
		(void) startNode;
	}

	virtual void updateAfter(WalkState& state, const Node& startNode, const Node& endNode) override {
		(void) state;
		(void) startNode;
		(void) endNode;
	}

	virtual void step(WalkState& state, const Node& curNode, const Node& nextNode) override {

		(void) curNode;
		state.spread.departFrom = state.spread.departFrom * (1.0f-kappa) + nextNode * (kappa);

	}

	double getProbability(const WalkState& state, const Node& startNode, const Node& curNode, const Node& potentialNode) const override {

		(void) startNode;

		// current distance from the depart-from position
		const float dOld = state.spread.departFrom.getDistanceInCM(curNode);

		// potential distance from the depart-from position
		const float dNew = state.spread.departFrom.getDistanceInCM(potentialNode);

		// now, favor edges that depart even further from the depart-from position!

		if (dNew > dOld)	{return 0.90;}		// departing
		if (dNew == dOld)	{return 0.09;}		// distance does not change
							{return 0.01;}		// NOT departing.. unlikely

	}


};


#endif // WALKMODULESPREAD_H