#ifndef WALKMODULE_H
#define WALKMODULE_H

#include "../../../Grid.h"
#include "../../../GridPoint.h"

/** base-class for all WalkStates */
struct WalkState {

	/** current position within the grid (-> in cm!) */
	GridPoint position;

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

		/**
		 * for every walk, the walker is given a desired distance
		 * however, the walking distance depends on the grid size and can
		 * therefore never be reached exactly. therefor we track the
		 * error between desired and walked distance to ensure "in average"
		 * the walked distance is correct
		 */
		float error_m;

		Distance() : error_m(0) {;}

	} distance;

	/** ctor */
	explicit WalkState(const GridPoint& position) : position(position) {;}

};


/**
 * base-class for all walk-modules that influence p(e)
 */
template <typename Node, typename WalkState> class WalkModule {

public:

	/** update the given WalkState before starting the walk. e.g. based on sensor readings */
	virtual void updateBefore(WalkState& state, const Node& startNode) = 0;

	/** get the probability p(e) from curNode to potentialNode */
	virtual double getProbability(const WalkState& state, const Node& startNode, const Node& curNode, const Node& potentialNode) const = 0;

	/** one step (edge) is taken */
	virtual void step(WalkState& state, const Node& curNode, const Node& nextNode) = 0;

	/** update the walk state based on the given transition (if any update is necssary) */
	virtual void updateAfter(WalkState& state, const Node& startNode, const Node& endNode) = 0;

};

#endif // WALKMODULE_H