#ifndef WIFIPROBABILITYGRID_H
#define WIFIPROBABILITYGRID_H

#include <fstream>

#include "../../math/Distributions.h"
#include "../../data/Timestamp.h"

#include "WiFiProbability.h"


/**
 * probability is calculated by comparing pre-calculated wifi-signal-strengths
 * attached to each grid-node with a given WiFiMeasurements data structure
 */
class WiFiObserverGrid : public WiFiProbability {

private:

	/** base-sigma to use for comparison */
	float sigma = 8.0f;

	/** additional sigma-per-second (measurement age) to*/
	float sigmaPerSecond = 1.5;


public:

	/** ctor with uncertainty */
	WiFiObserverGrid(const float sigma) : sigma(sigma) {
		;
	}

	/**
	 * get the given GridNode's probability.
	 * compares the predicted signal-strengths stored on the given node
	 * with the provided WiFi measurements
	 */
	template <typename Node> double getProbability(const Node& n, const Timestamp curTime, const WiFiMeasurements& obs) const {

		double prob = 0;

		// process each observed measurement
		for (const WiFiMeasurement& measurement : obs.entries) {

			// determine the age for this measurement
			const Timestamp age = curTime - measurement.getTimestamp();

			// sigma grows with measurement age
			const float sigma = this->sigma + this->sigmaPerSecond * age.sec();

			// the RSSI from the scan
			const float measuredRSSI = measurement.getRSSI();

			// the RSSI from the model (if available!)
			const float modelRSSI = n.getRSSI(measurement.getAP().getMAC());

			// no model RSSI available?
			if (modelRSSI == 0) {continue;}

			// compare both
			const double p = Distribution::Normal<double>::getProbability(measuredRSSI, sigma, modelRSSI);

			// adjust using log
			prob += std::log(p);

		}

		//return std::pow(std::exp(prob), 0.1);
		return std::exp(prob);

	}

	/** gnuplot debug dump */
	template <typename Node> void dump(Grid<Node>& grid, const Timestamp curTime, const WiFiMeasurements& obs, const std::string& fileName) {

		std::ofstream out(fileName);
		out << "splot '-' with points palette\n";

		for (const Node& n : grid) {
			const float p = getProbability(n, curTime, obs);
			out << n.x_cm << " " << n.y_cm << " " << n.z_cm << " " << p << "\n";
		}
		out << "e\n";

		out.close();

	}

};

#endif // WIFIPROBABILITYGRID_H