#ifndef WIFIOBSERVATION_H
#define WIFIOBSERVATION_H

#include <vector>
#include <fstream>

#include "../MACAddress.h"
#include "../../math/Distributions.h"


/** observed one AP with the given signal strength */
struct WiFiObservationEntry {

	/** AP's MAC address */
	MACAddress mac;

	/** AP's RSSI */
	float rssi;

	/** ctor */
	WiFiObservationEntry(const MACAddress& mac, const float rssi) : mac(mac), rssi(rssi) {;}

};

/** all observed APs and their signal strength */
struct WiFiObservation {

	/** one entry per AP */
	std::vector<WiFiObservationEntry> entries;

};


class WiFiObserver {

private:

	float sigma = 8.0f;

public:

	/** ctor */
	WiFiObserver(const float sigma) : sigma(sigma) {
		;
	}

	/**
	 * get the given GridNode's probability based on the provided WiFi measurements
	 */
	template <typename Node> double getProbability(const Node& n, const WiFiObservation& obs, const int age_ms = 0) {

		double prob = 0;

		// sigma grows with measurement age
		const double sigma = this->sigma * (1 + age_ms / 500.0f);

		// process each observed AP
		for (const WiFiObservationEntry& ap : obs.entries) {

			// the RSSI from the scan
			const float measuredRSSI = ap.rssi;

			// the RSSI from the model (if available!)
			const float modelRSSI = n.getRSSI(ap.mac);

			// 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 WiFiObservation& 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, obs);
			out << n.x_cm << " " << n.y_cm << " " << n.z_cm << " " << p << "\n";
		}
		out << "e\n";

		out.close();

	}

};

#endif // WIFIOBSERVATION_H