// demonstration of common memory leak

#include <iostream>
#include <fstream>
#include <math.h>
#include <memory>

using namespace std;

const double conv = 45.0/atan(1.0);

class GPScoords {
public:
	GPScoords() { cout << "made GPS coords @ " << this << endl; }
	~GPScoords() { cout << "del  GPS coords @ " << this << endl; }
	void load(istream &is) { is >> lat >> lon; lat /= conv; lon /= conv; }
	void save(ostream &os) const { os << lat*conv << ' ' << lon*conv; }
/*
	double distance(unique_ptr<GPScoords> gps) const { // in km
		// this assumes the Earth is a sphere -- much better formulae exist
		return acos(sin(lat)*sin(gps->lat) + cos(lat)*cos(gps->lat)*cos(lon-gps->lon))*6371.0;
	}
*/
	double distance(const GPScoords *gps) const { // in km
		// this assumes the Earth is a sphere -- much better formulae exist
		return acos(sin(lat)*sin(gps->lat) + cos(lat)*cos(gps->lat)*cos(lon-gps->lon))*6371.0;
	}
private:
	double lat, lon;
};

// find distance between next two GPS coords in file
double dist(istream &s) {
	unique_ptr<GPScoords> first(new GPScoords);
	unique_ptr<GPScoords> second(new GPScoords);
	first->load(s);
	second->load(s);
	return first->distance(second.get());
	//return first->distance(std::move(second));
}

int main(int argc, char **argv) {
	fstream file;
	file.exceptions(ifstream::eofbit);
	try {
		file.open(argc>1 ? argv[1] : "testgps.txt");
		cout << dist(file) << " km" << endl;
	} catch (std::exception e) {
		cout << "file not properly formatted" << endl;
	}
}