import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class NBody {

    public static void main(String[] args){
            double totalTime = 157788000.0;
            double dt = 25000.0;
            String pfile = "data/planets.txt"; // ./data/planets.txt
            if (args.length > 2) {
                    totalTime = Double.parseDouble(args[0]);
                    dt = Double.parseDouble(args[1]);
                    pfile = args[2];
            }

            String fname = pfile;
            Planet[] planets = readPlanets(fname);
            double radius = readRadius(fname);

            System.out.printf("%d\n", planets.length);
            System.out.printf("%.2e\n", radius);
            for (int i = 0; i < planets.length; i++) {
                System.out.printf("%11.4e %11.4e %11.4e %11.4e %11.4e %12s\n",
                                          planets[i].myXPos, planets[i].myYPos,
                                  planets[i].myXVel, planets[i].myYVel,
                                  planets[i].myMass, planets[i].myFileName);
            }

            StdDraw.setScale(-radius, radius);
            StdDraw.picture(0,0,"images/starfield.jpg");

            for(double t = 0.0; t < totalTime; t += dt) {
                double[] xForces = new double[planets.length];
                double[] yForces = new double[planets.length];

                for (int i = 0; i < planets.length; i++) {
                    xForces[i] = planets[i].calcNetForceExertedByX(planets);
                    yForces[i] = planets[i].calcNetForceExertedByY(planets);
                }

                for (int i = 0; i < planets.length ; i++) {
                    planets[i].update(dt, xForces[i], yForces[i]);
                }

                StdDraw.picture(0,0,"images/starfield.jpg");
                Arrays.stream(planets).forEach(p -> p.draw());
                StdDraw.show(10);
            }

            Arrays.stream(planets).forEach(p -> p.draw());
    }

    public static double readRadius(String fname) {
        try {
            Scanner scanner = new Scanner(new File(fname));
            scanner.next();
            double radius = scanner.nextDouble();
            scanner.close();
            return radius;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        return -1.0;
    }

    public static Planet[] readPlanets(String fname) {
        Planet[] planets = new Planet[5];
        try {
            Scanner scanner = new Scanner(new File(fname));
            scanner.next();
            scanner.next();
            for (int i = 0; i < planets.length; i++) {
                planets[i] = new Planet(scanner.nextDouble(),
                        scanner.nextDouble(),
                        scanner.nextDouble(),
                        scanner.nextDouble(),
                        scanner.nextDouble(),
                        scanner.next());
            }
            scanner.close();
        } catch (FileNotFoundException ex) {
            Logger.getLogger(NBody.class.getName()).log(Level.SEVERE, null, ex);
        }
        return planets;
    }
}