import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

import javax.swing.JFileChooser;

import princeton.StdAudio;
import princeton.StdDraw;

public class NBody {
	
    public static final double G = 6.67E-11;

    /**
     * returns Euclidean distance between (x1, y1) and (x2, y2)
     *
     * @param x1
     *            x-coordinate of point 1
     * @param y1
     *            y-coordinate of point 1
     * @param x2
     *            x-coordinate of point 2
     * @param y2
     *            y-coordinate of point 2
     * @return Euclidean distance between (x1, y1) and (x2, y2)
     */
    public double distance(double x1, double y1, double x2, double y2) {
    	//TODO: Complete distance
    	
        return 0;
    }
    
    
    /**
     * return the magnitude of the gravitational force between two bodies of
     * mass m1 and m2 that are distance r apart
     *
     * @param m1
     *            mass of body 1 in kg
     * @param m2
     *            mass of body 2 in kg
     * @param r
     *            distance in m
     * @return force between m1 and m2 that are distance r apart
     */
    public double force(double m1, double m2, double r) {
        //TODO: Complete force
    	
        return 0;
    }


    /**
     * Returns the x positions and y positions of bodies
     * @param totalTime The total amount of universe time to run for
     * @param timeStep The value of delta t in the equations to calculate position
     * @param info The scanner with info about the initial conditions of the
     * bodies
     * @return an array whose first element is the x and y position of the first body, and so on
     * t = totalTime
     */
    public double[][] positions(Scanner info, int totalTime, int timeStep) {
        //TODO: Complete positions
        double[][] output = new double[0][2]; //Replace 0 with the number of
                                              //bodies, read from the file

        return output;	
    }

    public static void main(String[] args) {
        Scanner info = openFile();
        int time = 10000000;
        int dt = 25000;
        
        if (info != null) {
            //StdAudio.play("data/2001.mid");
            NBody myNBody = new NBody();
            double[][] results = myNBody.positions(info, time, dt);
            for(int i = 0; i < results.length; i++) {
                for(int j = 0; j < results[i].length; j++) {
                    System.out.print(results[i][j]+" ");
                }
                System.out.println();
            }
            StdAudio.close();
        }
    }

    /**
     * Displays file chooser for browsing in the project directory. and opens
     * the selected file
     *
     * @return a new Scanner that produces values scanned from the selected
     *         file. null if file could not be opened or was not selected
     */
    
    public static Scanner openFile() {
        Scanner scan = null;
        System.out.println("Opening file dialog.");
        JFileChooser openChooser = new JFileChooser(System.getProperties()
                                                    .getProperty("user.dir"));
        
        int retval = openChooser.showOpenDialog(null);
        if (retval == JFileChooser.APPROVE_OPTION) {
            File file = openChooser.getSelectedFile();
            System.out.println(file.getAbsolutePath());
            try {
                scan = new Scanner(file);
                System.out.println("Opening: " + file.getName() + ".");
            } catch (FileNotFoundException e) {
                System.out.println("Could not open selected file.");
                e.printStackTrace();
            }
        } else {
            System.out.println("File open canceled.");
            System.exit(0);
        }
        
        return scan;
    }
}