//********************************************************************
//  The primary panel for the Graph program
//  Author: Zdravko Markov
//********************************************************************
import java.util.ArrayList;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class GraphPanel extends JPanel
{
   private final int SIZE = 10;  // radius of each node
   
   private Point point1 = null, point2 = null;

   private ArrayList<Point> nodeList;   // Graph nodes
   private ArrayList<Edge> edgeList;    // Graph edges
   
   private int[][] a = new int[100][100];  // Graph adjacency matrix
   
   public GraphPanel()
   {
      nodeList = new ArrayList<Point>();
      edgeList = new ArrayList<Edge>();
      
      GraphListener listener = new GraphListener();
      addMouseListener (listener);
      addMouseMotionListener (listener);
      
      JButton print = new JButton("Print adjacency matrix");
      print.addActionListener (new ButtonListener());
      
      setBackground (Color.black);
      setPreferredSize (new Dimension(400, 300));
      add(print);
   }

//  Draws the graph
   public void paintComponent (Graphics page)
   {
      super.paintComponent(page);

      // Draws the edge that is being dragged
      page.setColor (Color.green);
      if (point1 != null && point2 != null) {
         page.drawLine (point1.x, point1.y, point2.x, point2.y);
         page.fillOval (point2.x-3, point2.y-3, 6, 6);
        }
// Draws the nodes      
      for (int i=0; i<nodeList.size(); i++) {
          page.setColor (Color.green);
          page.fillOval (nodeList.get(i).x-SIZE, nodeList.get(i).y-SIZE, SIZE*2, SIZE*2);
          page.setColor (Color.black);
          page.drawString (String.valueOf(i), nodeList.get(i).x-SIZE/2, nodeList.get(i).y+SIZE/2);
        }
// Draws the edges
      for (int i=0; i<edgeList.size(); i++) {
          page.setColor (Color.green);
          page.drawLine (edgeList.get(i).a.x, edgeList.get(i).a.y,edgeList.get(i).b.x, edgeList.get(i).b.y);
          page.fillOval (edgeList.get(i).b.x-3, edgeList.get(i).b.y-3, 6, 6);
        }
    }

//  The listener for mouse events.
   private class GraphListener implements MouseListener, MouseMotionListener
   {
      public void mouseClicked (MouseEvent event)
      {
         nodeList.add(event.getPoint());
         repaint();
      }

      public void mousePressed (MouseEvent event)
      {
         point1 = event.getPoint();
      }

      public void mouseDragged (MouseEvent event)
      {
        point2 = event.getPoint();
        repaint();
      }
      
      public void mouseReleased (MouseEvent event)
      {
          point2 = event.getPoint();
          if (point1.x != point2.x && point1.y != point2.y)
          {
            edgeList.add(new Edge(point1,point2));
            repaint();
          }
      }

//  Empty definitions for unused event methods.
      public void mouseEntered (MouseEvent event) {}
      public void mouseExited (MouseEvent event) {}
      public void mouseMoved (MouseEvent event) {}
   }

// Represents the graph edges
   private class Edge {
       Point a, b;
       
      public Edge(Point a, Point b) 
      {
          this.a = a;
          this.b = b;
      }
   }
   private class ButtonListener implements ActionListener
   {
      public void actionPerformed (ActionEvent event)
      {
// Initializes graph adjacency matrix
          for (int i=0; i<nodeList.size(); i++)
              for (int j=0; j<nodeList.size(); j++) a[i][j]=0;
          
// Includes the edges in the graph adjacency matrix
          for (int i=0; i<edgeList.size(); i++)
          {
            for (int j=0; j<nodeList.size(); j++)
                if (distance(nodeList.get(j),edgeList.get(i).a)<=SIZE+3)
                    for (int k=0; k<nodeList.size(); k++)
                        if (distance(nodeList.get(k),edgeList.get(i).b)<=SIZE+3) 
                        {
                            System.out.println(j+"->"+k);
                            a[j][k]=1;
                        }
          }
// Prints the graph adjacency matrix
          for (int i=0; i<nodeList.size(); i++)
          {
              for (int j=0; j<nodeList.size(); j++)
                System.out.print(a[i][j]+"\t");
              System.out.println();
          }    
      }

// Euclidean distance function      
      private int distance(Point p1, Point p2) {
         return (int)Math.sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));
      }
  }
  
}