import java.io.*;
import java.awt.Graphics;  
import java.awt.Color;  
public class Edge {	
	public static final int	WIDTH = 7;
	
	// These are the instance variables
	private String   label;
	private Node     startNode, endNode;
	private boolean  selected;

	// Some constructors.  Note that the default is not acceptable since we WANT nodes
	public Edge(Node start, Node end) {
		label = "";
		startNode = start;
		endNode = end;
	}

	public Edge(String aLabel, Node start, Node end) {
		label = aLabel;
		startNode = start;
		endNode = end;
	}

	// The get & set methods
	public String getLabel() { return label; }
	public Node getStartNode() { return startNode; }
	public Node getEndNode() { return endNode; }

	public void setLabel(String newLabel) { label = newLabel; }
	public void setStartNode(Node aNode) { startNode = aNode; }
	public void setEndNode(Node aNode) { endNode = aNode; }
	
	public boolean isSelected() { return selected; }
	public void setSelected(boolean state) { selected = state; }
	public void toggleSelected() { selected = !selected; }
	
	public Node otherEndFrom(Node aNode) {
		if (startNode == aNode)
			return endNode;
		else
			return startNode;
	}
	
	// Edges look like this:  sNode(12,43) --> eNode(67,34)
	public String toString() {
		return(startNode.toString() + " --> " + endNode.toString());
	}
	
	public void draw(Graphics aPen) {
		if (selected) {
			aPen.setColor(Color.RED);
			int xDiff = Math.abs(startNode.getLocation().x - endNode.getLocation().x);
			int yDiff = Math.abs(startNode.getLocation().y - endNode.getLocation().y);
			for (int i= -WIDTH/2; i<=WIDTH/2; i++) {
				if (yDiff > xDiff)
					aPen.drawLine(startNode.getLocation().x+i, startNode.getLocation().y,
					 	 endNode.getLocation().x+i, endNode.getLocation().y);
				else
					aPen.drawLine(startNode.getLocation().x, startNode.getLocation().y+i,
					 	 endNode.getLocation().x, endNode.getLocation().y+i);
			}
		}
		else {
	        aPen.setColor(Color.black);
			aPen.drawLine(startNode.getLocation().x, startNode.getLocation().y,
					      endNode.getLocation().x, endNode.getLocation().y);
		}
	}
	
	// Save the edge to the given file.  Note that the nodes themselves are not saved.
	// We assume here that node locations are unique identifiers for the nodes.
	public void saveTo(PrintWriter aFile) { 
		aFile.println(label); 
		aFile.println(startNode.getLocation().x); 
		aFile.println(startNode.getLocation().y); 
		aFile.println(endNode.getLocation().x); 
		aFile.println(endNode.getLocation().y); 
		aFile.println(selected); 
	}

	// Load an edge from the given file.  Note that the nodes themselves are not loaded.
	// We are actually making temporary nodes here that do not correspond to the actual
	// graph nodes that this edge connects.  We'll have to throw out these TEMP nodes later
	// and replace them with the actual graph nodes that connect to this edge.
	public static Edge loadFrom(BufferedReader aFile) throws IOException { 
		Edge	anEdge;
		String	aLabel = aFile.readLine();

		Node	start = new Node("TEMP");
		Node	end	= new Node("TEMP");
		
		start.setLocation(Integer.parseInt(aFile.readLine()), 
						  Integer.parseInt(aFile.readLine()));
		end.setLocation(Integer.parseInt(aFile.readLine()), 
						  Integer.parseInt(aFile.readLine()));

		anEdge = new Edge(aLabel, start, end);
		anEdge.setSelected(Boolean.valueOf(aFile.readLine()).booleanValue());

		return (anEdge);
	}
	
}