package jsetool.gui;

import java.awt.Cursor;
import java.awt.event.MouseEvent;

/**
 * 
 * @author Mike Lawson
 *
 * @since Nov 2, 2004
 * 
 * This is the state that the drawing pane will be in when the user is
 * connecting two states together with a directed edge.
 *
 */
 
class DrawingAnEdgeState extends FSMDrawingState
{
  
  /** This is a temporary state that allows us to draw a temporary edge while dragging. */
  protected LabeledState tempStateForDragging = new LabeledState("");
  
  /** This is a temporary edge that allows us to draw a line while the user is draggin. */
  protected ConnectivityEdge tempEdgeForDragging;

  protected Cursor drawingEdgeCursor = new Cursor(Cursor.CROSSHAIR_CURSOR);
  
  protected LabeledState sourceState;
  
  /**
   * Constructs a new state for drawing edges for the given pane.
   * @param pane
   */
  public DrawingAnEdgeState(FSMDrawingPane pane)
  {
    super(pane);
  }
  
  /**
   * Entering this state results in the cursor being set
   * to the one associated with adding an edge, and dragging
   * is disabled.
   */
  public void enter()
  {
    getPane().setCursor(drawingEdgeCursor);
    getPane().setIsDragging(false);
  }

  /**
   * Does nothing for this state.
   * @param e
   * @throws Exception
   */
  public void mouseClicked(MouseEvent e) throws Exception
  {
    // nada for this state
  }
  
  
  /**
   * Draws a temporary line while the edge is being drawn
   * on the display.
   * @param e
   * @throws Exception
   */
  public void mouseDragged(MouseEvent e) throws Exception
  {  
    // Move the temporary state around to follow the mouse.
    // The temporary edge will follow magically.
    tempStateForDragging.setFrame(e.getX(), e.getY(), 1, 1);
  }
  
  /**
   * Starts the drawing process.  If this object is not
   * on top of a state, it will blow up.  The source object will
   * be selected if there is an object under the mouse.
   * @param e
   * @throws Exception
   * 
   */
  public void mousePressed(MouseEvent e) throws Exception
  {
    Object sourceObject = getPane().getObjectMouseIsOn(e);
    if (sourceObject == null)
    {
      throw new Exception("You must start an edge from a state");
    }
    
    sourceState = (LabeledState)sourceObject;
    
    // Set the temporary state (which is invisible to the user)
    // to the X, Y coordinates of the source state.
    tempStateForDragging.setFrame(sourceState.getX(), sourceState.getY(), 1, 1);
    
    // Create a temporary edge that follow the temporary state around while
    // the user is dragging.
    tempEdgeForDragging = new ConnectivityEdge(sourceState, tempStateForDragging);
    
    getPane().addDrawingObject(tempEdgeForDragging);

  }
  
  /**
   * Stops the drawing process.  If this object is not
   * on top of a state, it will blow up.  The target object will
   * be selected, the new edge will be added to the pane.
   * @param e
   * @throws Exception
   */
  public void mouseReleased(MouseEvent e) throws Exception
  {
    tempEdgeForDragging.objectIsBeingDeleted();
    
    getPane().removeDrawingObject(tempEdgeForDragging);
    
    tempEdgeForDragging = null;
    
    Object targetObject = getPane().getObjectMouseIsOn(e);
    
    if (targetObject == null)
    {
      throw new Exception("You must end an edge on a state");
    } 

    if (targetObject instanceof LabeledState)
    {
     
      String edgeLabel = "";
      
      ConnectivityEdge edge = new ConnectivityEdge(sourceState, (LabeledState)targetObject);
      edge.setEdgeLabel(edgeLabel);
      getPane().addDrawingObject(edge);    
      getPane().drawingNormalOpsSelected();
    }
    else
    {
      throw new Exception("You must end an edge on a state");

    }
  }
  
  
}