/**
 * 
 */
package uk.org.ury.frontend;

import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.JApplet;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

import uk.org.ury.frontend.exceptions.LoadFailureException;
import uk.org.ury.testrig.Launcher;

/**
 * A frame that hosts a FrontendModulePanel, used for serving frontend 
 * panels in a window (application mode).
 * 
 * @author Matt Windsor
 *
 */

public class FrontendApplet extends JApplet implements FrontendMaster, Launcher
{
  /**
   * 
   */
  
  private static final long serialVersionUID = 740928181256928433L;
  
  private FrontendModulePanel child;
  private FrontendControlPanel cpanel;

  
  /**
   * Main method.
   * 
   * @param args  The command-line arguments to the program.  These 
   *              will currently be ignored.
   */
  
  @Override
  public void
  init ()
  {
    try
      {
        javax.swing.SwingUtilities.invokeAndWait (new Runnable()
          {
            public void
            run () 
            {
              try
                {
                  loadModule (DEFAULT_MODULE_NAME);
                }
              catch (LoadFailureException e)
                {
                  // TODO Auto-generated catch block
                  e.printStackTrace ();
                }
              setupUI ();
            }
          });
      }
    catch (Exception e)
      {
        e.printStackTrace ();
        System.err.println("createGUI didn't successfully complete");
      }
  }

  
  /**
   * Set up the user interface of the frame.
   */
  
  @Override
  public void
  setupUI ()
  {
    try
      {
        // Set System L&F
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName ());
      } 
    catch (UnsupportedLookAndFeelException e)
      {
        // handle exception
      }
    catch (ClassNotFoundException e)
      {
       // handle exception
      }
    catch (InstantiationException e)
      {
       // handle exception
      }
    catch (IllegalAccessException e)
      {
       // handle exception
      }
    
    
    // Composition
    
    add (child, BorderLayout.CENTER);
    
    setPreferredSize (new Dimension (800, 600));
    setMinimumSize (new Dimension (800, 600)); 
    
    setVisible (true);
  }


  /**
   * Load a module into the frontend frame.
   * 
   * Loading will fail with a fatal error if the class is not found,
   * or is not an implementor of FrontendModule.
   * 
   * @param moduleName  The fully qualified class-name of the module,
   *                    minus the leading "uk.org.ury." domain.
   *                    
   * @throws            LoadFailureException if the class is 
   *                    not found, or is not an implementor of 
   *                    FrontendModule.
   */
  
  @Override
  public void
  loadModule (String moduleName)
  throws LoadFailureException
  {
    Class<?> moduleClass = null;
    
    try
      {
        moduleClass = Class.forName ("uk.org.ury." + moduleName);
      }
    catch (ClassNotFoundException e)
      {
        throw new LoadFailureException ("Could not load module: "
                                        + e.getMessage ());
      }

    
    if (FrontendModule.class.isAssignableFrom (moduleClass) == false)
      {
        throw new LoadFailureException ("Could not load module: Not a FrontendModule");
      }
    else
      {
        FrontendModulePanel temp = child;
        
        try
          {
            child = ((FrontendModule) moduleClass.newInstance ()).runFrontend (this);         
          }
        catch (InstantiationException e)
          {
            throw new LoadFailureException ("Could not load module: "
                                                  + e.getMessage ());
          }
        catch (IllegalAccessException e)
          {
            throw new LoadFailureException ("Could not load module: "
                                                  + e.getMessage ());
          }
        
        if (temp != null)
          remove (temp);
        
        getContentPane ().add (child, BorderLayout.CENTER);
        child.setMaster (this);
        
        repaint ();
      }
  }
  
  
  /**
   * Load a module into the frontend frame, additionally installing 
   * a control panel to communicate with the previous module.
   * 
   * Loading will fail with a fatal error if the class is not found,
   * or is not an implementor of FrontendModule.
   * 
   * @param moduleName  The fully qualified class-name of the module,
   *                    minus the leading "uk.org.ury." domain.
   *                 
   * @param cPanelName  The fully qualified class-name of the control
   *                    panel to install, minus the leading 
   *                    "uk.org.ury." domain.
   *                    
   * @throws            LoadFailureException if the class is 
   *                    not found, or is not an implementor of 
   *                    FrontendModule.
   */
  
  @Override
  public void
  loadModule (String moduleName, String cPanelName)
  throws LoadFailureException
  {
    FrontendModulePanel newParent = child;
    loadModule (moduleName);
    FrontendModulePanel newChild = child;
    
    loadControlPanel (cPanelName, newParent, newChild);
  }
  
  
  /**
   * Load and install a control panel class given the class name.
   * 
   * @param cPanelName  The fully qualified class-name of the control
   *                    panel to load, minus the leading 
   *                    "uk.org.ury." domain.
   *                    
   * @param parent      The parent panel in the relationship modelled 
   *                    by the control panel interface.
   *                    
   * @param child       The child panel in the relationship modelled
   *                    by the control panel interface.
   *                    
   * @throws            LoadFailureException if the class is 
   *                    not found, or is not an implementor of 
   *                    FrontendControlPanel.
   */

  private void
  loadControlPanel (String cPanelName, FrontendModulePanel parent, 
                    FrontendModulePanel child)
  throws LoadFailureException
  {
    Class<?> cPanelClass = null;
    
    try
      {
        cPanelClass = Class.forName ("uk.org.ury." + cPanelName);
      }
    catch (ClassNotFoundException e)
      {
        throw new LoadFailureException ("Could not load control panel: "
                                        + e.getMessage ());
      }

    
    if (FrontendControlPanel.class.isAssignableFrom (cPanelClass))
      {
        FrontendControlPanel temp = cpanel;
        
        try
          {
            cpanel = ((FrontendControlPanel) cPanelClass.newInstance ());         
          }
        catch (InstantiationException e)
          {
            throw new LoadFailureException ("Could not load control panel: "
                                            + e.getMessage ());
          }
        catch (IllegalAccessException e)
          {
            throw new LoadFailureException ("Could not load control panel: "
                                            + e.getMessage ());
          }
        
        if (temp != null)
          remove (temp);
        
        cpanel.setPanels (parent, child);
        cpanel.setMaster (this);
        cpanel.setPreviousCPanel (temp);
        
        add (cpanel, BorderLayout.SOUTH);
        repaint ();
      }    
  }

  
  /**
   * Restore an existing module and control panel into the frontend 
   * frame.
   * 
   * @param mpanel  The module panel to restore.
   * 
   * @param cpanel  The control panel to restore, if any.  A null 
   *                value signifies a lack of control panel.
   * 
   * @throws        IllegalArgumentException if the mpanel is null.
   */
  
  @Override
  public void
  restoreModule (FrontendModulePanel mpanel,
                 FrontendControlPanel cpanel)
  {
    if (mpanel == null)
      throw new IllegalArgumentException ("mpanel is null.");
    
    remove (child);
    remove (this.cpanel);
    
    child = mpanel;
    add (child);
    
    if (cpanel != null)
      add (cpanel, BorderLayout.SOUTH);
    
    this.cpanel = cpanel;
    
    repaint ();
  }

  
  /**
   * Report a fatal error,
   * 
   * @param message  The message, eg the exception message, to report
   *                 to the user.
   */

  @Override
  public void
  fatalError (String message)
  {
    FrontendError.reportFatal (message, this);
  }

  
  /**
   * @return  the resource directory.
   */
  
  @Override
  public String
  getResourceDirectory ()
  {
    return getCodeBase () + "res/";
  }
}