import java.awt.Color;
import java.io.File;
import java.net.URL;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.awt.image.BufferedImageOp;
import java.awt.image.ColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;

/**
 * This class allows you to view and edit pictures.
 */
public class Picture
{ 
   private String source;
   private JFrame frame;
   private JLabel label;
   private BufferedImage image;

   /**
      Constructs a blank picture.
   */
   public Picture()
   {
      frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      label = new JLabel("(No image)");
      frame.add(label);
      frame.pack();
      frame.setVisible(true);      
   }
  
   /**
      Gets the width of this picture.
      @return the width
    */
   public int getWidth() { return image.getWidth(); }
   
   /**
      Gets the height of this picture.
      @return the height
    */
   public int getHeight() { return image.getHeight(); }
   
   /**
      Loads a picture from a given source. 
      @param source the image source. If the source starts
      with http://, it is a URL, otherwise, a filename.
    */
   public void load(String source)
   {
      try 
      {
         this.source = source;
         BufferedImage img;
         if (source.startsWith("http://"))
            img = ImageIO.read(new URL(source).openStream());
         else
            img = ImageIO.read(new File(source));

         setImage(img);        
      }
      catch (Exception ex)
      {
         this.source = null;
         ex.printStackTrace();
      }
   }      

   /**
      Reloads this picture, undoing any manipulations.
    */
   public void reload()
   {
      load(source);
   }
   
   /**
      Displays a file chooser for picking a picture.
    */
   public void pick()
   {
      JFileChooser chooser = new JFileChooser(".");
      if (chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION)
      {
         load(chooser.getSelectedFile().getAbsolutePath());
      }
   }   

   /**
      Moves this picture by the given amount in x- and y-direction. 
      @param dx the offset in the x-direction
      @param dy the offset in the y-direction
    */
   public void move(int dx, int dy)
   {
      BufferedImageOp op = new AffineTransformOp(
         AffineTransform.getTranslateInstance(dx, dy), 
         AffineTransformOp.TYPE_BILINEAR);
      BufferedImage filteredImage
         = new BufferedImage(image.getWidth(), image.getHeight(), 
            BufferedImage.TYPE_INT_ARGB);
      op.filter(image, filteredImage);
      setImage(filteredImage);
   }

   /**
      Scales this picture to a new size. If the new size is smaller 
      than the old size, the remainder is filled with transparent 
      pixels. If it is larger, it is clipped.
      @param newWidth the new width of the picture
      @param newHeight the new height of the picture
   */
   public void scale(int newWidth, int newHeight)
   {
      double dx = newWidth * 1.0 / image.getWidth();
      double dy = newHeight * 1.0 / image.getHeight();
      BufferedImageOp op = new AffineTransformOp(
         AffineTransform.getScaleInstance(dx, dy), 
         AffineTransformOp.TYPE_BILINEAR);
      BufferedImage filteredImage
         = new BufferedImage(image.getWidth(), image.getHeight(), 
            BufferedImage.TYPE_INT_ARGB);
      op.filter(image, filteredImage);
      setImage(filteredImage);
   }

   /**
      Adds a black border to the image.
      @param width the border width
   */
   public void border(int width)
   {
      for (int x = 0; x < width; x++)
      {
         for (int y = 0; y < image.getHeight(); y++)
         {
            setColorAt(x, y, Color.BLACK);
            setColorAt(image.getWidth() - 1 - x, y, Color.BLACK);      
         }
      }
      for (int y = 0;  y < width; y++)
      {
         for (int x = width; x < image.getWidth() - width; x++)
         {
            setColorAt(x, y, Color.BLACK);
            setColorAt(x, image.getHeight() - 1 - y, Color.BLACK);      
         }
      }
   }

   /**
      Gets the color of a pixel.
      @param x the column index (between 0 and getWidth() - 1)
      @param y the row index (between 0 and getHeight() - 1)
      @return the color of the pixel at position (x, y)
   */
   public Color getColorAt(int x, int y)
   {
      Raster raster = image.getRaster();
      ColorModel model = image.getColorModel();
      int argb = model.getRGB(raster.getDataElements(x, y, null));
      return new Color(argb, true);
   }

   /**
      Sets the color of a pixel.
      @param x the column index (between 0 and getWidth() - 1)
      @param y the row index (between 0 and getHeight() - 1)
      @param c the color for the pixel at position (x, y)
   */
   public void setColorAt(int x, int y, Color c)
   {
      WritableRaster raster = image.getRaster();
      ColorModel model = image.getColorModel();
      Object colorData = model.getDataElements(c.getRGB(), null);
      raster.setDataElements(x, y, colorData);
      label.repaint();
   }

   private void setImage(BufferedImage image)
   {
      this.image = image;
      label.setIcon(new ImageIcon(image));
      label.setText("");
      label.setSize(image.getWidth(), image.getHeight());
      frame.pack();
   }
}