/*
 * Copyright (c) 2002 Lightweight Java Game Library Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'Light Weight Java Game Library' nor the names of
 *   its contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.lwjgl.input;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.IntBuffer;

import org.lwjgl.Sys;

/**
 * $Id$
 *
 * A class representing a native cursor. Instances of this
 * class can be used with Mouse.setCursor(), if available.
 *
 * @author elias_naur <elias_naur@users.sourceforge.net>
 * @version $Revision$
 */

public class Cursor {
  
  /** Lazy initialization */
  private static boolean initialized = false;
  
  /** First element to display */
  private CursorElement[] cursors = null;
  
  /** Index into list of cursors */
  private int index = -1;
  
  /**
   * Constructs a new Cursor, with the given parameters. Mouse must have been created before you can create
   * Cursor objects. Cursor images are in ARGB format, but only one bit transparancy is guaranteed to be supported.
   * So to maximize portability, lwjgl applications should only create cursor images with 0x00 or 0xff as alpha values.
   * The constructor will copy the images and delays, so there's no need to keep them around.
   *
   * @param width cursor image width
   * @param height cursor image height
   * @param xHotspot the x coordinate of the cursor hotspot
   * @param yHotspot the y coordinate of the cursor hotspot
   * @param numImages number of cursor images specified. Must be 1 if animations are not supported.
   * @param images A buffer containing the images. The origin is at the lower left corner, like OpenGL.
   * @param delays An int buffer of animation frame delays, if numImages is greater than 1, else null
   * @throws Exception if the cursor could not be created for any reason
   */  
  public Cursor(int width, int height, int xHotspot, int yHotspot, int numImages, IntBuffer images, IntBuffer delays) throws Exception {
    assert Mouse.isCreated();
    assert width*height*numImages <= images.remaining()       : "width*height*numImages > images.remaining()";
    assert delays == null || numImages <= delays.remaining()  : "delays != null && numImages > delays.remaining()";
    assert xHotspot < width && xHotspot >= 0                  : "xHotspot > width || xHotspot < 0";
    assert yHotspot < height && yHotspot >= 0                 : "yHotspot > height || yHotspot < 0";
    
    // initialize
    if (!initialized) {
      initialize();
    }
    
    // Hmm 
    yHotspot = height - 1 - yHotspot;    
    
    // create cursor (or cursors if multiple images supplied)
    createCursors(width, height, xHotspot, yHotspot, numImages, images, delays);
  }
  
  /**
   * Initializes the cursor class
   */
  private static void initialize() {
    System.loadLibrary(Sys.getLibraryName());
    initialized = true;
  }  

  /**
   * Creates the actual cursor, using a platform specific class
   */
  private void createCursors(int width, int height, int xHotspot, int yHotspot, int numImages, IntBuffer images, IntBuffer delays) throws Exception {
    // create copy and flip images to match ogl
    IntBuffer images_copy = ByteBuffer.allocateDirect(images.remaining()*4).order(ByteOrder.nativeOrder()).asIntBuffer();
    flipImages(width, height, numImages, images, images_copy);
    
    // create our cursor elements
    cursors = new CursorElement[numImages];
    for(int i=0; i<numImages; i++) {
    	cursors[i] = new CursorElement();
      cursors[i].cursorHandle = nCreateCursor(width, height, xHotspot, yHotspot, 1, images_copy, images_copy.position());
      cursors[i].delay = (delays != null) ? delays.get(i) : 0;
      cursors[i].timeout = System.currentTimeMillis();
      
      // offset to next image
      images_copy.position(width*height*(i+1));
    }
    
    // set index
    index = 0;
  }
 
  
  /**
   * Flips the images so they're oriented according to opengl
   * 
   * @param width Width of image
   * @param height Height of images 
   * @param numImages How many images to flip
   * @param images Source images
   * @param images_copy Destination images
   */
  private static void flipImages(int width, int height, int numImages, IntBuffer images, IntBuffer images_copy) {
    for (int i = 0; i < numImages; i++) {
      int start_index = i*width*height;
      flipImage(width, height, start_index, images, images_copy);
    }
  }

  /**
   * @param width Width of image
   * @param height Height of images 
   * @param start_index index into source buffer to copy to
   * @param images Source images
   * @param images_copy Destination images
   */
  private static void flipImage(int width, int height, int start_index, IntBuffer images, IntBuffer images_copy) {
    for (int y = 0; y < height>>1; y++) {
      int index_y_1 = y*width + start_index;
      int index_y_2 = (height - y - 1)*width + start_index;
      for (int x = 0; x < width; x++) {
        int index1 = index_y_1 + x;
        int index2 = index_y_2 + x;
        int temp_pixel = images.get(index1 + images.position());
        images_copy.put(index1, images.get(index2 + images.position()));
        images_copy.put(index2, temp_pixel);
      }
    }
  }  
  
  /**
   * Gets the native handle associated with the cursor object.
   */
  public long getHandle() {
  	return cursors[index].cursorHandle;
  }
  
  /**
   * Destroy the native cursor. Cursor must not be current.
   */
  public void destroy() {
		for(int i=0; i<cursors.length; i++) {
      nDestroyCursor(cursors[i].cursorHandle);
    }
  }

  /**
   * Sets the timout property to the time it should be changed
   */
  protected void setTimeout() {
    cursors[index].timeout = System.currentTimeMillis() + cursors[index].delay;
  }

  /**
   * Determines whether this cursor has timed out
   * @return true if the this cursor has timed out, false if not
   */
  protected boolean hasTimedOut() {
  	return cursors.length > 1 && cursors[index].timeout < System.currentTimeMillis();
  }

  /** 
   * Changes to the next cursor 
   */
  protected void nextCursor() {
    index = ++index % cursors.length;
  }

  /** 
   * Resets the index of the cursor animation to the first in the list. 
   */
  public void resetAnimation() {
    index = 0;
  }
  
  /**
   * Native method to create a native cursor
   */
  private static native long nCreateCursor(int width, int height, int xHotspot, int yHotspot, int numImages, IntBuffer images, int images_offset);

  /**
   * Native method to destroy a native cursor
   */
  private static native void nDestroyCursor(long cursorHandle);  
  
  /**
   * A single cursor element, used when animating
   */
  protected class CursorElement {
    /** Handle to cursor */
  	long cursorHandle;
    
    /** How long a delay this element should have */
    long delay;
    
    /** Absolute time this element times out */
    long timeout;
  }
}