/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.myfaces.custom.captcha.util;
  
  import java.awt.Color;
  import java.awt.Font;
  import java.awt.GradientPaint;
  import java.awt.Graphics;
  import java.awt.Graphics2D;
  import java.awt.RenderingHints;
  import java.awt.font.TextLayout;
  import java.awt.image.BufferedImage;
  import java.io.IOException;
  import java.util.Random;
  
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.batik.ext.awt.image.codec.PNGEncodeParam;
  import org.apache.batik.ext.awt.image.codec.PNGImageEncoder;
  
  /**
   * This class is responsible for generating the CAPTCHA image.
   * 
   * @since 1.1.7
   */
  public class CAPTCHAImageGenerator
  {
  
      //private static final Color startingColor = new Color(150, 50, 150);
      //private static final Color endingColor = new Color(255, 255, 255);
  
      /*
      * A helper method to draw the captcha text on the generated image.
      */
      private void drawTextOnImage(Graphics2D graphics, String captchaText)
      {
  
          Font font;
          TextLayout textLayout;
          double currentFontStatus = Math.random();
  
          // Generate random font status.
          if (currentFontStatus >= 0.5)
          {
              font = new Font("Arial", Font.PLAIN, 60);
          }
          else
          {
              font = new Font("Arial", Font.BOLD, 60);
          }
  
          graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                  RenderingHints.VALUE_ANTIALIAS_ON);
          textLayout = new TextLayout(captchaText, font, graphics
                  .getFontRenderContext());
  
          textLayout.draw(graphics, CAPTCHAConstants.TEXT_X_COORDINATE,
                  CAPTCHAConstants.TEXT_Y_COORDINATE);
      }
  
      /*
      * A helper method to apply noise on the generated image.
      */
      private void applyNoiseOnImage(Graphics2D graphics, int bufferedImageWidth,
              int bufferedImageHeight, Color startingColor, Color endingColor)
      {
  
          // Applying shear.
          applyShear(graphics, bufferedImageWidth, bufferedImageHeight,
                  startingColor, endingColor);
  
          // Drawing a broken line on the image.
          drawBrokenLineOnImage(graphics);
      }
  
      /*
      * This helper method is used for applying current gradient paint to the
      * Graphics2D object.
      */
      private static void applyCurrentGradientPaint(Graphics2D graphics,
              int width, int height, Color startingColor, Color endingColor)
      {
  
         GradientPaint gradientPaint = new GradientPaint(0, 0, startingColor,
                 width, height, endingColor);
 
         graphics.setPaint(gradientPaint);
     }
 
     /**
      * This method generates the CAPTCHA image. 
      * @param response
      * @param captchaText
      * @param startingColor
      * @param endingColor
      * @throws IOException
      */
     public void generateImage(HttpServletResponse response, String captchaText,
             Color startingColor, Color endingColor) throws IOException
     {
 
         BufferedImage bufferedImage;
         Graphics2D graphics;
         PNGEncodeParam param;
         PNGImageEncoder captchaPNGImage;
 
         // Create the CAPTCHA Image.
         bufferedImage = new BufferedImage(
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT,
                 BufferedImage.TYPE_BYTE_INDEXED);
 
         // Setup the graphics object.
         graphics = bufferedImage.createGraphics();
 
         applyCurrentGradientPaint(graphics, bufferedImage.getWidth(),
                 bufferedImage.getHeight(), startingColor, endingColor);
 
         graphics.fillRect(0, 0, bufferedImage.getWidth(), bufferedImage
                 .getHeight());
 
         graphics.setColor(Color.black);
 
         // Draw text on the CAPTCHA image.
         drawTextOnImage(graphics, captchaText);
 
         // Apply noise on the CAPTCHA image.
         applyNoiseOnImage(graphics, bufferedImage.getWidth(), bufferedImage
                 .getHeight(), startingColor, endingColor);
 
         // Draw the image border.
         drawBorders(graphics, bufferedImage.getWidth(), bufferedImage
                 .getHeight());
 
         // Set the reponse content type to jpeg.
         response.setContentType("image/jpg");
 
         param = PNGEncodeParam.getDefaultEncodeParam(bufferedImage);
         captchaPNGImage = new PNGImageEncoder(response.getOutputStream(), param);
 
         captchaPNGImage.encode(bufferedImage);
     }
 
     /*
     * This helper method is used for drawing a thick line on the image.
     */
     private void drawThickLineOnImage(Graphics graphics, int x1, int y1,
             int x2, int y2)
     {
 
         int dX = x2 - x1;
         int dY = y2 - y1;
         int xPoints[] = new int[4];
         int yPoints[] = new int[4];
         int thickness = 2;
 
         double lineLength = Math.sqrt(dX * dX + dY * dY);
         double scale = (double) (thickness) / (2 * lineLength);
         double ddx = -scale * (double) dY;
         double ddy = scale * (double) dX;
 
         graphics.setColor(Color.black);
 
         ddx += (ddx > 0) ? 0.5 : -0.5;
         ddy += (ddy > 0) ? 0.5 : -0.5;
         dX = (int) ddx;
         dY = (int) ddy;
 
         xPoints[0] = x1 + dX;
         yPoints[0] = y1 + dY;
         xPoints[1] = x1 - dX;
         yPoints[1] = y1 - dY;
         xPoints[2] = x2 - dX;
         yPoints[2] = y2 - dY;
         xPoints[3] = x2 + dX;
         yPoints[3] = y2 + dY;
 
         graphics.fillPolygon(xPoints, yPoints, 4);
     }
 
     /*
     * This helper method is used for drawing a broken line on the image.
     */
     private void drawBrokenLineOnImage(Graphics2D graphics)
     {
 
         int yPoint1;
         int yPoint2;
         int yPoint3;
         int yPoint4;
         int yPoint5;
         Random random = new Random();
 
         // Random Y Points.
         yPoint1 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
         yPoint2 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
         yPoint3 = CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT / 2;
         yPoint4 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
         yPoint5 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
 
         // Draw the random broken line.
         drawThickLineOnImage(graphics, 0, yPoint1,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint2);
         drawThickLineOnImage(graphics,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint2,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 2, yPoint3);
         drawThickLineOnImage(graphics,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 2, yPoint3,
                 3 * CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint4);
         drawThickLineOnImage(graphics,
                 3 * CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint4,
                 CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH, yPoint5);
     }
 
     /*
     * This helper method is used for calculating the delta of the shearing
     * equation.
     */
     private double getDelta(int period, double i, double phase, double frames)
     {
         return (double) (period / 2)
                 * Math.sin(i / (double) period
                         + (2 * CAPTCHAConstants.PI * phase) / frames);
     }
 
     /*
     * This helper method is used for applying shear on the image.
     */
     private void applyShear(Graphics2D graphics, int bufferedImageWidth,
             int bufferedImageHeight, Color startingColor, Color endingColor)
     {
 
         int periodValue = 20;
         int numberOfFrames = 15;
         int phaseNumber = 7;
         double deltaX;
         double deltaY;
 
         applyCurrentGradientPaint(graphics, bufferedImageWidth,
                 bufferedImageHeight, startingColor, endingColor);
 
         for (int i = 0; i < bufferedImageWidth; ++i)
         {
             deltaX = getDelta(periodValue, i, phaseNumber, numberOfFrames);
             graphics.copyArea(i, 0, 1, bufferedImageHeight, 0, (int) deltaX);
             graphics.drawLine(i, (int) deltaX, i, 0);
             graphics.drawLine(i, (int) deltaX + bufferedImageHeight, i,
                     bufferedImageHeight);
         }
 
         for (int i = 0; i < bufferedImageHeight; ++i)
         {
             deltaY = getDelta(periodValue, i, phaseNumber, numberOfFrames);
             graphics.copyArea(0, i, bufferedImageWidth, 1, (int) deltaY, 0);
             graphics.drawLine((int) deltaY, i, 0, i);
             graphics.drawLine((int) deltaY + bufferedImageWidth, i,
                     bufferedImageWidth, i);
         }
     }
 
     /*
     * This helper method is used for drawing the borders the image.
     */
     private void drawBorders(Graphics2D graphics, int width, int height)
     {
         graphics.setColor(Color.black);
 
         graphics.drawLine(0, 0, 0, width - 1);
         graphics.drawLine(0, 0, width - 1, 0);
         graphics.drawLine(0, height - 1, width, height - 1);
         graphics.drawLine(width - 1, height - 1, width - 1, 0);
     }
 
 }