Chatto/src/main/java/org/ros/chatto/captcha/SimpleCaptcha.java

package org.ros.chatto.captcha;

import javax.imageio.ImageIO;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * This class represents a simple captcha consisting of an image {@code png} and
 * its text value. Comic Neue Bold Font. Capital english letters {@code ONLY}.
 *
 * @since 1.3
 * @author Gennadiy Golovin
 */
public final class SimpleCaptcha {

	private BufferedImage imagePng;
	private char[] text;

	/**
	 * Initializes a newly created default object consisting of 8 capital
	 * english letters.
	 */
	public SimpleCaptcha() {
		this.text = getRandomChars();

		try {
			generateCaptcha();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * Initializes a newly created object, which length depends on the passed
	 * {@code int} parameter, which {@code MUST} be greater than 0. If the
	 * condition is not met, initializes a newly created default object
	 * consisting of 8 symbols.
	 *
	 * @param length
	 *            the quantity of symbols, that the captcha consists of, greater
	 *            than 0.
	 */
	public SimpleCaptcha(int length) {
		if (length < 1) {
			this.text = getRandomChars();
		} else {
			this.text = getRandomChars(length);
		}

		try {
			generateCaptcha();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * Initializes a newly created object based on the passed {@link String}
	 * parameter, consisting of capital english letters. If the condition is not
	 * met, initializes a newly created default object consisting of 8 capital
	 * english letters.
	 *
	 * @param text
	 *            the text string with the value of the captcha, length greater
	 *            than 0.
	 */
	public SimpleCaptcha(String text) {
		if (text == null || text.equals("")) {
			this.text = getRandomChars();
		} else {
			this.text = text.toCharArray();
		}

		try {
			generateCaptcha();
		} catch (IOException e) {
			this.text = getRandomChars();
			try {
				generateCaptcha();
			} catch (IOException ex) {
				ex.printStackTrace();
			}
		}
	}

	/**
	 * Returns the picture with captcha
	 *
	 * @return {@link BufferedImage}
	 */
	public BufferedImage getImagePng() {
		return imagePng;
	}

	/**
	 * Returns the text value of the captcha
	 *
	 * @return {@link String}
	 */
	public String getText() {
		return String.valueOf(text);
	}

	//////// //////// //////// //////// //////// //////// //////// ////////

	private char[] getRandomChars() {
		return getRandomChars(8);
	}

	private char[] getRandomChars(int quantity) {

		char[] randomString = new char[quantity];

		Random random = new Random();

		int capitalLetter;

		for (int i = 0; i < quantity; i++) {
			capitalLetter = 65 + random.nextInt(26);
			randomString[i] = (char) capitalLetter;
		}

		return randomString;
	}

	private void generateCaptcha() throws IOException {
		int charsQuantity = this.text.length;
		BufferedImage[] images = new BufferedImage[charsQuantity];

		for (int i = 0; i < charsQuantity; i++) {
			images[i] = ImageIO.read(SimpleCaptcha.class
					.getResourceAsStream("/pictures/" + this.text[i] + ".png"));
			if (i % 2 == 0) {
				images[i] = rotateImage(images[i], 25);
			} else {
				images[i] = rotateImage(images[i], -20);
			}
		}

		int imageSize = 30;
		int rotatedImageSize = (int) Math.sqrt(imageSize * imageSize * 2);

		BufferedImage captchaImg = new BufferedImage(
				rotatedImageSize * (charsQuantity - 1) / 10 * 6
						+ rotatedImageSize,
				rotatedImageSize, BufferedImage.TYPE_INT_ARGB);
		Graphics2D graphics2d = captchaImg.createGraphics();
		graphics2d.setBackground(Color.WHITE);
		graphics2d.clearRect(0, 0, captchaImg.getWidth(),
				captchaImg.getHeight());
		for (int i = 0; i < charsQuantity; i++) {
			captchaImg.getGraphics().drawImage(images[i],
					rotatedImageSize * i / 10 * 6, 0, null);
		}
		graphics2d.dispose();
		this.imagePng = captchaImg;
	}

	private BufferedImage rotateImage(BufferedImage buffImage, double angle) {

		double radian = Math.toRadians(angle);
		double sin = Math.abs(Math.sin(radian));
		double cos = Math.abs(Math.cos(radian));

		int width = buffImage.getWidth();
		int height = buffImage.getHeight();

		int nWidth = (int) Math
				.floor((double) width * cos + (double) height * sin);
		int nHeight = (int) Math
				.floor((double) height * cos + (double) width * sin);

		BufferedImage rotatedImage = new BufferedImage(nWidth, nHeight,
				BufferedImage.TYPE_INT_ARGB);

		Graphics2D graphics = rotatedImage.createGraphics();

		graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
				RenderingHints.VALUE_INTERPOLATION_BICUBIC);
		graphics.translate((nWidth - width) / 2, (nHeight - height) / 2);
		graphics.rotate(radian, (double) (width / 2), (double) (height / 2));
		graphics.drawImage(buffImage, 0, 0, null);
		graphics.dispose();

		return rotatedImage;
	}
}