/**
 * 
 */
package rezend.ecomm.tools;

import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;

import javax.imageio.ImageIO;

import net.sourceforge.tess4j.Tesseract;
import net.sourceforge.tess4j.TesseractException;

/**
 * This class provides the necessary methods to read the text content of simple
 * images using the tesseract library.
 * 
 * @author Rafael Rezende
 * 
 */
public final class OCRModule {

	/**
	 * Scale factor of the price image for Tesseract OCR. It strongly affects
	 * the precision of the OCR. Recommended: 2 for AffineTransform; 3 for
	 * Graphics.
	 */
	static final int SCALE = 2;
	/**
	 * Flag to use graphics. readImage() will use AffineTransform otherwise.
	 * Default: false.
	 */
	static final boolean USE_GRAPHICS = false;

	/**
	 * Type of transformation in case AffineTransform is used. It strongly
	 * affects the precision of the OCR. Types are
	 * AffineTransformOp.TYPE_BICUBIC (recommended),
	 * AffineTransformOp.TYPE_BILINEAR and
	 * AffineTransformOp.TYPE_NEAREST_NEIGHBOR.
	 */
	static final int AFFINE_TRANSFORMATION_TYPE = AffineTransformOp.TYPE_BICUBIC;

	/**
	 * Singleton instance of Tesseract.
	 */
	static Tesseract instance = Tesseract.getInstance();

	/**
	 * Get value from the price image. This image must be scaled before running
	 * through Tesseract. Options are available as constants above.
	 * 
	 * @param url
	 *            URL of the image
	 * @return the value read in the price image.
	 */
	public static double readImage(URL url) {

		// product price
		Double price = null;

		try {

			// buffer that holds the image from url
			BufferedImage priceImg = ImageIO.read(url);

			// preventive for too small figures (invalid values) returned from
			// the url
			if (priceImg.getWidth() < 20 || priceImg.getHeight() < 20)
				return 0.0;

			// buffer that holds the scaled image
			BufferedImage scaledPriceImg = new BufferedImage(
					priceImg.getWidth() * SCALE, priceImg.getHeight() * SCALE,
					BufferedImage.TYPE_INT_RGB);

			if (USE_GRAPHICS) {
				// Scale solution using Graphics
				Graphics2D grph = (Graphics2D) scaledPriceImg.getGraphics();
				grph.scale(SCALE, SCALE);
				grph.drawImage(priceImg, 0, 0, null);
				grph.dispose();
			} else {
				// Scale solution using AffineTransform
				AffineTransform at = new AffineTransform();
				at.scale(SCALE, SCALE);
				AffineTransformOp scaleOp = new AffineTransformOp(at,
						AFFINE_TRANSFORMATION_TYPE);
				scaledPriceImg = scaleOp.filter(priceImg, scaledPriceImg);
			}

			// run the Tesseract OCR to get the text from the image
			String priceStr = instance.doOCR(scaledPriceImg);

			// get the german number format due to comma
			NumberFormat format = NumberFormat.getInstance(Locale.GERMAN);
			price = format.parse(priceStr).doubleValue();

		} catch (IOException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		} catch (TesseractException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return price;
	}

	/**
	 * Get value from the price image. This image must be scaled before running
	 * through Tesseract. Options are available as constants above.
	 * 
	 * @param url
	 *            URL String of the image
	 * @return the value read in the price image.
	 */
	public static double readImage(String urlStr) {
		
		URL url = null;
		try {
			// complete the url with "http://" in case the given one does not
			// provide the protocol (https, ftp etc)
			if (!urlStr.toLowerCase().contains("://")) {
				urlStr = "http://" + urlStr;
			}
			
			// create URL from string
			url = new URL(urlStr);
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		// if the URL is invalid, return -1
		if (url == null)
			return -1.0;

		// else return the readImage(url) accordingly
		return readImage(url);

	}
}