/**

  * copy-image-resizer

  * Copyright © 2014 František Kučera (frantovo.cz)

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. If not, see <http://www.gnu.org/licenses/>.

  */

 package cz.frantovo.copyImageResizer;

 import java.awt.Graphics2D;

 import java.awt.image.BufferedImage;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStream;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import java.util.regex.Pattern;

 import javax.imageio.ImageIO;

 /**

  *

  * @author Ing. František Kučera (frantovo.cz)

  */

 public class SingleImageResizer {

 	private static final Logger log = Logger.getLogger(SingleImageResizer.class.getName());

 	/**

 	 *

 	 * @param input

 	 * @param output

 	 * @param size

 	 * @param outputFormat

 	 * @return whether image was resized → if false, you should just copy the image after calling

 	 * this method. Image is resized if larger than requested size or if {@linkplain SizeSpecification#isResizeSmaller()

 	 * }.

 	 * @throws ResizeException

 	 */

 	public boolean resize(InputStream input, OutputStream output, SizeSpecification size, ImageFormat outputFormat) throws ResizeException {

 		try {

 			BufferedImage image = readImage(input);

 			if (shouldResize(image, size)) {

 				BufferedImage resized = resize(image, size.getWidth(), size.getHeight(), image.getType());

 				ImageIO.write(resized, outputFormat.getFormat(), output);

 				return true;

 			} else {

 				return false;

 			}

 		} catch (IOException e) {

 			throw new ResizeException("Error while resizing image", e);

 		}

 	}

 	private BufferedImage resize(BufferedImage original, int maxWidth, int maxHeight, int type) {

 		int width;

 		int height;

 		float aspectRatio = (float) original.getWidth() / (float) original.getHeight();

 		if (aspectRatio > 1) {

 			width = maxWidth;

 			height = Math.max(Math.round(maxWidth / aspectRatio), 1);

 		} else {

 			width = Math.max(Math.round(maxHeight * aspectRatio), 1);

 			height = maxHeight;

 		}

 		if (type == BufferedImage.TYPE_CUSTOM) {

 			log.log(Level.FINER, "Setting default image type: from TYPE_CUSTOM to TYPE_INT_ARGB");

 			type = BufferedImage.TYPE_INT_ARGB;

 		}

 		BufferedImage resized = new BufferedImage(width, height, type);

 		Graphics2D g = resized.createGraphics();

 		g.drawImage(original, 0, 0, width, height, null);

 		g.dispose();

 		return resized;

 	}

 	private static BufferedImage readImage(InputStream input) throws ResizeException {

 		try {

 			return ImageIO.read(input);

 		} catch (IOException e) {

 			throw new ResizeException("Unable to read image from stream", e);

 		}

 	}

 	private static boolean shouldResize(BufferedImage input, SizeSpecification requested) {

 		if (requested.isResizeSmaller()) {

 			return input.getHeight() != requested.getHeight() || input.getWidth() != requested.getWidth();

 		} else {

 			return input.getHeight() > requested.getHeight() || input.getWidth() > requested.getWidth();

 		}

 	}

 	public static enum ImageFormat {

 		JPEG("jpg", Pattern.compile(".*\\.(jpg|jpeg)$", Pattern.CASE_INSENSITIVE)),

 		PNG("png", Pattern.compile(".*\\.png$", Pattern.CASE_INSENSITIVE)),

 		GIF("gif", Pattern.compile(".*\\.gif$", Pattern.CASE_INSENSITIVE));

 		private final String format;

 		private final Pattern regex;

 		private ImageFormat(String format, Pattern regex) {

 			this.format = format;

 			this.regex = regex;

 		}

 		/**

 		 * @return format name for {@linkplain ImageIO#write(java.awt.image.RenderedImage, java.lang.String, java.io.File)

 		 */

 		public String getFormat() {

 			return format;

 		}

 		public static ImageFormat getMatching(String fileName) {

 			for (ImageFormat type : values()) {

 				if (type.regex.matcher(fileName).matches()) {

 					return type;

 				}

 			}

 			return null;

 		}

 	}

 }