/**

 * 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;

		}

	}

}