/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.resource;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.eclipse.core.runtime.FileLocator;
import org.eclipse.core.runtime.Path;
import org.eclipse.jface.internal.JFaceActivator;
import org.eclipse.jface.util.Policy;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.graphics.Device;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;

/**
 * An image descriptor that loads its image information from a file.
 */
class FileImageDescriptor extends ImageDescriptor {

	/**
	 * The class whose resource directory contain the file, or <code>null</code>
	 * if none.
	 */
	private Class location;

	/**
	 * The name of the file.
	 */
	private String name;

	/**
	 * Creates a new file image descriptor. The file has the given file name and
	 * is located in the given class's resource directory. If the given class is
	 * <code>null</code>, the file name must be absolute.
	 * <p>
	 * Note that the file is not accessed until its <code>getImageDate</code>
	 * method is called.
	 * </p>
	 * 
	 * @param clazz
	 *            class for resource directory, or <code>null</code>
	 * @param filename
	 *            the name of the file
	 */
	FileImageDescriptor(Class clazz, String filename) {
		this.location = clazz;
		this.name = filename;
	}

	/*
	 * (non-Javadoc) Method declared on Object.
	 */
	public boolean equals(Object o) {
		if (!(o instanceof FileImageDescriptor)) {
			return false;
		}
		FileImageDescriptor other = (FileImageDescriptor) o;
		if (location != null) {
			if (!location.equals(other.location)) {
				return false;
			}
		} else {
			if (other.location != null) {
				return false;
			}
		}
		return name.equals(other.name);
	}

	/**
	 * @see org.eclipse.jface.resource.ImageDescriptor#getImageData() The
	 *      FileImageDescriptor implementation of this method is not used by
	 *      {@link ImageDescriptor#createImage(boolean, Device)} as of version
	 *      3.4 so that the SWT OS optimised loading can be used.
	 */
	public ImageData getImageData() {
		InputStream in = getStream();
		ImageData result = null;
		if (in != null) {
			try {
				result = new ImageData(in);
			} catch (SWTException e) {
				if (e.code != SWT.ERROR_INVALID_IMAGE) {
					throw e;
					// fall through otherwise
				}
			} finally {
				try {
					in.close();
				} catch (IOException e) {
					// System.err.println(getClass().getName()+".getImageData():
					// "+
					// "Exception while closing InputStream : "+e);
				}
			}
		}
		return result;
	}

	/**
	 * Returns a stream on the image contents. Returns null if a stream could
	 * not be opened.
	 * 
	 * @return the buffered stream on the file or <code>null</code> if the
	 *         file cannot be found
	 */
	private InputStream getStream() {
		InputStream is = null;

		if (location != null) {
			is = location.getResourceAsStream(name);

		} else {
			try {
				is = new FileInputStream(name);
			} catch (FileNotFoundException e) {
				return null;
			}
		}
		if (is == null) {
			return null;
		}
		return new BufferedInputStream(is);

	}

	/*
	 * (non-Javadoc) Method declared on Object.
	 */
	public int hashCode() {
		int code = name.hashCode();
		if (location != null) {
			code += location.hashCode();
		}
		return code;
	}

	/*
	 * (non-Javadoc) Method declared on Object.
	 */
	/**
	 * The <code>FileImageDescriptor</code> implementation of this
	 * <code>Object</code> method returns a string representation of this
	 * object which is suitable only for debugging.
	 */
	public String toString() {
		return "FileImageDescriptor(location=" + location + ", name=" + name + ")";//$NON-NLS-3$//$NON-NLS-2$//$NON-NLS-1$
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.resource.ImageDescriptor#createImage(boolean,
	 *      org.eclipse.swt.graphics.Device)
	 */
	public Image createImage(boolean returnMissingImageOnError, Device device) {
		String path = getFilePath();
		if (path == null)
			return createDefaultImage(returnMissingImageOnError, device);
		try {			
			return new Image(device, path);
		} catch (SWTException exception) {
			//if we fail try the default way using a stream
		}
		return super.createImage(returnMissingImageOnError, device);
	}

	/**
	 * Return default image if returnMissingImageOnError is true.
	 * 
	 * @param device
	 * @return Image or <code>null</code>
	 */
	private Image createDefaultImage(boolean returnMissingImageOnError,
			Device device) {
		try {
			if (returnMissingImageOnError)
				return new Image(device, DEFAULT_IMAGE_DATA);
		} catch (SWTException nextException) {
			return null;
		}
		return null;
	}

	/**
	 * Returns the filename for the ImageData.
	 * 
	 * @return {@link String} or <code>null</code> if the file cannot be found
	 */
	private String getFilePath() {

		if (location == null)
			return new Path(name).toOSString();

		URL resource = location.getResource(name);

		if (resource == null)
			return null;
		try {
			if (JFaceActivator.getBundleContext() == null) {// Stand-alone case

				return new Path(resource.getFile()).toOSString();
			}
			return new Path(FileLocator.toFileURL(resource).getPath()).toOSString();
		} catch (IOException e) {
			Policy.logException(e);
			return null;
		}
	}
}