/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.ide;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;

import org.eclipse.core.runtime.IBundleGroup;
import org.eclipse.core.runtime.IBundleGroupProvider;
import org.eclipse.core.runtime.IProduct;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.util.Assert;
import org.eclipse.ui.internal.BundleGroupProperties;
import org.eclipse.ui.internal.ProductProperties;

/**
 * The information within this object is obtained from the about INI file.
 * This file resides within an install configurations directory and must be a 
 * standard java property file.  
 * <p>
 * This class is not intended to be instantiated or subclassed by clients.
 * </p>
 */
public final class AboutInfo {
	private ProductProperties productProperties;
	private BundleGroupProperties bundleGroupProperties;

	private Long featureImageCRC;
	private boolean calculatedImageCRC = false;

	/**
	 * The information contained in this info will apply to only the argument product.
	 */
	public AboutInfo(IProduct product) {
	    this.productProperties = new ProductProperties(product);
	}

	/**
	 * This info object will apply to the argument bundle group.
	 */
	public AboutInfo(IBundleGroup bundleGroup) {
	    this.bundleGroupProperties = new BundleGroupProperties(bundleGroup);
	}

	/**
     * Returns the configuration information for the feature with the given id.
     * 
     * @param featureId
     *            the feature id
     * @param versionId
     *            the version id (of the feature)
     * @return the configuration information for the feature
     */
	public static AboutInfo readFeatureInfo(String featureId, String versionId) {
		Assert.isNotNull(featureId);
		Assert.isNotNull(versionId);

		// first see if the id matches the product
		IProduct product = Platform.getProduct();
		if (product != null && featureId.equals(ProductProperties.getProductId(product)))
		    return new AboutInfo(product);

		// then check the bundle groups
		IBundleGroup bundleGroup = getBundleGroup(featureId, versionId);
		if (bundleGroup != null)
		    return new AboutInfo(bundleGroup);

		return null;
	}

	private static IBundleGroup getBundleGroup(String id, String versionId) {
	    if(id == null || versionId == null)
	        return null;

	    IBundleGroupProvider[] providers = Platform.getBundleGroupProviders();
	    for(int p = 0; p < providers.length; ++p) {
	        IBundleGroup[] groups = providers[p].getBundleGroups();
	        for(int g = 0; g < groups.length; ++g)
	            if(id.equals(groups[g].getIdentifier()) && versionId.equals(groups[g].getVersion()))
	                return groups[g];
	    }

	    return null;
	}
	
	/**
	 * Returns the descriptor for an image which can be shown in an "about" dialog 
	 * for this product. Products designed to run "headless" typically would not 
	 * have such an image.
	 * 
	 * @return the descriptor for an about image, or <code>null</code> if none
	 */
	public ImageDescriptor getAboutImage() {
	    return productProperties == null ? null : productProperties.getAboutImage();
	}

	/**
	 * Returns the descriptor for an image which can be shown in an "about features" 
	 * dialog. Products designed to run "headless" typically would not have such an image.
	 * 
	 * @return the descriptor for a feature image, or <code>null</code> if none
	 */
	public ImageDescriptor getFeatureImage() {
	    return bundleGroupProperties == null ? null : bundleGroupProperties.getFeatureImage();
	}

	/**
	 * Returns the simple name of the feature image file.
	 * 
	 * @return the simple name of the feature image file,
	 * or <code>null</code> if none
	 */
	public String getFeatureImageName() {
	    if (bundleGroupProperties == null)
	        return null;

	    URL url = bundleGroupProperties.getFeatureImageUrl();
	    return url == null ? null : new Path(url.getPath()).lastSegment();
	}

	/**
	 * Returns the CRC of the feature image as supplied in the properties file.
	 * 
	 * @return the CRC of the feature image, or <code>null</code> if none
	 */
	public Long getFeatureImageCRC() {
	    if (bundleGroupProperties == null)
	        return null;

	    if (!calculatedImageCRC) {
            featureImageCRC = calculateImageCRC(bundleGroupProperties.getFeatureImageUrl());
            calculatedImageCRC = featureImageCRC != null;
        }

	    return featureImageCRC;
	}

	/**
	 * Calculate a CRC for the feature image
	 */
	private static Long calculateImageCRC(URL url) {
	    if (url == null)
			return null;
			
		InputStream in = null;
		try {
		    CRC32 checksum = new CRC32();
		    in = new CheckedInputStream(url.openStream(), checksum);

		    // the contents don't matter, the read just needs a place to go
		    byte[] sink = new byte[2048];
		    while(true)
		        if(in.read(sink) <= 0)
		            break;

			return new Long(checksum.getValue());
		} catch (IOException e) {
			return null;
		} finally {
			if (in != null)
				try {
					in.close();
				} catch (IOException e) {
					// do nothing
				}
		}
	}	
		
	/**
	 * Returns a label for the feature plugn, or <code>null</code>.
	 */
	public String getFeatureLabel() {
	    if (productProperties != null)
	        return productProperties.getProductName();
	    if (bundleGroupProperties != null)
	        return bundleGroupProperties.getFeatureLabel();
	    return null;
	}

	/**
	 * Returns the id for this feature.
	 * 
	 * @return the feature id
	 */
	public String getFeatureId() {
	    String id = null;
	    if (productProperties != null)
	        id = productProperties.getProductId();
	    else if (bundleGroupProperties != null)
	        id = bundleGroupProperties.getFeatureId();
	    return id != null ? id : ""; //$NON-NLS-1$ 
	}

	/**
	 * Returns the text to show in an "about" dialog for this product.
	 * Products designed to run "headless" typically would not have such text.
	 * 
	 * @return the about text, or <code>null</code> if none
	 */
	public String getAboutText() {
	    return productProperties == null ? null : productProperties.getAboutText();
	}

	/**
	 * Returns the application name or <code>null</code>.
	 * Note this is never shown to the user.
	 * It is used to initialize the SWT Display.
	 * <p>
	 * On Motif, for example, this can be used
	 * to set the name used for resource lookup.
	 * </p>
	 *
	 * @return the application name, or <code>null</code>
	 * 
	 * @see org.eclipse.swt.widgets.Display#setAppName
	 */
	public String getAppName() {
	    return productProperties == null ? null : productProperties.getAppName();
	}

	/**
	 * Returns the product name or <code>null</code>.
	 * This is shown in the window title and the About action.
	 *
	 * @return the product name, or <code>null</code>
	 */
	public String getProductName() {
	    return productProperties == null ? null : productProperties.getProductName();
	}

	/**
	 * Returns the provider name or <code>null</code>.
	 *
	 * @return the provider name, or <code>null</code>
	 */
	public String getProviderName() {
	    return bundleGroupProperties == null ? null : bundleGroupProperties.getProviderName();
	}

	/**
	 * Returns the feature version id.
	 *
	 * @return the version id of the feature
	 */
	public String getVersionId() {
	    return bundleGroupProperties == null ? "" : bundleGroupProperties.getFeatureVersion(); //$NON-NLS-1$
	}

	/**
	 * Returns a <code>URL</code> for the welcome page.
	 * Products designed to run "headless" typically would not have such an page.
	 * 
	 * @return the welcome page, or <code>null</code> if none
	 */
	public URL getWelcomePageURL() {
	    if (productProperties != null)
	        return productProperties.getWelcomePageUrl();
	    if (bundleGroupProperties != null)
	        return bundleGroupProperties.getWelcomePageUrl();
	    return null;
	}

	/**
	 * Returns the ID of a perspective in which to show the welcome page.
	 * May be <code>null</code>.
	 * 
	 * @return the welcome page perspective id, or <code>null</code> if none
	 */
	public String getWelcomePerspectiveId() {
	    return bundleGroupProperties == null ? null : bundleGroupProperties.getWelcomePerspective();
	}

	/**
	 * Returns a <code>String</code> for the tips and trick href.
	 * 
	 * @return the tips and tricks href, or <code>null</code> if none
	 */
	public String getTipsAndTricksHref() {
	    return bundleGroupProperties == null ? null : bundleGroupProperties.getTipsAndTricksHref();
	}

	/**
	 * Return an array of image descriptors for the window images to use for
	 * this product. The expectations is that the elements will be the same
	 * image rendered at different sizes. Products designed to run "headless"
	 * typically would not have such images.
	 * 
	 * @return an array of the image descriptors for the window images, or
	 *         <code>null</code> if none
	 * @since 3.0
	 */
	public ImageDescriptor[] getWindowImages() {
	    return productProperties == null ? null : productProperties.getWindowImages();
	}
}
