package org.eclipse.core.internal.runtime;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Vector;

/**
 * A utility for manipulating <code>URL</code>s.
 */
public class URLTool {
/**
 * Returns the given URL with a trailing slash appended to it. If the URL
 * already has a trailing slash the URL is returned unchanged.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Returned URL</th>
 * <tr>
 *   <td>"http://hostname/folder"</td>
 *   <td>"http://hostname/folder/"</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>"http://hostname/folder/"</td>
 * </table>
 *
 * @param url a URL
 * @return    the given URL with a trailing slash
 * @throws    MalformedURLException if the given URL is malformed
 */
public static URL appendTrailingSlash(String url) throws MalformedURLException {
	return appendTrailingSlash(new URL(url));
}
/**
 * Returns the given <code>URL</code> with a trailing slash appended to
 * it. If the <code>URL</code> already has a trailing slash the
 * <code>URL</code> is returned unchanged.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Returned URL</th>
 * <tr>
 *   <td>"http://hostname/folder"</td>
 *   <td>"http://hostname/folder/"</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>"http://hostname/folder/"</td>
 * </table>
 *
 * @param url a URL
 * @return    the given URL with a trailing slash
 */
public static URL appendTrailingSlash(URL url){
	String file = url.getFile();
	if (file.endsWith("/"))
		return url;
	try {
		return new URL(url.getProtocol(), url.getHost(), url.getPort(), file + "/");
	} catch(MalformedURLException e){
		Assert.isTrue(false, "internal error");
	}
	return null;
}
/**
 * Returns the child URL formed by joining the given member with the
 * given parent URL.
 *
 * @return a child URL of the given parent
 * @throws MalformedURLException if the given parent is malformed
 */
public static URL getChild(String parent, String member) throws MalformedURLException {
	return getChild(new URL(parent), member);
}
/**
 * Returns the child URL formed by joining the given member with the
 * given parent URL.
 *
 * @return a child URL of the given parent
 */
public static URL getChild(URL parent, String member){
	String file = parent.getFile();
	if (!file.endsWith("/"))
		file = file + "/";
	try {
		return new URL(parent.getProtocol(), parent.getHost(), parent.getPort(), file + member);
	} catch(MalformedURLException e){
		Assert.isTrue(false, "internal error");
	}
	return null;
}
/**
 * Returns all elements in the given URLs path.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Element</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>[]</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>[folder]</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>[folder, file]</td>
 * </table>
 * @param url a URL
 * @return    all elements in the given URLs path
 * @throws    MalformedURLException if the given URL is malformed
 */
public static Vector getElements(String url) throws MalformedURLException {
	return getElements(new URL(url));
}
/**
 * Returns all elements in the given URLs path.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Element</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>[]</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>[folder]</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>[folder, file]</td>
 * </table>
 * @param url a URL
 * @return    all elements in the given URLs path
 */
public static Vector getElements(URL url){
	Vector result = new Vector(5);
	String lastElement = null;
	while((lastElement = getLastElement(url)) != null){
		result.insertElementAt(lastElement, 0);
		url = getParent(url);
	}
	return result;
}
/**
 * Returns the last element in the given URLs path, or <code>null</code>
 * if the URL is the root.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Last Element</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>null</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>folder</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>file</td>
 * </table>
 * @param url a URL
 * @return    the last element in the given URLs path, or
 *            <code>null</code> if the URL is the root
 * @throws    MalformedURLException if the given URL is malformed
 */
public static String getLastElement(String url) throws MalformedURLException {
	return getLastElement(new URL(url));
}
/**
 * Returns the last element in the given URLs path, or <code>null</code>
 * if the URL is the root.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Last Element</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>null</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>folder</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>file</td>
 * </table>
 * @param url a URL
 * @return    the last element in the given URLs path, or
 *            <code>null</code> if the URL is the root
 */
public static String getLastElement(URL url){
	String file = url.getFile();
	int len = file.length();
	if (len == 0 || len == 1 && file.charAt(0) == '/')
		return null;

	int lastSlashIndex = -1;
	for(int i = len - 2; lastSlashIndex == -1 && i >= 0; --i) {
		if (file.charAt(i) == '/')
			lastSlashIndex = i;
	}
	boolean isDirectory = file.charAt(len - 1) == '/';
	if (lastSlashIndex == -1) {
		if (isDirectory){
			return file.substring(0, len - 1);
		} else {
			return file;
		}
	} else {
		if (isDirectory) {
			return file.substring(lastSlashIndex + 1, len - 1);
		} else {
			return file.substring(lastSlashIndex + 1, len);
		}
	}
}
/**
 * Returns the parent URL of the given URL, or <code>null</code> if the
 * given URL is the root.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Parent URL</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>null</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>"http://hostname/folder/</td>
 * </table>
 *
 * @param url a URL
 * @return    the parent of the given URL
 * @throws    MalformedURLException if the given URL is malformed
 */
public static URL getParent(String url) throws MalformedURLException {
	return getParent(new URL(url));
}
/**
 * Returns the parent URL of the given URL, or <code>null</code> if the
 * given URL is the root.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Parent URL</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>null</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>"http://hostname/folder/</td>
 * </table>
 *
 * @param url a URL
 * @return    the parent of the given URL
 */
public static URL getParent(URL url) {
	String file = url.getFile();
	int len = file.length();
	if (len == 0 || len == 1 && file.charAt(0) == '/')
		return null;
	int lastSlashIndex = -1;
	for (int i = len - 2; lastSlashIndex == -1 && i >= 0; --i){
		if (file.charAt(i) == '/')
			lastSlashIndex = i;
	}
	if (lastSlashIndex == -1)
		file = "";
	else
		file = file.substring(0, lastSlashIndex + 1);

	try {
		url = new URL(url.getProtocol(), url.getHost(), url.getPort(), file);
	} catch(MalformedURLException e){
		Assert.isTrue(false, e.getMessage());
	}
	return url;
}
/**
 * Returns the root URL of the given URL.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Root URL</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>"http://hostname/"</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>"http://hostname/"</td>
 * </table>
 *
 * @param urlString a URL
 * @return          the root url of the given URL
 * @throws          MalformedURLException if the given URL is malformed
 */
public static URL getRoot(String urlString) throws MalformedURLException {
	return getRoot(new URL(urlString));
}
/**
 * Returns the root URL of the given URL.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Root URL</th>
 * <tr>
 *   <td>"http://hostname/"</td>
 *   <td>"http://hostname/"</td>
 * <tr>
 *   <td>"http://hostname/folder/file</td>
 *   <td>"http://hostname/"</td>
 * </table>
 *
 * @param url a URL
 * @return    the root URL of the given URL
 */
public static URL getRoot(URL url) {
	try {
		return new URL(url.getProtocol(), url.getHost(), url.getPort(), "/");
	} catch(MalformedURLException e){
		Assert.isTrue(false, "internal error");
	}

	return null;
}
/**
 * Returns the given URL with its trailing slash removed. If the URL has
 * no trailing slash, the URL is returned unchanged.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Returned URL</th>
 * <tr>
 *   <td>"http://hostname/folder"</td>
 *   <td>"http://hostname/folder"</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>"http://hostname/folder"</td>
 * </table>
 *
 * @param url a URL
 * @return    the given URL with its last slash removed
 * @throws    MalformedURLException if the given URL is malformed
 */
public static URL removeTrailingSlash(String url) throws MalformedURLException {
	return removeTrailingSlash(new URL(url));
}
/**
 * Returns the given URL with its trailing slash removed. If the URL has
 * no trailing slash, the URL is returned unchanged.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>Given URL</th>
 *   <th>Returned URL</th>
 * <tr>
 *   <td>"http://hostname/folder"</td>
 *   <td>"http://hostname/folder"</td>
 * <tr>
 *   <td>"http://hostname/folder/</td>
 *   <td>"http://hostname/folder"</td>
 * </table>
 *
 * @param url a URL
 * @return    the given URL with its last slash removed
 */
public static URL removeTrailingSlash(URL url) {
	String file = url.getFile();

	if(file.endsWith("/")){
		file = file.substring(0, file.length() - 1);
		try {
			return new URL(
				url.getProtocol(),
				url.getHost(),
				url.getPort(),
				file);
		} catch(MalformedURLException e){
			Assert.isTrue(false, e.getMessage());
		}
	} else {
		return url;
	}

	return null;
}
/**
 * Returns a boolean indicating whether the given URLs overlap.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>First URL</th>
 *   <th>Second URL</th>
 *   <th>Do they overlap</th>
 * <tr>
 *   <td>"http://hostname/folder/"</td>
 *   <td>"http://hostname/folder/"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder/"</td>
 *   <td>"http://hostname/folder/file"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder/file"</td>
 *   <td>"http://hostname/folder/"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder1/"</td>
 *   <td>"http://hostname/folder2/"</td>
 *   <td>false</td>
 * </table>
 * @param  url1 firt URL
 * @param  url2 second URL
 * @return a boolean indicating whether the given URLs overlap
 */
public static boolean urlsOverlap(String url1, String url2) throws MalformedURLException {
	return urlsOverlap(new URL(url1), new URL(url2));
}
/**
 * Returns a boolean indicating whether the given URLs overlap.
 * <table>
 * <caption>Example</caption>
 * <tr>
 *   <th>First URL</th>
 *   <th>Second URL</th>
 *   <th>Do they overlap</th>
 * <tr>
 *   <td>"http://hostname/folder/"</td>
 *   <td>"http://hostname/folder/"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder/"</td>
 *   <td>"http://hostname/folder/file"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder/file"</td>
 *   <td>"http://hostname/folder/"</td>
 *   <td>true</td>
 * <tr>
 *   <td>"http://hostname/folder1/"</td>
 *   <td>"http://hostname/folder2/"</td>
 *   <td>false</td>
 * <tr>
 *   <td>"http://hostname1/folder/"</td>
 *   <td>"http://hostname2/folder/"</td>
 *   <td>false</td>
 * </table>
 * @param  url1 firt URL
 * @param  url2 second URL
 * @return a boolean indicating whether the given URLs overlap
 */
public static boolean urlsOverlap(URL url1, URL url2){
	if(!getRoot(url1).equals(getRoot(url2))){
		return false;
	}

	Vector elements1 = URLTool.getElements(url1);
	Vector elements2 = URLTool.getElements(url2);

	for(int i = 0; i < elements1.size() && i < elements2.size(); ++i){
		String element1 = (String)elements1.elementAt(i);
		String element2 = (String)elements2.elementAt(i);
		if(!element1.equals(element2)){
			return false;
		}
	}

	return true;
}
}