/*******************************************************************************
 * Copyright (c) 2004, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.osgi.storage.url;

import java.io.IOException;
import java.net.*;
import org.eclipse.osgi.container.Module;
import org.eclipse.osgi.container.ModuleContainer;
import org.eclipse.osgi.internal.messages.Msg;
import org.eclipse.osgi.storage.bundlefile.BundleEntry;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.AdminPermission;
import org.osgi.framework.Bundle;

/**
 * URLStreamHandler the bundleentry and bundleresource protocols.
 */

public abstract class BundleResourceHandler extends URLStreamHandler {
	// Bundle resource URL protocol
	public static final String OSGI_RESOURCE_URL_PROTOCOL = "bundleresource"; //$NON-NLS-1$
	// Bundle entry URL protocol
	public static final String OSGI_ENTRY_URL_PROTOCOL = "bundleentry"; //$NON-NLS-1$

	public static final String SECURITY_CHECKED = "SECURITY_CHECKED"; //$NON-NLS-1$
	public static final String SECURITY_UNCHECKED = "SECURITY_UNCHECKED"; //$NON-NLS-1$
	public static final String BID_FWKID_SEPARATOR = ".fwk"; //$NON-NLS-1$
	protected final ModuleContainer container;
	protected BundleEntry bundleEntry;

	public BundleResourceHandler(ModuleContainer container, BundleEntry bundleEntry) {
		this.container = container;
		this.bundleEntry = bundleEntry;
	}

	/** 
	 * Parse reference URL. 
	 */
	protected void parseURL(URL url, String str, int start, int end) {
		if (end < start)
			return;
		if (url.getPath() != null)
			// A call to a URL constructor has been made that uses an authorized URL as its context.
			// Null out bundleEntry because it will not be valid for the new path
			bundleEntry = null;
		String spec = ""; //$NON-NLS-1$
		if (start < end)
			spec = str.substring(start, end);
		end -= start;
		//Default is to use path and bundleId from context
		String path = url.getPath();
		String host = url.getHost();
		int resIndex = url.getPort();
		if (resIndex < 0) // -1 indicates port was not set; must default to 0
			resIndex = 0;
		int pathIdx = 0;
		if (spec.startsWith("//")) { //$NON-NLS-1$
			int bundleIdIdx = 2;
			pathIdx = spec.indexOf('/', bundleIdIdx);
			if (pathIdx == -1) {
				pathIdx = end;
				// Use default
				path = ""; //$NON-NLS-1$
			}
			int bundleIdEnd = spec.indexOf(':', bundleIdIdx);
			if (bundleIdEnd > pathIdx || bundleIdEnd == -1)
				bundleIdEnd = pathIdx;
			if (bundleIdEnd < pathIdx - 1)
				try {
					resIndex = Integer.parseInt(spec.substring(bundleIdEnd + 1, pathIdx));
				} catch (NumberFormatException e) {
					// do nothing; results in resIndex == 0
				}
			host = spec.substring(bundleIdIdx, bundleIdEnd);
		}
		if (pathIdx < end && spec.charAt(pathIdx) == '/')
			path = spec.substring(pathIdx, end);
		else if (end > pathIdx) {
			if (path == null || path.equals("")) //$NON-NLS-1$
				path = "/"; //$NON-NLS-1$
			int last = path.lastIndexOf('/') + 1;
			if (last == 0)
				path = spec.substring(pathIdx, end);
			else
				path = path.substring(0, last) + spec.substring(pathIdx, end);
		}
		if (path == null)
			path = ""; //$NON-NLS-1$
		//modify path if there's any relative references
		// see RFC2396 Section 5.2
		// Note: For ".." references above the root the approach taken is removing them from the resolved path
		if (path.endsWith("/.") || path.endsWith("/..")) //$NON-NLS-1$ //$NON-NLS-2$
			path = path + '/';
		int dotIndex;
		while ((dotIndex = path.indexOf("/./")) >= 0) //$NON-NLS-1$
			path = path.substring(0, dotIndex + 1) + path.substring(dotIndex + 3);
		while ((dotIndex = path.indexOf("/../")) >= 0) { //$NON-NLS-1$
			if (dotIndex != 0)
				path = path.substring(0, path.lastIndexOf('/', dotIndex - 1)) + path.substring(dotIndex + 3);
			else
				path = path.substring(dotIndex + 3);
		}
		while ((dotIndex = path.indexOf("//")) >= 0) //$NON-NLS-1$
			path = path.substring(0, dotIndex + 1) + path.substring(dotIndex + 2);

		// Check the permission of the caller to see if they
		// are allowed access to the resource.
		String authorized = SECURITY_UNCHECKED;
		long bundleId = getBundleID(host);
		Module module = getModule(bundleId);
		if (checkAuthorization(module))
			authorized = SECURITY_CHECKED;
		// Always force the use of the hash from the adaptor
		host = Long.toString(bundleId) + BID_FWKID_SEPARATOR + Integer.toString(container.hashCode());
		// Setting the authority portion of the URL to SECURITY_ATHORIZED
		// ensures that this URL was created by using this parseURL
		// method.  The openConnection method will only open URLs
		// that have the authority set to this.
		setURL(url, url.getProtocol(), host, resIndex, authorized, null, path, null, url.getRef());
	}

	private Module getModule(long id) {
		return container.getModule(id);
	}

	/**
	 * Establishes a connection to the resource specified by <code>URL</code>.
	 * Since different protocols may have unique ways of connecting, it must be
	 * overridden by the subclass.
	 *
	 * @return java.net.URLConnection
	 * @param url java.net.URL
	 *
	 * @exception	IOException 	thrown if an IO error occurs during connection establishment
	 */
	protected URLConnection openConnection(URL url) throws IOException {
		if (bundleEntry != null) // if the bundleEntry is not null then return quick
			return (new BundleURLConnection(url, bundleEntry));

		String host = url.getHost();
		if (host == null) {
			throw new IOException(NLS.bind(Msg.URL_NO_BUNDLE_ID, url.toExternalForm()));
		}
		long bundleID;
		try {
			bundleID = getBundleID(host);
		} catch (NumberFormatException nfe) {
			throw (MalformedURLException) new MalformedURLException(NLS.bind(Msg.URL_INVALID_BUNDLE_ID, host)).initCause(nfe);
		}
		Module module = getModule(bundleID);
		if (module == null)
			throw new IOException(NLS.bind(Msg.URL_NO_BUNDLE_FOUND, url.toExternalForm()));
		// check to make sure that this URL was created using the
		// parseURL method.  This ensures the security check was done
		// at URL construction.
		if (!url.getAuthority().equals(SECURITY_CHECKED)) {
			// No admin security check was made better check now.
			checkAuthorization(module);
		}
		return (new BundleURLConnection(url, findBundleEntry(url, module)));
	}

	/**
	 * Finds the bundle entry for this protocal.  This is handled
	 * differently for Bundle.gerResource() and Bundle.getEntry()
	 * because getResource uses the bundle classloader and getEntry
	 * only used the base bundle file.
	 * @param url The URL to find the entry for.
	 * @param module the module to find the entry for.
	 * @return the bundle entry
	 */
	abstract protected BundleEntry findBundleEntry(URL url, Module module) throws IOException;

	/**
	 * Converts a bundle URL to a String.
	 *
	 * @param   url   the URL.
	 * @return  a string representation of the URL.
	 */
	protected String toExternalForm(URL url) {
		StringBuffer result = new StringBuffer(url.getProtocol());
		result.append("://"); //$NON-NLS-1$

		String host = url.getHost();
		if ((host != null) && (host.length() > 0))
			result.append(host);
		int index = url.getPort();
		if (index > 0)
			result.append(':').append(index);

		String path = url.getPath();
		if (path != null) {
			if ((path.length() > 0) && (path.charAt(0) != '/')) /* if name doesn't have a leading slash */
			{
				result.append("/"); //$NON-NLS-1$
			}

			result.append(path);
		}
		String ref = url.getRef();
		if (ref != null && ref.length() > 0)
			result.append('#').append(ref);

		return (result.toString());
	}

	protected int hashCode(URL url) {
		int hash = 0;
		String protocol = url.getProtocol();
		if (protocol != null)
			hash += protocol.hashCode();

		String host = url.getHost();
		if (host != null)
			hash += host.hashCode();

		hash += url.getPort();

		String path = url.getPath();
		if (path != null)
			hash += path.hashCode();

		hash += container.hashCode();
		return hash;
	}

	protected boolean equals(URL url1, URL url2) {
		return sameFile(url1, url2);
	}

	protected synchronized InetAddress getHostAddress(URL url) {
		return null;
	}

	protected boolean hostsEqual(URL url1, URL url2) {
		String host1 = url1.getHost();
		String host2 = url2.getHost();
		if (host1 != null && host2 != null)
			return host1.equalsIgnoreCase(host2);
		return (host1 == null && host2 == null);
	}

	protected boolean sameFile(URL url1, URL url2) {
		// do a hashcode test to allow each handler to check the adaptor first
		if (url1.hashCode() != url2.hashCode())
			return false;
		String p1 = url1.getProtocol();
		String p2 = url2.getProtocol();
		if (!((p1 == p2) || (p1 != null && p1.equalsIgnoreCase(p2))))
			return false;

		if (!hostsEqual(url1, url2))
			return false;

		if (url1.getPort() != url2.getPort())
			return false;

		String path1 = url1.getPath();
		String path2 = url2.getPath();
		if (!((path1 == path2) || (path1 != null && path1.equals(path2))))
			return false;

		return true;
		// note that the authority is not checked here because it can be different for two
		// URLs depending on how they were constructed.
	}

	protected boolean checkAuthorization(Module module) {
		SecurityManager sm = System.getSecurityManager();
		if (sm == null)
			return true;
		Bundle bundle = module == null ? null : module.getBundle();
		if (bundle == null)
			return false;
		sm.checkPermission(new AdminPermission(bundle, AdminPermission.RESOURCE));
		return true;
	}

	private long getBundleID(String host) {
		int dotIndex = host.indexOf('.');
		return (dotIndex >= 0 && dotIndex < host.length() - 1) ? Long.parseLong(host.substring(0, dotIndex)) : Long.parseLong(host);
	}
}