/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.

 */

package org.opensolaris.os.vp.client.common;

import java.io.*;

import java.lang.reflect.InvocationTargetException;

import java.net.*;

import java.security.*;

import java.util.*;

import java.util.regex.*;

public class PanelClassLoader extends URLClassLoader {

    //

    // Static data

    //

    private static Set<Permission> permSet = new HashSet<Permission>();

    private static Class[] ARGS_NAME = { String.class };

    private static Class[] ARGS_NAME_ACTIONS = { String.class, String.class };

    //

    // Constructors

    //

    public PanelClassLoader(URL[] urls) {

	super(urls);

    }

    //

    // SecureClassLoader methods

    //

    @Override

    protected PermissionCollection getPermissions(CodeSource codeSource) {

	PermissionCollection perms = super.getPermissions(codeSource);

	for (Permission perm : permSet) {

	    perms.add(perm);

	}

	return perms;

    }

    //

    // Static methods

    //

    public static void loadPermissions(URL url) throws IOException,

	PermissionParseException {

	BufferedReader in = new BufferedReader(new InputStreamReader(

	    url.openStream()));

	String line;

	Pattern ignore = Pattern.compile("^\\s*(//.*)?$");

	Pattern valid = Pattern.compile("^\\s*permission\\s+(\\S+)" +

	    "(\\s+\"([^\"]*)\"(,\\s+\"([^\"]*)\")?)?;$");

	Set<Permission> perms = new HashSet<Permission>();

	while ((line = in.readLine()) != null) {

	    if (ignore.matcher(line).matches()) {

		continue;

	    }

	    Matcher matcher = valid.matcher(line);

	    if (!matcher.matches()) {

                throw new PermissionParseException("invalid syntax: " + line);

	    }

	    int nGroups = matcher.groupCount();

	    String type = matcher.group(1);

	    String name = expand(nGroups >= 3 ? matcher.group(3) : null);

	    String actions = expand(nGroups >= 5 ? matcher.group(5) : null);

	    try {

		Permission perm = getPermission(type, name, actions);

		perms.add(perm);

	    } catch (Throwable e) {

		String message = String.format(

		    "could not instantiate permission: " +

		    "type=%s name=%s actions=", type, name, actions);

		throw new PermissionParseException(message, e);

	    }

	}

	in.close();

	permSet.addAll(perms);

    }

    //

    // Private static methods

    //

    private static String expand(String str) {

	if (str == null) {

	    return null;

	}

	StringBuffer result = new StringBuffer();

	Pattern re = Pattern.compile("^(.*?)\\$\\{([^}]*)\\}(.*)");

	while (true) {

	    Matcher matcher = re.matcher(str);

	    if (matcher.matches()) {

		result.append(matcher.group(1));

		String property = matcher.group(2);

		if (property.equals("/")) {

		    property = "file.separator";

		}

		String value = System.getProperty(property);

		if (value != null) {

		    result.append(value);

		}

		str = matcher.group(3);

	    } else {

		result.append(str);

		break;

	    }

	}

	return result.toString();

    }

    @SuppressWarnings({"fallthrough"})

    private static Permission getPermission(String type, String name,

        String actions) throws ClassNotFoundException, InstantiationException,

        IllegalAccessException, NoSuchMethodException, InvocationTargetException

    {

        Class<?> clazz = Class.forName(type);

	int nArgs = actions != null ? 2 : name != null ? 1 : 0;

	switch (nArgs) {

	    case 0:

		try {

		    return (Permission)clazz.getConstructor().newInstance();

		} catch (NoSuchMethodException e) {

		}

	    case 1:

		try {

		    return (Permission)clazz.getConstructor(ARGS_NAME).

			newInstance(name);

		} catch (NoSuchMethodException e) {

		}

	    case 2:

		return (Permission)clazz.getConstructor(ARGS_NAME_ACTIONS).

		    newInstance(name, actions);

	}

	assert false;

	return null;

    }

}