// --- BEGIN COPYRIGHT BLOCK ---
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// (C) 2007 Red Hat, Inc.
// All rights reserved.
// --- END COPYRIGHT BLOCK ---
package netscape.security.acl;

import java.security.Principal;
import java.security.acl.AclEntry;
import java.security.acl.Group;
import java.security.acl.Permission;
import java.util.Enumeration;
import java.util.Vector;

/**
 * This is a class that describes one entry that associates users
 * or groups with permissions in the ACL.
 * The entry may be used as a way of granting or denying permissions.
 *
 * @author Satish Dharmaraj
 */
public class AclEntryImpl implements AclEntry {
    private Principal user = null;
    private Vector<Permission> permissionSet = new Vector<Permission>(10, 10);
    private boolean negative = false;

    /**
     * Construct an ACL entry that associates a user with permissions
     * in the ACL.
     *
     * @param user The user that is associated with this entry.
     */
    public AclEntryImpl(Principal user) {
        this.user = user;
    }

    /**
     * Construct a null ACL entry
     */
    public AclEntryImpl() {
    }

    /**
     * Sets the principal in the entity. If a group or a
     * principal had already been set, a false value is
     * returned, otherwise a true value is returned.
     *
     * @param user The user that is associated with this entry.
     * @return true if the principal is set, false if there is
     *         one already.
     */
    public boolean setPrincipal(Principal user) {
        if (this.user != null)
            return false;
        this.user = user;
        return true;
    }

    /**
     * This method sets the ACL to have negative permissions.
     * That is the user or group is denied the permission set
     * specified in the entry.
     */
    public void setNegativePermissions() {
        negative = true;
    }

    /**
     * Returns true if this is a negative ACL.
     */
    public boolean isNegative() {
        return negative;
    }

    /**
     * A principal or a group can be associated with multiple
     * permissions. This method adds a permission to the ACL entry.
     *
     * @param permission The permission to be associated with
     *            the principal or the group in the entry.
     * @return true if the permission was added, false if the
     *         permission was already part of the permission set.
     */
    public boolean addPermission(Permission permission) {

        if (permissionSet.contains(permission))
            return false;

        permissionSet.addElement(permission);

        return true;
    }

    /**
     * The method disassociates the permission from the Principal
     * or the Group in this ACL entry.
     *
     * @param permission The permission to be disassociated with
     *            the principal or the group in the entry.
     * @return true if the permission is removed, false if the
     *         permission is not part of the permission set.
     */
    public boolean removePermission(Permission permission) {
        return permissionSet.removeElement(permission);
    }

    /**
     * Checks if the passed permission is part of the allowed
     * permission set in this entry.
     *
     * @param permission The permission that has to be part of
     *            the permission set in the entry.
     * @return true if the permission passed is part of the
     *         permission set in the entry, false otherwise.
     */
    public boolean checkPermission(Permission permission) {
        return permissionSet.contains(permission);
    }

    /**
     * return an enumeration of the permissions in this ACL entry.
     */
    public Enumeration<Permission> permissions() {
        return permissionSet.elements();
    }

    /**
     * Return a string representation of the contents of the ACL entry.
     */
    public String toString() {
        StringBuffer s = new StringBuffer();
        if (negative)
            s.append("-");
        else
            s.append("+");
        if (user instanceof Group)
            s.append("Group.");
        else
            s.append("User.");
        s.append(user + "=");
        Enumeration<Permission> e = permissions();
        while (e.hasMoreElements()) {
            Permission p = e.nextElement();
            s.append(p);
            if (e.hasMoreElements())
                s.append(",");
        }
        return new String(s);
    }

    /**
     * Clones an AclEntry.
     */
    public synchronized Object clone() {
        AclEntryImpl cloned;
        cloned = new AclEntryImpl(user);
        cloned.permissionSet = new Vector<Permission>(permissionSet);
        cloned.negative = negative;
        return cloned;
    }

    /**
     * Return the Principal associated in this ACL entry.
     * The method returns null if the entry uses a group
     * instead of a principal.
     */
    public Principal getPrincipal() {
        return user;
    }
}
