/*
 * @(#)PrintServiceLookup.java	1.15 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */


package javax.print;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.print.attribute.AttributeSet;

import sun.awt.AppContext;
import sun.misc.Service;

/** Implementations of this class provide lookup services for
  * print services (typically equivalent to printers) of a particular type.
  * <p>
  * Multiple implementations may be installed concurrently.
  * All implementations must be able to describe the located printers
  * as instances of a PrintService.   
  * Typically implementations of this service class are located
  * automatically in JAR files (see the SPI JAR file specification).
  * These classes must be instantiable using a default constructor.
  * Alternatively applications may explicitly register instances
  * at runtime.
  * <p>
  * Applications use only the static methods of this abstract class.
  * The instance methods are implemented by a service provider in a subclass
  * and the unification of the results from all installed lookup classes
  * are reported by the static methods of this class when called by
  * the application.
  * <p>
  * A PrintServiceLookup implementor is recommended to check for the
  * SecurityManager.checkPrintJobAccess() to deny access to untrusted code.
  * Following this recommended policy means that untrusted code may not
  * be able to locate any print services. Downloaded applets are the most
  * common example of untrusted code.
  * <p>
  * This check is made on a per lookup service basis to allow flexibility in
  * the policy to reflect the needs of different lookup services.
  * <p>
  * Services which are registered by registerService(PrintService)
  * will not be included in lookup results if a security manager is
  * installed and its checkPrintJobAccess() method denies access.
  */

public abstract class PrintServiceLookup {
   
    static class Services {
	private ArrayList listOfLookupServices = null;
	private ArrayList registeredServices = null;	
    }

    private static Services getServicesForContext() {
	Services services =
	    (Services)AppContext.getAppContext().get(Services.class);
	if (services == null) {
	    services = new Services();
	    AppContext.getAppContext().put(Services.class, services);
	}
	return services;	
    }

    private static ArrayList getListOfLookupServices() {
	return getServicesForContext().listOfLookupServices;
    }

    private static ArrayList initListOfLookupServices() {
	ArrayList listOfLookupServices = new ArrayList();
	getServicesForContext().listOfLookupServices = listOfLookupServices;
	return listOfLookupServices;
    }


    private static ArrayList getRegisteredServices() {
	return getServicesForContext().registeredServices;
    }

    private static ArrayList initRegisteredServices() {
	ArrayList registeredServices = new ArrayList();
	getServicesForContext().registeredServices = registeredServices;
	return registeredServices;
    }

    /**
     * Locates print services capable of printing the specified
     * {@link DocFlavor}.
     *
     * @param flavor the flavor to print. If null, this constraint is not
     *        used.
     * @param attributes attributes that the print service must support.
     * If null this constraint is not used.
     *
     * @return array of matching <code>PrintService</code> objects
     * representing print services that support the specified flavor
     * attributes.  If no services match, the array is zero-length.