/*
 * @(#)OpenMBeanInfoSupport.java	3.29 06/03/15
 * 
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */


package javax.management.openmbean;


// java import
//
import java.util.Arrays;
import java.util.HashSet;
import javax.management.Descriptor;
import javax.management.MBeanInfo;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanConstructorInfo;
import javax.management.MBeanNotificationInfo;



/**
 * The {@code OpenMBeanInfoSupport} class describes the management
 * information of an <i>open MBean</i>: it is a subclass of {@link
 * javax.management.MBeanInfo}, and it implements the {@link
 * OpenMBeanInfo} interface.  Note that an <i>open MBean</i> is
 * recognized as such if its {@code getMBeanInfo()} method returns an
 * instance of a class which implements the OpenMBeanInfo interface,
 * typically {@code OpenMBeanInfoSupport}.
 *
 * @version     3.29  06/03/15
 * @author      Sun Microsystems, Inc.
 *
 * @since 1.5
 * @since.unbundled JMX 1.1
 */
public class OpenMBeanInfoSupport extends MBeanInfo
    implements OpenMBeanInfo {

    /* Serial version */
    static final long serialVersionUID = 4349395935420511492L;

    // As this instance is immutable, these two values
    // need only be calculated once.
    private transient Integer myHashCode = null;
    private transient String  myToString = null;


    /**
     * <p>Constructs an {@code OpenMBeanInfoSupport} instance, which
     * describes a class of open MBeans with the specified {@code
     * className}, {@code description}, {@code openAttributes}, {@code
     * openConstructors} , {@code openOperations} and {@code
     * notifications}.</p>
     *
     * <p>The {@code openAttributes}, {@code openConstructors},  
     * {@code openOperations} and {@code notifications}
     * array parameters are internally copied, so that subsequent changes 
     * to the arrays referenced by these parameters have no effect on this
     * instance.</p>
     *
     * @param className The fully qualified Java class name of the
     * open MBean described by this <CODE>OpenMBeanInfoSupport</CODE>
     * instance.
     *
     * @param description A human readable description of the open
     * MBean described by this <CODE>OpenMBeanInfoSupport</CODE>
     * instance.
     *
     * @param openAttributes The list of exposed attributes of the
     * described open MBean; Must be an array of instances of a
     * subclass of {@code MBeanAttributeInfo}, typically {@code
     * OpenMBeanAttributeInfoSupport}.
     *
     * @param openConstructors The list of exposed public constructors
     * of the described open MBean; Must be an array of instances of a
     * subclass of {@code MBeanConstructorInfo}, typically {@code
     * OpenMBeanConstructorInfoSupport}.
     *
     * @param openOperations The list of exposed operations of the
     * described open MBean.  Must be an array of instances of a
     * subclass of {@code MBeanOperationInfo}, typically {@code
     * OpenMBeanOperationInfoSupport}.
     *
     * @param notifications The list of notifications emitted by the
     * described open MBean.
     *
     * @throws ArrayStoreException If {@code openAttributes}, {@code
     * openConstructors} or {@code openOperations} is not an array of
     * instances of a subclass of {@code MBeanAttributeInfo}, {@code
     * MBeanConstructorInfo} or {@code MBeanOperationInfo}
     * respectively.
     */
    public OpenMBeanInfoSupport(String className, 
				String description,
				OpenMBeanAttributeInfo[] openAttributes, 
				OpenMBeanConstructorInfo[] openConstructors,
				OpenMBeanOperationInfo[] openOperations, 
				MBeanNotificationInfo[] notifications) {
	this(className, description,
	     openAttributes, openConstructors, openOperations, notifications,
	     (Descriptor) null);
    }
	
    /**
     * <p>Constructs an {@code OpenMBeanInfoSupport} instance, which
     * describes a class of open MBeans with the specified {@code
     * className}, {@code description}, {@code openAttributes}, {@code
     * openConstructors} , {@code openOperations}, {@code
     * notifications}, and {@code descriptor}.</p>
     *
     * <p>The {@code openAttributes}, {@code openConstructors}, {@code
     * openOperations} and {@code notifications} array parameters are
     * internally copied, so that subsequent changes to the arrays
     * referenced by these parameters have no effect on this
     * instance.</p>
     *
     * @param className The fully qualified Java class name of the
     * open MBean described by this <CODE>OpenMBeanInfoSupport</CODE>
     * instance.
     *
     * @param description A human readable description of the open
     * MBean described by this <CODE>OpenMBeanInfoSupport</CODE>
     * instance.
     *
     * @param openAttributes The list of exposed attributes of the
     * described open MBean; Must be an array of instances of a
     * subclass of {@code MBeanAttributeInfo}, typically {@code
     * OpenMBeanAttributeInfoSupport}.
     *
     * @param openConstructors The list of exposed public constructors
     * of the described open MBean; Must be an array of instances of a
     * subclass of {@code MBeanConstructorInfo}, typically {@code
     * OpenMBeanConstructorInfoSupport}.
     *
     * @param openOperations The list of exposed operations of the
     * described open MBean.  Must be an array of instances of a
     * subclass of {@code MBeanOperationInfo}, typically {@code
     * OpenMBeanOperationInfoSupport}.
     *
     * @param notifications The list of notifications emitted by the
     * described open MBean.
     *
     * @param descriptor The descriptor for the MBean.  This may be null
     * which is equivalent to an empty descriptor.
     *
     * @throws ArrayStoreException If {@code openAttributes}, {@code
     * openConstructors} or {@code openOperations} is not an array of
     * instances of a subclass of {@code MBeanAttributeInfo}, {@code
     * MBeanConstructorInfo} or {@code MBeanOperationInfo}
     * respectively.
     *
     * @since 1.6
     */
    public OpenMBeanInfoSupport(String className, 
				String description,
				OpenMBeanAttributeInfo[] openAttributes, 
				OpenMBeanConstructorInfo[] openConstructors,
				OpenMBeanOperationInfo[] openOperations, 
				MBeanNotificationInfo[] notifications,
				Descriptor descriptor) {
	super(className, 
	      description, 
	      attributeArray(openAttributes),
	      constructorArray(openConstructors),
	      operationArray(openOperations),
	      (notifications == null) ? null : notifications.clone(),
	      descriptor);
    }


    private static MBeanAttributeInfo[]
	    attributeArray(OpenMBeanAttributeInfo[] src) {
	if (src == null)
	    return null;
	MBeanAttributeInfo[] dst = new MBeanAttributeInfo[src.length];
	System.arraycopy(src, 0, dst, 0, src.length);
	// may throw an ArrayStoreException
	return dst;
    }

    private static MBeanConstructorInfo[]
	    constructorArray(OpenMBeanConstructorInfo[] src) {
	if (src == null)
	    return null;
	MBeanConstructorInfo[] dst = new MBeanConstructorInfo[src.length];
	System.arraycopy(src, 0, dst, 0, src.length);
	// may throw an ArrayStoreException
	return dst;
    }

    private static MBeanOperationInfo[]
	    operationArray(OpenMBeanOperationInfo[] src) {
	if (src == null)
	    return null;
	MBeanOperationInfo[] dst = new MBeanOperationInfo[src.length];
	System.arraycopy(src, 0, dst, 0, src.length);
	return dst;
    }



    /* ***  Commodity methods from java.lang.Object  *** */


    /**
     * <p>Compares the specified {@code obj} parameter with this
     * {@code OpenMBeanInfoSupport} instance for equality.</p>
     *
     * <p>Returns {@code true} if and only if all of the following
     * statements are true:
     *
     * <ul>
     * <li>{@code obj} is non null,</li>
     * <li>{@code obj} also implements the {@code OpenMBeanInfo}
     * interface,</li>
     * <li>their class names are equal</li>
     * <li>their infos on attributes, constructors, operations and
     * notifications are equal</li>
     * </ul>
     *
     * This ensures that this {@code equals} method works properly for
     * {@code obj} parameters which are different implementations of
     * the {@code OpenMBeanInfo} interface.
     *
     * @param obj the object to be compared for equality with this
     * {@code OpenMBeanInfoSupport} instance;
     * 
     * @return {@code true} if the specified object is equal to this
     * {@code OpenMBeanInfoSupport} instance.
     */
    public boolean equals(Object obj) { 

	// if obj is null, return false
	//
	if (obj == null) {
	    return false;
	}

	// if obj is not a OpenMBeanInfo, return false
	//
	OpenMBeanInfo other;
	try {
	    other = (OpenMBeanInfo) obj;
	} catch (ClassCastException e) {
	    return false;
	}

	// Now, really test for equality between this OpenMBeanInfo
	// implementation and the other:
	//
	
	// their MBean className should be equal
	if ( ! this.getClassName().equals(other.getClassName()) )
	    return false;

	// their infos on attributes should be equal (order not
	// significant => equality between sets, not arrays or lists)
	if (!sameArrayContents(this.getAttributes(), other.getAttributes()))
	    return false;
       
	// their infos on constructors should be equal (order not
	// significant => equality between sets, not arrays or lists)
	if (!sameArrayContents(this.getConstructors(), other.getConstructors()))
	    return false;
       
	// their infos on operations should be equal (order not
	// significant => equality between sets, not arrays or lists)
	if (!sameArrayContents(this.getOperations(), other.getOperations()))

	    return false;
       
	// their infos on notifications should be equal (order not
	// significant => equality between sets, not arrays or lists)
	if (!sameArrayContents(this.getNotifications(), other.getNotifications()))
	    return false;
       
	// All tests for equality were successful
	//
	return true;
    }

    private static <T> boolean sameArrayContents(T[] a1, T[] a2) {
	return (new HashSet<T>(Arrays.asList(a1))
		.equals(new HashSet<T>(Arrays.asList(a2))));
    }

    /**
     * <p>Returns the hash code value for this {@code
     * OpenMBeanInfoSupport} instance.</p>
     *
     * <p>The hash code of an {@code OpenMBeanInfoSupport} instance is
     * the sum of the hash codes of all elements of information used
     * in {@code equals} comparisons (ie: its class name, and its
     * infos on attributes, constructors, operations and
     * notifications, where the hashCode of each of these arrays is
     * calculated by a call to {@code new
     * java.util.HashSet(java.util.Arrays.asList(this.getSignature)).hashCode()}).</p>
     *
     * <p>This ensures that {@code t1.equals(t2)} implies that {@code
     * t1.hashCode()==t2.hashCode()} for any two {@code
     * OpenMBeanInfoSupport} instances {@code t1} and {@code t2}, as
     * required by the general contract of the method {@link
     * Object#hashCode() Object.hashCode()}.</p>
     *
     * <p>However, note that another instance of a class implementing
     * the {@code OpenMBeanInfo} interface may be equal to this {@code
     * OpenMBeanInfoSupport} instance as defined by {@link
     * #equals(java.lang.Object)}, but may have a different hash code
     * if it is calculated differently.</p>
     *
     * <p>As {@code OpenMBeanInfoSupport} instances are immutable, the
     * hash code for this instance is calculated once, on the first
     * call to {@code hashCode}, and then the same value is returned
     * for subsequent calls.</p>
     *
     * @return the hash code value for this {@code
     * OpenMBeanInfoSupport} instance
     */
    public int hashCode() {

	// Calculate the hash code value if it has not yet been done
	// (ie 1st call to hashCode())
	//
	if (myHashCode == null) {
	    int value = 0;
	    value += this.getClassName().hashCode();
	    value += arraySetHash(this.getAttributes());
	    value += arraySetHash(this.getConstructors());
	    value += arraySetHash(this.getOperations());
	    value += arraySetHash(this.getNotifications());
	    myHashCode = new Integer(value);
	}
	
	// return always the same hash code for this instance (immutable)
	//
	return myHashCode.intValue();
    }

    private static <T> int arraySetHash(T[] a) {
	return new HashSet<T>(Arrays.asList(a)).hashCode();
    }



    /**
     * <p>Returns a string representation of this {@code
     * OpenMBeanInfoSupport} instance.</p>
     *
     * <p>The string representation consists of the name of this class
     * (ie {@code javax.management.openmbean.OpenMBeanInfoSupport}),
     * the MBean class name, the string representation of infos on
     * attributes, constructors, operations and notifications of the
     * described MBean and the string representation of the descriptor.</p>
     *
     * <p>As {@code OpenMBeanInfoSupport} instances are immutable, the
     * string representation for this instance is calculated once, on
     * the first call to {@code toString}, and then the same value is
     * returned for subsequent calls.</p>
     * 
     * @return a string representation of this {@code
     * OpenMBeanInfoSupport} instance
     */
    public String toString() { 

	// Calculate the string value if it has not yet been done (ie
	// 1st call to toString())
	//
	if (myToString == null) {
	    myToString = new StringBuffer()
		.append(this.getClass().getName())
		.append("(mbean_class_name=")
		.append(this.getClassName())
		.append(",attributes=")
		.append(Arrays.asList(this.getAttributes()).toString())
		.append(",constructors=")
		.append(Arrays.asList(this.getConstructors()).toString())
		.append(",operations=")
		.append(Arrays.asList(this.getOperations()).toString())
		.append(",notifications=")
		.append(Arrays.asList(this.getNotifications()).toString())
		.append(",descriptor=")
		.append(this.getDescriptor())
		.append(")")
		.toString();
	}

	// return always the same string representation for this
	// instance (immutable)
	//
	return myToString;
    }

}