/*
 * @(#)FeatureDescriptor.java	1.33 04/05/05
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.beans;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.lang.ref.SoftReference;

/**
 * The FeatureDescriptor class is the common baseclass for PropertyDescriptor,
 * EventSetDescriptor, and MethodDescriptor, etc.
 * <p>
 * It supports some common information that can be set and retrieved for
 * any of the introspection descriptors.
 * <p>
 * In addition it provides an extension mechanism so that arbitrary
 * attribute/value pairs can be associated with a design feature.
 */

public class FeatureDescriptor {

    private Reference classRef;

    /**
     * Constructs a <code>FeatureDescriptor</code>.
     */
    public FeatureDescriptor() {
    }

    /**
     * Gets the programmatic name of this feature.
     *
     * @return The programmatic name of the property/method/event
     */
    public String getName() {
	return name;
    }

    /**
     * Sets the programmatic name of this feature.
     *
     * @param name  The programmatic name of the property/method/event
     */
    public void setName(String name) {
	this.name = name;
    }

    /**
     * Gets the localized display name of this feature.
     *
     * @return The localized display name for the property/method/event.
     *	This defaults to the same as its programmatic name from getName.
     */
    public String getDisplayName() {
	if (displayName == null) {
	    return getName();
	}
	return displayName;
    }

    /**
     * Sets the localized display name of this feature.
     *
     * @param displayName  The localized display name for the
     *		property/method/event.
     */
    public void setDisplayName(String displayName) {
	this.displayName = displayName;
    }

    /**
     * The "expert" flag is used to distinguish between those features that are
     * intended for expert users from those that are intended for normal users.
     *
     * @return True if this feature is intended for use by experts only.
     */
    public boolean isExpert() {
	return expert;
    }

    /**
     * The "expert" flag is used to distinguish between features that are
     * intended for expert users from those that are intended for normal users.
     *
     * @param expert True if this feature is intended for use by experts only.
     */
    public void setExpert(boolean expert) {
	this.expert = expert;
    }

    /**
     * The "hidden" flag is used to identify features that are intended only
     * for tool use, and which should not be exposed to humans.
     *
     * @return True if this feature should be hidden from human users.
     */
    public boolean isHidden() {
	return hidden;
    }

    /**
     * The "hidden" flag is used to identify features that are intended only
     * for tool use, and which should not be exposed to humans.
     *
     * @param hidden  True if this feature should be hidden from human users.
     */
    public void setHidden(boolean hidden) {
	this.hidden = hidden;
    }

    /**
     * The "preferred" flag is used to identify features that are particularly
     * important for presenting to humans.
     *
     * @return True if this feature should be preferentially shown to human users.
     */
    public boolean isPreferred() {
	return preferred;
    }

    /**
     * The "preferred" flag is used to identify features that are particularly
     * important for presenting to humans.
     *
     * @param preferred  True if this feature should be preferentially shown
     *		    	 to human users.
     */
    public void setPreferred(boolean preferred) {
	this.preferred = preferred;
    }

    /**
     * Gets the short description of this feature.
     *
     * @return  A localized short description associated with this 
     *   property/method/event.  This defaults to be the display name.
     */
    public String getShortDescription() {
	if (shortDescription == null) {
	    return getDisplayName();
	}
	return shortDescription;
    }

    /**
     * You can associate a short descriptive string with a feature.  Normally
     * these descriptive strings should be less than about 40 characters.
     * @param text  A (localized) short description to be associated with
     * this property/method/event.
     */
    public void setShortDescription(String text) {
	shortDescription = text;
    }

    /**
     * Associate a named attribute with this feature.
     *
     * @param attributeName  The locale-independent name of the attribute
     * @param value  The value.
     */
    public void setValue(String attributeName, Object value) {
	if (table == null) {
	    table = new java.util.Hashtable();
	}
	table.put(attributeName, value);
    }

    /**
     * Retrieve a named attribute with this feature.
     *
     * @param attributeName  The locale-independent name of the attribute
     * @return  The value of the attribute.  May be null if
     *	   the attribute is unknown.
     */
    public Object getValue(String attributeName) {
	if (table == null) {
	   return null;
	}
	return table.get(attributeName);
    }

    /**
     * Gets an enumeration of the locale-independent names of this
     * feature.
     *
     * @return  An enumeration of the locale-independent names of any 
     *    attributes that have been registered with setValue.
     */
    public java.util.Enumeration<String> attributeNames() {
	if (table == null) {
	    table = new java.util.Hashtable();
	}
	return table.keys();
    }

    /**
     * Package-private constructor,
     * Merge information from two FeatureDescriptors.
     * The merged hidden and expert flags are formed by or-ing the values.
     * In the event of other conflicts, the second argument (y) is
     * given priority over the first argument (x).
     *
     * @param x  The first (lower priority) MethodDescriptor
     * @param y  The second (higher priority) MethodDescriptor
     */
    FeatureDescriptor(FeatureDescriptor x, FeatureDescriptor y) {
	expert = x.expert | y.expert;
	hidden = x.hidden | y.hidden;
	preferred = x.preferred | y.preferred;
	name = y.name;
	shortDescription = x.shortDescription;
	if (y.shortDescription != null) {
	    shortDescription = y.shortDescription;
	}
	displayName = x.displayName;
	if (y.displayName != null) {
	    displayName = y.displayName;
	}
	classRef = x.classRef;
	if (y.classRef != null) {
	    classRef = y.classRef;
	}
	addTable(x.table);
	addTable(y.table);
    }

    /*
     * Package-private dup constructor
     * This must isolate the new object from any changes to the old object.
     */
    FeatureDescriptor(FeatureDescriptor old) {
	expert = old.expert;
	hidden = old.hidden;
	preferred = old.preferred;
	name = old.name;
	shortDescription = old.shortDescription;
	displayName = old.displayName;
	classRef = old.classRef;

	addTable(old.table);
    }

    private void addTable(java.util.Hashtable t) {
	if (t == null) {
	    return;
	}
	java.util.Enumeration keys = t.keys();
	while (keys.hasMoreElements()) {
	    String key = (String)keys.nextElement();
	    Object value = t.get(key);
	    setValue(key, value);
	}
    }

    // Package private methods for recreating the weak/soft referent

    void setClass0(Class cls) {
	classRef = createReference(cls);
    }

    Class getClass0() {
	return (Class)getObject(classRef);
    }

    /**
     * Create a Reference wrapper for the object.
     *
     * @param obj object that will be wrapped
     * @param soft true if a SoftReference should be created; otherwise Soft
     * @return a Reference or null if obj is null.
     */
    static Reference createReference(Object obj, boolean soft) {
	Reference ref = null;
	if (obj != null) {
	    if (soft) {
		ref = new SoftReference(obj);
	    } else {
		ref = new WeakReference(obj);
	    }
	}
	return ref;
    }

    // Convenience method which creates a WeakReference.
    static Reference createReference(Object obj) {
	return createReference(obj, false);
    }

    /**
     * Returns an object from a Reference wrapper.
     *
     * @return the Object in a wrapper or null.
     */
    static Object getObject(Reference ref) {
	return (ref == null) ? null : (Object)ref.get();
    }

    static String capitalize(String s) {
	return NameGenerator.capitalize(s);
    }

    private boolean expert;
    private boolean hidden;
    private boolean preferred;
    private String shortDescription;
    private String name;
    private String displayName;
    private java.util.Hashtable table;
}
