/*

 * Copyright 1998-2004 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.swing.text.html;

import java.util.Enumeration;

import java.awt.*;

import javax.swing.*;

import javax.swing.text.*;

import java.beans.*;

import java.lang.reflect.*;

/**

 * Component decorator that implements the view interface

 * for <object> elements.

 * <p>

 * This view will try to load the class specified by the

 * <code>classid</code> attribute.  If possible, the Classloader

 * used to load the associated Document is used.

 * This would typically be the same as the ClassLoader

 * used to load the EditorKit.  If the document's

 * ClassLoader is null, <code>Class.forName</code> is used.

 * <p>

 * If the class can successfully be loaded, an attempt will

 * be made to create an instance of it by calling

 * <code>Class.newInstance</code>.  An attempt will be made

 * to narrow the instance to type <code>java.awt.Component</code>

 * to display the object.

 * <p>

 * This view can also manage a set of parameters with limitations.

 * The parameters to the <object> element are expected to

 * be present on the associated elements attribute set as simple

 * strings.  Each bean property will be queried as a key on

 * the AttributeSet, with the expectation that a non-null value

 * (of type String) will be present if there was a parameter

 * specification for the property.  Reflection is used to

 * set the parameter.  Currently, this is limited to a very

 * simple single parameter of type String.

 * <p>

 * A simple example HTML invocation is:

 * <pre>

 *      <object classid="javax.swing.JLabel">

 *      <param name="text" value="sample text">

 *      </object>

 * </pre>

 *

 * @author Timothy Prinzing

 */

public class ObjectView extends ComponentView  {

    /**

     * Creates a new ObjectView object.

     *

     * @param elem the element to decorate

     */

    public ObjectView(Element elem) {

        super(elem);

    }

    /**

     * Create the component.  The classid is used

     * as a specification of the classname, which

     * we try to load.

     */

    protected Component createComponent() {

        AttributeSet attr = getElement().getAttributes();

        String classname = (String) attr.getAttribute(HTML.Attribute.CLASSID);

        try {

            Class c = Class.forName(classname, true,Thread.currentThread().

                                    getContextClassLoader());

            Object o = c.newInstance();

            if (o instanceof Component) {

                Component comp = (Component) o;

                setParameters(comp, attr);

                return comp;

            }

        } catch (Throwable e) {

            // couldn't create a component... fall through to the

            // couldn't load representation.

        }

        return getUnloadableRepresentation();

    }

    /**

     * Fetch a component that can be used to represent the

     * object if it can't be created.

     */

    Component getUnloadableRepresentation() {

        // PENDING(prinz) get some artwork and return something

        // interesting here.

        Component comp = new JLabel("??");

        comp.setForeground(Color.red);

        return comp;

    }

    /**

     * Get a Class object to use for loading the

     * classid.  If possible, the Classloader

     * used to load the associated Document is used.

     * This would typically be the same as the ClassLoader

     * used to load the EditorKit.  If the documents

     * ClassLoader is null,

     * <code>Class.forName</code> is used.

     */

    private Class getClass(String classname) throws ClassNotFoundException {

        Class klass;

        Class docClass = getDocument().getClass();

        ClassLoader loader = docClass.getClassLoader();

        if (loader != null) {

            klass = loader.loadClass(classname);

        } else {

            klass = Class.forName(classname);

        }

        return klass;

    }

    /**

     * Initialize this component according the KEY/VALUEs passed in

     * via the <param> elements in the corresponding

     * <object> element.

     */

    private void setParameters(Component comp, AttributeSet attr) {

        Class k = comp.getClass();

        BeanInfo bi;

        try {

            bi = Introspector.getBeanInfo(k);

        } catch (IntrospectionException ex) {

            System.err.println("introspector failed, ex: "+ex);

            return;             // quit for now

        }

        PropertyDescriptor props[] = bi.getPropertyDescriptors();

        for (int i=0; i < props.length; i++) {

            //      System.err.println("checking on props[i]: "+props[i].getName());

            Object v = attr.getAttribute(props[i].getName());

            if (v instanceof String) {

                // found a property parameter

                String value = (String) v;

                Method writer = props[i].getWriteMethod();

                if (writer == null) {

                    // read-only property. ignore

                    return;     // for now

                }

                Class[] params = writer.getParameterTypes();

                if (params.length != 1) {

                    // zero or more than one argument, ignore

                    return;     // for now

                }

                Object [] args = { value };

                try {

                    writer.invoke(comp, args);

                } catch (Exception ex) {

                    System.err.println("Invocation failed");

                    // invocation code

                }

            }

        }

    }

}