package net.sf.tapestry.form;

import java.awt.Point;

import net.sf.tapestry.IActionListener;
import net.sf.tapestry.IAsset;
import net.sf.tapestry.IBinding;
import net.sf.tapestry.IForm;
import net.sf.tapestry.IMarkupWriter;
import net.sf.tapestry.IRequestCycle;
import net.sf.tapestry.RequestContext;
import net.sf.tapestry.RequestCycleException;
import net.sf.tapestry.RequiredParameterException;

/**
 *  Used to create an image button inside a {@link Form}.  Although it
 *  is occasionally useful to know the {@link Point} on the image that was clicked
 *  (i.e., use the image as a kind of image map, which was the original intent
 *  of the HTML element), it is more commonly used to provide a graphic
 *  image for the user to click, rather than the rather plain <input type=submit>.
 *
 *  [<a href="../../../../../ComponentReference/ImageSubmit.html">Component Reference</a>]
 *
 *
 *  @author Howard Lewis Ship
 *  @version $Id: ImageSubmit.java,v 1.12 2002/11/27 17:58:47 hship Exp $
 **/

public class ImageSubmit extends AbstractFormComponent
{
    private IAsset _image;
    private IAsset _disabledImage;
    private Object _tag;
    private String _name;
    private String _nameOverride;
    private IActionListener _listener;
    private boolean _disabled;

    private IBinding _pointBinding;
    
    /** 
     * 
     *  Can't use a "form" direction parameter, because updates
     *  the binding before invoking the listener.
     * 
     **/
    
    private IBinding _selectedBinding;

    public void setPointBinding(IBinding value)
    {
        _pointBinding = value;
    }

    public IBinding getPointBinding()
    {
        return _pointBinding;
    }

    public void setSelectedBinding(IBinding value)
    {
        _selectedBinding = value;
    }

    public IBinding getSelectedBinding()
    {
        return _selectedBinding;
    }

    protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) throws RequestCycleException
    {
        IForm form = getForm(cycle);

        boolean rewinding = form.isRewinding();

        if (_nameOverride == null)
            _name = form.getElementId(this);
        else
            _name = form.getElementId(_nameOverride);

        if (rewinding)
        {
            // If disabled, do nothing.

            if (_disabled)
                return;

            RequestContext context = cycle.getRequestContext();

            // Image clicks get submitted as two request parameters: 
            // foo.x and foo.y

            String parameterName = _name + ".x";

            String value = context.getParameter(parameterName);

            if (value == null)
                return;

            // The point parameter is not really used, unless the
            // ImageButton is used for its original purpose (as a kind
            // of image map).  In modern usage, we only care about
            // whether the user clicked on the image (and thus submitted
            // the form), not where in the image the user actually clicked.

            if (_pointBinding != null)
            {
                int x = Integer.parseInt(value);

                parameterName = _name + ".y";
                value = context.getParameter(parameterName);

                int y = Integer.parseInt(value);

                _pointBinding.setObject(new Point(x, y));
            }

            // Notify the application, by setting the select parameter
            // to the tag parameter.

            if (_selectedBinding != null)
                _selectedBinding.setObject(_tag);

            if (_listener != null)
                _listener.actionTriggered(this, cycle);

            return;
        }

        // Not rewinding, do the real render

        IAsset finalImage = (_disabled && _disabledImage != null) ? _disabledImage : _image;

        String imageURL = finalImage.buildURL(cycle);

        writer.beginEmpty("input");
        writer.attribute("type", "image");
        writer.attribute("name", _name);

        if (_disabled)
            writer.attribute("disabled");

        // NN4 places a border unless you tell it otherwise.
        // IE ignores the border attribute and never shows a border.

        writer.attribute("border", 0);

        writer.attribute("src", imageURL);

        generateAttributes(writer, cycle);

        writer.closeTag();
    }

    public boolean isDisabled()
    {
        return _disabled;
    }

    public void setDisabled(boolean disabled)
    {
        _disabled = disabled;
    }

    public IAsset getDisabledImage()
    {
        return _disabledImage;
    }

    public void setDisabledImage(IAsset disabledImage)
    {
        _disabledImage = disabledImage;
    }

    public IAsset getImage()
    {
        return _image;
    }

    public void setImage(IAsset image)
    {
        _image = image;
    }

    public IActionListener getListener()
    {
        return _listener;
    }

    public void setListener(IActionListener listener)
    {
        _listener = listener;
    }

    public String getName()
    {
        return _name;
    }

    public Object getTag()
    {
        return _tag;
    }

    public void setTag(Object tag)
    {
        _tag = tag;
    }

    public String getNameOverride()
    {
        return _nameOverride;
    }

    public void setNameOverride(String nameOverride)
    {
        _nameOverride = nameOverride;
    }

    protected void prepareForRender(IRequestCycle cycle) throws RequestCycleException
    {
        super.prepareForRender(cycle);
        
        if (_image == null)
            throw new RequiredParameterException(this, "image", getBinding("image"));
    }

}