/*
    * Copyright 2004 the original author or authors.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.nordija.tapestry.bayeux.form;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.tapestry.IActionListener;
  import org.apache.tapestry.IBinding;
  import org.apache.tapestry.IForm;
  import org.apache.tapestry.IMarkupWriter;
  import org.apache.tapestry.IRequestCycle;
  import org.apache.tapestry.form.AbstractFormComponent;
  
  /**
   * Component which renders a HTML4 button element (<button type="...">Create</button>).
   * <p/>
   * The implementation of this component has been heavily inspired by the standard Tapestry Button and Submit components.
   *
   * @author Per Olesen, www.nordija.com
   * @version $Id: Html4Button.java 90 2007-05-18 13:53:39Z jeyben $
   */
  public abstract class Html4Button extends AbstractFormComponent {
  
      /**
       * the value of hidden button control element which is set when button is clicked (workaround on an IE bug)
       */
      public static final String BUTTON_SUBMIT_VALUE = "x";
  
      private static final Log LOG = LogFactory.getLog(Html4Button.class);
  
      public abstract String getLabel();
  
      public abstract String getType();
  
      public abstract IBinding getSelectedBinding();
  
      public abstract boolean isDisabled();
  
      public abstract String getOnclickEventHandler();
  
      public abstract IActionListener getListener();
  
      public abstract Object getTag();
  
      protected void renderFormComponent(IMarkupWriter writer, IRequestCycle cycle) {
          IForm form = getForm();
          String buttonName = form.getElementId(this);
          String formName = form.getName();
  
          if (LOG.isDebugEnabled()) {
              LOG.debug("form=" + form + ", buttonName=" + buttonName);
          }
          processRendering(cycle, formName, buttonName, writer);
      }
  
      protected void rewindFormComponent(IMarkupWriter writer, IRequestCycle cycle) {
          IForm form = getForm();
          String buttonName = form.getElementId(this);
         if (LOG.isDebugEnabled()) {
              LOG.debug("rewinding: form=" + form + ", buttonName=" + buttonName);
          }
           processRewinding(cycle, buttonName);
      }
  
      private void processRendering(IRequestCycle cycle, String formName, String buttonName, IMarkupWriter writer) {
          //
          // A bug in IE6 makes it submit ALL buttons on a form if one of the buttons are clicked
          // which again makes tapestry think all buttons where clicked which results in all listeners
          // being activated.
          //
          // We work around this by putting a hidden input field in form for each submit button, and
          // letting the button set the value of this field if it is clicked, before submit.
          // At rewind, we then dispatch on this hidden value instead of button name.
          //
          writer.begin("input");
          writer.attribute("type", "hidden");
          writer.attribute("name", getHiddenElementName(buttonName));
          writer.end();
  
          writer.begin("button");
          writer.attribute("type", getType());
          writer.attribute("name", buttonName);
  
          if (isDisabled()) {
              writer.attribute("disabled", "disabled");
          }
 
         String label = getLabel();
         if (label != null) {
             writer.attribute("value", label);
         }
 
         // this is the js code, that sets the hidden element before the button-click submits the form
         String onclickEvent = "document." + formName + "." + getHiddenElementName(buttonName) + ".value='" + BUTTON_SUBMIT_VALUE + "'";
 
         // if a specific onclick handler was specified, this js code is appended
         if ((getOnclickEventHandler() != null) && (getOnclickEventHandler().trim().length() > 0)) {
             onclickEvent += "; " + getOnclickEventHandler();
         }
 
         writer.attribute("onclick", onclickEvent);
 
         renderInformalParameters(writer, cycle);
         renderBody(writer, cycle);
         writer.end();
     }
 
     private void processRewinding(IRequestCycle cycle, String buttonName) {
         if (isDisabled()) {
             return;
         }
 
         // As with the standard Submit component, the value of the button is submitted with the
         // form and is used to determine if we should dispatch to listener (ie. if it was this button that was clicked).
         // A bug in IE6 makes it submit all button-elements in a form if one such is clicked, which makes
         // dispatching on the button value break. This is worked around by letting the button set a hidden
         // value in form and use that to determine if we should dispatch.
         String value = cycle.getParameter(getHiddenElementName(buttonName));
         if (value == null || (!value.equals(BUTTON_SUBMIT_VALUE))) {
             return; // button was not clicked, submit of form was from some other component on same form
         }
 
         if (LOG.isDebugEnabled()) {
             LOG.debug("determined that it was this button '" + buttonName + "' that was clicked");
         }
         // copy tag over into selected paramter
         IBinding selectedBinding = getSelectedBinding();
         if (selectedBinding != null) {
             selectedBinding.setObject(getTag());
         }
 
         IActionListener listener = getListener();
         if (listener != null) {
             listener.actionTriggered(this, cycle);
         }
     }
 
     private String getHiddenElementName(String buttonName) {
         return buttonName + "_ctrl";
     }
 }