/*
  Copyright (C) 2006 Helge Hess

  This file is part of JOPE.

  JOPE is free software; you can redistribute it and/or modify it under
  the terms of the GNU Lesser General Public License as published by the
  Free Software Foundation; either version 2, or (at your option) any
  later version.

  JOPE 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 Lesser General Public
  License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with JOPE; see the file COPYING.  If not, write to the
  Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

package org.opengroupware.jope.appserver.elements;

import java.util.Map;

import org.opengroupware.jope.appserver.core.WOAssociation;
import org.opengroupware.jope.appserver.core.WOContext;
import org.opengroupware.jope.appserver.core.WOElement;
import org.opengroupware.jope.appserver.core.WORequest;
import org.opengroupware.jope.appserver.core.WOResponse;

/*
 * WOCheckBox
 * 
 * Create HTML form checkbox field.
 * 
 * Checkboxes are different to other form elements in the request handling.
 * Regular form elements always send a value when being submitted. Checkboxes
 * only do so if they are checked.
 * So we cannot distinguish between a checkbox not being submitted and a
 * checkbox being disabled :-/
 * 
 * To fix the issue we also render a hidden form field which is always
 * submitted. If this is not required, it can be turned off with the 'safeGuard'
 * binding.
 * 
 * Sample:
 *   IsAdmin: WOCheckBox {
 *     name    = "isadmin";
 *     checked = account.isAdmin;
 *   }
 * 
 * Renders:
 *   <input type="hidden"   name="isadmin_sg" value="1" />
 *   <input type="checkbox" name="isadmin"    value="1" />
 * 
 * Bindings:
 *   selection [io] - object
 *   checked   [io] - boolean
 *   safeGuard [in] - boolean 
 *   
 * Bindings (WOInput):
 *   name      [in] - string
 *   value     [io] - object
 *   disabled  [in] - boolean
 */
public class WOCheckBox extends WOInput {
  
  protected WOAssociation selection;
  protected WOAssociation checked;
  protected WOAssociation safeGuard;

  public WOCheckBox(String _name, Map<String, WOAssociation> _assocs,
                    WOElement _template)
  {
    super(_name, _assocs, _template);

    this.selection = grabAssociation(_assocs, "selection");
    this.checked   = grabAssociation(_assocs, "checked");
    this.safeGuard = grabAssociation(_assocs, "safeGuard");
  }
  
  /* responder */

  @Override
  public void takeValuesFromRequest(WORequest _rq, WOContext _ctx) {
    /*
     * Checkboxes are special in their form-value handling. If the form is
     * submitted and the checkbox is checked, a 'YES' value is transferred in
     * the request.
     * BUT: If the checkbox is not-checked, no value is transferred at all!
     * 
     * TODO: this one is really tricky because we don't know whether the
     *       takeValues is actually triggered by a request which represents the
     *       form that contains the checkbox!
     *       Best workaround for now is to run takeValues only for POST.
     */
    Object cursor = _ctx.cursor();
    
    if (this.disabled != null) {
      if (this.disabled.booleanValueInComponent(cursor))
        return;
    }
    
    String  formName  = this.elementNameInContext(_ctx);
    Object  formValue = _rq.formValueForKey(formName);
    boolean doIt      = true;
    
    if (this.safeGuard==null || this.safeGuard.booleanValueInComponent(cursor)){
      /* we are configured to have a safeguard, check whether its submitted */
      doIt = _rq.formValueForKey(formName + "_sg") != null;
    }
    
    if (doIt && this.checked != null) {
      if (this.checked.isValueSettableInComponent(cursor))
        this.checked.setBooleanValue(formValue != null, cursor);
    }
    
    // TODO: document why we don't reset the value if missing
    if (doIt && formValue != null && this.value != null) {
      if (this.value.isValueSettableInComponent(cursor))
        this.value.setValue(formValue, cursor);
    }
  }
  
  @Override
  public void appendToResponse(WOResponse _r, WOContext _ctx) {
    if (_ctx.isRenderingDisabled())
      return;

    String cbname = this.elementNameInContext(_ctx);
    _r.appendBeginTag("input");
    _r.appendAttribute("type", "checkbox");
    _r.appendAttribute("name", cbname);
    
    Object cursor = _ctx.cursor();
    String v = null;
    if (this.value != null)
      v = this.value.stringValueInComponent(cursor);
    if (v == null || v.length() == 0)
      v = "1";
    _r.appendAttribute("value", v);
    
    if (this.disabled != null) {
      if (this.disabled.booleanValueInComponent(_ctx.cursor()))
        _r.appendAttribute("disabled", "disabled");
    }

    if (this.checked != null) {
      if (this.checked.booleanValueInComponent(_ctx.cursor()))
        _r.appendAttribute("checked", "checked");
    }
    
    this.appendExtraAttributesToResponse(_r, _ctx);
    // TODO: otherTagString
    
    _r.appendBeginTagClose();
    
    /* add safeguard field */
    
    if (this.safeGuard==null || this.safeGuard.booleanValueInComponent(cursor)){
      _r.appendBeginTag("input");
      _r.appendAttribute("type", "hidden");
      _r.appendAttribute("name",  cbname + "_sg");
      _r.appendAttribute("value", cbname); /* doesn't really matter */
      _r.appendBeginTagClose();
    }
  }

  
  /* description */
  
  @Override
  public void appendAttributesToDescription(StringBuffer _d) {
    super.appendAttributesToDescription(_d);
    
    this.appendAssocToDescription(_d, "selection", this.selection);
    this.appendAssocToDescription(_d, "checked",   this.checked);
  }  
}