/*******************************************************************************

 *  Copyright: 2004-2010 1&1 Internet AG, Germany, http://www.1und1.de,

 *                       and EclipseSource

 *

 * This program and the accompanying materials are made available under the

 * terms of the Eclipse Public License v1.0 which accompanies this

 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html

 *

 *  Contributors:

 *    1&1 Internet AG and others - original API and implementation

 *    EclipseSource - adaptation for the Eclipse Rich Ajax Platform

 ******************************************************************************/

qx.Class.define( "org.eclipse.swt.widgets.Scrollable", {

  extend : qx.ui.layout.CanvasLayout,

  construct : function( clientArea ) {

    this.base( arguments );

    this._clientArea = clientArea;

    this._horzScrollBar = new qx.ui.basic.ScrollBar( true );

    this._vertScrollBar = new qx.ui.basic.ScrollBar( false );

    this._blockScrolling = false;

    this._internalChangeFlag = false;

    this.add( this._clientArea );

    this.add( this._horzScrollBar );

    this.add( this._vertScrollBar );

    this._configureScrollBars();

    this._configureClientArea();

    this.__onscroll = qx.lang.Function.bindEvent( this._onscroll, this );

  },

  destruct : function() {

    var el = this._clientArea._getTargetNode();

    if( el ) {

      var eventUtil = qx.html.EventRegistration;

      eventUtil.removeEventListener( el, "scroll", this.__onscroll );

      delete this.__onscroll;

    }

    this._clientArea = null;

    this._horzScrollBar = null;

    this._vertScrollBar = null;

  },

  events : {

    "userScroll" : "qx.event.type.Event"

  },

  members : {

    /////////

    // Public

    setScrollBarsVisible : function( horizontal, vertical ) {

      this._horzScrollBar.setDisplay( horizontal );  

      this._vertScrollBar.setDisplay( vertical );

      var overflow = "hidden";

      if( horizontal && vertical ) {

        overflow = "scroll";

      } else if( horizontal ) {

        overflow = "scrollX";

      } else if( vertical ) {

        overflow = "scrollY";

      }

      this._clientArea.setOverflow( overflow );

      this._layoutX();

      this._layoutY();

    },

    setHBarSelection : function( value ) {

      this._internalChangeFlag = true;

      if( this._horzScrollBar.getMaximum() < value ) {

        // TODO [tb] : The ScrollBar should do that itself

        this._horzScrollBar.setMaximum( value );

      }

      this._horzScrollBar.setValue( value );

      this._internalChangeFlag = false;

    },

    setVBarSelection : function( value ) {

      this._internalChangeFlag = true;

      if( this._vertScrollBar.getMaximum() < value ) {

        // TODO [tb] : The ScrollBar should do that itself

        this._vertScrollBar.setMaximum( value );

      }

      this._vertScrollBar.setValue( value );

      this._internalChangeFlag = false;

    },

    setBlockScrolling : function( value ) {

      this._blockScrolling = value;

    },

    /////////

    // Layout

    _configureClientArea : function() {

      this._clientArea.setOverflow( "scroll" );

      this._clientArea.setLeft( 0 );

      this._clientArea.setTop( 0 );

      this._clientArea.addEventListener( "create", this._onClientCreate, this );

      this._clientArea.addEventListener( "appear", this._onClientAppear, this );

      // TOOD [tb] : Do this with an eventlistner after fixing Bug 327023 

      this._clientArea._layoutPost 

        = qx.lang.Function.bindEvent( this._onClientLayout, this );

    },

    _configureScrollBars : function() {

      var dragBlocker = function( event ) { event.stopPropagation(); };

      var preferredWidth = this._vertScrollBar.getPreferredBoxWidth();

      var preferredHeight = this._horzScrollBar.getPreferredBoxHeight();

      this._horzScrollBar.setLeft( 0 );

      this._horzScrollBar.setHeight( preferredHeight );

      this._horzScrollBar.addEventListener( "dragstart", dragBlocker );

      this._vertScrollBar.setTop( 0 );

      this._vertScrollBar.setWidth( preferredWidth );

      this._vertScrollBar.addEventListener( "dragstart", dragBlocker );

      this._horzScrollBar.addEventListener( "changeValue", 

                                            this._onHorzScrollBarChangeValue, 

                                            this );

      this._vertScrollBar.addEventListener( "changeValue", 

                                            this._onVertScrollBarChangeValue, 

                                            this );      

    },

    _applyWidth : function( newValue, oldValue ) {

      this.base( arguments, newValue, oldValue );

      this._layoutX();

    },

    _applyHeight : function( newValue, oldValue ) {

      this.base( arguments, newValue, oldValue );

      this._layoutY();

    },

    _applyBorder : function( newValue, oldValue ) {

      this.base( arguments, newValue, oldValue );

      this._layoutX();

      this._layoutY();

    },    

    _layoutX : function() {

      var clientWidth = this.getWidth() - this.getFrameWidth();

      if( this._vertScrollBar.getDisplay() ) {

        clientWidth -= this._vertScrollBar.getWidth();

      } 

      this._clientArea.setWidth( clientWidth );

      this._vertScrollBar.setLeft( clientWidth );

      this._horzScrollBar.setWidth( clientWidth );

    },

    _layoutY : function() {        

      var clientHeight = this.getHeight() - this.getFrameHeight();

      if( this._horzScrollBar.getDisplay() ) {

        clientHeight -= this._horzScrollBar.getHeight();

      } 

      this._clientArea.setHeight( clientHeight );

      this._vertScrollBar.setHeight( clientHeight );

      this._horzScrollBar.setTop( clientHeight );

    },

    _onClientCreate : function( evt ) {

      this._clientArea.prepareEnhancedBorder();

      var el = this._clientArea._getTargetNode();

      var eventUtil = qx.html.EventRegistration;

      eventUtil.addEventListener( el, "scroll", this.__onscroll );

    },

    _onClientLayout : function() {

      // TODO [tb] : _getScrollBarWidth should be a static function, it has 

      // nothing to do with the instance, which here is only used to call it

      var barWidth = this._horzScrollBar._getScrollBarWidth();

      var node = this._clientArea._getTargetNode();

      var el = this._clientArea.getElement();

      var overflow = this._clientArea.getOverflow();

      var width = parseInt( el.style.width );

      var height = parseInt( el.style.height );

      if( overflow === "scroll" || overflow === "scrollY" ) {

        width += barWidth;

      }

      if( overflow === "scroll" || overflow === "scrollX" ) {

        height += barWidth;

      }

      node.style.width = width

      node.style.height = height;

    },

    ////////////

    // Scrolling

    _onHorzScrollBarChangeValue : function() {

      if( this._isCreated ) {

        this._syncClientArea( true, false );

      }

      if( !this._internalChangeFlag ) {

        this.createDispatchEvent( "userScroll" );

      }

    }, 

    _onVertScrollBarChangeValue : function() {

      if( this._isCreated ) {

        this._syncClientArea( false, true );

      }

      if( !this._internalChangeFlag ) {

        this.createDispatchEvent( "userScroll" );

      }

    },

    _onClientAppear : function() {

      this._internalChangeFlag = true;

      this._syncClientArea( true, true );

      this._internalChangeFlag = false;

    },

    _onscroll : function( evt ) {

      if( !this._internalChangeFlag ) {

        org.eclipse.rwt.EventHandlerUtil.stopDomEvent( evt );

        var blockH = this._blockScrolling || !this._horzScrollBar.getDisplay();

        var blockV = this._blockScrolling || !this._vertScrollBar.getDisplay();

        this._internalChangeFlag = true;

        this._syncClientArea( blockH, blockV );        

        this._internalChangeFlag = false;

        this._syncScrollBars();

      }

    },

    _syncClientArea : function( horz, vert ) {

      if( horz ) {

        var scrollX = this._horzScrollBar.getValue();

        this._clientArea.setScrollLeft( scrollX );

      }

      if( vert ) {

        var scrollY = this._vertScrollBar.getValue();

        this._clientArea.setScrollTop( scrollY );

      }

    },

    _syncScrollBars : function() {

      var scrollX = this._clientArea.getScrollLeft();

      this._horzScrollBar.setValue( scrollX );

      var scrollY = this._clientArea.getScrollTop();

      this._vertScrollBar.setValue( scrollY );

    }

  }

} );