/*
 *  Copyright 2012 GWT-Bootstrap
 *
 *  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.github.gwtbootstrap.client.ui;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;

//@formatter:off
/**
 * {@linkplain Navbar} uses this class for the scrollspy.
 * 
 * @since 2.0.4.0
 * @author Carlos Alexandro Becker
 * @see <a href="http://twitter.github.com/bootstrap/javascript.html#scrollspy">Twitter Bootstrap ScrollSpy</a>
 */
//@formatter:on
public class Scrollspy {

        private Navbar navbar;
        
        /** spy target element */
        private Element spyElement;

        /** data-target */
        private String target;

        /** data-offset */
        private Integer offset;
        
        private boolean configured;

        /**
         * 
         * @param navbar
         *            The navbar that will be spied.
         */
        public Scrollspy(Navbar navbar) {
                super();
                this.navbar = navbar;
                
                if(navbar.getId() != null && navbar.getId().length() > 0) {
                        setTarget("#" + navbar.getId());
                }
        }
        
        /**
         * Create Empty Scrollspy
         */
        public Scrollspy() {
            super();
        }

        /**
         * Get navbar
         * @return nabvar.
         */
        public Navbar getNavbar() {
                return navbar;
        }

        /**
         * set navbar
         * @param navbar
         */
        public void setNavbar(Navbar navbar) {
                this.navbar = navbar;
        }
        
        /**
         * set data-target.
         * <p>
         * If set this,{@link #spyElement} is set {@code data-target} attribute this {@code target} when {@link #configure()} is called.
         * </p>
         * @param target
         *                               data-target value.like this,{@code #some-id} {@code .some-classes}
         * 
         * @see <a href="http://twitter.github.com/bootstrap/javascript.html#scrollspy">Twitter Bootstrap ScrollSpy Options</a>
         */
        public void setTarget(String target) {
                this.target = target;
                
        }
        
        /**
         * set spy target element.
         * <p>
         * If set this,Scrollspy set some setting to this argment 
         * when {@link #configure()} is called.<br/>
         * 
         * If don't set this,Scrollspy set some setting to {@code body} tag.
         * </p>
         * 
         * @param element
         *                               spy target element.
         * @see <a href="http://twitter.github.com/bootstrap/javascript.html#scrollspy">Twitter Bootstrap ScrollSpy Options</a>
         */
        public void setSpyElement(Element element) {
                this.spyElement = element;
        }
        
        /**
         * set data-offset.
         * <p>
         * If set this,{@link #spyElement} is set {@code data-offset} attribute this {@code target} when {@link #configure()} is called.
         * </p>
         * @param target
         *                               data-offset value.
         * @see <a href="http://twitter.github.com/bootstrap/javascript.html#scrollspy">Twitter Bootstrap ScrollSpy Options</a>
         */
        public void setOffset(Integer offset) {
                this.offset = offset;
        }

        /**
         * Configure the scrollspy in the configured navbar.
         */
        public void configure() {
                
                Element spyTargetElement = getSpyElement();
                
                assert spyTargetElement != null : "houston, we need a spy element here!";
                
                jsConfigure(spyTargetElement , target, offset == null ? -1 : offset );
                
                configured = true;
        }
        
        public boolean isConfigured() {
                return configured;
        }
        
        public Element getSpyElement() {
                return spyElement != null ? spyElement : Document.get().getBody();
        }
        
        public void refresh() {
            refresh(getSpyElement());
        }
        
        private native void refresh(Element e) /*-{
            $wnd.jQuery(e).scrollspy('refresh');
        }-*/;
        
        
    private native void jsConfigure(Element e, String target,int offset) /*-{
        var $this = $wnd.jQuery(e);
        if($this.data('scrollspy')) {
            $this.data('scrollspy').$scrollElement.off('scroll.scroll.data-api');
            $this.removeData('spy');
            $this.removeData('target');
            $this.removeData('offset');
            $this.removeData('scrollspy');
        }
        
        var applyOptions = false;
        var options = {};
        if(target) {
            options.target = target;
            applyOptions = true;
        }
        
        if(offset != -1) {
            options.offset = offset;
            applyOptions = true;
        }
        
        
        if(applyOptions) {
            $this.scrollspy(options);
        } else {
            $this.scrollspy();
        }
        }-*/;

}