/*Sag Content Scroller (Aug 7th, 2010)
* This notice must stay intact for usage 
* Author: Dynamic Drive at http://www.dynamicdrive.com/
* Visit http://www.dynamicdrive.com/ for full source code
*/

//Updated Aug 28th, 10 to v1.3

var sagscroller_constants={
    navpanel: {height:'16px', downarrow:'http://www.info-resource.org.uk/images/down-arrow.gif', opacity:0.6, title:'Go to Next Content', background:'black'},
    loadingimg: {src:'http://www.info-resource.org.uk/images/ajaxloading.gif', dimensions:[100,15]}
}

function sagscroller(options){

    this.setting={mode:'manual', inittype:'stunted', pause:3000, animatespeed:500, ajaxsource:null, rssdata:null, refreshsecs:0, navpanel:{show:true, cancelauto:false}} //default settings
    jQuery.extend(this.setting, options) //merge default settings with options
    options=null
    this.curmsg=0
    this.addloadingpanel(jQuery, 'preload')
    if (this.setting.rssdata) //if rss contents
        google.load("feeds", "1") //init google ajax api
    var slider=this
    jQuery(function($){ //on document.ready
        slider.$slider=$('#'+slider.setting.id)
        if (slider.setting.ajaxsource||slider.setting.rssdata)
            slider.$slider.empty()
        slider.addloadingpanel(jQuery, 'show')
        if (slider.setting.ajaxsource) //if ajax data
            slider.getajaxul(slider.setting.ajaxsource)
        else if (slider.setting.rssdata){ //if rss data
            slider.fetchfeeds()
        }
        else{ //if inline content
            if (slider.setting.inittype=="onload") //load scroller when page has completely loaded?
                $(window).load(function(){slider.init($)})
            else //load scroller immediately and get dimensions progressively instead
                slider.init($)
        }
    })
}

sagscroller.prototype={

    getajaxul:function(path){
        var $=jQuery, slider=this
        this.stopscroll() //stop animation/ scrolling of slider, in the event this is a subsequent call to getajaxul()
        this.$loadingpanel.show()
        $.ajax({
            url: path, //path to external content
            async: true,
            error:function(ajaxrequest){
                slider.$slider.html('Error fetching content.<br />Server Response: '+ajaxrequest.responseText)
            },
            success:function(content){
                slider.reloadul(content)
                if (slider.setting.refreshsecs>0) //refetch contents every x sec?
                    setTimeout(function(){slider.getajaxul(path)}, slider.setting.refreshsecs*1000)
            }
        })
    },

    addloadingpanel:function($, mode){
        var loadingimgref=sagscroller_constants.loadingimg
        if (mode=="preload"){
            var loadingimg=new Image(loadingimgref.dimensions[0], loadingimgref.dimensions[1])
            loadingimg.src=loadingimgref.src
            this.$loadingimg=$(loadingimg).css({position:'absolute', zIndex:1003})
        }
        else{
            var sliderdimensions=[this.$slider.width(), this.$slider.height()]
            var $loadingpanel=$('<div />').css({position:'absolute', left:0, top:0, background:'black', opacity:0.5, width:sliderdimensions[0], height:sliderdimensions[1], zIndex:1002}).appendTo(this.$slider)
            this.$loadingimg.css({left:sliderdimensions[0]/2-loadingimgref.dimensions[0]/2, top:sliderdimensions[1]/2-loadingimgref.dimensions[1]/2}).appendTo(this.$slider)
            this.$loadingpanel=$loadingpanel.add(this.$loadingimg)
        }
    },

    addnavpanel:function(){
        var slider=this, setting=this.setting
        var $navpanel=$('<div class="sliderdesc"><div class="sliderdescbg"></div><div class="sliderdescfg"><div class="sliderdesctext"></div></div></div>')
            .css({position:'absolute', width:'100%', left:0, top:-1000, zIndex:'1001'})
            .find('div').css({position:'absolute', left:0, top:0, width:'100%'})
            .eq(0).css({background:sagscroller_constants.navpanel.background, opacity:sagscroller_constants.navpanel.opacity}).end() //"sliderdescbg" div
            .eq(1).css({color:'white'}).end() //"sliderdescfg" div
            .eq(2).css({textAlign:'center', cursor:'pointer', paddingTop:'2px'}).html('<img src="'+sagscroller_constants.navpanel.downarrow+'"/>').end().end()
            .appendTo(this.$slider)
        var $descpanel=$navpanel.find('div.sliderdesctext').attr('title', sagscroller_constants.navpanel.title).click(function(){ //action when nav bar is clicked on
            slider.stopscroll()
            slider.scrollmsg(setting.mode=="auto" && !setting.navpanel.cancelauto? true : false)
        })
        $navpanel.css({top:this.$slider.height()-parseInt(sagscroller_constants.navpanel.height), height:sagscroller_constants.navpanel.height}).find('div').css({height:'100%'})
    },

    resetuls:function(){ //function to swap between primary and secondary ul
        var $tempul=this.$mainul
        this.$mainul=this.$secul.css({zIndex:1000})
        this.$secul=$tempul.css({zIndex:999})
        this.$secul.css('top', this.ulheight)
    },

    reloadul:function(newhtml){ //function to empty out SAG scroller UL contents then reload with new contents
        this.$slider.find('ul').remove()
        this.ulheight=null
        this.curmsg=0;
        this.$slider.append(newhtml)
        this.init($)        
    },

    setgetoffset:function($li){
        var recaldimensions=(this.setting.ajaxsource || this.setting.rssdata) && this.setting.inittype=="onload" //bool to see if script should always refetch dimensions
        if (this.curmsg==this.$lis.length)
            return (!this.ulheight || recaldimensions)? this.ulheight=this.$mainul.height() : this.ulheight
        else{
            if (!$li.data('toppos') || recaldimensions)
                $li.data('toppos', $li.position().top)
            return $li.data('toppos')
        }
    },

    scrollmsg:function(repeat){
        var slider=this, setting=this.setting
        var ulheight=this.ulheight || this.$mainul.height()
        var endpoint=-this.setgetoffset(this.$lis.eq(this.curmsg))
        this.$mainul.animate({top: endpoint}, setting.animatespeed, function(){
            slider.curmsg=(slider.curmsg<slider.$lis.length+1)? slider.curmsg+1 : 0
            if (slider.curmsg==slider.$lis.length+1){ //if at end of UL
                slider.resetuls() //swap between main and sec UL
                slider.curmsg=1
            }
            if (repeat)
                slider.scrolltimer=setTimeout(function(){slider.scrollmsg(repeat)}, setting.pause)
        })
        var secendpoint=endpoint+ulheight
        this.$secul.animate({top: secendpoint}, setting.animatespeed)
    },

    stopscroll:function(){
        if (this.$mainul){
            this.$mainul.add(this.$secul).stop(true, false)
            clearTimeout(this.scrolltimer)
        }
    },

    init:function($){
        var setting=this.setting
        this.$loadingpanel.hide()
        this.$mainul=this.$slider.find('ul:eq(0)').css({zIndex:1000})
        this.$lis=this.$mainul.find('li')
        if (setting.navpanel.show)
            this.addnavpanel()
        this.$secul=this.$mainul.clone().css({top:this.$mainul.height(), zIndex:999}).appendTo(this.$slider) //create sec UL and add it to the end of main UL
        this.scrollmsg(setting.mode=="auto")
    },

    ///////////////////////RSS related methods below///////////////////


    fetchfeeds:function(){
        var slider=this, rssdata=this.setting.rssdata
        this.stopscroll() //stop animation/ scrolling of slider, in the event this is a subsequent call to fetchfeeds()
        this.$loadingpanel.show()
        this.entries=[] //array holding combined RSS feeds' entries from Feed API (result.feed.entries)
        this.feedsfetched=0
        for (var i=0; i<rssdata.feeds.length; i++){ //loop through the specified RSS feeds' URLs
            var feedpointer=new google.feeds.Feed(rssdata.feeds[i][1]) //create new instance of Google Ajax Feed API
            feedpointer.setNumEntries(rssdata.entries) //set number of items to display
            feedpointer.load(function(label){
                return function(r){
                    slider.storefeeds(r, label)
                }
            }(rssdata.feeds[i][0])) //call Feed.load() to retrieve and output RSS feed.
        }   
    },

    storefeeds:function(result, label){
        var thisfeed=(!result.error)? result.feed.entries : "" //get all feed entries as a JSON array or "" if failed
        if (thisfeed==""){ //if error has occured fetching feed
            alert("Google Feed API Error: "+result.error.message)
        }
        for (var i=0; i<thisfeed.length; i++){ //For each entry within feed
            result.feed.entries[i].label=label //extend it with a "label" property
        }
        this.entries=this.entries.concat(thisfeed) //add entry to array holding all feed entries
        this.feedsfetched+=1
        if (this.feedsfetched==this.setting.rssdata.feeds.length){ //if all feeds fetched
            if (this.setting.rssdata.groupbylabel){ //sort by label name?
                this.entries.sort(function(a,b){
                    var fielda=a.label.toLowerCase(), fieldb=b.label.toLowerCase()
                    return (fielda<fieldb)? -1 : (fielda>fieldb)? 1 : 0
                })
            }
            else{ //just sort by date
                this.entries.sort(function(a,b){return new Date(b.publishedDate)-new Date(a.publishedDate)})
            }
            this.formatfeeds()
        }
    },

    formatfeeds:function(){
        function formatdate(datestr, showoptions){
            var itemdate=new Date(datestr)
            var parseddate=(showoptions.indexOf("datetime")!=-1)? itemdate.toLocaleString() : (showoptions.indexOf("date")!=-1)? itemdate.toLocaleDateString() : ""
            return "<span class='datefield'>"+parseddate+"</span>"
        }
        var sagcontent='<ul>'
        var slider=this, rssdata=this.setting.rssdata, entries=this.entries
        for (var i=0; i<entries.length; i++){
            sagcontent+='<li><a href="'+entries[i].link+'" target="'+rssdata.linktarget+'">'+entries[i].title+'</a>'
                +'<div class="rsscontent">'
                +(/description/.test(rssdata.displayoptions)? entries[i].content : entries[i].contentSnippet)
                +'</div>'
                +'<div class="rsslabel">'
                +(/label/.test(rssdata.displayoptions)? "<b>Source("+(i+1)+"):</b> "+entries[i].label+" " : "")
                +(/date/.test(rssdata.displayoptions)? formatdate(entries[i].publishedDate, rssdata.displayoptions): "")
                +'</div>'
                +'</li>\n\n'
        }
    sagcontent+='</ul>'
    this.reloadul(sagcontent)
    if (slider.setting.refreshsecs>0) //refetch contents every x sec?
        setTimeout(function(){slider.fetchfeeds()}, slider.setting.refreshsecs*1000)
    }
}