function relatedPostsWidget(userOp){
    var self = this;
    var op = {
        'blogURL':''
        ,'maxPosts':5
        ,'maxTags':5
        ,'maxPostsPerTag':5
        ,'containerSelector':'div.post-body'
        ,'tags':null
        ,'loadingText':''
        ,'loadingClass':''
        ,'relevantTip':''
        ,'relatedTitle':'Posty o podobnej tematyce'
        ,'recentTitle':'Ostatnie posty'
        ,'postScoreClass':''
        ,'onLoad':false
    };
    op = $.extend({}, op, userOp);
    var tagsLoaded = 0,div= null,ul=null;
    // If no contianer selected , will create div in place of script call
    if (!op.containerSelector) {
        document.write('<div id="related-posts" />');
        op.containerSelector = '#related-posts';
    }
    // Tag json posts are loaded
    var tagLoaded = function(json,status){
        tagsLoaded++;
        if(json.feed.entry) {
            for (var i=0; i<json.feed.entry.length; i++) {
                var entry = json.feed.entry[i];
                var url='';
                for (var k=0; k<entry.link.length; k++) {
                    if(entry.link[k].rel=='alternate') {
                        url = entry.link[k].href;
                        break;
                    }
                }
                var title = entry.title.$t;
                //Ignore current url
                if(location.href.toLowerCase()!= url.toLowerCase()) addPost(url,title);
            }
        } 
        // Loading posts of all tags is done
        if(tagsLoaded>=op.tags.length) {
             ul.attr('class','');
             $('#related-posts-loadingtext',div).remove();
             // Hide extra posts if maxPosts >0
             if(op.maxPosts>0) $('li:gt('+ (op.maxPosts-1) +')',ul).remove();
        }    
    }
    // Add post and re-order
    var addPost = function(url,title) {
        //current LI items inside of UL
        var list = $('li',ul);
        for(var i=0; i<list.length; i++) {
            //get score
            var a= $('a', list.eq(i) );
            var sc = getScore(a);
            //Post exists ?
            if(a.attr('href')==url) {
                //Yes : Then increment score
                setScore(a,++sc);
                //Re-order : compare with prevoius li items
                for(var j=i-1; j>=0; j--){
                    // find the item with higher score than current
                    var jA= $('a', list.eq(j) );
                    if (getScore(jA)>sc) {
                        // re-order if only there are items in the middle to appear before
                        if(i-j>1) list.eq(j).after(list.eq(i));
                        return;
                    }
                };
                // If no higher item then this one should go first
                if(i>0) list.eq(0).before(list.eq(i));
                return;
            }
        }
        //Add new post
        ul.append('<li><a href="'+url+'" title="'+(op.relevantTip? op.relevantTip.replace('\d',1):'')+'">'+title+'</a></li>');
    }
    // parse score from attribute
    var getScore = function(a){
        var score = parseInt(a.attr('score'));
        return score>0? score : 1;
    }
    // set score from attribute
    var setScore = function(a,sc) {
        a.attr('score',sc);
        if(op.relevantTip) a.attr('title',op.relevantTip.replace('\d',sc)); 
        if(op.postScoreClass) a.attr('class',op.postScoreClass+sc); 
    }
    // init 
    var initRelatedPosts = function() {
        // append my div to user selected container 
        if(op.containerSelector != '#related-posts'){
            var container = $(op.containerSelector);
            // check contianer is there and only one for pages like home
            if (container.length!=1) return;
            div = $('<div id="related-posts"/>').appendTo(container);
        }
        else div = $(op.containerSelector); // div which I wrote on document
        
        // get tags if wasn't preset
        if (!op.tags) {
            op.tags = [];
            $('a[rel="tag"]:lt('+op.maxTags+')').each(function () {
                var tag= $.trim($(this).text().replace(/\n/g,''));
                if($.inArray(tag,op.tags)==-1) op.tags[op.tags.length]=tag;
            });
        }
        // should make recent posts but no recent title :exit
        if(op.tags.length==0 && !op.recentTitle) return;
        
        //add recent posts title
        if(op.tags.length==0) $('<h2>'+op.recentTitle+'</h2>').appendTo(div);
        //add related posts title if any
        else if(op.relatedTitle) $('<h2>'+op.relatedTitle+'</h2>').appendTo(div);
        
        //Add loading text if any
        if(op.loadingText) $('<div id="related-posts-loadingtext">'+op.loadingText+'</div>').appendTo(div);
        // Appending UL with loading class if selected
        ul= $('<ul '+(op.loadingClass? 'class="'+ op.loadingClass+'"':'')+'/>').appendTo(div);
        
        //recent posts
        if(op.tags.length==0){
            $.ajax({url:op.blogURL+'/feeds/posts/summary/'
                    ,data:{'max-results':op.maxPostsPerTag,'alt':'json-in-script'}
                    ,success:tagLoaded
                    ,dataType:'jsonp'
                    ,cache:true });
        // Tags found , do related posts widget
        }else{
            // Requesting json feeds for each tag    
            for(var t=0; t<op.tags.length;t++) 
                $.ajax({url:op.blogURL+'/feeds/posts/summary/'
                        ,data:{'category':op.tags[t],'max-results':op.maxPostsPerTag,'alt':'json-in-script'}
                        ,success:tagLoaded
                        ,dataType:'jsonp'
                        ,cache:true });
        }    
    }
    // Call init on document ready
    if(op.onLoad) $(window).load(initRelatedPosts);
    else $(document).ready(initRelatedPosts);
}