// Usage - var rdObj = new RevisionsData( 'Some Page' );
// the ready and error functions are executed in the context of the newly created RevisionData object
// limit restricts the number of revisions to load, loading starts for the most recent revisions
// and the summaries are load a batch of listSize at a time (note that if listSize not a multiple of limit the limit may be breached)

// this object only fetches revision summaries when first created
// that content text of each revisions needs to be loaded with calls to the objects loadRevision method
// due to browser localStorage size constraints the ability of this object to store a client side cache of assembled revisions data is not very useful  

// 


function RevisionsData(page, whenReady, onerror, limit , listSize){

	this.baseURL='/w/api.php?action=';

	this.dataLimit=limit?limit:1400; //number of revisions summaries
	this.dataSize=listSize?listSize:'max' //number of revisions summaries per call

	this.onListingLoaded=whenReady;
	this.onError=(onerror) ? (onerror) : ( function(jqXHR, textStatus, errorThrown){ /*alert('Uncaught RD error' +textStatus);*/ } );
	this.errors=[];

	this.page=page.replace(/_/g,' ');
	this.revisions=[];

	this.afterLoadingContent=[];

	this.loadCount=0;
	this.loadThrottle=5;
	this.loadWaiting=false;
	this.pendingLoads=[];


	this.cacheText=false;
	this.cacheListing=false;

	this.storagePrefix='rev';
	this.storagePrefixLisiting='list';

	this.loadInfo = function(){

		var url=this.baseURL+'query&titles='+ this.page +'&prop=info&format=json';
	
		var action=function(data) {
var ids=''; var pageFound=false;
			for(var i in data.query.pages){
ids+=i+' '+data.query.pages[i].title+' ';
				if( data.query.pages[i].title == this.page ){
pageFound=data.query.pages[i].title;
					this.pageId=data.query.pages[i].pageid;
					this.finalRevId=data.query.pages[i].lastrevid;
					this.nextRevId=this.finalRevId;
				}
			}


			if(!pageFound && this.msg) alert(ids+'\n'+this.page); else{
if(this.msg)  alert('page found '+pageFound);
}

			this.loadListing();
		};


		$.ajax({'url':url, 'context':this,'dataType':'json','success':action ,
				'error':function(jqXHR, textStatus, errorThrown){
					this.lastError={'requestObject':jqXHR,'message':textStatus,'errorObject':errorThrown};
					this.onError(jqXHR, textStatus, errorThrown);
				}});


	}

	this.checkForNewRevisions=  function(){


		var url=this.baseURL+'query&titles='+ this.page +'&prop=revisions';
		url += '&rvlimit=1&rvprop=timestamp&format=json';

		var action=function(data){

			if(data.query.pages[this.pageId].revisions[0].timestamp!=this.revisions[0].timestamp){

				var action= function(data){ this.newerVersion=data.query.pages[this.pageId].revisions[0]; }
	

				var url=this.baseURL+'query&titles='+ this.page +'&prop=revisions';
				url += '&rvlimit=1&rvprop=timestamp|user|comment|ids|size|content&format=json';

				$.ajax({'url':url, 'context':this,'dataType':'json','success':action ,
				'error':function(jqXHR, textStatus, errorThrown){
					this.lastError={'requestObject':jqXHR,'message':textStatus,'errorObject':errorThrown};
					this.onError(jqXHR, textStatus, errorThrown);
				}});

 			
			}
		}

		$.ajax({'url':url, 'context':this,'dataType':'json','success':action ,
				'error':function(jqXHR, textStatus, errorThrown){
					this.lastError={'requestObject':jqXHR,'message':textStatus,'errorObject':errorThrown};
					this.onError(jqXHR, textStatus, errorThrown);
				}});
	}

	this.loadListing=function(){

		if(this.cacheListing){

			var key=this.storagePrefixLisiting+this.page.replace(/ /g,'_');
			if(localStorage.getItem(key)){
				this.revisions=JSON.parse(localStorage.getItem(key)); alert('load cached listing');
				return;
			}else{
if(this.msg) alert('no cache found for '+key);
			}

		}

		if(this.nextRevId){

			var url=this.baseURL+'query&titles='+ this.page +'&prop=revisions';
			url += '&rvdir=older&rvlimit=max&rvprop=timestamp|user|comment|ids|size|tags|flags&rvstartid=';
 			url += this.nextRevId +'&format=json';

			var action= function(data) {

				if( !data.query.pages[this.pageId]) alert('error not found '+this.pageId);

				var nrevs=data.query.pages[this.pageId].revisions;

				if((new Date(nrevs[0].timestamp))<=(new Date(nrevs[nrevs.length-1].timestamp))){
if(this.msg) alert('wrong order');
					this.nextRevId=false;
					this.nextRevisionI=this.revisions.length-1;

					this.loadRevision(0,function(){
						this.revObj.onListingLoaded(true);
					},function(){
						this.revObj.onListingLoaded(false);
					});
					this.loadListing();
					return false;
				}


/*alert(this.revisions.length+' got listing chunk '+nrevs.length+' '+nrevs[nrevs.length-1].parentid);
if( this.revisions.length>1 && (new Date(nrevs[0].timestamp)) < (new Date( this.revisions[this.revisions.length-1].timestamp )) && (new Date(nrevs[0].timestamp))>(new Date(nrevs[nrevs.length-1].timestamp))) alert('ok newT '+nrevs[0].timestamp+'- '+nrevs[nrevs.length-1].timestamp+'  lastT'+this.revisions[this.revisions.length-1].timestamp);*/


				this.revisions= this.revisions.concat( data.query.pages[this.pageId].revisions );

				if(this.revisions[this.revisions.length-1].parentid && this.revisions.length<this.dataLimit){
					this.nextRevId=this.revisions[this.revisions.length-1].parentid;
				}else{

					if(this.cacheListing){
						var key=this.storagePrefixLisiting+this.page.replace(/ /g,'_');
						localStorage.setItem(key,JSON.stringify(this.revisions));
					}
		
					this.loadRevision(0,function(){
						this.revObj.onListingLoaded(true);
					},function(){
						this.revObj.onListingLoaded(false);
					});

					this.nextRevId=false;
					this.nextRevisionI=this.revisions.length-1;
				}

				this.loadListing();
			
			};

			$.ajax({'url':url, 'context':this,'dataType':'json','success':action ,
				'error':function(jqXHR, textStatus, errorThrown){
					this.lastError={'requestObject':jqXHR,'message':textStatus,'errorObject':errorThrown};
					this.onError(jqXHR, textStatus, errorThrown);
				}});

		}else{
if(this.msg) alert('nothing next');
			if(this.cacheText) this.checkCache(); 
		}
	}


	this.continueLoading=function(){ //alert('continue');
		var c=true;
	
		this.loadWaiting=false;
		while(this.pendingLoads.length && c){
			var p=this.pendingLoads.shift();
			c = this.loadRevision(p[0],p[1],p[2],p[3],p[4]);
		}
	}

	this.checkFinishedLoading=function(rObj){
		if(this.pendingLoads.length==0 && this.loadCount==0){
			while(this.afterLoadingContent.length){
				var f=this.afterLoadingContent.shift();
				if(typeof f == 'function'){
					this.tempF=f;
					this.tempF(rObj);
				}
			}
		}
	}

	this.loadRevision=function(i,after,error,caller,afterall){

		this.afterLoadingContent.push(afterall);


		if(this.loadCount<0 || this.loadCount>=this.loadThrottle){
			this.pendingLoads.push([i,after,error,caller,afterall]);
			if(!this.loadWaiting){
				this.loadWaiting=true;
				window.setTimeout("window.revisionsObject.data.continueLoading();",1000);
			}
			return false;
		}

		this.loadCount++;

		var revid = this.revisions[i].revid;
		var url=this.baseURL+'query&titles='+ this.page +'&prop=revisions';
		url += '&rvlimit=1&rvprop=timestamp|user|comment|ids|size|content&rvstartid=';
 		url += revid +'&format=json';

		var request={
			'revObj':this,
			'url':url,
			'i':i,
			'caller': caller ,
			'after': (after) ? (after) : ( function(){} ),
			'error': (error) ? (error) : ( function(jqXHR, textStatus, errorThrown){ alert('Uncaught error loading revision text '+textStatus); } ) 
		};



		if(typeof this.revisions[i].text == 'string'){
			this.loadCount--;
			request.after(i,request.caller,request);
			this.checkFinishedLoading();
			return true;
		}

		$.ajax({	'url':url,
				'context':request,
				'dataType':'json',
				'success':function(data) {
					this.revObj.loadCount--;
					var r=data.query.pages[this.revObj.pageId].revisions[0];
if(!r || !r['*'] && this.msg) alert(' details load failed '+ this.readingURL+' \n'+r);
if(this.msg) $('body').append($('<div>'+(r['*'].length+' '+this.i)+'</div>'));

					if(this.cacheText) this.revObj.setCache(r.revid, r['*']);
					this.revObj.revisions[this.i].content=r['*'];
//if(){ alert('loading done');
					this.after(this.i,this.caller,this);
					this.revObj.checkFinishedLoading();
				},
				'error':function(jqXHR, textStatus, errorThrown){
					this.revObj.loadCount--;
					this.errors.push( {'requestObject':jqXHR,'message':textStatus,'errorObject':errorThrown,'request':this} );
					this.error(jqXHR, textStatus, errorThrown,this);
				}
		});

		return true;

	}

	this.loadInfo();













	this.checkCache=function(revid){
		var k=0;
		for(var i=0; i<this.revisions.length; i++){
			var t=localStorage.getItem(this.storagePrefix+this.revisions[i].revid);
			if(t){
				k++;
				this.revisions[i].text=t;
			}
		}
		if(this.msg && k>0) alert('Found ' +k +' cached revision texts');
	}

	this.setCache=function(revid,text){
		if(!this.cacheText) return false;
		try{
			localStorage.setItem(this.storagePrefix+revid+':'+(new Date()).getTime() ,text);
		}catch(e){
alert(e); window.status='Cache overflow';
//		this.purgeCache();	
			
		}
	}
	this.purgeCache=function(purgeAll){
		var revids={};
		for(var i=0; i<this.revisions.length; i++) revids[this.revisions[i].revid]=this.revisions[i];
		for(var i=0; i<localStorage.length;i++){
			var k=localStorage.key(i);
			if(!revids[k]){
				var parts=k.split(':');
				localStorage.removeItem(k);
			}
		}
	}

	//this.purgeCache();





}