/**
 * Created by Hinderling Volkart AG.
 * User: sev
 * Date: 23.06.11
 * Time: 17:02
 * Copyright 2011, Hinderling Volkart AG. All rights reserved.
 */


function ProgressiveImageSequence( imgpath , count ,  options ) {
	var myself = this;

	var images = [];
	var numLoaded = 0;
	var isComplete = false;
	this.length = count;


	var defaultOptions = {
		indexSize: 4 ,
		initialStep: 64 ,
		onComplete: null ,
		onProgress: null ,
		stopAt: 1
	};
	var pref = {};
	$.extend(pref,defaultOptions,options);

	var step = pref.initialStep;
	var current = 0;
	var hasRestepped = false;

	function callback( f , o ) {
		if ( !!f ) f.apply(o);
	}

	this.stop = function() {
		step = pref.stopAt / 2;
	};

	this.reset = function() {
		isComplete = false;
		numLoaded = 0;
		step = pref.initialStep;
		current = 0;
		hasRestepped = false;
		this.nearestIndex = -1;
		$.each( images , function(k,v){
			!!v && v.unload();
		});
	};

	this.getAt = function( index ) {
		return images[index].image;
	};

	this.nearestIndex = -1;

	this.getNearest = function( index ) {
		index = Math.floor(index);
		var diff = 0;
		var i,img;
		for ( diff = 0; diff <images.length ; diff++ ) {
			i = index+diff;
			if ( i>=0 && i<images.length) {
				img = images[i];
				if ( img && img.isLoaded() ) {
					this.nearestIndex = i;
					return img.image;
				}
			}
			i = index-diff;
			if ( i>=0 && i<images.length) {
				img = images[i];
				if ( img && img.isLoaded() ) {
					this.nearestIndex = i;
					return img.image;
				}
			}
		}
		return null;
	};




	// Loading

	this.getNumLoaded = function() {
		return numLoaded;
	};

	this.getLoadProgress = function() {
		return numLoaded * pref.stopAt / myself.length;
	};

	this.isLoaded = function(index) {
		if ( index === undefined ) {
			return numLoaded == myself.length;
		} else {
			return images[index].isLoaded();
		}
	};

	this.loadPosition = function( position , complete ) {
		position = Math.min( 1 , Math.max(0, position) );
		var index = position * (myself.length-1);
		index = Math.round(index);
		myself.loadIndex(index, complete);
	};
	
	this.loadIndex = function(index, complete) {
		if ( index < 0 || index >= myself.length ) return false;

		if ( index != Math.floor(index) ) {
			return false;
		}

		//console.log( "Loading " + index + " ("+[current,step]+")" );

		var img = images[index];
		if ( img == null ) {
			var src = getSrcAt(index);
			img = new ImageLoader(src);
			images[index] = img;
		}
		img.load( function() {
			numLoaded++;
			if ( !isComplete ) {
				callback(pref.onProgress,this);
			} else {
				//console && console.log("On progress?");
			}
			callback(complete,this);
		} );
	};

	this.loadNext = function(complete) {
		if ( step < pref.stopAt ) return; // in this case we've already loaded all images - other threads just don't know yet
		
		function next() {
			loadNextImage();
			callback(complete,this);
		}
		function end() {
			finished();
			callback(complete,this);
		}
		current+=step;
		if ( current >= myself.length ) {
			if ( hasRestepped ) step /= 2;
			hasRestepped = true;
			current = step/2;
			if ( current >= pref.stopAt ) {
				myself.loadIndex(current,next);
			} else {
				finished();
			}
		} else {
			myself.loadIndex(current,next);
		}
	};

	this.getImageLoader = function(index) {
		return images[index];
	};

	function loadNextImage() {
		setTimeout( function(){ myself.loadNext(); } , $.browser.mozilla || $.browser.msie ? 50 : 5 );
	}

	function finished() {
		isComplete = true;
		callback(pref.onComplete,this);
		//console.log( "All images loaded" , numLoaded, 'of', myself.length );
	}


	function getSrcAt( index ) {
		var str = (index+Math.pow(10,pref.indexSize)).toString(10).substr(1);
		return imgpath.replace( '{index}' , str );
	}


	this.load = function() {
		myself.loadIndex(0,loadNextImage);
	}
}



function ImageLoader( src ) {
	//var elem = $('<img>');
	this.image = new Image();
	var img = this.image;
	var loadStarted = false;

	this.getSrc = function() {
		return src;
	};
	
	this.load = function(complete) {
		loadStarted = true;
		img.src = src;
		if ( img.complete ) {
			complete.apply(img);
		} else {
			$(img).load(complete);
		}
	};

	this.unload = function() {
		loadStarted = false;
		//img.src = '';
		img = this.image = new Image();
	};

	this.isLoaded = function() {
		return loadStarted && img.complete;
	}
}