/**
 *	ImageFlow 0.9
 *
 *	This code is based on Michael L. Perrys Cover flow in Javascript.
 *	For he wrote that "You can take this code and use it as your own" [1]
 *	this is my attempt to improve some things. Feel free to use it! If
 *	you have any questions on it leave me a message in my shoutbox [2].
 *
 *	The reflection is generated server-sided by a slightly hacked  
 *	version of Richard Daveys easyreflections [3] written in PHP.
 *	
 *	The mouse wheel support is an implementation of Adomas Paltanavicius
 *	JavaScript mouse wheel code [4].
 *
 *	Thanks to Stephan Droste ImageFlow is now compatible with Safari 1.x.
 *
 *
 *	[1] http://www.adventuresinsoftware.com/blog/?p=104#comment-1981
 *	[2] http://shoutbox.finnrudolph.de/
 *	[3] http://reflection.corephp.co.uk/v2.php
 *	[4] http://adomas.org/javascript-mouse-wheel/
 */


/*
	05.05.2008, mJ: setCallback()
	
	22.05.2008, mJ:	hack hack images heigth kleiner
	21.07.2008, mJ:	image.pc getweakt
					slider cursor
					
	22.07.2008, mJ:	this.url fix
	
	15.10.2008, mJ:	division by zero fix (num_images-1)
	
	06.11.2008, mJ:	imageflow_div heigth 16 px höher wg. "Click on cover to browse"
					fester marginTop für slider_div
					
	24.11.2008, mJ:	conf_scrollbar_stickout
	
	04.12.2008, mJ:	call callback() only when needed
*/



/* Configuration variables */
var conf_reflection_p = 0.5;         // Sets the height of the reflection in % of the source image 
var conf_img_top_corr = -78;         // corrects the vertical image position

var conf_focus = 4;                  // Sets the numbers of images on each side of the focussed one
var conf_slider_width = 14;          // Sets the px width of the slider div

var	conf_scrollbar_stickout = 10;	//	sets the px the scrollbar sticks out left and right


var conf_images_cursor = 'pointer';  // Sets the cursor type for all images default is 'default'
//var conf_slider_cursor = 'default';  // Sets the slider cursor type: try "e-resize" default is 'default'
//	should be done in stylesheet


/* Id names used in the HTML */
var conf_imageflow = 'imageflow';    // Default is 'imageflow'
var conf_loading = 'loading';        // Default is 'loading'
var conf_images = 'images';          // Default is 'images'
var conf_captions = 'captions';      // Default is 'captions'
var conf_scrollbar = 'scrollbar';    // Default is 'scrollbar'
var conf_slider = 'slider';          // Default is 'slider'

/* Define global variables */
var caption_id = 0;					// index of current Image!
var new_caption_id = 0;
var current = 0;
var target = 0;
var mem_target = 0;
var timer = 0;
var array_images = new Array();
var new_slider_pos = 0;
var dragging = false;
var dragobject = null;
var dragx = 0;
var posx = 0;
var new_posx = 0;
var xstep = 150;

var	num_images = null;						//	number of images


var callback = null;
var last_caption_id = -1;

function setCallback( callback_ )
{
	callback = callback_;
}


function step()
{
	if (target < current-1 || target > current+1) {
		moveTo(current + (target-current)/3);
		window.setTimeout(step, 50);
		timer = 1;
	} else {
		timer = 0;
		if( callback ){
			if( last_caption_id != caption_id ) {
				last_caption_id = caption_id;
				callback();
			}
		}
	}
}

function glideTo(x, new_caption_id)
{	
	/* Animate gliding to new x position 
	
		x: new virtual x position ov leftmost images
		new_caption_id: index of middle Image
	
	*/
	
//	alert( "X=" + x + " new_caption_id=" + new_caption_id );

	createCookie( "flow_current_cover", new_caption_id );

	x = new_caption_id * -xstep;
	
	target = x;
	mem_target = x;
	if (timer == 0)
	{
		window.setTimeout(step, 50);
		timer = 1;
	}
	
	/* Display new caption */
	caption_id = new_caption_id;
	if( img_div && img_div.childNodes && array_images[caption_id] && img_div.childNodes.item(array_images[caption_id]) ) {
		caption = img_div.childNodes.item(array_images[caption_id]).getAttribute('alt');
	} else {
		caption = '';
	}
	if (caption == '') caption = '&nbsp;';
	caption_div.innerHTML = caption;

	/* Set scrollbar slider to new position */
	if( !dragging )
	{
		if( num_images > 1 ) {
			new_slider_pos = (scrollbar_width * (-(x*100/((num_images-1)*xstep))) / 100) - new_posx;
		} else {
			new_slider_pos = 0;
		}
//		alert( slider_div.style.marginLeft );
//		alert( (new_slider_pos - conf_slider_width) + 'px' ); 
		slider_div.style.marginLeft = (new_slider_pos - conf_slider_width) + 'px';
	}
}

function jumpTo(x, new_caption_id)
{	
	/* Jump to new x position 
		like glideTo without animation
	
		x: new virtual x position ov leftmost images
		new_caption_id: index of middle Image
	
	*/
	
//	alert( "X=" + x + " new_caption_id=" + new_caption_id );
	
	target = x;
	mem_target = x;
	
	/* Display new caption */
	caption_id = new_caption_id;
	caption = img_div.childNodes.item(array_images[caption_id]).getAttribute('alt');
	if (caption == '') caption = '&nbsp;';
	caption_div.innerHTML = caption;

	moveTo( x );
	timer = 0;
	if( callback ){
		callback();
	}

	/* Set scrollbar slider to new position */
	if( !dragging )
	{
		new_slider_pos = (scrollbar_width * (-(x*100/((num_images-1)*xstep))) / 100) - new_posx;
		slider_div.style.marginLeft = (new_slider_pos - conf_slider_width) + 'px';
	}
}

function moveTo( x )
{

//	alert( "moveTo( "+ x + " )" );
	
	current = x;
	var zIndex = num_images;
	
	/* Main loop */
	for( var index = 0; index < num_images; index++ ) {
		
		var image = img_div.childNodes.item(array_images[index]);
		var current_image = index * -xstep;

		/* Don't display images that are not conf_focussed */
		if ((current_image+max_conf_focus) < mem_target || (current_image-max_conf_focus) > mem_target)
		{
			image.style.visibility = 'hidden';
			image.style.display = 'none';
		} else {
			var z = Math.sqrt(10000 + x * x) + 100;
			var xs = x / z * size + size;

			/* Still hide images until they are processed, but set display style to block */
			image.style.display = 'block';
		
			/* Process new image height and image width */
			var new_img_h = (image.h / image.w * image.pc) / z * size;
			
			if( new_img_h > max_height ) {
				new_img_h = max_height;
				var new_img_w = image.w * new_img_h / image.h;
			} else {
				var new_img_w = image.pc / z * size;
			}
			var new_img_top = (images_width * 0.34 - new_img_h) + images_top + ((new_img_h / (conf_reflection_p + 1)) * conf_reflection_p);
			new_img_top += conf_img_top_corr;
			
			/* Set new image properties */
			image.style.left = xs - (image.pc / 2) / z * size + images_left + 'px';
			
			if(new_img_w && new_img_h)
			{ 
				image.style.height = new_img_h + 'px'; 
				image.style.width = new_img_w + 'px'; 
				image.style.top = new_img_top + 'px';
			}
			image.style.visibility = 'visible';

			/* Set image layer through zIndex */
			if ( x < 0 ) {
				zIndex++;
			} else {
				zIndex-=1;
			}
			
			/* Change zIndex and onclick function of the focussed image */
			if( image.i != caption_id )	{
				image.onclick = function() { 
					glideTo( this.x_pos, this.i ); 
				}
			} else {
				zIndex = zIndex + 1;
				image.onclick = function() { 
					if( this.url )
						document.location = this.url; 
				}
			}
			image.style.zIndex = zIndex;
		}
		x += xstep;
	}
}

/* Main function */
function refresh( onload )
{
	/* Cache document objects in global variables */
	imageflow_div = document.getElementById(conf_imageflow);
	img_div = document.getElementById(conf_images);
	scrollbar_div = document.getElementById(conf_scrollbar);
	slider_div = document.getElementById(conf_slider);
	caption_div = document.getElementById(conf_captions);

	/* Cache global variables, that only change on refresh */
	images_width = img_div.offsetWidth;
	images_top = imageflow_div.offsetTop;
	images_left = imageflow_div.offsetLeft;
	max_conf_focus = conf_focus * xstep;
	size = images_width * 0.5;
	scrollbar_width = images_width * 0.6;
	conf_slider_width = conf_slider_width * 0.5;
	max_height = images_width * 0.51;

	/* Change imageflow div properties */
//	imageflow_div.style.height = max_height - 96 + 'px';	//hack hack
	imageflow_div.style.height = max_height - 80 + 'px';	//hack hack

	/* Change images div properties */
	img_div.style.height = images_width * 0.338 + 'px';

	/* Change captions div properties */
	caption_div.style.width = images_width + 'px';
//	caption_div.style.marginTop = images_width * 0.03 + 'px';
	caption_div.style.marginTop = max_height * 0.13 + 'px';

	/* Change scrollbar div properties */
	scrollbar_div.style.marginTop = "6px"; //images_width * 0.02 -4 + 'px';
	
	scrollbar_div.style.marginLeft = images_width * 0.2 - conf_scrollbar_stickout + 'px';
	scrollbar_div.style.width = scrollbar_width + 2*conf_scrollbar_stickout + 'px';
	conf_slider_width -= conf_scrollbar_stickout;
	slider_div.style.marginLeft = (0 - conf_slider_width) + 'px';
	
	/* Set slider attributes */
	slider_div.onmousedown = function () { dragstart(this); };
//	slider_div.style.cursor = conf_slider_cursor;

	/* Cache EVERYTHING! */
	var i = 0;
	
	for( var index = 0; index < img_div.childNodes.length; index++ ) { 
		
		var image = img_div.childNodes.item(index);
		
		if( image.nodeType == 1 ) {
			array_images[i] = index;
			
			/* Set image onclick by adding i and x_pos as attributes! */
			image.onclick = function() { 
				glideTo(this.x_pos, this.i); 
			}
			
			image.x_pos = (-i * xstep);
			image.i = i;
			
			/* Add width and height as attributes ONLY once onload */
			if(onload == true)
			{
				image.w = image.width;
				image.h = image.height;
			}

			/* Check source image format. Get image height minus reflection height! */
		
		//	if( (image.w + 1) > (image.h / (conf_reflection_p + 1)) ) {
			if( image.w > image.h * 0.98 ) {	//	mJ	21.07.2008
			
				/* Landscape format */
				image.pc = 128;	//	100;
			} else {
				/* Portrait and square format */
				image.pc = 90;	//	118;
			}

			/* Set ondblclick event */
			image.url = image.getAttribute( 'href' );
			image.ondblclick = function() { 
				if( this.url )
					document.location = this.url; 
			}

			/* Set image cursor type */
			image.style.cursor = conf_images_cursor;

			i++;
		} else {
		//	text node
		}
	}
	
	num_images = array_images.length;


	var coming_back = readCookie( "flow_coming_back" );
	var current_cover = readCookie( "flow_current_cover" );
	
	if( coming_back && current_cover ) {
		eraseCookie( "flow_coming_back" );
		caption_id = parseInt( current_cover );
		if( caption_id == "NaN" )
			caption_id = 0;
	}
	
	current = caption_id * -xstep;

	/* Display images in current order */
	
//	mJ: this was the other way round...
	glideTo( current, caption_id );
	moveTo( current );
}

/* Show/hide element functions */
function show(id)
{
	var element = document.getElementById(id);
	element.style.visibility = 'visible';
}

function hide(id)
{
	var element = document.getElementById(id);
	element.style.visibility = 'hidden';
	element.style.display = 'none';
}

/* Hide loading bar, show content and initialize mouse event listening after loading */
window.onload = function()
{
	if(document.getElementById(conf_imageflow))
	{
		hide(conf_loading);
		refresh(true);
		show(conf_images);
		show(conf_scrollbar);
		initMouseWheel();
		initMouseDrag();
	}
}

/* Refresh ImageFlow on window resize */
window.onresize = function()
{
	if(document.getElementById(conf_imageflow)) refresh();
}

/* Fixes the back button issue */
/*
window.onunload = function()
{
  document = null;
}
*/

/* Handle the wheel angle change (delta) of the mouse wheel */
function handle(delta)
{
	var change = false;
	if( delta > 0 ){
		if(caption_id >= 1)	{
			target = target + xstep;
			new_caption_id = caption_id - 1;
			change = true;
		}
	} else {
		if(caption_id < (num_images-1)) {
			target = target - xstep;
			new_caption_id = caption_id + 1;
			change = true;
		}
	}

	/* Glide to next (mouse wheel down) / previous (mouse wheel up) image */
	if (change) {
		glideTo(target, new_caption_id);
	}
}

/* Event handler for mouse wheel event */
function wheel(event)
{
	var delta = 0;
	if (!event) event = window.event;
	if (event.wheelDelta)
	{
		delta = event.wheelDelta / 120;
	}
	else if (event.detail)
	{
		delta = -event.detail / 3;
	}
	if (delta) handle(delta);
	if (event.preventDefault) event.preventDefault();
	event.returnValue = false;
}

/* Initialize mouse wheel event listener */
function initMouseWheel()
{
	if(window.addEventListener) imageflow_div.addEventListener('DOMMouseScroll', wheel, false);
	imageflow_div.onmousewheel = wheel;
}

/* This function is called to drag an object (= slider div) */
function dragstart(element)
{
	dragobject = element;
	dragx = posx - dragobject.offsetLeft + new_slider_pos;
}

/* This function is called to stop dragging an object */
function dragstop()
{
	dragobject = null;
	dragging = false;
}


/* This function is called on mouse movement and moves an object (= slider div) on user action */
function drag(e)
{
	posx = document.all ? window.event.clientX : e.pageX;
	if(dragobject != null)
	{
		dragging = true;
		new_posx = (posx - dragx) + conf_slider_width;

		/* Make sure, that the slider is moved in proper relation to previous movements by the glideTo function */
		if( new_posx < ( - new_slider_pos) ) 
			new_posx = - new_slider_pos;
		
		if( new_posx > (scrollbar_width - new_slider_pos) ) 
			new_posx = scrollbar_width - new_slider_pos;
		
		var slider_pos = (new_posx + new_slider_pos);
		var step_width = slider_pos / ((scrollbar_width) / (num_images-1));
		var image_number = Math.round(step_width);
		var new_target = (image_number) * -xstep;
		var new_caption_id = image_number;

		dragobject.style.left = new_posx + 'px';
		glideTo(new_target, new_caption_id);
		
	}
}

/* Initialize mouse event listener */
function initMouseDrag()
{
	document.onmousemove = drag;
	document.onmouseup = dragstop;

	/* Avoid text and image selection while dragging  */
	document.onselectstart = function () 
	{
		return !dragging;
	}
}

function getKeyCode(event)
{
	event = event || window.event;
	return event.keyCode;
}

document.onkeydown = function(event)
{
	var charCode  = getKeyCode(event);
	switch (charCode)
	{
		/* Right arrow key */
		case 39:
			handle(-1);
			break;
		
		/* Left arrow key */
		case 37:
			handle(1);
			break;
	}
}