/* Configuration variables */
var conf_reflection_p = 0.5;         // Sets the height of the reflection in % of the source image
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_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'

/* Id names used in the HTML */
var conf_imageflow = 'flutsch';    // 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;
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;


function step()
{
        switch (target < current-1 || target > current+1)
        {
                case true:
                        moveTo(current + (target-current)/3);
                        window.setTimeout(step, 50);
                        timer = 1;
                        break;

                default:
                        timer = 0;
                        break;
        }
}

function glideTo(x, new_caption_id)
{
        /* Animate gliding to new x position */
        target = x;
        mem_target = x;
        if (timer == 0)
        {
                window.setTimeout(step, 50);
                timer = 1;
        }

        /* 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;

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

function moveTo(x)
{
        current = x;
        var zIndex = max;

        /* Main loop */
        for (var index = 0; index < max; 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;
                        switch ( new_img_h > max_height )
                        {
                                case false:
                                        var new_img_w = image.pc / z * size;
                                        break;

                                default:
                                        new_img_h = max_height;
                                        var new_img_w = image.w * new_img_h / image.h;
                                        break;
                        }
                        var new_img_top = (images_width * 0.34 - new_img_h) + images_top + ((new_img_h / (conf_reflection_p + 1)) * conf_reflection_p);

                        /* 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 */
                        switch ( x < 0 )
                        {
                                case true:
                                        zIndex++;
                                        break;

                                default:
                                        zIndex = zIndex - 1;
                                        break;
                        }

                        /* Change zIndex and onclick function of the focussed image */
                        switch ( image.i == caption_id )
                        {
                                case false:
                                        image.onclick = function() { glideTo(this.x_pos, this.i); }
                                        break;

                                default:
                                        zIndex = zIndex + 1;
                                        image.onclick = function() { document.location = this.url; }
                                        break;
                        }
                        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 + 'px';

        /* 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';

        /* Change scrollbar div properties */
        scrollbar_div.style.marginTop = images_width * 0.02 + 'px';
        scrollbar_div.style.marginLeft = images_width * 0.2 + 'px';
        scrollbar_div.style.width = scrollbar_width + 'px';

        /* Set slider attributes */
        slider_div.onmousedown = function () { dragstart(this); };
        slider_div.style.cursor = conf_slider_cursor;

        /* Cache EVERYTHING! */
        max = img_div.childNodes.length;
        var i = 0;
        for (var index = 0; index < max; 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! */
                        switch ((image.w + 1) > (image.h / (conf_reflection_p + 1)))
                        {
                                /* Landscape format */
                                case true:
                                        image.pc = 118;
                                        break;

                                /* Portrait and square format */
                                default:
                                        image.pc = 100;
                                        break;
                        }

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

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

                        i++;
                }
        }
        max = array_images.length;

        /* Display images in current order */
        moveTo(current);
        glideTo(current, caption_id);
}

/* 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;
        switch (delta > 0)
        {
                case true:
                        if(caption_id >= 1)
                        {
                                target = target + xstep;
                                new_caption_id = caption_id - 1;
                                change = true;
                        }
                        break;

                default:
                        if(caption_id < (max-1))
                        {
                                target = target - xstep;
                                new_caption_id = caption_id + 1;
                                change = true;
                        }
                        break;
        }

        /* Glide to next (mouse wheel down) / previous (mouse wheel up) image */
        if (change == true)
        {
                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) / (max-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 ()
        {
                if (dragging == true)
                {
                        return false;
                }
                else
                {
                        return true;
                }
        }
}

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;
        }
}