/**
 *  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/
 */


/* 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 = 'imageflow';    // Default is 'imageflow'
var conf_loading = 'loading';        // Default is 'loading'
var conf_images = 'imagesCoverflow';          // 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()
{
  //~ funktioniert nicht !! gibt einen JS FEhler im IE
  //~ 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;
    }
}