// original from Jonathan Fingland ashita.org tutorial
//

var thumbNum;
var showNum = 5;
var curLeft = 0;
function getRanges() {
    var end = curLeft + showNum - 1; //calculate the image position at the end of the display

    var iva = new Array();	//create arrays for the in and out of range elements
    var ova = new Array();

    //get all of the <li> tags inside our imagrow
    var litags = document.getElementById("imagerow").getElementsByTagName("li");

    // loop through and add them to iva or ova if they
    // are in or out, respectively, of our desired range
    for (var i = 0; i < litags.length; i++) {
        if ((i < curLeft) || (i > end))
            ova.push(litags[i]);
        else
            iva.push(litags[i]);
    }
    return {
        in_var: iva,
        out: ova
    };
}

function filmstrip_onLoad() {
    if (document.addEventListener) {
        document.getElementById('strip').addEventListener('keypress',HandleKeyPress,false);
        document.getElementById('strip').addEventListener('DOMMouseScroll',HandleWheel,false);
        document.getElementById('larrow').addEventListener('click',moveLeft,false);
        document.getElementById('rarrow').addEventListener('click',moveRight,false);
        setLeft();
    } else {
        document.getElementById('strip').onkeypress = HandleKeyPress;
        document.getElementById('strip').onmousewheel = HandleWheel;
        document.getElementById('larrow').onclick = moveLeft;
        document.getElementById('rarrow').onclick = moveRight;
        setLeft();
    }
}

function HandleKeyPress(e) {
    switch (e.keyCode) {

        case e.DOM_VK_LEFT:
            moveLeft();
            break;
        case e.DOM_VK_RIGHT:
            moveRight();
            break;
        case e.DOM_VK_ESCAPE:
            content.focus();
            return;
    }
}

/** Event handler for mouse wheel event.
 * originally from http://adomas.org/javascript-mouse-wheel/
 */
function handle(delta) {
    if (delta < 0)
        moveRight();
    else
        moveLeft();
}

function HandleWheel(event){
    var delta = 0;
    if (!event) /* For IE. */
        event = window.event;
    if (event.wheelDelta) { /* IE/Opera. */
        delta = event.wheelDelta/120;
        /** In Opera 9, delta differs in sign as compared to IE.
                 */
        if (window.opera)
            delta = -delta;
    } else if (event.detail) { /** Mozilla case. */
        /** In Mozilla, sign of delta is different than in IE.
                 * Also, delta is multiple of 3.
                 */
        delta = -event.detail/3;
    }
    /** If delta is nonzero, handle it.
         * Basically, delta is now positive if wheel was scrolled up,
         * and negative, if wheel was scrolled down.
         */
    if (delta)
        handle(delta);
    /** Prevent default actions caused by mouse wheel.
         * That might be ugly, but we handle scrolls somehow
         * anyway, so don't bother here..
         */
    if (event.preventDefault)
        event.preventDefault();
    event.returnValue = false;
}


function setLeft(){
    var rng = getRanges();
    for (var i = 0; i < rng.out.length; i++ ) {
        rng.out[i].setAttribute("style","display:none;");
        rng.out[i].style.display = "none";
    }
    for (i = 0; i< rng.in_var.length; i++ ) {
        rng.in_var[i].setAttribute("style","display:inline;");
        rng.in_var[i].style.display = "inline";
    }
}

function moveLeft(){
    thumbNum = noOfItems;
    if (curLeft == 0) {
        curLeft = thumbNum - showNum - 1;
    }
    else {
        curLeft = curLeft - showNum;
        if (curLeft < 0) {
            curLeft = 0; 
        }
    }
    setLeft();
}

function moveRight() {
    thumbNum = noOfItems;
    if (curLeft >= thumbNum-showNum) curLeft = 0; //already at the right
    else {
        if (thumbNum - (curLeft + showNum) < showNum ) {
            curLeft = thumbNum - (curLeft + showNum) - 1;
        }
        else {
            curLeft = curLeft + showNum;
        }
        
    }
    setLeft();
}