var position = 0;
var MOVE_FORWARD_ENABLED = true;
var MOVE_BACK_ENABLED = false;
var maxIndex;
Event.observe(window, 'load', function(){
	var numAll = $$('#gal-nav a').length;
	maxIndex = (numAll - numVisible) / perStep;
	if(numAll > numVisible) {
	    MOVE_FORWARD_ENABLED = true;
	} else {
	    MOVE_FORWARD_ENABLED = false;
	}	
});
//This flag indicates if the animation is curentlly running - if so new animation is not runned
var disableControllers = false;

function changeImage(link) {
	big = $('big-img').down('img');
	
	img_src = $(link).down('img').src.replace( '/th', '/big');
	big.src = img_src;
	
	enlarge = $('enlarge');
	imgenlarge = $('imgenlarge');
	
	link_src = (big).src.replace( '/big', '/original');
	enlarge.href = link_src;
	imgenlarge.href = link_src;
}


var MOVE_BACK_ENABLED = true;

//toggle overrides
function arr_show(arr) {
    if(arr.id=='next') {
        MOVE_FORWARD_ENABLED = true;
    }
    if(arr.id=='prev') {
        MOVE_BACK_ENABLED = true;
    }
    arr.style.visibility = 'visible';
}
function arr_hide(arr) {
    //console.log(arr.id);
    if(arr.id=='next') {
        MOVE_FORWARD_ENABLED = false;
    }
    if(arr.id=='prev') {
        MOVE_BACK_ENABLED = false;
    }
    arr.style.visibility = 'hidden';
}
//Private functiont for moving inner div
function _move(index) {
    disableControllers = true;
    index = index || 1;
    new Effect.Move('gal-nav', {
        x: index * (perStep * imageWidth),
        y: 0,
        transition: Effect.Transitions.sinoidal,
        afterFinish: function() {
            disableControllers = false;
        }
    });
}
//
function moveForward() {
    if(disableControllers) {
        return;
    }
    if(!MOVE_FORWARD_ENABLED) {
        return;
    }
    position++;
    _move(-1)
    if(position==parseInt(maxIndex)) {
        arr_hide($('next'));
    } else {
        arr_show($('next'));
    }
    arr_show($('prev'));
}
function moveBack() {
    if(disableControllers) {
        return;
    }
    if(!MOVE_BACK_ENABLED) {
        return;
    }    
    position--;
    _move(1)
    if(position!=0) {
        arr_show($('prev'));
    } else {
        arr_hide($('prev'));
    }
    arr_show($('next'));
}