/*
*
* Swaps display: hides img1 and shows img2
*
*/
function swapImage(imgId1, imgId2) {

	if (!imgId1 || !imgId2) {
		return false;
	}
	document.getElementById(imgId1).style.display = 'none';
	document.getElementById(imgId2).style.display = 'block';
}

/*
*
* Change src of img
*
*/
function changeImgSrc(imgId, newSrc) {

	if (!imgId) {
		return false;
	}
	document.getElementById(imgId).style.display = 'none';
	document.getElementById(imgId).src = newSrc;
	new Effect.Appear(imgId, {delay:0.5});
}


var _snapshots = new Array();
var _streamUrl = '';
var _screenId = '';
var _currSnapshotIndex = 0;
var _prevSnapshotIndex = 0;
var _nextSnapshotIndex = 0;

function initGallery(imgIds, streamUrl, screenId) {

	_snapshots = imgIds.split(',');
	_streamUrl = streamUrl;
	_screenId = screenId;
	resetSnapshotIndex();
}

function resetSnapshotIndex() {
	
	_currSnapshotIndex = 0;
	_prevSnapshotIndex = _snapshots.length-1;
	if (_snapshots.length > 1) {
		_nextSnapshotIndex = 1;
	}
}

function nextSnapshot() {

	_currSnapshotIndex = (_currSnapshotIndex + 1) % _snapshots.length;
	_nextSnapshotIndex = (_nextSnapshotIndex + 1) % _snapshots.length;
	_prevSnapshotIndex = (_prevSnapshotIndex + 1) % _snapshots.length;
	changeImgSrc(_screenId, _streamUrl + '/' + _snapshots[_currSnapshotIndex]);
}

function prevSnapshot() {
	
	if (_currSnapshotIndex - 1 < 0) _currSnapshotIndex = _currSnapshotIndex + _snapshots.length;
	_currSnapshotIndex = (_currSnapshotIndex - 1) % _snapshots.length;
	if (_nextSnapshotIndex - 1 < 0) _nextSnapshotIndex = _nextSnapshotIndex + _snapshots.length;
	_nextSnapshotIndex = (_nextSnapshotIndex - 1) % _snapshots.length;
	if (_prevSnapshotIndex - 1 < 0) _prevSnapshotIndex = _prevSnapshotIndex + _snapshots.length;
	_prevSnapshotIndex = (_prevSnapshotIndex - 1) % _snapshots.length;
	changeImgSrc(_screenId, _streamUrl + '/' + _snapshots[_currSnapshotIndex]);
}

function gotoSnapshot(snapshotIndex) {
	
	_currSnapshotIndex = snapshotIndex;
	_nextSnapshotIndex = (snapshotIndex + 1) % _snapshots.length;
	if (snapshotIndex - 1 < 0) snapshotIndex = snapshotIndex + _snapshots.length;
	_prevSnapshotIndex = (snapshotIndex - 1) % _snapshots.length;
	changeImgSrc(_screenId, _streamUrl + '/' + _snapshots[_currSnapshotIndex]);
}