var video_thumbnails = new Array(); // the thumbnails to roll over to
var logged_videos = new Array();
var video_thumbnail_currently_rotating_id = -1;
var video_thumbnail_rotation_counter = 0;
function change_thumbnail(video_id, thumbnail_id, watch_log_url) {
	if (thumbnail_id > 8) {
		thumbnail_id = 0;
	}
	thumbnail = document.getElementById("video_" + video_id + "_thumbnail");
	thumbnail.src = video_thumbnails[video_id][thumbnail_id];
	next_id = thumbnail_id + 1;
	if (thumbnail_id == 5) {
		alert_thumbnail_watched(video_id, watch_log_url);
	}
}

function alert_thumbnail_watched(video_id, watch_log_url) {
	if ($.inArray(video_id, logged_videos) != -1) {
		return;
	}
	logged_videos.push(video_id);
	$.ajax({
	  url: watch_log_url
	});
}

function change_thumbnail_if_safe(video_id, rotation_id, thumbnail_id, watch_log_url) {
	if (video_thumbnail_currently_rotating_id == video_id && video_thumbnail_rotation_counter == rotation_id) {
		change_thumbnail(video_id, thumbnail_id, watch_log_url);
		setTimeout("change_thumbnail_if_safe(" + video_id + ", " + rotation_id + ", " + next_id + ", \"" + watch_log_url + "\")", 600);
	}
}

function end_animation_on_thumbnail(id) {
	if (video_thumbnail_currently_rotating_id == id) {
		video_thumbnail_currently_rotating_id = -1;
	}
	change_thumbnail(id, 0, '');
}

var loaded_images = new Array();
function animate_thumbnail(id, watch_log_url) {
	video_thumbnail_currently_rotating_id = id;
	// preload all images
	for (i = 0; i < video_thumbnails[id].length; i++) {
		src = video_thumbnails[id][i];
		if (loaded_images[src] == null) {
			img = new Image();
			img.src = src;
			loaded_images[src] = img;
		}
	}
	rotation_id = ++video_thumbnail_rotation_counter;
	change_thumbnail_if_safe(id, rotation_id, 1, watch_log_url);
}