var scroll_amount = 0;
var scroll_by = 25;

function init_scroll_pane() {
	/*
	 * This function should be called from any page
	 * which uses scrolling in the content area
	 * in the onload function.
	 * 
	 * - hide the scroll arrows if the content height is too short
	 */

	var height = $("#scroll-pane-contents").innerHeight();
	if (height <= $("#scroll-pane").innerHeight()) {
		$("#scroll-arrow-up").css("display", "none");
		$("#scroll-arrow-down").css("display", "none");
	} else {
		$("#scroll-arrow-up").css("display", "block");
		$("#scroll-arrow-down").css("display", "block");
	}
}

function scroll_up() {
	var current_top = parseInt($("#scroll-pane-contents").css("margin-top"));
	if (current_top < 0) {
		scroll_amount += scroll_by;
		$("#scroll-pane-contents").css("margin-top", scroll_amount + "px");
	}
}

function scroll_down() {
	var current_top = parseInt($("#scroll-pane-contents").css("margin-top"));
	current_top *= -1;
	var height = $("#scroll-pane-contents").innerHeight();
	height -= scroll_by;
	if (current_top < height) {
		scroll_amount -= scroll_by;
	}
	$("#scroll-pane-contents").css("margin-top", scroll_amount + "px");	
}

function reset_scroll() {
	$("#scroll-pane-contents").css("margin-top", "0px");	
}

function set_current_tab(event) {
	$(event.currentTarget).addClass("cur");
}

function clear_current_tab(event) {
	$(event.currentTarget).removeClass("cur");
}

function select_current_tab(event) {
	$(".tab").removeClass("cur_clicked");
	$(event.currentTarget).addClass("cur_clicked");
}

function link_follow(link_href) {
	document.location=link_href;
	return true;
}

function close_content() {
	$("#scroll-pane").hide();
	$("#side-bar-img").hide();
	$("#close-arrow").hide();
	$("#side-bar-hidden").show();
}

function open_content() {
	$("#scroll-pane").show();
	$("#side-bar-img").show();
	$("#close-arrow").show();
	$("#side-bar-hidden").hide();
}

$(function() {
	/* init the scroll pane */
	init_scroll_pane();
	$("#close-arrow").click(function () { close_content(); });
	$("#open-arrow").click(function () { open_content(); });
});