$(document).ready(function() {
    var body = $(".mainArticle .body");
    var pagerContent = $(".mainArticle .body .pagerContent");
    body.data("totalHeight", pagerContent.height());
    body.data("page", 1);
    body.data("pageCount", Math.ceil(pagerContent.height() / (body.height() - 15)));
    $(".pager .total").text(body.data("pageCount"));
    $(".pager .pagerLeft").click(function() {
        changePage(body.height() - 15, 1500);
    });
    $(".pager .pagerRight").click(function() {
        changePage(-1 * (body.height() - 15), 1500);
    });
    if (body.data("pageCount") > 1)
        $(".pagerRight").removeClass("disabled");
	
    pagerContent.css("top", 0);
    $(body).mousewheel(function(event, delta) {
        var pagerContent = $(".mainArticle .body .pagerContent");
        var height = changePage(delta * 30, 0);
        pagerContent.css("top", height + "px");
        return false;
    });

});

var changePage = function(d, speed) {
    var body = $(".mainArticle .body");
    var pagerContent = $(".mainArticle .body .pagerContent");
    var page = body.data("page");
    var pagerNum = $(".pager .pagerNum");
    var totalPages = body.data("pageCount");
    var ds;

    var currentHeight = parseInt(pagerContent.css("top"));
    var newHeight;
    var pagerHeight = parseInt(pagerContent.height());
    var bodyHeight = parseInt(body.height());

    if (currentHeight + d < -1 * (pagerHeight - bodyHeight))
        newHeight = -1 * (pagerHeight - bodyHeight);
    else if (currentHeight + d > 0)
        newHeight = 0;
    else
        newHeight = currentHeight + d;

    var page = Math.ceil(-1 * newHeight / ((pagerHeight + totalPages * 15) / totalPages)) + 1;

    body.data("page", page);

    pagerContent.animate({
        top: newHeight + "px"
    }, {
        "duration": speed,
        "easing": "easeOutSine"
    });
    pagerNum.text(body.data("page"));

    if (page == 1)
        $(".pagerLeft").addClass("disabled");
    else
        $(".pagerLeft").removeClass("disabled");
    if (page == totalPages)
        $(".pagerRight").addClass("disabled");
    else
        $(".pagerRight").removeClass("disabled");
};