'use strict';
    $.fn.calendar = function(options) {
        //check is select, if nothing select, return this
        if (!this.length) {
            if (options && options.debug && window.console) {
                console.log("nothing select");
            }
            return this;
        }
        var self = $(this);

        // default parameter setting
        var defaults = {
            cssPath: '', //user-define loading path of css file
            eventName: 'click', //user-define the event name that triggers the control
            onSelectDate: null, //callback function after select date
            autoClose: false
        };

        //inherit user-defined parameter
        defaults = $.extend(defaults, options);

        //default as data of the day
        var d_date = new Date();
        var _date = {
            year: d_date.getFullYear(),
            month: d_date.getMonth() + 1,
            day: d_date.getDate(),
            week: d_date.getDay()
        };

        //default template of plugin
        var calendarDiv = '

        var calendarAction = {
            //initialization
            initAction: function() {
                calendarAction.thisClick();
                calendarAction.inputChange();
                calendarAction.buttonChange();
                calendarAction.chooseDate();
            },

            //click to display
            thisClick: function() {
                self.bind(defaults.eventName, function(e) {
                    calendarAction.showCalendar();
                });
            },

            //when year and month in the input box changes
            inputChange: function() {
                $('#calendar_year, #calendar_month').bind('change', function() {
                    var year = $('#calendar_year').val(),
                        month = $('#calendar_month').val();
                    if (!/^d{4}$/.test(year)) {
                        alert('please input four-digit year');
                        return false;
                    }
                    if (!/^d{1,2}$/.test(month) || (month > 12 || month 0 ? parseInt($('#calendar_year').val()) - 1 : 1;
                    $('#calendar_year').val(lastYear);
                    init_day_numbers(lastYear, $('#calendar_month').val());
                });

                $('#last-month').bind('click', function() {
                    var lastMonth = parseInt($('#calendar_month').val()) - 1 > 0 ? parseInt($('#calendar_month').val()) - 1 : 12,
                        thisYear = lastMonth == 12 ? parseInt($('#calendar_year').val()) - 1 : $('#calendar_year').val();
                    $('#calendar_month').val(lastMonth);
                    $('#calendar_year').val(thisYear);
                    init_day_numbers(thisYear, lastMonth);
                });

                $('#next-year').bind('click', function() {
                    var nextYear = parseInt($('#calendar_year').val()) + 1;
                    $('#calendar_year').val(nextYear);
                    init_day_numbers(nextYear, $('#calendar_month').val());
                });

                $('#next-month').bind('click', function() {
                    var nextMonth = parseInt($('#calendar_month').val()) + 1