(function () {

    function incrementer(ct, increment) {
        var startDate = new Date();
        var startCt = ct;
        // Make sure we have an actual number for startCt
        if (!startCt) {
            startCt = 0;
        }
        var result = function () {
            return startCt + Math.round((new Date() - startDate) / increment) * increment;
        };
        result.restart = function (newCt) {
            startCt = newCt;
            startDate = new Date();
        }
        return result;
    }

    function pad2(number) {
        return (number < 10 ? '0' : '') + number;
    }

    function defaultFormatMilliseconds(millis) {
        var x, seconds, minutes, hours;
        x = millis / 1000;
        seconds = Math.floor(x % 60);
        x /= 60;
        minutes = Math.floor(x % 60);
        x /= 60;
        hours = Math.floor(x % 24);
        // x /= 24;
        // days = Math.floor(x);
        return [pad2(hours), pad2(minutes), pad2(seconds)].join(':');
    }

    //NOTE: This is a the 'lazy func def' pattern described at http://michaux.ca/articles/lazy-function-definition-pattern
    function formatMilliseconds(millis, data) {
        // Use jintervals if available, else default formatter
        var formatter;
        if (typeof jintervals == 'function') {
            formatter = function (millis, data) { return jintervals(millis / 1000, data.format); };
        } else {
            formatter = defaultFormatMilliseconds;
        }
        formatMilliseconds = function (millis, data) {
            return formatter(millis, data);
        };
        return formatMilliseconds(millis, data);
    }

    var methods = {

        init: function (options) {
            var defaults = {
                updateInterval: 1000,
                startTime: 0,
                format: '{HH}:{MM}:{SS}',
                formatter: formatMilliseconds
            };

            // if (options) { $.extend(settings, options); }

            return this.each(function () {
                var $this = $(this),
                    data = $this.data('stopwatch');

                // If the plugin hasn't been initialized yet
                if (!data) {
                    // Setup the stopwatch data
                    var settings = $.extend({}, defaults, options);
                    data = settings;
                    data.active = false;
                    data.target = $this;
                    data.elapsed = settings.startTime;
                    // create counter
                    data.incrementer = incrementer(data.startTime, data.updateInterval);
                    data.tick_function = function () {
                        var millis = data.incrementer();
                        data.elapsed = millis;
                        data.target.trigger('tick.stopwatch', [millis]);
                        data.target.stopwatch('render');
                    };
                    $this.data('stopwatch', data);
                }

            });
        },

        start: function () {
            return this.each(function () {
                var $this = $(this),
                    data = $this.data('stopwatch');
                // Mark as active
                if (!data.active) {
                    data.incrementer.restart(data.elapsed);
                }
                data.active = true;
                data.timerID = setInterval(data.tick_function, data.updateInterval);
                $this.data('stopwatch', data);
            });
        },

        stop: function () {
            return this.each(function () {
                var $this = $(this),
                    data = $this.data('stopwatch');
                clearInterval(data.timerID);
                data.active = false;
                $this.data('stopwatch', data);
            });
        },

        destroy: function () {
            return this.each(function () {
                var $this = $(this),
                    data = $this.data('stopwatch');
                $this.stopwatch('stop').unbind('.stopwatch').removeData('stopwatch');
            });
        },

        render: function () {
            var $this = $(this),
                data = $this.data('stopwatch');
            $this.html(data.formatter(data.elapsed, data));
        },

        getTime: function () {
            var $this = $(this),
                data = $this.data('stopwatch');
            return data.elapsed;
        },

        toggle: function () {
            return this.each(function () {
                var $this = $(this);
                var data = $this.data('stopwatch');
                if (data.active) {
                    $this.stopwatch('stop');
                } else {
                    $this.stopwatch('start');
                }
            });
        },

        reset: function () {
            return this.each(function () {
                var $this = $(this);
                data = $this.data('stopwatch');
                data.incrementer = incrementer(data.startTime, data.updateInterval);
                data.elapsed = data.startTime;
                $this.data('stopwatch', data);
            });
        }
    };


    // Define the function
    $.fn.stopwatch = function (method) {
        if (methods[method]) {
            return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
        } else if (typeof method === 'object' || !method) {
            return methods.init.apply(this, arguments);
        } else {
            $.error('Method ' + method + ' does not exist on jQuery.stopwatch');
        }
    };

})(jQuery);