(function($){
        $.fn.scrollText = function(action) {
            
            var defaults = {
                step: 1,
                marginLeft: 10,
                marginRight: 10,
                interval: 30
            };
            var options = {};
            
            if(typeof action === 'object') {
                options = action;
                action = "init";
            }
            else {
                action = action || "init";
            }
            var conf = $.extend(defaults, options);
            
            var $self = this;
            if(action == "init") {
                
                return this.each(function() {
                    var data = $(this).data("scrollText");
                    if(data) {
                        // stop running instance
                        $(this).find(".text-scroll-container").css({left: 0});
                        clearInterval(data.timer);
                    }
                    
                    var w_outer = $(this).width(),
                    w_inner = $(this).find(".text-scroll-inner").width(),
                    w_diff = w_inner - w_outer;
                    var need_scroll = (w_diff > 0);
                    
                    data = {
                        conf: conf,
                        need_scroll: need_scroll,
                        diff: w_diff,
                        direction: 0,
                        running: false,
                        timer: null
                    };
                    
                    $(this).data("scrollText", data);
                });
            }
            else if(action == "start") {
                var state = $self.data("scrollText");
                if( ! state) {
                    return this;
                }
                
                if( ! state.need_scroll) {
                    return this;
                }
                
                if(state.running) {
                    return this;
                }
                
                var $container = $self.find(".text-scroll-container");
                var scrollFunc = function() {
                    $container.css("left",
                        function(index, value) {
                            //console.log("direction=" + state.direction + " diff=" + state.diff + " val=" + value + " sum=" + (state.diff+value));
                            value = parseInt(value);
                            var current_direction = state.direction;
                            
                            if(state.direction == 0) {
                                if(state.diff+value > -state.conf.marginRight) {
                                    return (value - state.conf.step) + "px";
                                }
                                else {
                                    state.direction = 1;
                                    return (value + state.conf.step) + "px";
                                }
                            }
                            else {
                                if(value < state.conf.marginLeft) {
                                    return (value + state.conf.step) + "px";
                                }
                                else {
                                    state.direction = 0;
                                    return (value - state.conf.step) + "px";
                                }
                            }
                            
                            if(state.direction != current_direction) {
                                $self.data("scrollText", state);
                            }
                        });
                };
                
                state.running = true;
                state.timer = setInterval(scrollFunc, state.conf.interval);
                $self.data("scrollText", state);
                return this;
            }
            else if(action == "stop") {
                var state = $self.data("scrollText");
                if( ! state) {
                    return this;
                }
                if( ! state.running) {
                    return this;
                }
                state.running = false;
                clearInterval(state.timer);
                $self.data("scrollText", state);
                return this;
            }
        }
})( jQuery );