/**
 * jQuery Plugin Stepper.
 * @author NOSE
 *
 * @requires jquery.js 
 * @version 1.0.0	initial version			
 */
jQuery.fn.stepper = function(op) {	
	// defaults
	var defaults =  {
			selectorStepUp: ".stepperUp",
			selectorStepDown: ".stepperDown",
			selectorInput: "input"
	};
	jQuery.extend(defaults, op);
	
	// references
	var elStepper = jQuery(this);
	var elStepUp = jQuery(defaults.selectorStepUp,elStepper);
	var elStepDown = jQuery(defaults.selectorStepDown,elStepper);
	var elInput = jQuery(defaults.selectorInput,elStepper);
	
	// events
	jQuery(elStepUp).bind("click",function(){
		stepIt(true);
		return false;
	});
	jQuery(elStepDown).bind("click",function(){
		stepIt(false);
		return false;
	});
	
	
	/**
	* Step it.
	*/
	function stepIt(up) {
		
		// value
		var v = parseInt(jQuery(elInput).val());
		if (v == null || isNaN(v)) {
			v = 0;
		}
		
		// what goes up
		if (up) {
			v++;
		}
		// comes down
		else if (v > 0){
			v--;
		}
		
		// set
		jQuery(elInput).val(v);
	}

  
    // return
    return this;
};