(function($) {
        /*
    Validation Singleton
         */
        var Validation = function() {
        
            var rules = {
            
                email : {
                    check: function(value) {
                   
                        if(value)
                            return testPattern(value,"[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])");
                        return true;
                    },
                    msg : "Enter a valid e-mail address."
                },
                url : {

                    check : function(value) {

                        if(value)
                            return testPattern(value,"^https?://(.+\.)+.{2,4}(/.*)?$");
                        return true;
                    },
                    msg : "Enter a valid URL."
                },
                required : {
                
                    check: function(value) {

                        if(value)
                            return true;
                        else
                            return false;
                    },
                    msg : "This field is required."
                }
            }
            var testPattern = function(value, pattern) {

                var regExp = new RegExp(pattern,"");
                return regExp.test(value);
            }
            return {
            
                addRule : function(name, rule) {

                    rules[name] = rule;
                },
                getRule : function(name) {

                    return rules[name];
                }
            }
        }
    
        /* 
    Form factory 
         */
        var Form = function(form) {
        
            var fields = [];
    
            form.find("[validation]").each(function() {
                var field = $(this);
                if(field.attr('validation') !== undefined) {
                    fields.push(new Field(field));
                }
            });
            this.fields = fields;
        }
        Form.prototype = {
            validate : function() {

                for(field in this.fields) {
                
                    this.fields[field].validate();
                }
            },
            isValid : function() {
            
                for(field in this.fields) {
                
                    if(!this.fields[field].valid) {
            
                        this.fields[field].field.focus();
                        return false;
                    }
                }
                return true;
            }
        }
    
        /* 
    Field factory 
         */
        var Field = function(field) {

            this.field = field;
            this.valid = false;
            this.attach("change");
        }
        Field.prototype = {
        
            attach : function(event) {
        
                var obj = this;
                if(event == "change") {
                    obj.field.bind("change",function() {
                        return obj.validate();
                    });
                }
                if(event == "keyup") {
                    obj.field.bind("keyup",function(e) {
                        return obj.validate();
                    });
                }
            },
            validate : function() {
            
                var obj = this,
                field = obj.field,
                errorClass = "errorlist",
                errorlist = $(document.createElement("ul")).addClass(errorClass),
                types = field.attr("validation").split(" "),
                container = field.parent(),
                errors = []; 
            
                field.next(".errorlist").remove();
                for (var type in types) {

                    var rule = $.Validation.getRule(types[type]);
                    if(!rule.check(field.val())) {

                        container.addClass("error");
                        errors.push(rule.msg);
                    }
                }
                if(errors.length) {

                    obj.field.unbind("keyup")
                    obj.attach("keyup");
                    field.after(errorlist.empty());
                    for(error in errors) {
                
                        errorlist.append("<li>"+ errors[error] +"</li>");        
                    }
                    obj.valid = false;
                } 
                else {
                    errorlist.remove();
                    container.removeClass("error");
                    obj.valid = true;
                }
            }
        }
    
        /*
    Validation extends jQuery prototype
         */
        $.extend($.fn, {
        
            validation : function() {
            
                var validator = new Form($(this));
                $.data($(this)[0], 'validator', validator);
            
                $(this).bind("submit", function(e) {
                    validator.validate();
                    if(!validator.isValid()) {
                        e.preventDefault();
                    }
                });
            },
            validate : function() {
            
                var validator = $.data($(this)[0], 'validator');
                validator.validate();
                return validator.isValid();
            
            }
        });
        $.Validation = new Validation();
    })(jQuery);