function Validator(frmname) {
    this.formobj = document.forms[frmname];
    if (!this.formobj) {
        alert("BUG: couldnot get Form object "+frmname);
        return;
    }
    if (this.formobj.onsubmit) {
        this.formobj.old_onsubmit = this.formobj.onsubmit;
        this.formobj.onsubmit=null;
    } else {
        this.formobj.old_onsubmit = null;
    }
    this.formobj.onsubmit = form_submit_handler;
    this.addValidation = add_validation;
    this.setAddnlValidationFunction = set_addnl_vfunction;
    this.clearAllValidations = clear_all_validations;
}

function set_addnl_vfunction(functionname) {
    this.formobj.addnlvalidation = functionname;
}

function clear_all_validations() {
    for (var itr=0;itr < this.formobj.elements.length;itr++) {
        this.formobj.elements[itr].validationset = null;
    }
}

function form_submit_handler() {
    for (var itr=0;itr < this.elements.length;itr++) {
        if (this.elements[itr].validationset && !this.elements[itr].validationset.validate()) {
            return false;
        }
    }
    if (this.addnlvalidation) {
        str = " var ret = "+this.addnlvalidation+"()";
        eval(str);
        if (!ret) return ret;
    }
    return true;
}

function add_validation(itemname,descriptor,errstr) {
    if (!this.formobj) {
        alert("BUG: the form object is not set properly");
        return;
    }
    var itemobj = this.formobj[itemname];
    if (!itemobj) {
        alert("BUG: Couldnot get the input object named: "+itemname);
        return;
    }
    if (!itemobj.validationset) {
        itemobj.validationset = new ValidationSet(itemobj);
    }
    itemobj.validationset.add(descriptor,errstr);
}

function ValidationDesc(inputitem,desc,error) {
    this.desc=desc;
    this.error=error;
    this.itemobj = inputitem;
    this.validate=vdesc_validate;
}

function vdesc_validate() {
    if (!V2validateData(this.desc,this.itemobj,this.error)) {
        this.itemobj.focus();
        return false;
    }
    return true;
}

function ValidationSet(inputitem) {
    this.vSet = new Array();
    this.add = add_validationdesc;
    this.validate = vset_validate;
    this.itemobj = inputitem;
}

function add_validationdesc(desc,error) {
    this.vSet[this.vSet.length] = new ValidationDesc(this.itemobj,desc,error);
}

function vset_validate() {
    for (var itr=0;itr<this.vSet.length;itr++) {
        if (!this.vSet[itr].validate()) {
            return false;
        }
    }
    return true;
}

function validateEmailv2(email) {
// a very simple email validation checking. 
// you can add more complex email checking if it helps 
    if (email.length <= 0) {
        return true;
    }
    var splitted = email.match("^(.+)@(.+)$");
    if (splitted == null) return false;
    if (splitted[1] != null) {
        var regexp_user=/^\"?[\w-_\.]*\"?$/;
        if (splitted[1].match(regexp_user) == null) return false;
    }
    if (splitted[2] != null) {
        var regexp_domain=/^[\w-\.]*\.[A-Za-z]{2,4}$/;
        if (splitted[2].match(regexp_domain) == null) {
            var regexp_ip = /^\[\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\]$/;
            if (splitted[2].match(regexp_ip) == null) return false;
        }
        return true;
    }
    return false;
}

function V2validateData(strValidateStr,objValue,strError) {
    var epos = strValidateStr.search("=");
    var command  = "";
    var cmdvalue = "";
    if (epos >= 0) {
        command  = strValidateStr.substring(0,epos);
        cmdvalue = strValidateStr.substr(epos+1);
    } else {
        command = strValidateStr;
    }
    switch(command) {
        case "req":
        case "required": {
            if (eval(objValue.value.length) == 0) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name + " : Required Field";
                }
                alert(strError);
                return false;
            }
            break;
        }
        case "maxlength":
        case "maxlen": {
            if (eval(objValue.value.length) >  eval(cmdvalue)) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name + " : "+cmdvalue+" characters maximum ";
                }
                alert(strError + "\n[Current length = " + objValue.value.length + " ]");
                return false;
            }
            break;
        }
        case "minlength":
        case "minlen": {
            if (eval(objValue.value.length) <  eval(cmdvalue)) {
                if (!strError || strError.length ==0) {
                    strError = objValue.name + " : " + cmdvalue + " characters minimum ";
                }
                alert(strError + "\n[Current length = " + objValue.value.length + " ]");
                return false;
            }
            break;
        }
        case "alnum":
        case "alphanumeric": {
            var charpos = objValue.value.search("[^A-Za-z0-9]");
            if (objValue.value.length > 0 &&  charpos >= 0) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name+": Only alpha-numeric characters allowed ";
                }
                alert(strError + "\n [Error character position " + eval(charpos+1)+"]");
                return false;
            }
            break;
        }
        case "num":
        case "numeric": {
            var charpos = objValue.value.search("[^0-9]");
            if (objValue.value.length > 0 &&  charpos >= 0) {
                if (!strError || strError.length ==0) {
                    strError = objValue.name+": Only digits allowed ";
                }
                alert(strError + "\n [Error character position " + eval(charpos+1)+"]");
                return false;
            }
            break;
        }
        case "alphabetic":
        case "alpha": {
            var charpos = objValue.value.search("[^A-Za-z]");
            if (objValue.value.length > 0 &&  charpos >= 0) {
                if (!strError || strError.length ==0) {
                    strError = objValue.name+": Only alphabetic characters allowed ";
                }
                alert(strError + "\n [Error character position " + eval(charpos+1)+"]");
                return false;
            }
            break;
        }
        case "alnumhyphen": {
            var charpos = objValue.value.search("[^A-Za-z0-9\-_]");
            if (objValue.value.length > 0 &&  charpos >= 0) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name+": characters allowed are A-Z,a-z,0-9,- and _";
                }
                alert(strError + "\n [Error character position " + eval(charpos+1)+"]");
                return false;
            }
            break;
        }
        case "email": {
            if (!validateEmailv2(objValue.value)) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name+": Enter a valid Email address ";
                }
                alert(strError);
                return false;
            }
            break;
        }
        case "lt":
        case "lessthan": {
            if (isNaN(objValue.value)) {
                alert(objValue.name+": Should be a number ");
                return false;
            }
            if (eval(objValue.value) >=  eval(cmdvalue)) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name + " : value should be less than "+ cmdvalue;
                }
                alert(strError);
                return false;
            }
            break;
        }
        case "gt":
        case "greaterthan": {
            if (isNaN(objValue.value)) {
                alert(objValue.name+": Should be a number ");
                return false;
            }
            if (eval(objValue.value) <=  eval(cmdvalue)) {
                if (!strError || strError.length == 0) {
                    strError = objValue.name + " : value should be greater than "+ cmdvalue;
                }
                alert(strError);
                return false;
            }
            break;
        }
        case "regexp": {
            if (objValue.value.length > 0) {
                if (!objValue.value.match(cmdvalue)) {
                    if (!strError || strError.length == 0) {
                        strError = objValue.name+": Invalid characters found ";
                    }
                    alert(strError);
                    return false;
                }
            }
            break;
        }
        case "dontselect": {
            if (objValue.selectedIndex == null) {
                alert("BUG: dontselect command for non-select Item");
                return false;
            }
            if (objValue.selectedIndex == eval(cmdvalue)) {
                if (!strError || strError.length ==0) {
                    strError = objValue.name+": Please Select one option ";
                }
                alert(strError);
                return false;
            }
            break;
        }
    }
    return true;
}