/**
 * Form validation
 * Check for mandatory field and type field
 * first arg = field name (input tag attribute name)
 * second arg = form label (user side)
 * third arg = 'R' for mandatory field, 'isEmail' if e-mail required, 'inRange' if numeric required
 * and so on...
 **/
function MM_validateForm() { //v4.0

    var i,j,p,q,nm,field,errorField,test,label,type,value,num,min,max,errors='',args=MM_validateForm.arguments;
  
    errorField = null;
    
    form = document.forms["htmlForm"];
    
    try {
        
        for (i=0; i<(args.length-2); i+=3) {
      
            field = form.elements[args[i]];
                  
            test=args[i+2];
            label=args[i+1];
            
            if (field) {
            
                if (field.length && !field.type) {
                    type = field[0].type;
                }
                else {
                    type = field.type;
                }
                
                if (type != 'text' && type != 'radio' && type != 'checkbox' && type != 'select-one' && type != 'select-multiple') {
                    throw "errorType";
                }
                
                if (!field.length) {
                
                    if (type == 'text') {
                        value = field.value;
                        if (value!='') {
                        
                            if (test.indexOf('isEmail')!=-1) {
                            
                                p=value.indexOf('@');
                                if (p<1 || p==(value.length-1)) {
                                    errors+='- '+label+' must contain an e-mail address.\n';
                                    errorField = (errorField != null)? errorField : field;
                                }
                            }
                            else if (test!='R') {
                            
                                num = parseFloat(value);
                                
                                if (isNaN(value)) {
                                    errors+='- '+label+' must contain a number.\n';
                                    errorField = (errorField != null)? errorField : field;
                                }
                                if (test.indexOf('inRange') != -1) {
                                    p=test.indexOf(':');
                                    min=test.substring(8,p);
                                    max=test.substring(p+1);
                                    if (num<min || max<num) {
                                        errors+='- '+label+' must contain a number between '+min+' and '+max+'.\n';
                                        errorField = (errorField != null)? errorField : field;
                                    }
                                }
                            }
                        }
                        else if (test.charAt(0) == 'R') {
                            errors += '- '+label+' is required.\n'; 
                            errorField = (errorField != null)? errorField : field;
                        }
                    }
                    else if (test.charAt(0) == 'R') {
                        if ( ((type == 'checkbox' || type == 'radio') && !field.checked) || // checkbox & radio
                             ((type == 'select-one' || type == 'select-multiple') && field.selectedIndex == -1)) // select
                            
                         {
                                errors += '- '+label+' is required.\n';
                                errorField = (errorField != null)? errorField : field;
                        }
                    }
                }
                else {
                    if (test.charAt(0) == 'R') {
                        if (type == 'select-one' || type == 'select-multiple') { // select-option field
                             if (field.selectedIndex == -1 || !field.options[field.selectedIndex].value.length) {
                                errors += '- '+label+' is required.\n';
                                errorField = (errorField != null)? errorField : field;
                            }
                        }
                        else if (type == 'checkbox' || type == 'radio') { // radio button, checkbox
                            for (j=0;j<field.length; j++) {
                                if (field[j].checked) {
                                    break;
                                }
                            }
                            if (j==field.length) {
                                errors += '- '+label+' is required.\n';
                                errorField = (errorField != null)? errorField : field;
                            }                            
                        }
                        else if (type == 'text') {
                            for (j=0;j<field.length; j++) {
                                if (field[j].value.length) {
                                    break;
                                }
                            }
                            if (j==field.length) {
                                errors += '- '+label+' is required.\n';
                                errorField = (errorField != null)? errorField : field;
                            } 
                        }
                    }
                }
            }
        }
    }
    catch (e) {
        if (e != 'errorType') {
            errors = '- unexpected error: '+e.description+'.\n';
        }
        else {
            errors = '- unexpected error: type '+type+' for field '+args[i]+' unknown.\n';
        }
    }
    if (errors.length) {
        alert('The following error(s) occurred:\n\n'+errors);
        if (errorField) {
            if (!errorField.type) {
                // radio button field
                errorField[0].focus();
            }
            else {
                errorField.focus();
            }
        }
    }
    
    return (errors == '');
}