/*
http://www.gerd-tentler.de/tools/checkform/
  - form-name or -number
  - 'field:title:type:minimum length'[, ...]  (type = number / mail / url / [none])
 Example:
 checkForm('frm1', 'name:::2', 'age::number:1', 'eMail:e-mail:mail:1', 'homepage::url:0');
*/

var msgNumber  = "must be a number";
var msgEMail   = "Please enter a valid ";
var msgURL     = "must be a web address";
var msgFillOut = "You need more characters in your";
var msgNoForm  = "Form does not exist";
var msgNoField = "Field does not exist";


function _trim(str) {
  if(str) {
    str = str.replace(/^\s+/, "");
    str = str.replace(/\s+$/, "");
  }
  return str;
}

function checkForm() {
  var args = checkForm.arguments;
  var f = args[0];
  var msg = "";
  var arr, field, title, type, minLength, elem, val, cnt, i, j;

  var valid_url = /^(https?|ftp):\/\/([a-z0-9._-]+:[a-z0-9._-]+@)?[a-z0-9äöüÄÖÜ#._\/~% -]+(\?([a-z0-9_-]+(=[a-zA-Z0-99äöüÄÖÜß+%?_-]+&?)?)*)?$/i;
  var valid_mail = /^[a-z0-9._-]+@[a-z0-9äöüÄÖÜ.-]+\.[a-z]{2,4}$/i;

  if(document.forms[f]) {
    for(i = 1; i < args.length; i++) {
      arr = args[i].split(":");
      field = _trim(arr[0]);
      title = _trim(arr[1]);
      if(!title) title = field;
      type = _trim(arr[2]);
      minLength = _trim(arr[3]);
      elem = document.forms[f].elements[field];

      if(elem) {
        val = _trim(elem.value);

        if(val != "") {
          if(type == "number") {
            val = val.replace(",", ".");
            if(isNaN(val)) msg += '"' + title + '" ' + msgNumber + "\n";
          }
          else if(type == "mail" && val.search(valid_mail) == -1) msg += msgEMail + title + "\n";
          else if(type == "url" && val.search(valid_url) == -1) msg += '"' + title + '" ' + msgURL + "\n";
        }

        if(minLength) {
          if(elem.length) {
            if(elem.options) {
              for(j = cnt = 0; j < elem.options.length; j++) {
                if(elem.options[j].selected && elem.options[j].value != "") cnt++;
              }
            }
            else for(j = cnt = 0; j < elem.length; j++) {
              if(elem[j].checked) cnt++;
            }
          }
          else if(elem.type == "checkbox") cnt = elem.checked ? 1 : 0;
          else cnt = val.length;
          if(cnt < minLength) msg += msgFillOut + ' ' + title + '\n';
        }
      }
      else msg += msgNoField + ' ' + field + '\n';
    }

    if(msg) alert(msg);
    else document.forms[f].submit();
  }
  else alert(msgNoForm + ' ' + f + '');
}