var form = "";
var submitted = false;
var error = false;
var error_message = "";

function check_input(field_name, field_size, message) {
  if (form.elements[field_name] && (form.elements[field_name].type != "hidden")) {
    var field_value = form.elements[field_name].value;

    if (field_value == '' || field_value.length < field_size) {
      error_message = error_message + "* " + message + "\n";
      error = true;
    }
  }
}
function check_email(field_name, field_size, message){
	adresse = form.elements[field_name].value;
	var place = adresse.indexOf("@",1);
	var point = adresse.indexOf(".",place+1);
	if ((place > -1)&&(adresse.length >2)&&(point > 1)){
		cesbon = true
	}
	else{
		error_message = error_message + "* " + message + "\n";
      	error = true;
	}
}
function check_form(form_name) {
  if (submitted == true) {
    alert("Ce formulaire a &eacute;t&eacute; d&eacute;jà soumis. Veuillez appuyer sur Ok et attendez jusqu'à ce que le traitement soit fini.");
    return false;
  }

  error = false;
  form = form_name;
  error_message = "Des erreurs sont survenues durant le traitement de votre formulaire.\nVeuillez renseigner les champs suivants :\n\n";
  check_input("nom", 4, "Nom");
  check_input("prenom", 4, "Prenom");
  check_input("tel", 10, "Telephone");
  check_email("Nmail", 6, "Adresse email");
  check_input("Ndemand", 10, "Votre demande");

  check_input("Ndep", 3, "Provenance");
  check_input("Ndest", 3, "Destination");
  
  check_input("Nvol1", 4, "Date de depart");
  check_input("Nvol2", 4, "Date de retour");

  if (error == true) {
    alert(error_message);
    return false;
  } else {
    submitted = true;
    return true;
  }
}