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.length < field_size) {
      error_message = error_message + "* " + message + "\n";
      error = true;
    }
  }
}

function check_radio(field_name, message) {
  var isChecked = false;

  if (form.elements[field_name] && (form.elements[field_name].type != "hidden")) {
    var radio = form.elements[field_name];

    for (var i=0; i<radio.length; i++) {
      if (radio[i].checked == true) {
        isChecked = true;
        break;
      }
    }

    if (isChecked == false) {
      error_message = error_message + "* " + message + "\n";
      error = true;
    }
  }
}

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

    if (field_value == field_default) {
      error_message = error_message + "* " + message + "\n";
      error = true;
    }
  }
}

function check_checked(field_name, message) {
  var isChecked = false;

  if (form.elements[field_name] && (form.elements[field_name].type != "hidden")) {
    var checkbox = form.elements[field_name];

    for (var i=0; i<checkbox.length; i++) {
      if (checkbox[i].checked == true) {
        isChecked = true;
        break;
      }
    }

    if (isChecked == false) {
      error_message = error_message + "* " + message + "\n";
      error = true;
    }
  }
}

function check_form(form_name) {
  if (submitted == true) {
    alert("Dit formulier is al verzonden. Klik op OK en wacht tot de verwerking van deze bestelling klaar is.");
    return false;
  }

  error = false;
  form = form_name;
  error_message = "Er hebben zich fouten voorgedaan tijdens het verwerken van het formulier!\nMaak de volgende aanpassingen:\n\n";

  check_select("rating", "" , "Vul de product waardering in.");
  check_input("review", 10, "De beoordeling moet minimaal 10 tekens lang zijn.");
  check_checked("tags[]", "Selecteer minimaal 1 trefwoord");
  
  check_input("review_name", 2, "Uw naam moet minimaal 2 tekens lang zijn.");
  check_input("review_email", 6, "Uw e-mail adres moet minimaal 6 tekens lang zijn.");
  check_input("review_city", 3, "Uw woonplaats moet minimaal 3 tekens lang zijn.");
 
  check_select("review_gender", "" , "Vul uw geslacht in.");
  check_select("review_age", "" , "Vul uw leeftijd in.");
  
  check_input("private_key", 4, "De controle code moet minimaal 4 tekens lang zijn.");
    
  if (error == true) {
    alert(error_message);
    return false;
  } else {
    submitted = true;
    return true;
  }
}