function fnum(v)
{
  var parts;

  if (v.indexOf(':') >= 0)
  {
    parts = v.split(':');
    return parts[0];
  }

  return v;
}

function add_selected_fields()
{
  var from = document.getElementById('available_fields').options;
  var to = document.getElementById('selected_fields').options;
  var i, j, k, n;

  n = from.length;
  j = to.length;

  for (i = 0; i < n; i++)
  {
    if (from[i].selected == true)
    {
      if (from[i].text.length > 0)
      {
        k = j;
        to[j++] = new Option('', '', false, false);

        to[k].text = from[i].text;
        to[k].value = from[i].value;
      }

      from[i].selected = false;
    }
  }
}

function remove_selected_fields()
{
  var fields = document.getElementById('selected_fields').options;
  var n = fields.length;
  var i;

  for (i = n - 1; i >= 0; i--)
  {
    if (fields[i].selected == true)
      fields[i] = null;
  }
}

function move_field(fields_list, incr)
{
  var fields = document.getElementById(fields_list);
  var options = fields.options;
  var text, value;
  var i, j, n;

  i = fields.selectedIndex;
  if (i >= 0)
  {
    j = i + incr;
    n = options.length;

    if ((incr < 0 && j < 0) || (incr > 0 && j >= n))
      return false;

    text = options[j].text;
    value = options[j].value;
    options[j].text = options[i].text;
    options[j].value = options[i].value;
    options[i].text = text;
    options[i].value = value;

    options[i].selected = false;
    options[j].selected = true;
  }

  return false;
}

function return_selected_fields()
{
  var fields = document.getElementById('selected_fields').options;
  var return_fields = '';
  var i;

  for (i = 0; i < fields.length; i++)
    return_fields += '|' + fields[i].value;

  if (i > 0)
    return_fields += '|';

  with (window.opener.document.forms[0])
  {
    selected_fields.value = return_fields;
    download_fields[selected_fields_option].checked = true;
  }

  window.close();
}

function resize_box(incr)
{
  var box = document.getElementById('selected_fields');
  var width = box.style.width;

  width = width.split('p', 1);
  width = Math.max(Number(width) + incr, 230);
  box.style.width = width + 'px';
}

function change_field_name(fields)
{
  var value, parts, text;
  var field, orig_name;
  var i, j, n;

  fields = document.getElementById(fields);
  i = fields.selectedIndex;
  if (i < 0)
  {
    alert(select_download_field);
    return;
  }

  n = fields.options.length;
  for (i = 0; i < n; i++)
  {
    field = fields.options[i];
    if (field.selected)
    {
      text = field.text;
      value = field.value;
      parts = value.split(':');

      j = text.indexOf('-> ', 0);
      if (j > 0)
        orig_name = text.substr(j + 3);
      else
        orig_name = text;

      with (document.forms[0])
      {
        if (field_label.value.length > 0)
        {
          field.value = parts[0] + ':' + field_label.value;
          field.text = field_label.value + ' -> ' + orig_name;
        }
        else
        {
          field.value = parts[0];
          field.text = orig_name;
        }
      }
    }
  }
}

function get_field_label()
{
  var selected_fields = document.getElementById('selected_fields');
  var field_label = document.getElementById('field_label');
  var i = selected_fields.selectedIndex;
  var values, label = '';

  if (i >= 0)
  {
    values = selected_fields.options[i].value.split(':');
    if (values.length > 1)
      label = values[1];
  }

  field_label.value = label;
}

function return_fieldmap()
{
  var selected_fields, fieldmap_name, map_fields;
  var valid = "abcdefghijklmnopqrstuvwxyz0123456789._- ";
  var names, check, saveas, empty;
  var fields = '';
  var i, n;

  selected_fields = document.getElementById('selected_fields');
  fieldmap_name = document.getElementById('fieldmap_name');
  map_fields = document.getElementById('map_fields');
  
  // collect the selected fields for the field map
  n = selected_fields.options.length;
  if (n > 0)
  {
    for (i = 0; i < n; i++)
      fields += '|' + selected_fields.options[i].value;

    if (i > 0)
      fields = fields + '|';
  }

  // get the name that the field map should be saved as
  saveas = fieldmap_name.value;
  if (saveas.length == 0)
  {
    alert(enter_map_name);
    fieldmap_name.focus();
    return false;
  }

  // check for invalid characters in the name
  check = saveas.toLowerCase();
  for (i = 0; i < check.length; i++)
  {
    if (valid.indexOf(check.charAt(i)) == -1)
    {
      alert(use_valid_characters + '\n' + valid_characters);
      fieldmap_name.focus();
      return false;
    }
  }

  map_fields.value = fields;

  with (window.opener.document.forms[0])
  {
    i = fieldmap.options.selectedIndex;
    names = fieldmap.options;

    // check if fields were selected or removed for the field map
    if (fields.length > 0)
    {
      // check if saveas name is different
      if (names[i].value != saveas)
      {
        // look for a place to put the new or changed name
        n = fieldmap.options.length - 1;
        for (i = 0, empty = -1; i < n; i++)
        {
          // check if field map is replacing an existing one
          if (names[i].value == saveas)
          {
            empty = -1;
            break;
          }
          else
          if (names[i].value == '' && empty < 0)
              empty = i; // remember first empty slot
        }

        if (empty >= 0)
          i = empty;

        names[i].text = saveas;
        names[i].value = saveas;
        names[i].selected = true;
      }

      download_fields[2].checked = true;

    }
    else
    {
      // remove entry name for deleted field map
      names[i].text = '<' + new_entry + '>';
      names[i].value = '';
      names[i].selected = true;
    }
  }

  return true;
}

function confirm_delete()
{
  var proceed = false;
  var names, i;

  with (window.opener.document.forms[0])
  {
    names = fieldmap.options;
    i = fieldmap.options.selectedIndex;
    if (confirm('Are you sure you want to delete ' + names[i].text + '?'))
    {
      proceed = true;
      names[i].text = '<New>';
      names[i].value = '';
      names[i].selected = true;
    }
  }

  if (proceed)
  {
    // sending an empty list of fields will delete the field map
    document.forms[0].map_fields.value = '';
    return true;
  }

  return false;
}