var layer = 4;

function selectCalculator(e) {
  $$('li.calculatorMode').each(function (mode) {
    mode.hide();
  });
  
  switch (e.immediateDescendants()[e.selectedIndex].value) {
    case '1': // External Wall
      $('external-wall').show();
      break;
    case '2': // Single Span Internal
      $('internal-wall').show();
      break;
    case '3': // Single Span Internal Ceiling
      $('internal-ceiling').show();
      break;
    case '4': // U-Value
      $('u-value').show();
      break;
  }
}

function addLayer() {
  var url = '/calculator/add-layer'; 
  
  new Ajax.Updater('u-value-layers', url, {
    method: 'post',
    parameters: { layer: layer },
    insertion: 'bottom',
    onSuccess: function() {
      layer++;
      $('u_value_layers').setAttribute('value', layer - 1);
      if (layer >= 8) {
        $('addLayer').hide();
      }
    }
  });
}

function removeLayer(id) {
  var layerNo = id.substring(13);
  Element.remove('u-value-layer-'+layerNo+'-header');
  Element.remove('u-value-layer-'+layerNo+'-material');
  layer--;
  
  var tempLayer = 4;
  $$('ul#u-value-layers li.header span').each(function(el) {
    el.innerHTML = tempLayer;
    tempLayer++;
  });
  
  tempLayer = 1;
  $$('ul#u-value-layers li.header').each(function(el) {
    el.id = 'u-value-layer-'+tempLayer+'-header';
    tempLayer++;
  });
  
  tempLayer = 4;
  $$('ul#u-value-layers li.material').each(function(el) {
    el.id = 'u-value-layer-'+tempLayer+'-material';
    el.down('label').setAttribute('for', 'u_value_material_'+tempLayer);
    el.down('select').setAttribute('id', 'u_value_material_'+tempLayer);
    el.down('select').setAttribute('name', 'u_value_material_'+tempLayer);
    tempLayer++;
  });
  
  tempLayer = 4;
  $$('ul#u-value-layers li.header a').each(function(el) {
    el.id = 'remove-layer-'+tempLayer;
    tempLayer++;
  });
  
  $('u_value_layers').setAttribute('value', layer - 1);
  
  if (tempLayer < 8) {
    $('addLayer').show();
  }
}