<?php

/**
 * Adds a field to an Entity bundle.
 *
 * @param $field_name
 *   The name of the field.
 * @param $field_info
 *   An associative array containing the field information.  The following
 *   key/value pairs are supported:
 *     'field_type' : a valid field type.  May be any of the Drupal default
 *       fields, one created by the tripal_chado module or another custom module.
 *     'widget_type' : a valid widget type. May be any of the Drupal default
 *       fields, one created by the tripal_chado module or another custom module.
 *     'field_settings' : an array of settings that are appropriate for the
 *       selected field type.
 *     'widget_settings' : an array of settings that are appropriate for the
 *       selected widget type.
 *     'description' :  a default description for this field.
 *     'label' : a label used as a header for this field.
 *     'is_required' : indicates if the field is required in the edit form.
 *     'cardinality' : indicates the number of values this field can support.
 *       the default is 1 (meaning only one value). Use a value of
 *       FIELD_CARDINALITY_UNLIMITED for unlimited number of values.
 * @param $entity_type_name
 *   The entity type name.
 * @param $bundle_id
 *   The bundle name.
 *
 */
function tripal_add_bundle_field($field_name, $field_info, $entity_type_name, $bundle_id) {

      $field = field_info_field($field_name);

      // If the field exists and is attached to this bundle then just return,
      // there is nothing left to do.
      if ($field and array_key_exists('bundles', $field) and
          array_key_exists($entity_type_name, $field['bundles']) and
          in_array($bundle_id, $field['bundles'][$entity_type_name])) {
            return;
          }

          // Allow other modules to alter the field information array.
          drupal_alter('chado_field', $field_info);

          $cardinality = 1;
          if (array_key_exists('cardinality', $field_info) and is_numeric($field_info['cardinality'])) {
            $cardinality = $field_info['cardinality'];
          }

          // If the field doesn't exist then create it.
          if (!$field) {
            $field = array(
              'field_name' => $field_name,
              'type' => $field_info['field_type'],
              'cardinality' => $cardinality,
              'locked' => FALSE,
              'storage' => array(
                'type' => 'field_chado_storage'
              ),
              'settings' => $field_info['field_settings'],
            );
            field_create_field($field);
          }

          // Attach the field to the bundle.
          $field_instance = array(
            'field_name' => $field_name,
            'label' => $field_info['label'],
            'description' => $field_info['description'],
            'widget' => array(
              'type' => $field_info['widget_type'],
              'settings' => $field_info['widget_settings'],
            ),
            'entity_type' => $entity_type_name,
            'required' => $field_info['is_required'],
            'settings' => $field_info['field_settings'],
            'bundle' => $bundle_id,
          );
          field_create_instance($field_instance);
}