<?php
/**
 * @file
 * The Serial module main file.
 */

define('SERIAL_FIELD_TYPE', 'serial');

/**
 * Implements hook_field_info().
 */
function serial_field_info() {
  return array(
    SERIAL_FIELD_TYPE => array(
      'label' => t('Serial'),
      'description' => t('Auto increment serial field type.'),
      // The "property_type" should be defined for accessing the
      // field by entity metadata wrapper.
      'property_type' => 'integer',
      'default_widget' => 'serial_widget_default',
      'default_formatter' => 'serial_formatter_default',
    ),
  );
}

/**
 * Implements hook_field_widget_info().
 */
function serial_field_widget_info() {
  return array(
    'serial_widget_default' => array(
      'label' => t('Hidden (Automatic)'),
      'field types' => array(SERIAL_FIELD_TYPE),
    ),
  );
}

/**
 * Implements hook_field_formatter_info().
 */
function serial_field_formatter_info() {
  return array(
    'serial_formatter_default' => array(
      'label' => t('Default'),
      'field types' => array(SERIAL_FIELD_TYPE),
    ),
  );
}

/**
 * Implements hook_field_create_instance().
 */
function serial_field_create_instance(array $instance) {
  $field = field_read_field($instance['field_name']);

  if (SERIAL_FIELD_TYPE === $field['type']) {
    // Create the assistant table:
    module_load_include('inc', 'serial');
    _serial_create_table($field, $instance);

    // Set serial values for old objects.
    $old_count = _serial_init_old_entities($instance['entity_type'], $instance['bundle'], $field['field_name']);

    if ($old_count > 0) {
      drupal_set_message(t('Serial values have been automatically set for %count existing entities.', array(
        '%count' => $old_count,
      )));
    }
  }
}

/**
 * Implements hook_field_delete_instance().
 */
function serial_field_delete_instance(array $instance) {
  $field = field_read_field($instance['field_name']);

  if (SERIAL_FIELD_TYPE == $field['type']) {
    // Drop the assistant table.
    module_load_include('inc', 'serial');
    _serial_drop_table($field, $instance);
  }
}

/**
 * Implements hook_field_presave().
 */
function serial_field_presave($entity_type, $entity, array $field, array $instance, $langcode, array &$items) {
  if (empty($items)) {
    module_load_include('inc', 'serial');

    $items[] = array(
      'value' => _serial_generate_value($entity_type, $instance['bundle'], $field['field_name']),
    );
  }
}

/**
 * Implements hook_field_is_empty().
 */
function serial_field_is_empty($item, $field) {
  // Never should be treated as empty.
  return empty($item['value']);
}

/**
 * Implements hook_clone_node_alter().
 */
function serial_clone_node_alter(stdClass $node) {
  // Reset values of all serial fields when cloning a node.
  foreach (field_info_instances('node', $node->type) as $field_name => $instance) {
    $info = field_info_field($field_name);

    if ('serial' === $info['type']) {
      $node->{$field_name} = array();
    }
  }
}

/**
 * Implements hook_field_attach_rename_bundle().
 */
function serial_field_attach_rename_bundle($entity_type, $bundle_old, $bundle_new) {
  if ($bundle_old !== $bundle_new) {
    module_load_include('inc', 'serial');
    _serial_rename_tables($entity_type, $bundle_old, $bundle_new);
  }
}

/**
 * Implements hook_field_formatter_view().
 */
function serial_field_formatter_view($entity_type, $entity, array $field, array $instance, $langcode, array $items, array $display) {
  $element = array();

  // Define the field contents for the single default formatter.
  foreach ($items as $delta => $item) {
    $element[$delta] = array(
      '#markup' => theme('serial_formatter_default', array(
        'serial_id' => $item['value'],
      )),
    );
  }

  return $element;
}

/**
 * Implements hook_theme().
 */
function serial_theme() {
  // Register the theme for the default formatter.
  return array(
    'serial_formatter_default' => array(
      'variables' => array(
        'serial_id' => NULL,
      ),
    ),
  );
}

/**
 * Theme function for the default formatter.
 */
function theme_serial_formatter_default(array $variables) {
  return $variables['serial_id'];
}

/**
 * Implements hook_field_widget_form().
 */
function serial_field_widget_form(
  array &$form,
  array &$form_state,
  array $field,
  array $instance,
  $langcode,
  array $items,
  $delta,
  array $element
) {
  $element['#type'] = 'hidden';

  if (isset($items[$delta]['value'])) {
    $element['#default_value'] = $items[$delta]['value'];
  }

  return array('value' => $element);
}