Put the logic for checking if a user can submit webforms into a function

Over in an issue on the webform_entity module (#1794960: Put the logic for checking if a user can submit webforms into a function) we were trying to test if someone had permissions to create a webform submission... While webform_submission_access() will tell you about editing, deleting, listing or viewing... it doesn't say anything about creation.

All the logic for create permissions is stuck in webform_node_view() where no one else can use it:

  if ($node->webform['status'] == 0) {
    $closed = TRUE;
    $enabled = FALSE;
  }
  else {
    // Check if the user's role can submit this webform.
    if (variable_get('webform_submission_access_control', 1)) {
      foreach ($node->webform['roles'] as $rid) {
        $allowed_roles[$rid] = isset($user->roles[$rid]) ? TRUE : FALSE;
      }
      if (array_search(TRUE, $allowed_roles) === FALSE && $user->uid != 1) {
        $enabled = FALSE;
      }
    }
    else {
      // If not using Webform submission access control, allow for all roles.
      $allowed_roles = array_keys(user_roles());
    }
  }

  // Get a count of previous submissions by this user. Note that the
  // webform_submission_access() function may disable the page cache for
  // anonymous users if they are allowed to edit their own submissions!
  if ($page && webform_submission_access($node, NULL, 'list')) {
    module_load_include('inc', 'webform', 'includes/webform.submissions');
    $submission_count = webform_get_submission_count($node->nid, $user->uid);
  }

  // Check if this page is cached or not.
  $cached = $user->uid == 0 && (variable_get('cache', 0) || drupal_page_is_cacheable() === FALSE);

  // Check if the user can add another submission.
  if ($node->webform['submit_limit'] != -1) { // -1: Submissions are never throttled.
    module_load_include('inc', 'webform', 'includes/webform.submissions');

    // Disable the form if the limit is exceeded and page cache is not active.
    if (($user_limit_exceeded = _webform_submission_user_limit_check($node)) && !$cached) {
      $enabled = FALSE;
    }
  }

  // Check if the user can add another submission if there is a limit on total
  // submissions.
  if ($node->webform['total_submit_limit'] != -1) { // -1: Submissions are never throttled.
    module_load_include('inc', 'webform', 'includes/webform.submissions');

    // Disable the form if the limit is exceeded and page cache is not active.
    if (($total_limit_exceeded = _webform_submission_total_limit_check($node)) && !$cached) {
      $enabled = FALSE;
    }
  }

  // Check if this user has a draft for this webform.
  $is_draft = FALSE;
  if (($node->webform['allow_draft'] || $node->webform['auto_save']) && $user->uid != 0) {
    // Draft found - display form with draft data for further editing.
    if ($draft_sid = _webform_fetch_draft_sid($node->nid, $user->uid)) {
      module_load_include('inc', 'webform', 'includes/webform.submissions');
      $submission = webform_get_submission($node->nid, $draft_sid);
      $enabled = TRUE;
      $is_draft = TRUE;
    }
  }

And finally that gets distilled down to the $enabled variable:

  $node->content['webform'] = array(
    '#theme' => 'webform_view',
    '#node' => $node,
    '#teaser' => $teaser,
    '#page' => $page,
    '#form' => $form,
    '#enabled' => $enabled,
    '#weight' => 10,
  );

So it seems like the cleanest way to check the create permissions at this point is:

$copy = clone $node;
webform_node_view($copy, 'foo');
if ($copy->content['webform']['#enabled']) {
 // we're good to go...
}

Which is kind of embarrassing.