OJSPaymentManager::purchaseIssueEnabled PHP Method

    function purchaseIssueEnabled()
    {
        $journal = $this->request->getJournal();
        return $this->isConfigured() && $journal->getSetting('purchaseIssueFeeEnabled') && $journal->getSetting('purchaseIssueFee') > 0;
    }

 /**
  * Determines whether a user can view this article galley or not.
  * @param $request Request
  * @param $articleId string
  * @param $galleyId int or string
  */
 function userCanViewGalley($request, $articleId, $galleyId = null)
 {
     import('classes.issue.IssueAction');
     $issueAction = new IssueAction();
     $journal = $request->getJournal();
     $publishedArticle = $this->article;
     $issue = $this->issue;
     $journalId = $journal->getId();
     $user = $request->getUser();
     $userId = $user ? $user->getId() : 0;
     // If this is an editorial user who can view unpublished/unscheduled
     // articles, bypass further validation. Likewise for its author.
     if ($publishedArticle && $issueAction->allowedPrePublicationAccess($journal, $publishedArticle)) {
         return true;
     }
     // Make sure the reader has rights to view the article/issue.
     if ($issue && $issue->getPublished() && $publishedArticle->getStatus() == STATUS_PUBLISHED) {
         $subscriptionRequired = $issueAction->subscriptionRequired($issue);
         $isSubscribedDomain = $issueAction->subscribedDomain($journal, $issue->getId(), $publishedArticle->getId());
         // Check if login is required for viewing.
         if (!$isSubscribedDomain && !Validation::isLoggedIn() && $journal->getSetting('restrictArticleAccess') && isset($galleyId) && $galleyId) {
             Validation::redirectLogin();
         }
         // bypass all validation if subscription based on domain or ip is valid
         // or if the user is just requesting the abstract
         if (!$isSubscribedDomain && $subscriptionRequired && (isset($galleyId) && $galleyId)) {
             // Subscription Access
             $subscribedUser = $issueAction->subscribedUser($journal, $issue->getId(), $publishedArticle->getId());
             import('classes.payment.ojs.OJSPaymentManager');
             $paymentManager = new OJSPaymentManager($request);
             $purchasedIssue = false;
             if (!$subscribedUser && $paymentManager->purchaseIssueEnabled()) {
                 $completedPaymentDao = DAORegistry::getDAO('OJSCompletedPaymentDAO');
                 $purchasedIssue = $completedPaymentDao->hasPaidPurchaseIssue($userId, $issue->getId());
             }
             if (!(!$subscriptionRequired || $publishedArticle->getAccessStatus() == ARTICLE_ACCESS_OPEN || $subscribedUser || $purchasedIssue)) {
                 if ($paymentManager->purchaseArticleEnabled() || $paymentManager->membershipEnabled()) {
                     /* if only pdf files are being restricted, then approve all non-pdf galleys
                      * and continue checking if it is a pdf galley */
                     if ($paymentManager->onlyPdfEnabled()) {
                         if ($this->galley && !$this->galley->isPdfGalley()) {
                             $this->issue = $issue;
                             $this->article = $publishedArticle;
                             return true;
                         }
                     }
                     if (!Validation::isLoggedIn()) {
                         Validation::redirectLogin("payment.loginRequired.forArticle");
                     }
                     /* if the article has been paid for then forget about everything else
                      * and just let them access the article */
                     $completedPaymentDao = DAORegistry::getDAO('OJSCompletedPaymentDAO');
                     $dateEndMembership = $user->getSetting('dateEndMembership', 0);
                     if ($completedPaymentDao->hasPaidPurchaseArticle($userId, $publishedArticle->getId()) || !is_null($dateEndMembership) && $dateEndMembership > time()) {
                         $this->issue = $issue;
                         $this->article = $publishedArticle;
                         return true;
                     } else {
                         $queuedPayment = $paymentManager->createQueuedPayment($journalId, PAYMENT_TYPE_PURCHASE_ARTICLE, $user->getId(), $publishedArticle->getId(), $journal->getSetting('purchaseArticleFee'));
                         $queuedPaymentId = $paymentManager->queuePayment($queuedPayment);
                         $paymentManager->displayPaymentForm($queuedPaymentId, $queuedPayment);
                         exit;
                     }
                 }
                 if (!isset($galleyId) || $galleyId) {
                     if (!Validation::isLoggedIn()) {
                         Validation::redirectLogin('reader.subscriptionRequiredLoginText');
                     }
                     $request->redirect(null, 'about', 'subscriptions');
                 }
             }
         }
     } else {
         $request->redirect(null, 'search');
     }
     return true;
 }