OCA\Richdocuments\Controller\SessionController::save PHP Method

    public function save()
    {
        $response = new JSONResponse();
        try {
            $esId = $this->request->server['HTTP_WEBODF_SESSION_ID'];
            $session = $this->loadSession($esId);
            $memberId = $this->request->server['HTTP_WEBODF_MEMBER_ID'];
            $currentMember = $this->loadMember($memberId, $esId);
            // Extra info for future usage
            // $sessionRevision = $this->request->server['HTTP_WEBODF_SESSION_REVISION'];
            //NB ouch! New document content is passed as an input stream content
            $stream = fopen('php://input', 'r');
            if (!$stream) {
                throw new \Exception('New content missing');
            }
            $content = stream_get_contents($stream);
            try {
                if ($currentMember->getIsGuest()) {
                    $file = File::getByShareToken($currentMember->getToken());
                } else {
                    $file = new File($session->getFileId());
                }
                $view = $file->getOwnerView(true);
                $path = $file->getPath(true);
            } catch (\Exception $e) {
                //File was deleted or unshared. We need to save content as new file anyway
                //Sorry, but for guests it would be lost :(
                if ($this->uid) {
                    $view = new View('/' . $this->uid . '/files');
                    $dir = '/';
                    $path = Helper::getNewFileName($view, $dir . 'New Document.odt');
                } else {
                    throw $e;
                }
            }
            $member = new Db\Member();
            $members = $member->getActiveCollection($esId);
            $memberIds = array_map(function ($x) {
                return $x['member_id'];
            }, $members);
            // Active users except current user
            $memberCount = count($memberIds) - 1;
            if ($view->file_exists($path)) {
                $currentHash = $view->hash('sha1', $path, false);
                if (!Helper::isVersionsEnabled() && $currentHash !== $session->getGenesisHash()) {
                    // Original file was modified externally. Save to a new one
                    $path = Helper::getNewFileName($view, $path, '-conflict');
                }
                $mimetype = $view->getMimeType($path);
            } else {
                $mimetype = Storage::MIMETYPE_LIBREOFFICE_WORDPROCESSOR;
            }
            $data = Filter::write($content, $mimetype);
            if ($view->file_put_contents($path, $data['content'])) {
                // Not a last user
                if ($memberCount > 0) {
                    // Update genesis hash to prevent conflicts
                    $this->logger->debug('Update hash', ['app' => $this->appName]);
                    $session->updateGenesisHash($esId, sha1($data['content']));
                } else {
                    // Last user. Kill session data
                    Db\Session::cleanUp($esId);
                }
                $view->touch($path);
            }
            $response->setData(['status' => 'success']);
        } catch (\Exception $e) {
            $response->setStatus(Http::STATUS_INTERNAL_SERVER_ERROR);
            $response->setData([]);
            $this->logger->warning('Saving failed. Reason:' . $e->getMessage(), ['app' => $this->appName]);
        }
        return $response;
    }