BookStack\Http\Controllers\PageController::saveDraft PHP Method

    public function saveDraft(Request $request, $pageId)
    {
        $page = $this->pageRepo->getById($pageId, true);
        $this->checkOwnablePermission('page-update', $page);
        if (!$this->signedIn) {
            return response()->json(['status' => 'error', 'message' => 'Guests cannot save drafts'], 500);
        }
        if ($page->draft) {
            $draft = $this->pageRepo->updateDraftPage($page, $request->only(['name', 'html', 'markdown']));
        } else {
            $draft = $this->pageRepo->saveUpdateDraft($page, $request->only(['name', 'html', 'markdown']));
        }
        $updateTime = $draft->updated_at->timestamp;
        $utcUpdateTimestamp = $updateTime + Carbon::createFromTimestamp(0)->offset;
        return response()->json(['status' => 'success', 'message' => 'Draft saved at ', 'timestamp' => $utcUpdateTimestamp]);
    }