Extracted ContentManager::getRemoteOrLocalBook()

... mainly for readability.

src/contentmanager.cpp

@@ -463,29 +463,35 @@ QString ContentManager::downloadBook(const QString &id, QModelIndex index)
     return downloadStatus;
 }
 
+const kiwix::Book& ContentManager::getRemoteOrLocalBook(const QString &id)
+{
+    try {
+        QMutexLocker locker(&remoteLibraryLocker);
+        return mp_remoteLibrary->getBookById(id.toStdString());
+    } catch (...) {
+        return mp_library->getBookById(id);
+    }
+}
 
 QString ContentManager::downloadBook(const QString &id)
 {
     if (!mp_downloader)
         return "";
-    const auto& book = [&]()->const kiwix::Book& {
+
-        try {
+    const auto& book = getRemoteOrLocalBook(id);
-            QMutexLocker locker(&remoteLibraryLocker);
-            return mp_remoteLibrary->getBookById(id.toStdString());
-        } catch (...) {
-            return mp_library->getBookById(id);
-        }
-    }();
     auto downloadPath = KiwixApp::instance()->getSettingsManager()->getDownloadDir();
     QStorageInfo storage(downloadPath);
     auto bytesAvailable = storage.bytesAvailable();
     if (bytesAvailable == -1 || book.getSize() > (unsigned long long) bytesAvailable) {
         return "storage_error";
     }
+
     auto booksList = mp_library->getBookIds();
-    for (auto b : booksList)
+    for (auto b : booksList) {
         if (b.toStdString() == book.getId())
             return "";
+    }
+
     std::shared_ptr<kiwix::Download> download;
     try {
         std::pair<std::string, std::string> downloadDir("dir", downloadPath.toStdString());

src/contentmanager.h

@@ -81,6 +81,10 @@ private: // functions
     void setCategories();
     void setLanguages();
 
+    // Get the book with the specified id from
+    // the remote or local library (in that order).
+    const kiwix::Book& getRemoteOrLocalBook(const QString &id);
+
     void downloadStarted(const kiwix::Book& book, const std::string& downloadId);
     void downloadCancelled(QString bookId);
     void downloadCompleted(QString bookId, QString path);