diff --git a/src/session_manager.cpp b/src/session_manager.cpp
new file mode 100644
index 0000000..71ea227
--- /dev/null
+++ b/src/session_manager.cpp
@@ -0,0 +1,40 @@
+#include "session_manager.h"
+
+SessionManager::SessionManager() 
+    : current_user_(""),
+      current_difficulty_(""),
+      current_generator_(nullptr) {}
+
+void SessionManager::SetUser(const std::string& username, 
+                            const std::string& difficulty) {
+  current_user_ = username;
+  SwitchDifficulty(difficulty);
+}
+
+bool SessionManager::SwitchDifficulty(const std::string& difficulty) {
+  if (difficulty == "primary") {
+    current_generator_ = &primary_generator_;
+    current_difficulty_ = "小学";
+  } else if (difficulty == "junior") {
+    current_generator_ = &junior_generator_;
+    current_difficulty_ = "初中";
+  } else if (difficulty == "senior") {
+    current_generator_ = &senior_generator_;
+    current_difficulty_ = "高中";
+  } else {
+    return false;
+  }
+  return true;
+}
+
+QuestionGenerator* SessionManager::GetCurrentGenerator() {
+  return current_generator_;
+}
+
+std::string SessionManager::GetCurrentDifficulty() const {
+  return current_difficulty_;
+}
+
+std::string SessionManager::GetCurrentUser() const {
+  return current_user_;
+}
\ No newline at end of file