Reduce code duplication in auto-generated API protocol code (#9097)

esphome/components/api/proto.h

@@ -379,6 +379,26 @@ class ProtoService {
     // Send the buffer
     return this->send_buffer(buffer, message_type);
   }
+
+  // Authentication helper methods
+  bool check_connection_setup_() {
+    if (!this->is_connection_setup()) {
+      this->on_no_setup_connection();
+      return false;
+    }
+    return true;
+  }
+
+  bool check_authenticated_() {
+    if (!this->check_connection_setup_()) {
+      return false;
+    }
+    if (!this->is_authenticated()) {
+      this->on_unauthenticated_access();
+      return false;
+    }
+    return true;
+  }
 };
 
 }  // namespace api

script/api_protobuf/api_protobuf.py

@@ -1424,18 +1424,32 @@ def main() -> None:
         hpp_protected += f"  void {on_func}(const {inp} &msg) override;\n"
         hpp += f"  virtual {ret} {func}(const {inp} &msg) = 0;\n"
         cpp += f"void {class_name}::{on_func}(const {inp} &msg) {{\n"
-        body = ""
-        if needs_conn:
-            body += "if (!this->is_connection_setup()) {\n"
-            body += "  this->on_no_setup_connection();\n"
-            body += "  return;\n"
-            body += "}\n"
-        if needs_auth:
-            body += "if (!this->is_authenticated()) {\n"
-            body += "  this->on_unauthenticated_access();\n"
-            body += "  return;\n"
-            body += "}\n"
 
+        # Start with authentication/connection check if needed
+        if needs_auth or needs_conn:
+            # Determine which check to use
+            if needs_auth:
+                check_func = "this->check_authenticated_()"
+            else:
+                check_func = "this->check_connection_setup_()"
+
+            body = f"if ({check_func}) {{\n"
+
+            # Add the actual handler code, indented
+            handler_body = ""
+            if is_void:
+                handler_body = f"this->{func}(msg);\n"
+            else:
+                handler_body = f"{ret} ret = this->{func}(msg);\n"
+                handler_body += "if (!this->send_message(ret)) {\n"
+                handler_body += "  this->on_fatal_error();\n"
+                handler_body += "}\n"
+
+            body += indent(handler_body) + "\n"
+            body += "}\n"
+        else:
+            # No auth check needed, just call the handler
+            body = ""
             if is_void:
                 body += f"this->{func}(msg);\n"
             else:
@@ -1443,6 +1457,7 @@ def main() -> None:
                 body += "if (!this->send_message(ret)) {\n"
                 body += "  this->on_fatal_error();\n"
                 body += "}\n"
+
         cpp += indent(body) + "\n" + "}\n"
 
         if ifdef is not None: