From ab7ed34dc05e56ca9dd8146abd4a8063bdfaa9ea Mon Sep 17 00:00:00 2001
From: Alexey Bashtanov <alexey.bashtanov@redpanda.com>
Date: Mon, 23 Sep 2024 15:00:25 +0100
Subject: [PATCH] json2code: allow "$ref" for custom type references

Swagger only allows to refer to custom composite types via "$ref",
not via "type", whether it is about array elements or individual items.

Disallowing "type" would break existing use, so allow "$ref" to
be used interchangeably.

Signed-off-by: Alexey Bashtanov <alexey.bashtanov@redpanda.com>
---
 scripts/seastar-json2code.py | 18 +++++++++---------
 tests/unit/api.json          | 13 +++++++++++--
 tests/unit/json2code_test.py |  4 ++--
 tests/unit/rest_api_httpd.cc |  4 +++-
 4 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/scripts/seastar-json2code.py b/scripts/seastar-json2code.py
index 298bc9746fd..673742d37d7 100755
--- a/scripts/seastar-json2code.py
+++ b/scripts/seastar-json2code.py
@@ -364,22 +364,22 @@ def add_operation(hfile, ccfile, path, oper):
 def get_base_name(param):
     return os.path.basename(param)
 
+def get_referenced_type(schema, name):
+    # to be backward compatible, support "type" as well
+    type = schema.get("$ref") or schema.get("type")
+    if type is None:
+       raise Exception(f"neither '$ref' nor 'type' found in {name}")
+    return type
 
 def is_model_valid(name, model):
     if name in valid_vars:
         return ""
     properties = getitem(model[name], "properties", name)
     for var in properties:
-        type = getitem(properties[var], "type", name + ":" + var)
+        type = get_referenced_type(properties[var], name + ":" + var)
         if type == "array":
             items = getitem(properties[var], "items", name + ":" + var)
-            try:
-                type = getitem(items, "type", name + ":" + var + ":items")
-            except Exception as e:
-                try:
-                    type = getitem(items, "$ref", name + ":" + var + ":items")
-                except:
-                    raise e
+            type = get_referenced_type(items, name + ":" + var + ":items")
         if type not in valid_vars:
             if type not in model:
                 raise Exception("Unknown type '" + type + "' in Model '" + name + "'")
@@ -563,7 +563,7 @@ def indent(s):
                     fprintln(hfile, create_enum_wrapper(model_name, member_name, member["enum"]))
                     fprintln(hfile, f"    {config.jsonns}::json_element<{member_name}_wrapper> {member_name};\n")
                 else:
-                    type_name = type_change(member["type"], member)
+                    type_name = type_change(member["type"] if "type" in member else member["$ref"], member)
                     fprintln(hfile, f"    {config.jsonns}::{type_name} {member_name};\n")
                 member_init += f'add(&{member_name}, "{member_name}");\n'
                 member_assignment += f'{member_name} = e.{member_name};\n'
diff --git a/tests/unit/api.json b/tests/unit/api.json
index 8132a37e395..f09fd030326 100644
--- a/tests/unit/api.json
+++ b/tests/unit/api.json
@@ -54,6 +54,15 @@
     }
   ],
   "models": {
+    "var2_referred": {
+      "type": "object",
+      "properties": {
+        "var21": {
+          "type": "string",
+          "description": "The inner part of the second parameter"
+        }
+      }
+    },
     "my_object": {
       "id": "my_object",
       "description": "Demonstrate an object",
@@ -63,8 +72,8 @@
           "description": "The first parameter in the path"
         },
         "var2": {
-          "type": "string",
-          "description": "The second parameter in the path"
+          "$ref": "var2_referred",
+          "description": "The second parameter in the path wrapped in an object"
         },
         "enum_var": {
           "type": "string",
diff --git a/tests/unit/json2code_test.py b/tests/unit/json2code_test.py
index 46c912bb76f..a4c8d98dbe5 100755
--- a/tests/unit/json2code_test.py
+++ b/tests/unit/json2code_test.py
@@ -57,7 +57,7 @@ def test_path_params(self):
         with urllib.request.urlopen(url) as f:
             response = json.loads(f.read().decode('utf-8'))
             self.assertEqual(response['var1'], f'/{var1}')
-            self.assertEqual(response['var2'], f'/{var2}')
+            self.assertEqual(response['var2']['var21'], f'/{var2}')
             self.assertEqual(response['enum_var'], query_enum)
 
     def test_bad_enum(self):
@@ -69,7 +69,7 @@ def test_bad_enum(self):
         with urllib.request.urlopen(url) as f:
             response = json.loads(f.read().decode('utf-8'))
             self.assertEqual(response['var1'], f'/{var1}')
-            self.assertEqual(response['var2'], f'/{var2}')
+            self.assertEqual(response['var2']['var21'], f'/{var2}')
             self.assertEqual(response['enum_var'], 'Unknown')
 
     def test_missing_path_param(self):
diff --git a/tests/unit/rest_api_httpd.cc b/tests/unit/rest_api_httpd.cc
index db29247f932..11f1d450d11 100644
--- a/tests/unit/rest_api_httpd.cc
+++ b/tests/unit/rest_api_httpd.cc
@@ -43,7 +43,9 @@ void set_routes(routes& r) {
     api_json::hello_world.set(r, [] (const_req req) {
         api_json::my_object obj;
         obj.var1 = req.param.at("var1");
-        obj.var2 = req.param.at("var2");
+        api_json::var2_referred var2_wrapped;
+        var2_wrapped.var21 = req.param.at("var2");
+        obj.var2 = var2_wrapped;
         api_json::ns_hello_world::query_enum v = api_json::ns_hello_world::str2query_enum(req.query_parameters.at("query_enum"));
         // This demonstrate enum conversion
         obj.enum_var = v;