refactor(asyncapi): enhance channel parameter handling with enum support

Author: radist2s

packages/asyncapi-typescript-plugin/src/transform/channels-object.ts

@@ -1,6 +1,7 @@
 import type {
   AsyncAPIChannelObject,
   AsyncAPIContext,
+  AsyncAPIParameterObject,
   ReferenceObject,
 } from '../types.js';
 import {
@@ -9,6 +10,7 @@ import {
   tsLiteral,
   tsModifiers,
   tsPropertyIndex,
+  tsUnion,
 } from 'openapi-typescript/dist/lib/ts.js';
 import { getEntries } from 'openapi-typescript/dist/lib/utils.js';
 import ts from 'typescript';
@@ -83,13 +85,16 @@ export default function transformChannelsObject(
     if (channel.parameters && typeof channel.parameters === 'object') {
       const paramMembers: ts.TypeElement[] = [];
 
-      for (const [paramId] of Object.entries(channel.parameters)) {
+      for (const [paramId, param] of Object.entries(channel.parameters)) {
         paramMembers.push(
           ts.factory.createPropertySignature(
             tsModifiers({ readonly: ctx.immutable }),
             tsPropertyIndex(paramId),
             undefined,
-            ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword)
+            transformChannelParameterType(
+              param as AsyncAPIParameterObject | ReferenceObject,
+              ctx
+            )
           )
         );
       }
@@ -151,3 +156,24 @@ export default function transformChannelsObject(
 
   return ts.factory.createTypeLiteralNode(members);
 }
+
+function transformChannelParameterType(
+  parameter: AsyncAPIParameterObject | ReferenceObject,
+  ctx: AsyncAPIContext
+): ts.TypeNode {
+  const parameterObject =
+    '$ref' in parameter
+      ? ctx.resolve<AsyncAPIParameterObject>(parameter.$ref)
+      : parameter;
+
+  const enumValues =
+    parameterObject?.enum?.filter(
+      (value): value is string => typeof value === 'string'
+    ) ?? [];
+
+  if (enumValues.length > 0) {
+    return tsUnion(enumValues.map(tsLiteral));
+  }
+
+  return ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword);
+}

packages/asyncapi-typescript-plugin/src/transform/components-object.ts

@@ -14,6 +14,7 @@ import {
   addJSDocComment,
   NEVER,
   QUESTION_TOKEN,
+  tsLiteral,
   tsModifiers,
   tsPropertyIndex,
 } from 'openapi-typescript/dist/lib/ts.js';
@@ -329,6 +330,17 @@ function transformParameters(
       );
     }
 
+    if (Array.isArray(param.enum) && param.enum.length > 0) {
+      members.push(
+        ts.factory.createPropertySignature(
+          tsModifiers({ readonly: ctx.immutable }),
+          tsPropertyIndex('enum'),
+          undefined,
+          ts.factory.createTupleTypeNode(param.enum.map(tsLiteral))
+        )
+      );
+    }
+
     if (param.schema) {
       let schemaType: ts.TypeNode;
       if ('$ref' in param.schema) {

packages/asyncapi-typescript-plugin/src/types.ts

@@ -162,6 +162,9 @@ export interface AsyncAPIMessageObject {
 
 export interface AsyncAPIParameterObject {
   description?: string;
+  enum?: string[];
+  default?: string;
+  examples?: string[];
   schema?: SchemaObject | ReferenceObject;
   location?: string;
   [key: `x-${string}`]: unknown;

packages/test-fixtures/asyncapi.json

@@ -69,6 +69,10 @@
       "parameters": {
         "streetlightId": {
           "description": "The ID of the streetlight.",
+          "enum": [
+            "streetlight-1",
+            "streetlight-2"
+          ],
           "location": "$message.payload#/item/id"
         }
       },
@@ -820,6 +824,10 @@
     "parameters": {
       "streetlightId": {
         "description": "The ID of the streetlight.",
+        "enum": [
+          "streetlight-1",
+          "streetlight-2"
+        ],
         "location": "$message.payload#/item/id"
       }
     },