Add typed DescMethod variants

packages/protobuf/src/types.ts

@@ -13,7 +13,12 @@
 // limitations under the License.
 
 import type { GenEnum, GenExtension, GenMessage } from "./codegenv1/types.js";
-import type { DescEnum, DescExtension, DescMessage } from "./descriptors.js";
+import type {
+  DescEnum,
+  DescExtension,
+  DescMessage,
+  DescMethod,
+} from "./descriptors.js";
 import type { OneofADT } from "./reflect/guard.js";
 import type { WireType } from "./wire/index.js";
 import type { JsonValue } from "./json-value.js";
@@ -89,6 +94,49 @@ export type UnknownField = {
   readonly data: Uint8Array;
 };
 
+/**
+ * Describes a streaming RPC declaration.
+ */
+export type DescMethodStreaming<
+  I extends DescMessage = DescMessage,
+  O extends DescMessage = DescMessage,
+> =
+  | DescMethodClientStreaming<I, O>
+  | DescMethodServerStreaming<I, O>
+  | DescMethodBiDiStreaming<I, O>;
+
+/**
+ * Describes a unary RPC declaration.
+ */
+export type DescMethodUnary<
+  I extends DescMessage = DescMessage,
+  O extends DescMessage = DescMessage,
+> = DescMethodTyped<"unary", I, O>;
+
+/**
+ * Describes a server streaming RPC declaration.
+ */
+export type DescMethodServerStreaming<
+  I extends DescMessage = DescMessage,
+  O extends DescMessage = DescMessage,
+> = DescMethodTyped<"server_streaming", I, O>;
+
+/**
+ * Describes a client streaming RPC declaration.
+ */
+export type DescMethodClientStreaming<
+  I extends DescMessage = DescMessage,
+  O extends DescMessage = DescMessage,
+> = DescMethodTyped<"client_streaming", I, O>;
+
+/**
+ * Describes a bidi streaming RPC declaration.
+ */
+export type DescMethodBiDiStreaming<
+  I extends DescMessage = DescMessage,
+  O extends DescMessage = DescMessage,
+> = DescMethodTyped<"bidi_streaming", I, O>;
+
 /**
  * The init type for a message, which makes all fields optional.
  * The init type is accepted by the function create().
@@ -119,3 +167,22 @@ type OneofSelectedMessage<K extends string, M extends Message> = {
   case: K;
   value: M;
 };
+
+type DescMethodTyped<
+  K extends DescMethod["methodKind"],
+  I extends DescMessage,
+  O extends DescMessage,
+> = Omit<DescMethod, "methodKind" | "input" | "output"> & {
+  /**
+   * One of the four available method types.
+   */
+  readonly methodKind: K;
+  /**
+   * The message type for requests.
+   */
+  readonly input: I;
+  /**
+   * The message type for responses.
+   */
+  readonly output: O;
+};