strict-client.ts

import {
  DescMessage,
  MessageShape,
  DescService,
  DescMethodUnary,
  DescMethodServerStreaming,
  DescMethodClientStreaming,
  DescMethodBiDiStreaming,
} from "@bufbuild/protobuf";
import type { Transport, CallOptions } from "@connectrpc/connect";
import { createClient } from "@connectrpc/connect";
import { OmitTypeName } from "./omit-type-name";

type Request<I extends DescMessage> = OmitTypeName<MessageShape<I>>;

// prettier-ignore
export type StrictClient<T extends DescService> = {
  [P in keyof T["method"]]:
    T["method"][P] extends DescMethodUnary<infer I, infer O>           ? <R extends Request<I>>(request: R, options?: CallOptions) => Promise<MessageShape<O>>
  : T["method"][P] extends DescMethodServerStreaming<infer I, infer O> ? <R extends Request<I>>(request: R, options?: CallOptions) => AsyncIterable<MessageShape<O>>
  : T["method"][P] extends DescMethodClientStreaming<infer I, infer O> ? <R extends Request<I>>(request: AsyncIterable<R>, options?: CallOptions) => Promise<MessageShape<O>>
  : T["method"][P] extends DescMethodBiDiStreaming<infer I, infer O>   ? <R extends Request<I>>(request: AsyncIterable<R>, options?: CallOptions) => AsyncIterable<MessageShape<O>>
  : never;
};

/**
 * Create a strict client from a service definition and a transport.
 *
 * With a strict client, all non-optional properties of the request message must
 * be specified.
 */
export function createStrictClient<S extends DescService>(
  service: S,
  transport: Transport,
) {
  return createClient(service, transport) as StrictClient<S>;
}