import { 
  FastifyInstance,
  FastifyReply,
  FastifyRequest, 
} from 'fastify';
import { Static, Type } from '@sinclair/typebox';

const GetUserRequestParamsSchema = Type.Object({
  userId: Type.String(),
});

type GetUserRequestParams = Static<typeof GetUserRequestParamsSchema>;

const usersMutationAccessPolicy =
  (fastify: FastifyInstance) =>
  async (
    // Looking to extend Params so Typescript knows about `userId` (below)
    request: FastifyRequest<{
      Params: Partial<GetUserRequestParams>;
    }>,
    reply: FastifyReply,
  ): Promise<void> => {
    const { user } = request.identity;
    // Without extending request.params, it thinks the type is unknown
    const isOwner = user?.id === request.params.userId;

    // do more work below
  }

// Leaving out app startup code to keep this concise

export async function usersController(fastify: FastifyInstance): Promise<void> {
  fastify.patch<{
    Params: UserParams;
    Body: UserPatchBody;
  }>(
    `/:userId`,
    {
      schema: { ... },
      // Getting TS error 
      onRequest: fastify.auth([usersMutationAccessPolicy(fastify)]),
    },
    async (req, res) => {
      const user = await doPatchStuffWithUser();
      res.send(user);
    },
  );
}

export async function usersController(fastify: FastifyInstance): Promise<void> {
  fastify.patch<{
    Params: UserParams;
    Body: UserPatchBody;
  }>(
    `/:userId`,
    {
      schema: { ... },
      // Works as expected 
      onRequest: usersMutationAccessPolicy(fastify),
    },
    async (req, res) => {
      const user = await doPatchStuffWithUser();
      res.send(user);
    },
  );
}