type HandlersContext<Rpcs, Handlers> = keyof Handlers extends infer K
  ? K extends keyof Handlers & string
    ? [Rpc.IsStream<Rpcs, K>] extends [true]
      ? Handlers[K] extends (
          ...args: any
        ) =>
          | Stream.Stream<infer _A, infer _E, infer _R>
          | Rpc.Fork<Stream.Stream<infer _A, infer _E, infer _R>>
          | Effect.Effect<ReadonlyMailbox<infer _A, infer _E>, infer _EX, infer _R>
          | Rpc.Fork<Effect.Effect<ReadonlyMailbox<infer _A, infer _E>, infer _EX, infer _R>>
        ? Exclude<Rpc.ExcludeProvides<_R, Rpcs, K>, Scope>
        : never
      : Handlers[K] extends (
            ...args: any
          ) => Effect.Effect<infer _A, infer _E, infer _R> | Rpc.Fork<Effect.Effect<infer _A, infer _E, infer _R>>
        ? Rpc.ExcludeProvides<_R, Rpcs, K>
        : never
    : never
  : never

type HandlersFrom<Rpc> = {
  readonly [Current in Rpc as Current["_tag"]]: (
    payload: Rpc.Payload<Current>,
    headers: Headers
  ) => ResultFrom<Current> | Rpc.Fork<ResultFrom<Current>>
}

type ResultFrom<Rpc> =
  Rpc extends Rpc.Rpc<infer _Tag, infer _Payload, infer _Success, infer _Error, infer _Middleware>
    ? [_Success] extends [RpcSchema.Stream<infer _SA, infer _SE>]
      ?
          | Stream.Stream<_SA["Type"], _SE["Type"] | _Error["Type"], any>
          | Effect.Effect<
              ReadonlyMailbox<_SA["Type"], _SE["Type"] | _Error["Type"]>,
              _SE["Type"] | Schema.Schema.Type<_Error>,
              any
            >
      : Effect.Effect<_Success["Type"], _Error["Type"], any>
    : never

export interface RpcGroup<in out Rpcs extends Rpc.Any> extends Pipeable {
  new (_: never): {}

  readonly [TypeId]: TypeId
  readonly requests: ReadonlyMap<string, Rpcs>
  readonly annotations: Context.Context<never>

  /**
   * Add one or more procedures to the group.
   */
  add<const Rpcs2 extends ReadonlyArray<Rpc.Any>>(...rpcs: Rpcs2): RpcGroup<Rpcs | Rpcs2[number]>

  /**
   * Merge this group with another group.
   */
  merge<Rpcs2 extends Rpc.Any>(that: RpcGroup<Rpcs2>): RpcGroup<Rpcs | Rpcs2>

  /**
   * Add middleware to all the procedures added to the group until this point.
   */
  middleware<M extends RpcMiddleware.TagClassAny>(middleware: M): RpcGroup<Rpc.AddMiddleware<Rpcs, M>>

  /**
   * Implement the handlers for the procedures in this group, returning a
   * context object.
   */
  toHandlersContext<Handlers extends HandlersFrom<Rpcs>, EX = never, RX = never>(
    build: Handlers | Effect.Effect<Handlers, EX, RX>
  ): Effect.Effect<Context.Context<Rpc.ToHandler<Rpcs>>, EX, RX | HandlersContext<Rpcs, Handlers>>

  /**
   * Implement the handlers for the procedures in this group.
   */
  toLayer<Handlers extends HandlersFrom<Rpcs>, EX = never, RX = never>(
    build: Handlers | Effect.Effect<Handlers, EX, RX>
  ): Layer.Layer<Rpc.ToHandler<Rpcs>, EX, Exclude<RX, Scope> | HandlersContext<Rpcs, Handlers>>

  /**
   * Annotate the group with a value.
   */
  annotate<I, S>(tag: Context.Tag<I, S>, value: S): RpcGroup<Rpcs>

  /**
   * Annotate the Rpc's above this point with a value.
   */
  annotateRpcs<I, S>(tag: Context.Tag<I, S>, value: S): RpcGroup<Rpcs>

  /**
   * Annotate the group with a context object.
   */
  annotateContext<S>(context: Context.Context<S>): RpcGroup<Rpcs>

  /**
   * Annotate the Rpc's above this point with a context object.
   */
  annotateRpcsContext<S>(context: Context.Context<S>): RpcGroup<Rpcs>
}

type Rpcs<Group> = Group extends RpcGroup<infer R> ? R : never

declare const make: <const Rpcs extends ReadonlyArray<Rpc.Any>>(...rpcs: Rpcs) => RpcGroup<Rpcs[number]>

declare const TypeId: unique symbol

type TypeId = typeof TypeId