crossws/src/hooks.ts

import type { AdapterOptions } from "./adapter.ts";
import type { WSError } from "./error.ts";
import type { Peer } from "./peer.ts";
import type { Message } from "./message.ts";

export class AdapterHookable {
  options: AdapterOptions;

  constructor(options?: AdapterOptions) {
    this.options = options || {};
  }

  callHook<N extends keyof Hooks>(
    name: N,
    arg1: Parameters<Hooks[N]>[0],
    arg2?: Parameters<Hooks[N]>[1],
  ): MaybePromise<ReturnType<Hooks[N]>> {
    // Call global hook first
    const globalHook = this.options.hooks?.[name];
    const globalPromise = globalHook?.(arg1 as any, arg2 as any);

    // Resolve hooks for request
    const resolveHooksPromise = this.options.resolve?.(arg1);
    if (!resolveHooksPromise) {
      return globalPromise as any; // Fast path: no hooks to resolve
    }
    const resolvePromise =
      resolveHooksPromise instanceof Promise
        ? resolveHooksPromise.then((hooks) => hooks?.[name])
        : resolveHooksPromise?.[name];

    // In parallel, call global hook and resolve hook implementation
    return Promise.all([globalPromise, resolvePromise]).then(
      ([globalRes, hook]) => {
        const hookResPromise = hook?.(arg1 as any, arg2 as any);
        return hookResPromise instanceof Promise
          ? hookResPromise.then((hookRes) => hookRes || globalRes)
          : hookResPromise || globalRes;
      },
    ) as Promise<any>;
  }
}

// --- types ---

export function defineHooks<T extends Partial<Hooks> = Partial<Hooks>>(
  hooks: T,
): T {
  return hooks;
}

export type ResolveHooks = (
  info: RequestInit | Peer,
) => Partial<Hooks> | Promise<Partial<Hooks>>;

export type MaybePromise<T> = T | Promise<T>;

type HookFn<ArgsT extends any[] = any, RT = void> = (
  info: Peer,
  ...args: ArgsT
) => MaybePromise<RT>;

export interface Hooks {
  /** Upgrading */
  upgrade: (
    request:
      | Request
      | {
          url: string;
          headers: Headers;
        },
  ) => MaybePromise<Response | ResponseInit | void>;

  /** A message is received */
  message: (peer: Peer, message: Message) => MaybePromise<void>;

  /** A socket is opened */
  open: (peer: Peer) => MaybePromise<void>;

  /** A socket is closed */
  close: (
    peer: Peer,
    details: { code?: number; reason?: string },
  ) => MaybePromise<void>;

  /** An error occurs */
  error: (peer: Peer, error: WSError) => MaybePromise<void>;
}