// The browser's own async APIs run outside the event loop's bookkeeping, so a guest
// whose only pending work is a fetch(), a blob.text() or a WebCrypto call would see the
// loop go idle and exit before the answer, where Node keeps running (an undici socket,
// a libuv job). Each wrapper holds the loop until its promise settles.
//
// Not wrapped: reads from a ReadableStream. A guest's own stream that never enqueues
// must not keep the process alive, and Node doesn't either; fetch's body methods are
// wrapped instead.
import type { Loop } from "./loop";

const BODY = ["arrayBuffer", "blob", "bytes", "formData", "json", "text"];
const SUBTLE = [
  "encrypt", "decrypt", "sign", "verify", "digest", "generateKey", "deriveKey", "deriveBits",
  "importKey", "exportKey", "wrapKey", "unwrapKey",
];
const WASM = ["compile", "instantiate", "compileStreaming", "instantiateStreaming"];

export function holdNativePromises(loop: Loop): void {
  const held = (p: unknown): unknown => {
    if (!(p instanceof Promise)) return p;
    loop.hold();
    return p.finally(() => loop.release());
  };
  const wrap = (target: object | undefined, name: string): void => {
    // A worker's globals (fetch) live on WorkerGlobalScope.prototype, not on globalThis.
    let owner = target;
    while (owner && !Object.hasOwn(owner, name)) owner = Object.getPrototypeOf(owner) as object | undefined;
    const desc = owner && Object.getOwnPropertyDescriptor(owner, name);
    const original = desc?.value as ((...args: unknown[]) => unknown) | undefined;
    if (typeof original !== "function") return;
    const wrapped = {
      [name](this: unknown, ...args: unknown[]): unknown {
        return held(original.apply(this, args));
      },
    }[name]!;
    Object.defineProperty(wrapped, "length", { value: original.length });
    Object.defineProperty(owner, name, { ...desc, value: wrapped });
  };

  wrap(globalThis, "fetch");
  for (const name of BODY) {
    wrap(globalThis.Response?.prototype, name);
    wrap(globalThis.Request?.prototype, name);
  }
  for (const name of ["arrayBuffer", "bytes", "text"]) wrap(globalThis.Blob?.prototype, name);
  for (const name of SUBTLE) wrap(globalThis.SubtleCrypto?.prototype, name);
  for (const name of WASM) wrap(globalThis.WebAssembly, name);
}