import { AsyncLocalStorage } from "node:async_hooks";
import type { Context } from "./context.ts";

/**
 * The request context for the currently executing server work.
 *
 * A server-side API call needs the request's cookies, session, and URL, but
 * `ctx` is not in scope everywhere server code runs: load blocks have it,
 * schema actions take it as a parameter, and plain actions and server
 * functions have neither. Threading it through every signature would make the
 * call site differ between server and browser, which defeats the point.
 */
const storage = new AsyncLocalStorage<Context>();

export function runWithRequestContext<T>(ctx: Context, fn: () => T): T {
  return storage.run(ctx, fn);
}

export function getRequestContext(): Context | undefined {
  return storage.getStore();
}

export function requireRequestContext(what: string): Context {
  const ctx = storage.getStore();

  if (!ctx) {
    throw new Error(
      `${what} needs a request context. It ran outside a request — server-side API calls are only available while handling one.`,
    );
  }

  return ctx;
}