import { AsyncLocalStorage } from "node:async_hooks";
import type { ComposeSpecification } from "../schema/docker.d";
import { getProject, throwWhen } from "./shared";
import { readCompose, resolveComposeFile } from "./yaml";

type AppContext = {
  project: string;
  cwd: string;
  path(): Promise<string | undefined>;
  compose(): Promise<ComposeSpecification>;
};

const appContext = new AsyncLocalStorage<AppContext>();

export function provideContext<T>(fn: () => T): T {
  const cwd = process.cwd();
  const path = createCachedGetter("composeFile", () => resolveComposeFile(cwd));
  return appContext.run(
    {
      project: getProject(),
      cwd,
      path,
      compose: createCachedGetter("compose", () =>
        path()
          .then(
            throwWhen(
              (path): path is undefined => path === undefined,
              "Compose file cannot be found",
            ),
          )
          .then(readCompose),
      ),
    },
    fn,
  );
}

export function ctx() {
  const store = appContext.getStore();
  if (!store) throw new Error("Not in context!");
  return store;
}

export function createCachedGetter<T>(
  _key: string,
  fn: () => Promise<T>,
): () => Promise<T> {
  let cached: Promise<T> | undefined;
  return () => {
    cached ??= fn().catch((error) => {
      cached = undefined;
      throw error;
    });
    return cached;
  };
}