import { createRequire } from "node:module";
import { join } from "node:path";

import { isEdgeRuntime, cwd as sysCwd } from "../sys.mjs";

function tryStat(path) {
  // In Cloudflare Workers, we can't use fs.statSync
  // Return a truthy value since we know the file was built
  if (isEdgeRuntime) {
    return true;
  }
  try {
    const __require = createRequire(import.meta.url);
    const { statSync } = __require("node:fs");
    return statSync(path);
  } catch {
    return null;
  }
}

const cwd = sysCwd();

function createChannelPair() {
  const listenersA = new Set();
  const listenersB = new Set();

  const createPort = (ownListeners, otherListeners) => ({
    on(event, listener) {
      if (event === "message") {
        ownListeners.add(listener);
      }
    },
    postMessage(message) {
      for (const listener of otherListeners) {
        listener(message);
      }
    },
    terminate() {
      listenersA.clear();
      listenersB.clear();
    },
  });

  return [
    createPort(listenersA, listenersB),
    createPort(listenersB, listenersA),
  ];
}

export function hasRenderer(options) {
  return Boolean(
    tryStat(
      join(cwd, options.outDir || ".react-server", "server/render-dom.mjs")
    )
  );
}

export async function createRenderer() {
  const [parentPort, workerPort] = createChannelPair();

  const { createRenderer } =
    await import("@lazarv/react-server/dist/server/render-dom");

  parentPort.on(
    "message",
    createRenderer({
      parentPort,
    })
  );

  return workerPort;
}