import type { ResourceElement } from "./types";
import {
  createResourceFiber,
  unmountResourceFiber,
  renderResourceFiber,
  commitResourceFiber,
} from "./ResourceFiber";
import { tapResourceRoot } from "../tapResourceRoot";
import { resource } from "./resource";
import { isDevelopment } from "./helpers/env";
import { flushResourcesSync, UpdateScheduler } from "./scheduler";
import { createResourceFiberRoot } from "./helpers/root";

const SubscribableResource = resource(tapResourceRoot);

export const createResourceRoot = () => {
  const fiber = createResourceFiber<
    tapResourceRoot.SubscribableResource<any>,
    ResourceElement<any>
  >(
    SubscribableResource,
    createResourceFiberRoot((callback) => {
      new UpdateScheduler(() => {
        if (callback()) {
          throw new Error(
            "Unexpected rerender of createResourceRoot outer fiber",
          );
        }
        return false;
      }).markDirty();
    }),
    undefined,
    isDevelopment ? "root" : null,
  );

  return {
    render: <R, P>(element: ResourceElement<R, P>) => {
      // In strict mode, render twice to detect side effects
      if (isDevelopment && fiber.devStrictMode === "root") {
        void renderResourceFiber(fiber, element);
      }

      const render = renderResourceFiber(fiber, element);

      flushResourcesSync(() => commitResourceFiber(fiber, render));

      return render.output;
    },
    unmount: () => {
      unmountResourceFiber(fiber);
    },
  };
};