import * as Data from "effect/Data";
import * as Effect from "effect/Effect";
import { Atom } from "effect/unstable/reactivity";

const WORKSPACE_IMAGE_IDLE_TTL_MS = 30 * 60_000;

type ImagePrefetch = (uri: string) => Promise<boolean>;

class WorkspaceImageCacheKey extends Data.Class<{ readonly uri: string }> {}

export class WorkspaceImagePrefetchError extends Data.TaggedError("WorkspaceImagePrefetchError")<{
  readonly cause?: unknown;
  readonly uri: string;
}> {}

async function prefetchWithNativeImage(uri: string): Promise<boolean> {
  const { Image } = await import("react-native");
  return Image.prefetch(uri);
}

export function createWorkspaceFileImageAtomFamily(options?: {
  readonly idleTtlMs?: number;
  readonly prefetch?: ImagePrefetch;
}) {
  const idleTtlMs = options?.idleTtlMs ?? WORKSPACE_IMAGE_IDLE_TTL_MS;
  const prefetch = options?.prefetch ?? prefetchWithNativeImage;
  const family = Atom.family((key: WorkspaceImageCacheKey) =>
    Atom.make(
      Effect.tryPromise({
        try: async () => {
          const cached = await prefetch(key.uri);
          if (!cached) {
            throw new WorkspaceImagePrefetchError({ uri: key.uri });
          }
          return key.uri;
        },
        catch: (cause) =>
          cause instanceof WorkspaceImagePrefetchError
            ? cause
            : new WorkspaceImagePrefetchError({ uri: key.uri, cause }),
      }),
    ).pipe(Atom.setIdleTTL(idleTtlMs), Atom.withLabel(`mobile:workspace-image:${key.uri}`)),
  );

  return (uri: string) => family(new WorkspaceImageCacheKey({ uri }));
}

export const workspaceFileImageAtom = createWorkspaceFileImageAtomFamily();