import * as Cause from "effect/Cause";
import * as Effect from "effect/Effect";
import * as Exit from "effect/Exit";

// Cloudflare must see a rejected callback to roll back. Carry the local Effect
// cause through that Promise boundary without flattening typed failures into
// defects or committing a failed program's partial writes.
export function transaction<A, E>(
  storage: DurableObjectStorage,
  action: (tx: DurableObjectTransaction) => Effect.Effect<A, E>,
) {
  class Rollback {
    constructor(readonly cause: Cause.Cause<E>) {}
  }
  return Effect.tryPromise({
    try: (signal) =>
      storage.transaction(async (tx) => {
        const exit = await Effect.runPromiseExit(action(tx), { signal });
        if (Exit.isSuccess(exit)) return exit.value;
        throw new Rollback(exit.cause);
      }),
    catch: (error) => error,
  }).pipe(
    Effect.catch((error) =>
      error instanceof Rollback
        ? Effect.failCause(error.cause)
        : Effect.die(error),
    ),
  );
}