import type { WorldDelta, WorldSnapshot } from "./contracts";

export async function fetchWorldSnapshot(signal?: AbortSignal) {
  const response = await fetch("/api/world", { signal });
  if (!response.ok) {
    throw new Error(`World request failed with ${response.status}`);
  }
  return response.json() as Promise<WorldSnapshot>;
}

export function openWorldStream(
  afterSequence: number,
  handlers: {
    onDelta: (delta: WorldDelta, rawBytes: number) => void;
    onOpen?: () => void;
    onError?: () => void;
  },
) {
  const stream = new EventSource(`/api/world/stream?afterSequence=${afterSequence}`);
  stream.addEventListener("open", () => handlers.onOpen?.());
  stream.addEventListener("error", () => handlers.onError?.());
  stream.addEventListener("world-delta", (event) => {
    const message = event as MessageEvent<string>;
    handlers.onDelta(
      JSON.parse(message.data) as WorldDelta,
      new Blob([message.data]).size,
    );
  });
  return stream;
}

export async function resetWorld() {
  const response = await fetch("/api/world/reset", {
    method: "POST",
  });
  if (!response.ok) {
    throw new Error(`Reset request failed with ${response.status}`);
  }
  return response.json() as Promise<WorldSnapshot>;
}