Made of little things.

import { INC_DOMAIN, inc } from '@napplet/sdk';
import { runtimeHasDomain } from './domain-availability.js';
import { parsePackLink } from './game/assets.js';

/**
 * The NAP-INTENT role this napplet fulfils (the manifest's archetype tag, set
 * in vite.config.ts): another napplet runs
 *   intent.invoke({ archetype: 'supersonicrc', action: 'play', convention: PLAY_CONVENTION, payload: { url } })
 * and the shell opens or focuses this napplet and delivers the payload as an
 * INC event on the convention's topic.
 */
export const GAME_ARCHETYPE = 'supersonicrc';
export const PLAY_CONVENTION = 'napplet:supersonicrc/play';

const MAX_LINK_LENGTH = 4096;

/**
 * The pack link in a play payload: `{ url }` or `{ uri }` (what the emit-only
 * query shorthand `napplet:supersonicrc/play?url=…` decodes to), or a bare
 * string. Anything parsePackLink accepts: an https Blossom blob URL, a
 * blossom: URI or a SHA-256. Null when the payload carries no usable link.
 */
export function playPayloadLink(payload: unknown): string | null {
  let value: unknown = payload;
  if (payload && typeof payload === 'object') {
    const fields = payload as { url?: unknown; uri?: unknown };
    value = fields.url ?? fields.uri;
  }
  if (typeof value !== 'string' || value.length > MAX_LINK_LENGTH) return null;
  return parsePackLink(value) ? value.trim() : null;
}

/**
 * Listen for play intents. `play` gets each valid pack link; `invalid` is told
 * about payloads without one. Payloads come from other napplets, so they are
 * untrusted. No-op without a working INC domain.
 */
export function onPlayIntent(play: (link: string) => void, invalid: () => void): () => void {
  if (!runtimeHasDomain(INC_DOMAIN)) return () => {};
  let sub: { close(): void };
  try {
    sub = inc.on(PLAY_CONVENTION, (event) => {
      if (event?.topic !== PLAY_CONVENTION) return;
      const link = playPayloadLink(event.payload);
      if (link) play(link);
      else invalid();
    });
  } catch {
    // A runtime whose INC domain cannot subscribe: no play intents, the game still runs.
    return () => {};
  }
  return () => sub.close();
}