// Parse the URL params the Phase 2 bot widget host appends when loading
// experience.url. Source of truth on the host side:
//   src/app/features/bots/BotWidgetEmbed.ts (getBotWidgetUrl).
// Keep this in sync if the host adds params.
//
// Identical shape to apps/widget-telegram/src/bootstrap.ts on purpose —
// the host emits the same param set for every bot. Differences between
// telegram and discord live in the bridge protocol, not in bootstrap.

export type WidgetBootstrap = {
  widgetId: string;
  parentUrl: string;
  parentOrigin: string;
  roomId: string;
  userId: string;
  botId: string;
  botMxid: string;
  /** Bridge command prefix (e.g. `!discord`). Always non-empty — the host
   * validator (catalog.ts) defaults missing values to `!tg` and rejects
   * malformed overrides, so the discord bot's /config.json entry MUST set
   * `experience.commandPrefix: "!discord"` to override the default. The
   * widget prepends `<commandPrefix> ` to every outbound command. */
  commandPrefix: string;
  theme: 'light' | 'dark';
  clientLanguage: string;
};

export type BootstrapResult =
  | { ok: true; bootstrap: WidgetBootstrap }
  | { ok: false; missing: string[] };

const REQUIRED = ['widgetId', 'parentUrl', 'roomId', 'userId', 'botMxid', 'commandPrefix'] as const;

export const readBootstrap = (search: string): BootstrapResult => {
  const params = new URLSearchParams(search);
  const get = (k: string) => params.get(k) ?? '';

  const missing = REQUIRED.filter((k) => !params.get(k));
  if (missing.length > 0) return { ok: false, missing: [...missing] };

  // Origin is what the widget validates against on incoming postMessage —
  // see widget-api.ts. Falling back to '*' would defeat the security
  // boundary, so a malformed parentUrl bails out as a missing-param error.
  let parentOrigin: string;
  try {
    parentOrigin = new URL(get('parentUrl')).origin;
  } catch {
    return { ok: false, missing: ['parentUrl'] };
  }

  const themeRaw = get('theme');
  const theme: 'light' | 'dark' = themeRaw === 'dark' ? 'dark' : 'light';

  return {
    ok: true,
    bootstrap: {
      widgetId: get('widgetId'),
      parentUrl: get('parentUrl'),
      parentOrigin,
      roomId: get('roomId'),
      userId: get('userId'),
      botId: get('botId'),
      botMxid: get('botMxid'),
      commandPrefix: get('commandPrefix'),
      theme,
      clientLanguage: get('clientLanguage'),
    },
  };
};