export type Scenario =
  | 'default'
  | 'slow'
  | 'loading'
  | 'empty'
  | 'error'
  // upload-only (the multipart POST is hand-written XHR, so it bypasses the HTTP
  // interceptor — these are simulated in upload.adapter.ts instead):
  | 'upload-slow'
  | 'upload-fail';

export const SCENARIOS: readonly Scenario[] = [
  'default',
  'slow',
  'loading',
  'empty',
  'error',
  'upload-slow',
  'upload-fail',
];

const STORAGE_KEY = 'dev-scenario';
const isScenario = (v: string | null): v is Scenario => !!v && SCENARIOS.includes(v as Scenario);

/**
 * Reads the active demo scenario so a demo can force each async state.
 * Sticky within the tab (sessionStorage), mirroring `role.ts`: a `?scenario=` in the
 * URL sets it; later navigation (which drops the query param) keeps the remembered
 * value. Set `?scenario=default`, use the dev switcher, or open a fresh tab to reset.
 * Dev-only — the interceptor that consumes this is wired only under `isDevMode()`.
 */
export function currentScenario(): Scenario {
  const fromUrl = new URLSearchParams(window.location.search).get('scenario');
  if (isScenario(fromUrl)) {
    sessionStorage.setItem(STORAGE_KEY, fromUrl);
    return fromUrl;
  }
  const stored = sessionStorage.getItem(STORAGE_KEY);
  return isScenario(stored) ? stored : 'default';
}

/** Dev switcher entry point: persist the chosen scenario for the tab (WP-33). */
export function setScenario(s: Scenario): void {
  sessionStorage.setItem(STORAGE_KEY, s);
}