// The public demo's refusal (docs/website/DEMO_MODE.md §3.1).
//
// With DEMO_MODE on, the server answers a locked write `403 { code:
// 'DEMO_LOCKED', message }`. Every request goes through api/client.js's req(),
// installed modules' included, so req() reports the refusal here and the one
// toast (components/DemoToast.jsx) shows it — wherever the action was, without
// each form learning the code. The form still gets its ApiError as usual.
//
// The lock is the server's (DM10). Nothing here decides what is allowed; it
// only explains what was refused.

export const DEMO_LOCKED = 'DEMO_LOCKED'

const listeners = new Set()

/** Subscribe to refusals. Returns the unsubscribe function. */
export function onDemoLocked(fn) {
  listeners.add(fn)
  return () => listeners.delete(fn)
}

/** Report a refusal, if this response body is one. Returns whether it was. */
export function reportIfDemoLocked(body) {
  if (!body || typeof body !== 'object' || body.code !== DEMO_LOCKED) return false
  const message = typeof body.message === 'string' && body.message ? body.message : 'This is turned off on the demo site.'
  for (const fn of listeners) {
    try {
      fn(message)
    } catch {
      // A broken listener must not turn a refusal into a different error.
    }
  }
  return true
}

/**
 * Was this ApiError the demo's refusal? For the few screens that turn a 403
 * into a sentence of their own ("only an administrator can…"), which would
 * otherwise blame the role of somebody who is signed in as an admin.
 */
export function isDemoLocked(err) {
  return Boolean(err && err.body && err.body.code === DEMO_LOCKED)
}

/**
 * "14:00 UTC" for the banner. The wipe runs on the hour in UTC (DM7), so the
 * banner says UTC rather than converting — a converted time in a reviewer's
 * zone reads as a different schedule from the one published on /beta.
 */
export function formatResetTime(iso) {
  const ms = Date.parse(iso)
  if (Number.isNaN(ms)) return null
  const d = new Date(ms)
  const hh = String(d.getUTCHours()).padStart(2, '0')
  const mm = String(d.getUTCMinutes()).padStart(2, '0')
  return `${hh}:${mm} UTC`
}