/**
 * editor_storm.js — the editor's ONE storm selection.  [Lane B, SPRINT15 gate 2.2]
 *
 * D scored the wildnight while looking at the southerly: B's SCORE IT and C's
 * WIND panel each carried a private `stormKey`, independently defaulted — the
 * exact two-harnesses-disagreeing failure this repo keeps paying for, arrived
 * inside a single page. This module is the fix: one storm selection, one storm
 * LIST, owned here; every panel that shows or uses a storm reads and writes
 * THIS and never a private copy.
 *
 * Deliberately not on A's `EDITOR.on` — emit is private to editor.js, and
 * widening A's seam for one dropdown is more contract than the problem needs.
 * B owns this file; C's panel subscribes (THREADS 2026-07-20, gate 2.2
 * proposal). The default is the southerly — C's old default, kept on purpose:
 * the WIND panel is live the moment the page opens and needs a storm that
 * shows something, while SCORE IT is an explicit click behind a visible
 * dropdown. (A funnel authored under the gentle storm looks like it does
 * nothing — C's own comment.)
 *
 * No I/O here: this holds the NAME, not the storm def. Fetching defs stays
 * with the panels (loadStorm), which already cache.
 */

/** Keep in step with data/storms/ — THE list; panels must not carry their own. */
export const STORM_KEYS = [
  'storm_01_gentle',
  'storm_02_wildnight',
  'storm_02b_icenight',
  'storm_03_southerly',
  'storm_03b_earlybuster',
];

export const DEFAULT_STORM = 'storm_03_southerly';

let key = DEFAULT_STORM;
const subs = new Set();

export const stormSel = {
  /** The currently selected storm key. */
  get key() { return key; },

  /**
   * Change the selection. No-op on the same key; throws on a stranger — a
   * typo'd storm silently becoming the default is setHardware's lesson again.
   * `source` is a free label ('score', 'wind', …) so a subscriber can skip
   * reacting to its own write.
   */
  set(next, source = null) {
    if (next === key) return;
    if (!STORM_KEYS.includes(next)) {
      throw new Error(`unknown storm "${next}" — the editor knows: ${STORM_KEYS.join(', ')}`);
    }
    key = next;
    for (const fn of [...subs]) {
      try { fn(key, source); } catch (err) { console.error('[storm] subscriber threw:', err); }
    }
  },

  /** Subscribe to changes; returns an unsubscribe function. */
  onChange(fn) { subs.add(fn); return () => subs.delete(fn); },

  STORM_KEYS,
};

// For consoles and selftests — same object, not a copy.
globalThis.EDITOR_STORM = stormSel;