/**
 * detector.ts — route + overlay observer.
 *
 * - Watches the document for SPA route changes (Next.js pushState)
 * - Watches for .bb-room-overlay appearing (in-game state)
 * - Emits `bbp:phase` on the document with `phase` ∈ "home" | "lobby-list" | "lobby" | "in-game" | "login"
 */

import { isHome, isLogin, isInGame, isLobbyList } from './util/selectors';

export type Phase = 'home' | 'lobby-list' | 'login' | 'in-game' | 'unknown';

let lastPhase: Phase = 'unknown';

function detectPhase(): Phase {
  if (isLogin()) return 'login';
  if (isInGame()) return 'in-game';
  if (isLobbyList()) return 'lobby-list';
  if (isHome()) return 'home';
  return 'unknown';
}

export function currentPhase(): Phase {
  return lastPhase;
}

function emit(newPhase: Phase): void {
  if (newPhase === lastPhase) return;
  lastPhase = newPhase;
  document.dispatchEvent(new CustomEvent('bbp:phase', { detail: { phase: newPhase } }));
}

/** Patch history.pushState / replaceState to detect SPA route changes. */
function patchHistory(): void {
  const origPush = history.pushState.bind(history);
  const origReplace = history.replaceState.bind(history);
  history.pushState = function (...args: Parameters<typeof history.pushState>) {
    const r = origPush(...args);
    queueMicrotask(() => emit(detectPhase()));
    return r;
  };
  history.replaceState = function (...args: Parameters<typeof history.replaceState>) {
    const r = origReplace(...args);
    queueMicrotask(() => emit(detectPhase()));
    return r;
  };
  window.addEventListener('popstate', () => emit(detectPhase()));
}

/** Observe DOM for overlay appearing / disappearing. */
function observeOverlay(): void {
  const obs = new MutationObserver(() => emit(detectPhase()));
  obs.observe(document.documentElement, { childList: true, subtree: true });
}

/**
 * Wait until any of the candidate selectors exist, then resolve.
 */
export function waitFor(selector: string | string[], timeoutMs = 8000): Promise<Element | null> {
  const sels = Array.isArray(selector) ? selector : [selector];
  return new Promise((resolve) => {
    for (const s of sels) {
      const el = document.querySelector(s);
      if (el) return resolve(el);
    }
    const obs = new MutationObserver(() => {
      for (const s of sels) {
        const el = document.querySelector(s);
        if (el) {
          obs.disconnect();
          return resolve(el);
        }
      }
    });
    obs.observe(document.documentElement, { childList: true, subtree: true });
    setTimeout(() => {
      obs.disconnect();
      resolve(null);
    }, timeoutMs);
  });
}

export function startDetector(): Phase {
  patchHistory();
  observeOverlay();
  // Run once now
  emit(detectPhase());
  return lastPhase;
}