/**
 * useBackgroundDelivery — Android-only closed-app notifications, **without
 * Google**. Registers a poll token with our `push-service` and hands the native
 * `skatespots-background` plugin the base URL + token so its worker can ask
 * "anything new since N?" and raise a local notification.
 *
 * Two modes (chosen in Settings): `standard` = WorkManager ~15 min (best-effort),
 * `fast` = a foreground service ~5 min (sticky notification).
 */
import { useCallback, useMemo, useState } from 'react';
import { registerPlugin } from '@capacitor/core';

import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useNotificationPrefs } from '@/hooks/useNotificationPrefs';
import { NOTIFICATION_CATEGORIES } from '@/lib/notificationPrefs';
import { isNativePlatform, getPlatform } from '@/lib/platform';
import { pushServiceBase, requestPushChallenge } from '@/lib/pushService';

type DeliveryMode = 'off' | 'standard' | 'fast';

/**
 * Registered by NAME (`@capacitor/core`), not imported from the package — the
 * plugin's TS source lives in `packages/skatespots-background` and is only a
 * build-time dependency of the Android shell (Capacitor finds it via package.json).
 */
interface SkateSpotsBackgroundPlugin {
  configure(options: { mode: DeliveryMode; intervalMinutes?: number }): Promise<void>;
  seed(options: { baseUrl: string; token: string; since: number }): Promise<void>;
  clearNotifications(): Promise<void>;
}
const SkateSpotsBackground = registerPlugin<SkateSpotsBackgroundPlugin>('SkateSpotsBackground');

export function useBackgroundDelivery() {
  const { user } = useCurrentUser();
  const supported = isNativePlatform() && getPlatform() === 'android';
  const [mode, setMode] = useState<DeliveryMode>('off');
  const [prefs] = useNotificationPrefs();
  const categories = useMemo(
    () => NOTIFICATION_CATEGORIES.map((c) => c.key).filter((k) => k !== 'reminders' && prefs[k]),
    [prefs],
  );

  const enable = useCallback(
    async (nextMode: Exclude<DeliveryMode, 'off'>, intervalMinutes = 5) => {
      if (!supported) throw new Error('Background delivery is Android-only.');
      if (!user?.pubkey || !user.signer) throw new Error('Log in first.');

      const challenge = await requestPushChallenge(user.pubkey);
      const proof = await user.signer.signEvent({
        kind: 27235,
        content: '',
        created_at: Math.floor(Date.now() / 1000),
        tags: [['challenge', challenge]],
      });

      const res = await fetch(`${pushServiceBase()}/native/poll/register`, {
        method: 'POST',
        headers: { 'content-type': 'application/json' },
        body: JSON.stringify({ pubkey: user.pubkey, proof, categories }),
      });
      if (!res.ok) throw new Error('Could not register for background delivery.');
      const { token, seq } = (await res.json()) as { token: string; seq: number };

      await SkateSpotsBackground.seed({ baseUrl: pushServiceBase(), token, since: seq ?? 0 });
      await SkateSpotsBackground.configure({ mode: nextMode, intervalMinutes });
      setMode(nextMode);
    },
    [supported, user, categories],
  );

  /** Re-register with the current category choices (after a toggle change). */
  const resubscribe = useCallback(async () => {
    if (mode === 'off') return;
    await enable(mode, mode === 'fast' ? 5 : undefined);
  }, [mode, enable]);

  const disable = useCallback(async () => {
    if (!supported) return;
    await SkateSpotsBackground.configure({ mode: 'off' });
    await SkateSpotsBackground.clearNotifications();
    setMode('off');
  }, [supported]);

  return { supported, mode, enable, disable, resubscribe, categories };
}