import { getDeviceId } from '../lib/device';

type PushSubscriptionPayload = {
  endpoint: string;
  keys: {
    p256dh: string;
    auth: string;
  };
  expirationTime?: number | null;
  contentEncoding?: string | null;
};

function buildHeaders(): HeadersInit {
  return {
    Accept: 'application/json',
    'Content-Type': 'application/json',
    'X-Device-Id': getDeviceId(),
  };
}

export async function registerPushSubscription(eventToken: string, subscription: PushSubscription): Promise<void> {
  const json = subscription.toJSON() as PushSubscriptionPayload;

  const body = {
    endpoint: json.endpoint,
    keys: json.keys,
    expiration_time: json.expirationTime ?? null,
    content_encoding: json.contentEncoding ?? null,
  };

  const response = await fetch(`/api/v1/events/${encodeURIComponent(eventToken)}/push-subscriptions`, {
    method: 'POST',
    headers: buildHeaders(),
    credentials: 'include',
    body: JSON.stringify(body),
  });

  if (!response.ok) {
    const message = await parseError(response);
    throw new Error(message ?? 'Push-Registrierung fehlgeschlagen.');
  }
}

export async function unregisterPushSubscription(eventToken: string, endpoint: string): Promise<void> {
  const response = await fetch(`/api/v1/events/${encodeURIComponent(eventToken)}/push-subscriptions`, {
    method: 'DELETE',
    headers: buildHeaders(),
    credentials: 'include',
    body: JSON.stringify({ endpoint }),
  });

  if (!response.ok) {
    const message = await parseError(response);
    throw new Error(message ?? 'Push konnte nicht deaktiviert werden.');
  }
}

async function parseError(response: Response): Promise<string | null> {
  try {
    const payload = await response.clone().json();
    const errorMessage = payload?.error?.message ?? payload?.message;
    if (typeof errorMessage === 'string' && errorMessage.trim() !== '') {
      return errorMessage;
    }
  } catch (error) {
    console.warn('Failed to parse push API error', error);
  }

  return null;
}