/**
 * Push Notifications Service
 *
 * Handles:
 * - Requesting push notification permissions
 * - Getting Expo Push Token
 * - Registering/unregistering token on server
 * - Handling incoming notifications
 */

import * as Notifications from 'expo-notifications';
import * as Device from 'expo-device';
import { Platform } from 'react-native';
import * as SecureStore from 'expo-secure-store';
import Constants from 'expo-constants';

const WELLNUO_API_URL = 'https://wellnuo.smartlaunchhub.com/api';
const PUSH_TOKEN_KEY = 'expoPushToken';

// Configure notification handler for foreground notifications
Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowAlert: true,
    shouldPlaySound: true,
    shouldSetBadge: true,
    shouldShowBanner: true,
    shouldShowList: true,
  }),
});

/**
 * Register for push notifications and get Expo Push Token
 * Returns the token or null if not available
 */
export async function registerForPushNotificationsAsync(): Promise<string | null> {
  let token: string | null = null;

  // Must be a physical device for push notifications
  if (!Device.isDevice) {
    // For simulator, return a fake token for testing
    if (__DEV__) {
      return 'ExponentPushToken[SIMULATOR_TEST_TOKEN]';
    }
    return null;
  }

  // Check/request permissions
  const { status: existingStatus } = await Notifications.getPermissionsAsync();
  let finalStatus = existingStatus;

  if (existingStatus !== 'granted') {
    const { status } = await Notifications.requestPermissionsAsync();
    finalStatus = status;
  }

  if (finalStatus !== 'granted') {
    return null;
  }

  // Get Expo Push Token
  try {
    const projectId = Constants.expoConfig?.extra?.eas?.projectId;

    const pushTokenResponse = await Notifications.getExpoPushTokenAsync({
      projectId: projectId,
    });

    token = pushTokenResponse.data;

    // Store locally
    await SecureStore.setItemAsync(PUSH_TOKEN_KEY, token);
  } catch (error) {
    return null;
  }

  // Android needs notification channel
  if (Platform.OS === 'android') {
    await Notifications.setNotificationChannelAsync('default', {
      name: 'default',
      importance: Notifications.AndroidImportance.MAX,
      vibrationPattern: [0, 250, 250, 250],
      lightColor: '#FF231F7C',
    });

    // Emergency alerts channel
    await Notifications.setNotificationChannelAsync('emergency', {
      name: 'Emergency Alerts',
      importance: Notifications.AndroidImportance.MAX,
      vibrationPattern: [0, 500, 200, 500],
      lightColor: '#FF0000',
      sound: 'default',
    });
  }

  return token;
}

/**
 * Register push token on WellNuo backend
 */
export async function registerTokenOnServer(token: string): Promise<boolean> {
  try {
    const accessToken = await SecureStore.getItemAsync('accessToken');

    if (!accessToken) {
      return false;
    }

    const response = await fetch(`${WELLNUO_API_URL}/push-tokens`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${accessToken}`,
      },
      body: JSON.stringify({
        token,
        platform: Platform.OS,
        deviceName: Device.deviceName || `${Device.brand} ${Device.modelName}`,
      }),
    });

    if (!response.ok) {
      const error = await response.json();
      return false;
    }

    return true;
  } catch (error) {
    return false;
  }
}

/**
 * Unregister push token from server (call on logout)
 */
export async function unregisterToken(): Promise<boolean> {
  try {
    const token = await SecureStore.getItemAsync(PUSH_TOKEN_KEY);
    const accessToken = await SecureStore.getItemAsync('accessToken');

    if (!token || !accessToken) {
      return true; // Nothing to unregister
    }

    const response = await fetch(`${WELLNUO_API_URL}/push-tokens`, {
      method: 'DELETE',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${accessToken}`,
      },
      body: JSON.stringify({ token }),
    });

    // Clear local storage regardless of server response
    await SecureStore.deleteItemAsync(PUSH_TOKEN_KEY);

    if (!response.ok) {
      return false;
    }

    return true;
  } catch (error) {
    // Still clear local storage
    await SecureStore.deleteItemAsync(PUSH_TOKEN_KEY);
    return false;
  }
}

/**
 * Full registration flow: get token + register on server
 * Call this after successful login
 */
export async function setupPushNotifications(): Promise<string | null> {

  const token = await registerForPushNotificationsAsync();

  if (token) {
    await registerTokenOnServer(token);
  }

  return token;
}

/**
 * Get stored push token (if any)
 */
export async function getStoredPushToken(): Promise<string | null> {
  try {
    return await SecureStore.getItemAsync(PUSH_TOKEN_KEY);
  } catch {
    return null;
  }
}

/**
 * Add listener for received notifications (while app is open)
 */
export function addNotificationReceivedListener(
  callback: (notification: Notifications.Notification) => void
): Notifications.EventSubscription {
  return Notifications.addNotificationReceivedListener(callback);
}

/**
 * Add listener for notification response (user tapped notification)
 */
export function addNotificationResponseListener(
  callback: (response: Notifications.NotificationResponse) => void
): Notifications.EventSubscription {
  return Notifications.addNotificationResponseReceivedListener(callback);
}

/**
 * Get last notification response (if app was opened from notification)
 */
export async function getLastNotificationResponse(): Promise<Notifications.NotificationResponse | null> {
  return await Notifications.getLastNotificationResponseAsync();
}

/**
 * Parse notification data to determine navigation target
 */
export function parseNotificationData(data: Record<string, unknown>): {
  type: string;
  deploymentId?: number;
  beneficiaryId?: number;
  alertId?: string;
} {
  return {
    type: (data.type as string) || 'unknown',
    deploymentId: data.deploymentId as number | undefined,
    beneficiaryId: data.beneficiaryId as number | undefined,
    alertId: data.alertId as string | undefined,
  };
}