import path from 'path';
import fs from 'fs';

import {
  type ConfigPlugin,
  withDangerousMod,
  withAndroidManifest,
  AndroidConfig,
} from '@expo/config-plugins';
import type { IntercomPluginProps } from './@types';

const SERVICE_CLASS_NAME = 'IntercomFirebaseMessagingService';

function hasExpoNotifications(): boolean {
  try {
    require('expo-notifications');
    return true;
  } catch (e: any) {
    return e?.code !== 'MODULE_NOT_FOUND';
  }
}

/**
 * Generates the Kotlin source for the FirebaseMessagingService that
 * forwards FCM tokens and Intercom push messages to the Intercom SDK.
 */
function generateFirebaseServiceKotlin(packageName: string): string {
  const extendsExpo = hasExpoNotifications();
  const baseClass = extendsExpo
    ? 'ExpoFirebaseMessagingService'
    : 'FirebaseMessagingService';
  const baseImport = extendsExpo
    ? 'import expo.modules.notifications.service.ExpoFirebaseMessagingService'
    : 'import com.google.firebase.messaging.FirebaseMessagingService';

  return `package ${packageName}

${baseImport}
import com.google.firebase.messaging.RemoteMessage
import com.intercom.reactnative.IntercomModule

class ${SERVICE_CLASS_NAME} : ${baseClass}() {

    override fun onNewToken(refreshedToken: String) {
        IntercomModule.sendTokenToIntercom(application, refreshedToken)
        super.onNewToken(refreshedToken)
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        if (IntercomModule.isIntercomPush(remoteMessage)) {
            IntercomModule.handleRemotePushMessage(application, remoteMessage)
        } else {
            super.onMessageReceived(remoteMessage)
        }
    }
}
`;
}

/**
 * Uses withDangerousMod to write the Kotlin FirebaseMessagingService file
 * into the app's Android source directory, and ensures firebase-messaging
 * is on the app module's compile classpath.
 */
const writeFirebaseService: ConfigPlugin<IntercomPluginProps> = (_config) =>
  withDangerousMod(_config, [
    'android',
    (config) => {
      const packageName = config.android?.package;
      if (!packageName) {
        throw new Error(
          '@intercom/intercom-react-native: android.package must be defined in your Expo config to use Android push notifications.'
        );
      }

      const projectRoot = config.modRequest.projectRoot;
      const packagePath = packageName.replace(/\./g, '/');
      const serviceDir = path.join(
        projectRoot,
        'android',
        'app',
        'src',
        'main',
        'java',
        packagePath
      );

      fs.mkdirSync(serviceDir, { recursive: true });
      fs.writeFileSync(
        path.join(serviceDir, `${SERVICE_CLASS_NAME}.kt`),
        generateFirebaseServiceKotlin(packageName),
        'utf-8'
      );

      // The native module declares firebase-messaging as an `implementation`
      // dependency, which keeps it private to the library. Since our generated
      // service lives in the app module, we need firebase-messaging on the
      // app's compile classpath too. We read the version from the native
      // module's build.gradle so it stays in sync automatically.
      const packageRoot = path.resolve(__dirname, '..', '..', '..');
      const nativeBuildGradle = fs.readFileSync(
        path.join(packageRoot, 'android', 'build.gradle'),
        'utf-8'
      );
      const versionMatch = nativeBuildGradle.match(
        /com\.google\.firebase:firebase-messaging:([\d.]+)/
      );
      const firebaseMessagingVersion = versionMatch
        ? versionMatch[1]
        : '24.1.2';

      const buildGradlePath = path.join(
        projectRoot,
        'android',
        'app',
        'build.gradle'
      );
      const buildGradle = fs.readFileSync(buildGradlePath, 'utf-8');
      if (!buildGradle.includes('firebase-messaging')) {
        const updatedBuildGradle = buildGradle.replace(
          /dependencies\s*\{/,
          `dependencies {\n    implementation("com.google.firebase:firebase-messaging:${firebaseMessagingVersion}")`
        );
        fs.writeFileSync(buildGradlePath, updatedBuildGradle, 'utf-8');
      }

      return config;
    },
  ]);

const registerServiceInManifest: ConfigPlugin<IntercomPluginProps> = (
  _config
) =>
  withAndroidManifest(_config, (config) => {
    const mainApplication = AndroidConfig.Manifest.getMainApplicationOrThrow(
      config.modResults
    );

    const packageName = config.android?.package;
    if (!packageName) {
      throw new Error(
        '@intercom/intercom-react-native: android.package must be defined in your Expo config to use Android push notifications.'
      );
    }

    const serviceName = `.${SERVICE_CLASS_NAME}`;

    const existingService = mainApplication.service?.find(
      (s) => s.$?.['android:name'] === serviceName
    );

    const hasExistingFcmService = mainApplication.service?.some(
      (s) =>
        s.$?.['android:name'] !== serviceName &&
        ([] as any[])
          .concat(s['intent-filter'] ?? [])
          .some((f: any) =>
            ([] as any[])
              .concat(f.action ?? [])
              .some(
                (a: any) =>
                  a.$?.['android:name'] ===
                  'com.google.firebase.MESSAGING_EVENT'
              )
          )
    );

    if (hasExistingFcmService) {
      console.warn(
        '@intercom/intercom-react-native: An existing FirebaseMessagingService was found in AndroidManifest.xml. ' +
          'Skipping automatic Intercom service registration to avoid conflicts. ' +
          'You will need to route Intercom pushes manually using IntercomModule.isIntercomPush() and IntercomModule.handleRemotePushMessage().'
      );
      return config;
    }

    if (!existingService) {
      if (!mainApplication.service) {
        mainApplication.service = [];
      }

      mainApplication.service.push({
        '$': {
          'android:name': serviceName,
          'android:exported': 'false' as any,
        },
        'intent-filter': [
          {
            $: {
              'android:priority': '10',
            } as any,
            action: [
              {
                $: {
                  'android:name': 'com.google.firebase.MESSAGING_EVENT',
                },
              },
            ],
          },
        ],
      } as any);
    }

    return config;
  });

export const withAndroidPushNotifications: ConfigPlugin<IntercomPluginProps> = (
  config,
  props
) => {
  let newConfig = config;
  newConfig = writeFirebaseService(newConfig, props);
  newConfig = registerServiceInManifest(newConfig, props);
  return newConfig;
};