import 'dart:async';
import 'dart:io' show Platform;

import 'package:flutter/foundation.dart';
import 'package:umeng_common_sdk/umeng_common_sdk.dart';
import 'package:umeng_push_sdk/umeng_push_sdk.dart';

import '../config/umeng_config.dart';
import '../privacy/privacy_gate.dart';
import '../services/device_header_service.dart';
import '../storage/storage_keys.dart';
import '../storage/storage_service.dart';

abstract final class UmengPushService {
  static const _maxPendingNotificationOpens = 20;
  static final _tokens = StreamController<String>.broadcast();
  static Future<void>? _starting;
  static bool _started = false;
  static void Function(String payload)? _onNotificationOpen;
  static final List<String> _pendingNotificationOpens = [];

  static Stream<String> get onDeviceToken => _tokens.stream;

  static void configureNotificationOpen(
    void Function(String payload) callback,
  ) {
    _onNotificationOpen = callback;
    final pending = List<String>.of(_pendingNotificationOpens);
    _pendingNotificationOpens.clear();
    for (final payload in pending) {
      callback(payload);
    }
  }

  static Future<void> startIfAllowed() {
    if (kIsWeb ||
        _started ||
        requiresAndroidPrivacyConsent(
          isWeb: kIsWeb,
          platform: defaultTargetPlatform,
          privacyAgreed: StorageService.to.getBool(storagePrivacyAgreed),
        )) {
      return Future.value();
    }
    return _starting ??= _start().whenComplete(() => _starting = null);
  }

  static Future<void> _start() async {
    await DeviceHeaderService.to.ensureInitialized();
    await UmengCommonSdk.initCommon(
      UmengConfig.androidAppKey,
      UmengConfig.iosAppKey,
      DeviceHeaderService.to.commonHeaders()['User-Channel'] ?? 'test',
      UmengConfig.androidPushSecret,
    );
    UmengPushSdk.setTokenCallback(_emit);
    UmengPushSdk.setNotificationCallback((_) {}, (payload) {
      final callback = _onNotificationOpen;
      if (callback == null) {
        if (_pendingNotificationOpens.length == _maxPendingNotificationOpens) {
          _pendingNotificationOpens.removeAt(0);
        }
        _pendingNotificationOpens.add(payload);
      } else {
        callback(payload);
      }
    });
    await UmengPushSdk.register(
      UmengConfig.iosAppKey,
      DeviceHeaderService.to.commonHeaders()['User-Channel'] ?? 'test',
    );
    if (Platform.isAndroid) await UmengPushSdk.setPushEnable(true);
    _started = true;
    await refreshDeviceToken();
  }

  static Future<void> refreshDeviceToken() async {
    if (!_started || kIsWeb) return;
    _emit(await UmengPushSdk.getRegisteredId());
  }

  static void emitCachedToken() =>
      _emit(StorageService.to.getString(storageDeviceToken));

  static void _emit(String? token) {
    if (token == null || token.isEmpty) return;
    _tokens.add(token);
    unawaited(StorageService.to.setString(storageDeviceToken, token));
  }
}