import 'dart:async';
import 'dart:collection';

import 'package:flutter/foundation.dart';
import 'package:yumi/shared/business_logic/models/res/gift_res.dart';
import 'package:yumi/shared/business_logic/models/res/mic_res.dart';

typedef RoomGiftComboSendExecutor =
    Future<void> Function(
      RoomGiftComboSendRequest request, {
      required String trigger,
    });

class RoomGiftComboSendRequest {
  const RoomGiftComboSendRequest({
    required this.acceptUserIds,
    required this.acceptUsers,
    required this.gift,
    required this.quantity,
    required this.clickCount,
    required this.roomId,
    required this.roomAccount,
    required this.isLuckyGiftRequest,
  });

  final List<String> acceptUserIds;
  final List<MicRes> acceptUsers;
  final SocialChatGiftRes gift;
  final int quantity;
  final int clickCount;
  final String roomId;
  final String roomAccount;
  final bool isLuckyGiftRequest;

  RoomGiftComboSendRequest copyWith({
    List<String>? acceptUserIds,
    List<MicRes>? acceptUsers,
    SocialChatGiftRes? gift,
    int? quantity,
    int? clickCount,
    String? roomId,
    String? roomAccount,
    bool? isLuckyGiftRequest,
  }) {
    return RoomGiftComboSendRequest(
      acceptUserIds: List<String>.from(acceptUserIds ?? this.acceptUserIds),
      acceptUsers: List<MicRes>.from(acceptUsers ?? this.acceptUsers),
      gift: gift ?? this.gift,
      quantity: quantity ?? this.quantity,
      clickCount: clickCount ?? this.clickCount,
      roomId: roomId ?? this.roomId,
      roomAccount: roomAccount ?? this.roomAccount,
      isLuckyGiftRequest: isLuckyGiftRequest ?? this.isLuckyGiftRequest,
    );
  }

  String get batchKey {
    final sortedAcceptUserIds = List<String>.from(acceptUserIds)..sort();
    return '${isLuckyGiftRequest ? "lucky" : "gift"}'
        '|${gift.id ?? ""}'
        '|$roomId'
        '|${sortedAcceptUserIds.join(",")}';
  }
}

class RoomGiftComboSendController extends ChangeNotifier {
  static final RoomGiftComboSendController _instance =
      RoomGiftComboSendController._internal();

  factory RoomGiftComboSendController() => _instance;

  RoomGiftComboSendController._internal();

  static const Duration comboFeedbackDuration = Duration(seconds: 3);
  static const Duration _comboSendBatchWindow = Duration(milliseconds: 200);
  static const Duration _countdownRefreshInterval = Duration(milliseconds: 50);

  final ListQueue<_PendingRoomGiftComboSendBatch> _queue =
      ListQueue<_PendingRoomGiftComboSendBatch>();

  RoomGiftComboSendRequest? _activeRequest;
  RoomGiftComboSendExecutor? _executor;
  Timer? _countdownTimer;
  Timer? _batchTimer;
  DateTime? _countdownDeadline;
  bool _isBatchInFlight = false;
  bool _visible = false;

  bool get isVisible => _visible && _activeRequest != null && _executor != null;

  double get countdownProgress {
    if (!isVisible) {
      return 0;
    }

    final deadline = _countdownDeadline;
    if (deadline == null) {
      return 0;
    }

    final totalMs = comboFeedbackDuration.inMilliseconds;
    if (totalMs <= 0) {
      return 1;
    }

    final remainingMs = deadline.difference(DateTime.now()).inMilliseconds;
    if (remainingMs <= 0) {
      return 1;
    }

    return (1 - remainingMs / totalMs).clamp(0.0, 1.0).toDouble();
  }

  void show({
    required RoomGiftComboSendRequest request,
    required RoomGiftComboSendExecutor executor,
  }) {
    _activeRequest = request.copyWith();
    _executor = executor;
    _visible = true;
    _restartCountdown();
    notifyListeners();
  }

  Future<void> sendActiveRequest() async {
    final request = _activeRequest;
    final executor = _executor;
    if (request == null || executor == null) {
      return;
    }

    _visible = true;
    _restartCountdown();
    _enqueueRequest(request.copyWith(clickCount: 1));
    notifyListeners();
  }

  void hide() {
    _countdownTimer?.cancel();
    _countdownTimer = null;
    _countdownDeadline = null;
    if (_visible) {
      _visible = false;
      notifyListeners();
    }
  }

  void clear() {
    _countdownTimer?.cancel();
    _countdownTimer = null;
    _batchTimer?.cancel();
    _batchTimer = null;
    _countdownDeadline = null;
    _queue.clear();
    _activeRequest = null;
    _executor = null;
    _isBatchInFlight = false;
    _visible = false;
    notifyListeners();
  }

  void _restartCountdown() {
    _countdownDeadline = DateTime.now().add(comboFeedbackDuration);
    _countdownTimer?.cancel();
    _countdownTimer = Timer.periodic(_countdownRefreshInterval, (timer) {
      final deadline = _countdownDeadline;
      if (deadline == null) {
        timer.cancel();
        return;
      }

      if (!DateTime.now().isBefore(deadline)) {
        timer.cancel();
        _countdownDeadline = null;
        if (_visible) {
          _visible = false;
          notifyListeners();
        }
        return;
      }

      notifyListeners();
    });
  }

  void _enqueueRequest(RoomGiftComboSendRequest request) {
    final now = DateTime.now();
    _PendingRoomGiftComboSendBatch? existingBatch;
    for (final batch in _queue) {
      if (batch.batchKey == request.batchKey) {
        existingBatch = batch;
        break;
      }
    }

    if (existingBatch != null) {
      existingBatch.quantity += request.quantity;
      existingBatch.clickCount += request.clickCount;
      existingBatch.readyAt = now.add(_comboSendBatchWindow);
    } else {
      _queue.add(
        _PendingRoomGiftComboSendBatch.fromRequest(
          request,
          readyAt: now.add(_comboSendBatchWindow),
        ),
      );
    }

    _scheduleNextFlush();
  }

  void _scheduleNextFlush() {
    _batchTimer?.cancel();
    _batchTimer = null;
    if (_isBatchInFlight || _queue.isEmpty) {
      return;
    }

    final nextBatch = _queue.first;
    final delay = nextBatch.readyAt.difference(DateTime.now());
    if (delay <= Duration.zero) {
      unawaited(_flushNextBatch());
      return;
    }

    _batchTimer = Timer(delay, () {
      unawaited(_flushNextBatch());
    });
  }

  Future<void> _flushNextBatch() async {
    _batchTimer?.cancel();
    _batchTimer = null;
    if (_isBatchInFlight || _queue.isEmpty) {
      return;
    }

    final executor = _executor;
    if (executor == null) {
      _queue.clear();
      return;
    }

    final batch = _queue.first;
    if (batch.readyAt.isAfter(DateTime.now())) {
      _scheduleNextFlush();
      return;
    }

    _queue.removeFirst();
    _isBatchInFlight = true;
    try {
      await executor(batch.toRequest(), trigger: 'floating_batched');
    } finally {
      _isBatchInFlight = false;
      _scheduleNextFlush();
    }
  }
}

class _PendingRoomGiftComboSendBatch {
  _PendingRoomGiftComboSendBatch({
    required this.batchKey,
    required this.acceptUserIds,
    required this.acceptUsers,
    required this.gift,
    required this.quantity,
    required this.clickCount,
    required this.roomId,
    required this.roomAccount,
    required this.isLuckyGiftRequest,
    required this.readyAt,
  });

  factory _PendingRoomGiftComboSendBatch.fromRequest(
    RoomGiftComboSendRequest request, {
    required DateTime readyAt,
  }) {
    return _PendingRoomGiftComboSendBatch(
      batchKey: request.batchKey,
      acceptUserIds: List<String>.from(request.acceptUserIds),
      acceptUsers: List<MicRes>.from(request.acceptUsers),
      gift: request.gift,
      quantity: request.quantity,
      clickCount: request.clickCount,
      roomId: request.roomId,
      roomAccount: request.roomAccount,
      isLuckyGiftRequest: request.isLuckyGiftRequest,
      readyAt: readyAt,
    );
  }

  final String batchKey;
  final List<String> acceptUserIds;
  final List<MicRes> acceptUsers;
  final SocialChatGiftRes gift;
  int quantity;
  int clickCount;
  final String roomId;
  final String roomAccount;
  final bool isLuckyGiftRequest;
  DateTime readyAt;

  RoomGiftComboSendRequest toRequest() {
    return RoomGiftComboSendRequest(
      acceptUserIds: List<String>.from(acceptUserIds),
      acceptUsers: List<MicRes>.from(acceptUsers),
      gift: gift,
      quantity: quantity,
      clickCount: clickCount,
      roomId: roomId,
      roomAccount: roomAccount,
      isLuckyGiftRequest: isLuckyGiftRequest,
    );
  }
}