import 'dart:async';
import 'dart:convert';
import 'dart:developer' as dev;
import 'dart:io' show SocketException;

// ignore: depend_on_referenced_packages
import 'package:http/http.dart' as http;

import 'package:didvan/config/auth_config.dart';
import 'package:didvan/services/auth/auth_interceptor.dart';
import 'package:didvan/services/auth/token_storage.dart';

class TicketMessageDto {
  final String id;
  final String body;
  final String senderId;
  final DateTime? createdAt;
  const TicketMessageDto({
    required this.id,
    required this.body,
    required this.senderId,
    this.createdAt,
  });

  factory TicketMessageDto.fromJson(Map<String, dynamic> json) {
    DateTime? ca;
    final c = json['createdAt'];
    if (c is String && c.isNotEmpty) ca = DateTime.tryParse(c);
    return TicketMessageDto(
      id: json['id']?.toString() ?? '',
      body: json['body']?.toString() ?? '',
      senderId: json['senderId']?.toString() ?? '',
      createdAt: ca,
    );
  }
}

class TicketDto {
  final String id;
  final String title;
  final String senderId;
  final String receiver;
  final String status;
  final DateTime? createdAt;
  final DateTime? updatedAt;
  final List<TicketMessageDto> messages;

  const TicketDto({
    required this.id,
    required this.title,
    required this.senderId,
    required this.receiver,
    required this.status,
    this.createdAt,
    this.updatedAt,
    this.messages = const [],
  });

  factory TicketDto.fromJson(Map<String, dynamic> json) {
    DateTime? ca, ua;
    final c = json['createdAt'];
    final u = json['updatedAt'];
    if (c is String && c.isNotEmpty) ca = DateTime.tryParse(c);
    if (u is String && u.isNotEmpty) ua = DateTime.tryParse(u);
    final msgsRaw = json['messages'];
    final msgs = msgsRaw is List
        ? msgsRaw
            .whereType<Map>()
            .map((e) => TicketMessageDto.fromJson(Map<String, dynamic>.from(e)))
            .toList()
        : <TicketMessageDto>[];
    return TicketDto(
      id: json['id']?.toString() ?? '',
      title: json['title']?.toString() ?? '',
      senderId: json['senderId']?.toString() ?? '',
      receiver: json['receiver']?.toString() ?? '',
      status: json['status']?.toString() ?? 'open',
      createdAt: ca,
      updatedAt: ua,
      messages: msgs,
    );
  }
}

class TicketResult<T> {
  final bool isSuccess;
  final int? statusCode;
  final T? data;
  final String? errorMessage;
  const TicketResult({
    required this.isSuccess,
    this.statusCode,
    this.data,
    this.errorMessage,
  });
}

class TicketService {
  TicketService._();
  static final TicketService instance = TicketService._();

  String get _base => AuthConfig.apiBaseUrl;
  static const _timeout = Duration(seconds: 15);

  Map<String, String> _headers() {
    final headers = <String, String>{
      'Accept': 'application/json',
      'Content-Type': 'application/json',
    };
    final t = TokenStorage.accessToken;
    if (t != null && t.isNotEmpty) headers['Authorization'] = 'Bearer $t';
    return headers;
  }

  Future<TicketResult<List<TicketDto>>> list({
    int page = 1,
    int limit = 50,
  }) async {
    await AuthInterceptor.ensureFreshToken();
    try {
      final params = <String, String>{
        'page': page.toString(),
        'limit': limit.toString(),
        'sortBy': 'createdAt:DESC',
        't': DateTime.now().millisecondsSinceEpoch.toString(),
      };
      final uri = Uri.parse('$_base/ticketing/tickets')
          .replace(queryParameters: params);
      final r = await _withRetry(
        () => http.get(uri, headers: _headers()).timeout(_timeout),
      );
      if (r.statusCode == 200) {
        final body = json.decode(r.body);
        final dataRaw = body is Map ? body['data'] : null;
        final list = dataRaw is List
            ? dataRaw
                .whereType<Map>()
                .map((e) => TicketDto.fromJson(Map<String, dynamic>.from(e)))
                .toList()
            : <TicketDto>[];
        return TicketResult(isSuccess: true, statusCode: 200, data: list);
      }
      return TicketResult(
        isSuccess: false,
        statusCode: r.statusCode,
        errorMessage: _extractError(r.body) ?? 'خطا در دریافت تیکت‌ها.',
      );
    } catch (e) {
      dev.log('list error: $e', name: 'TicketService');
      return const TicketResult(
        isSuccess: false,
        errorMessage: 'خطا در ارتباط با سرور.',
      );
    }
  }

  Future<TicketResult<TicketDto>> getOne(String id) async {
    await AuthInterceptor.ensureFreshToken();
    try {
      final ts = DateTime.now().millisecondsSinceEpoch.toString();
      final r = await _withRetry(
        () => http
            .get(
              Uri.parse('$_base/ticketing/tickets/$id?t=$ts'),
              headers: _headers(),
            )
            .timeout(_timeout),
      );
      if (r.statusCode == 200) {
        final body = json.decode(r.body);
        if (body is Map<String, dynamic>) {
          return TicketResult(
            isSuccess: true,
            statusCode: 200,
            data: TicketDto.fromJson(body),
          );
        }
      }
      return TicketResult(
        isSuccess: false,
        statusCode: r.statusCode,
        errorMessage: _extractError(r.body) ?? 'خطا در دریافت تیکت.',
      );
    } catch (e) {
      dev.log('getOne error: $e', name: 'TicketService');
      return const TicketResult(
        isSuccess: false,
        errorMessage: 'خطا در ارتباط با سرور.',
      );
    }
  }

  Future<TicketResult<TicketDto>> create({
    required String title,
    required String body,
    required String receiver,
  }) async {
    await AuthInterceptor.ensureFreshToken();
    try {
      final r = await _withRetry(() => http
          .post(
            Uri.parse('$_base/ticketing/tickets'),
            headers: _headers(),
            body: json.encode({
              'title': title,
              'body': body,
              'receiver': receiver,
            }),
          )
          .timeout(_timeout));
      if (r.statusCode >= 200 && r.statusCode < 300) {
        final body = json.decode(r.body);
        if (body is Map<String, dynamic>) {
          return TicketResult(
            isSuccess: true,
            statusCode: r.statusCode,
            data: TicketDto.fromJson(body),
          );
        }
        return const TicketResult(isSuccess: true);
      }
      return TicketResult(
        isSuccess: false,
        statusCode: r.statusCode,
        errorMessage: _extractError(r.body) ?? 'خطا در ایجاد تیکت.',
      );
    } catch (e) {
      dev.log('create error: $e', name: 'TicketService');
      return const TicketResult(
        isSuccess: false,
        errorMessage: 'خطا در ارتباط با سرور.',
      );
    }
  }

  Future<TicketResult<void>> reply({
    required String ticketId,
    required String body,
  }) async {
    await AuthInterceptor.ensureFreshToken();
    try {
      final r = await _withRetry(() => http
          .post(
            Uri.parse('$_base/ticketing/tickets/$ticketId/reply'),
            headers: _headers(),
            body: json.encode({'body': body}),
          )
          .timeout(_timeout));
      if (r.statusCode >= 200 && r.statusCode < 300) {
        return const TicketResult(isSuccess: true);
      }
      return TicketResult(
        isSuccess: false,
        statusCode: r.statusCode,
        errorMessage: _extractError(r.body) ?? 'خطا در ارسال پاسخ.',
      );
    } catch (e) {
      dev.log('reply error: $e', name: 'TicketService');
      return const TicketResult(
        isSuccess: false,
        errorMessage: 'خطا در ارتباط با سرور.',
      );
    }
  }

  Future<T> _withRetry<T>(Future<T> Function() body) async {
    for (var attempt = 0; attempt < 3; attempt++) {
      try {
        return await body();
      } on SocketException {
        if (attempt == 2) rethrow;
        await Future.delayed(Duration(milliseconds: 250 * (attempt + 1)));
      } on http.ClientException {
        if (attempt == 2) rethrow;
        await Future.delayed(Duration(milliseconds: 250 * (attempt + 1)));
      } on TimeoutException {
        if (attempt == 2) rethrow;
      }
    }
    throw StateError('retry loop exited without return');
  }

  String? _extractError(String body) {
    if (body.isEmpty) return null;
    try {
      final data = json.decode(body);
      if (data is Map) {
        final msg = data['message'] ?? data['error'];
        if (msg is String && msg.isNotEmpty) return msg;
        if (msg is List && msg.isNotEmpty) return msg.first.toString();
      }
    } catch (_) {}
    return null;
  }
}