// ============================================================
// 文件名: webdav_service.dart
// 功能: WebDAV 协议通信服务，支持文件夹浏览和音乐文件读取
// ============================================================

import 'dart:convert';
import 'package:dio/dio.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:xml/xml.dart';

// -----------------------------------------------------------------
// WebDAV 服务单例
// -----------------------------------------------------------------
class WebDAVService {
  static const String _keyBaseUrl = 'webdav_base_url';
  static const String _keyUsername = 'webdav_username';
  static const String _keyPassword = 'webdav_password';

  static WebDAVService? _instance;
  static WebDAVService get instance => _instance ??= WebDAVService._();

  WebDAVService._();

  Dio? _dio;
  String? _baseUrl;
  String? _username;

  // -------------------------------------------------------------
  // 公开 Getter
  // -------------------------------------------------------------
  bool get isConnected => _dio != null;
  String? get baseUrl => _baseUrl;
  String? get username => _username;

  // -------------------------------------------------------------
  // 凭据管理
  // -------------------------------------------------------------
  Future<void> saveCredentials(
      String baseUrl, String username, String password) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_keyBaseUrl, baseUrl);
    await prefs.setString(_keyUsername, username);
    await prefs.setString(_keyPassword, password);

    _baseUrl = baseUrl;
    _username = username;
    _dio = Dio(BaseOptions(
      baseUrl: baseUrl,
      headers: {
        'Authorization':
            'Basic ${base64Encode(utf8.encode('$username:$password'))}',
      },
    ));
  }

  Future<bool> loadCredentials() async {
    final prefs = await SharedPreferences.getInstance();
    final baseUrl = prefs.getString(_keyBaseUrl);
    final username = prefs.getString(_keyUsername);
    final password = prefs.getString(_keyPassword);

    if (baseUrl != null && username != null && password != null) {
      _baseUrl = baseUrl;
      _username = username;
      _dio = Dio(BaseOptions(
        baseUrl: baseUrl,
        headers: {
          'Authorization':
              'Basic ${base64Encode(utf8.encode('$username:$password'))}',
        },
      ));
      return true;
    }
    return false;
  }

  Future<void> clearCredentials() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_keyBaseUrl);
    await prefs.remove(_keyUsername);
    await prefs.remove(_keyPassword);
    _dio = null;
    _baseUrl = null;
    _username = null;
  }

  // -------------------------------------------------------------
  // 核心：列出目录内容（文件夹 + 音乐文件）
  // 这是浏览模式的核心方法，支持进入子目录
  // -------------------------------------------------------------
  Future<List<WebDAVItem>> listDirectory({String path = '/'}) async {
    if (_dio == null) throw Exception('WebDAV 未连接');

    final requestPath = path.startsWith('/') ? path : '/$path';

    final body = '''
<?xml version="1.0" encoding="utf-8"?>
<propfind xmlns="DAV:">
  <prop>
    <resourcetype/>
    <getcontentlength/>
    <getlastmodified/>
  </prop>
</propfind>
  ''';

    final response = await _dio!.request(
      requestPath,
      options: Options(
        method: 'PROPFIND',
        headers: {
          'Depth': '1',
          'Content-Type': 'application/xml; charset=utf-8',
        },
      ),
      data: body,
    );

    if (response.statusCode != 207) {
      throw Exception('WebDAV 响应异常: ${response.statusCode}');
    }

    final xml = XmlDocument.parse(response.data as String);
    final items = <WebDAVItem>[];
    final musicExtensions = ['.mp3', '.flac', '.m4a', '.ape', '.wav', '.opus'];

    final responseNodes = xml.findAllElements('D:response');
    for (final responseNode in responseNodes) {
      final hrefNode = responseNode.findElements('D:href').firstOrNull;
      if (hrefNode == null) continue;

      String fullPath = Uri.decodeComponent(hrefNode.text.trim());

      // 去掉 baseUrl 前缀
      String relativePath = fullPath;
      if (_baseUrl != null) {
        try {
          final baseUri = Uri.parse(_baseUrl!);
          final fullUri = Uri.parse(fullPath);
          String fullPathOnly = fullUri.path;
          if (baseUri.path.isNotEmpty &&
              fullPathOnly.startsWith(baseUri.path)) {
            relativePath = fullPathOnly.substring(baseUri.path.length);
          } else {
            relativePath = fullPathOnly;
          }
        } catch (_) {
          relativePath = fullPath;
        }
      }

      // 跳过根目录自身
      if (relativePath.isEmpty ||
          relativePath == '/' ||
          relativePath == requestPath) {
        continue;
      }

      final cleanPath = relativePath.endsWith('/')
          ? relativePath.substring(0, relativePath.length - 1)
          : relativePath;

      // ✅ 解码文件名
      String fileName = cleanPath.split('/').last;
      fileName = Uri.decodeComponent(fileName);
      if (fileName.isEmpty) continue;

      // 判断是否为目录
      bool isDirectory = false;
      final resTypeNode =
          responseNode.findElements('D:resourcetype').firstOrNull;
      if (resTypeNode != null) {
        final collection = resTypeNode.findElements('D:collection').firstOrNull;
        if (collection != null) {
          isDirectory = true;
        }
      }
      if (!isDirectory && fullPath.endsWith('/')) {
        isDirectory = true;
      }

      if (isDirectory) {
        items.add(WebDAVItem(
          path: cleanPath,
          name: fileName,
          isDirectory: true,
          size: null,
          modified: null,
        ));
        continue;
      }

      // 只保留音乐文件
      if (!musicExtensions.any((ext) => fileName.toLowerCase().endsWith(ext))) {
        continue;
      }

      int? size;
      DateTime? modified;
      final sizeNode =
          responseNode.findElements('D:getcontentlength').firstOrNull;
      if (sizeNode != null && sizeNode.text.isNotEmpty) {
        size = int.tryParse(sizeNode.text);
      }
      final modifiedNode =
          responseNode.findElements('D:getlastmodified').firstOrNull;
      if (modifiedNode != null) {
        try {
          modified = DateTime.parse(modifiedNode.text);
        } catch (_) {}
      }

      items.add(WebDAVItem(
        path: cleanPath,
        name: fileName,
        isDirectory: false,
        size: size,
        modified: modified,
      ));
    }

    // 排序
    items.sort((a, b) {
      if (a.isDirectory && !b.isDirectory) return -1;
      if (!a.isDirectory && b.isDirectory) return 1;
      return a.name.toLowerCase().compareTo(b.name.toLowerCase());
    });

    // 只保留一条日志，避免刷屏
    print('WebDAV listDirectory: 找到 ${items.length} 项，路径: $requestPath');
    return items;
  }

  // -------------------------------------------------------------
  // 兼容旧接口：获取所有音乐文件（递归扫描）
  // 用于主页的"我的收藏"列表（后续可改为读取用户收藏）
  // -------------------------------------------------------------
  Future<List<WebDAVFileItem>> getMusicFiles({String path = '/'}) async {
    if (_dio == null) throw Exception('WebDAV 未连接');

    // 递归获取所有文件（先获取当前目录，再递归子目录）
    final allItems = await _listAllRecursive(path);
    final musicExtensions = ['.mp3', '.flac', '.m4a', '.ape', '.wav', '.opus'];

    return allItems
        .where((item) =>
            !item.isDirectory &&
            musicExtensions.any((ext) => item.name.toLowerCase().endsWith(ext)))
        .map((item) => WebDAVFileItem(
              path: item.path,
              name: item.name,
              size: item.size,
              modified: item.modified,
            ))
        .toList();
  }

  // 递归获取所有目录和文件（内部使用）
  Future<List<WebDAVItem>> _listAllRecursive(String path) async {
    final items = await listDirectory(path: path);
    final result = <WebDAVItem>[];

    for (final item in items) {
      result.add(item);
      if (item.isDirectory) {
        // 递归获取子目录内容
        try {
          final subItems = await _listAllRecursive(item.path);
          result.addAll(subItems);
        } catch (_) {
          // 忽略无法读取的子目录
        }
      }
    }
    return result;
  }

  // -------------------------------------------------------------
  // 获取文件的完整下载 URL
  // -------------------------------------------------------------
  String getFileUrl(String path) {
    if (_baseUrl == null) throw Exception('WebDAV 未配置');
    final base = _baseUrl!.endsWith('/') ? _baseUrl! : '$_baseUrl/';
    final cleanPath = path.startsWith('/') ? path.substring(1) : path;
    return '$base$cleanPath';
  }
}

// -----------------------------------------------------------------
// 数据模型：WebDAV 目录项（用于浏览模式）
// -----------------------------------------------------------------
class WebDAVItem {
  final String path;
  final String name;
  final bool isDirectory;
  final int? size;
  final DateTime? modified;

  WebDAVItem({
    required this.path,
    required this.name,
    required this.isDirectory,
    this.size,
    this.modified,
  });
}

// -----------------------------------------------------------------
// 数据模型：WebDAV 文件项（用于播放列表）
// -----------------------------------------------------------------
class WebDAVFileItem {
  final String path;
  final String name;
  final int? size;
  final DateTime? modified;

  WebDAVFileItem({
    required this.path,
    required this.name,
    this.size,
    this.modified,
  });
}