/**
 * Zulip用户管理服务
 * 
 * 功能描述：
 * - 查询和验证Zulip用户信息
 * - 检查用户是否存在
 * - 获取用户详细信息
 * - 验证用户凭据和权限
 * 
 * 主要方法：
 * - checkUserExists(): 检查用户是否存在
 * - getUserInfo(): 获取用户详细信息
 * - validateUserCredentials(): 验证用户凭据
 * - getAllUsers(): 获取所有用户列表
 * 
 * 使用场景：
 * - 用户登录时验证用户存在性
 * - 获取用户基本信息
 * - 验证用户权限和状态
 * - 管理员查看用户列表
 * 
 * @author angjustinl
 * @version 1.0.0
 * @since 2025-01-06
 */

import { Injectable, Logger, Inject } from '@nestjs/common';
import { IZulipConfigService } from '../interfaces/zulip-core.interfaces';

/**
 * Zulip API响应接口
 */
interface ZulipApiResponse {
  result?: 'success' | 'error';
  msg?: string;
  message?: string;
}

/**
 * 用户信息接口
 */
interface ZulipUser {
  user_id: number;
  email: string;
  full_name: string;
  is_active: boolean;
  is_admin: boolean;
  is_owner: boolean;
  is_bot: boolean;
  date_joined: string;
}

/**
 * 用户列表响应接口
 */
interface ZulipUsersResponse extends ZulipApiResponse {
  members?: ZulipUser[];
}

/**
 * 用户查询请求接口
 */
export interface UserQueryRequest {
  email: string;
}

/**
 * 用户信息响应接口
 */
export interface UserInfoResponse {
  success: boolean;
  userId?: number;
  email?: string;
  fullName?: string;
  isActive?: boolean;
  isAdmin?: boolean;
  isBot?: boolean;
  dateJoined?: string;
  error?: string;
}

/**
 * 用户验证请求接口
 */
export interface UserValidationRequest {
  email: string;
  apiKey?: string;
}

/**
 * 用户验证响应接口
 */
export interface UserValidationResponse {
  success: boolean;
  isValid?: boolean;
  userId?: number;
  error?: string;
}

/**
 * 用户列表响应接口
 */
export interface UsersListResponse {
  success: boolean;
  users?: Array<{
    userId: number;
    email: string;
    fullName: string;
    isActive: boolean;
    isAdmin: boolean;
    isBot: boolean;
  }>;
  totalCount?: number;
  error?: string;
}

/**
 * Zulip用户管理服务类
 * 
 * 职责：
 * - 查询和验证Zulip用户信息
 * - 检查用户是否存在于Zulip服务器
 * - 获取用户详细信息和权限状态
 * - 提供用户管理相关的API接口
 */
@Injectable()
export class UserManagementService {
  private readonly logger = new Logger(UserManagementService.name);

  constructor(
    @Inject('ZULIP_CONFIG_SERVICE')
    private readonly configService: IZulipConfigService,
  ) {
    this.logger.log('UserManagementService初始化完成');
  }

  /**
   * 检查用户是否存在
   * 
   * 功能描述：
   * 通过Zulip API检查指定邮箱的用户是否存在
   * 
   * 业务逻辑：
   * 1. 获取所有用户列表
   * 2. 在列表中查找指定邮箱
   * 3. 返回用户存在性结果
   * 
   * @param email 用户邮箱
   * @returns Promise<boolean> 是否存在
   */
  async checkUserExists(email: string): Promise<boolean> {
    const startTime = Date.now();
    
    this.logger.log('开始检查用户是否存在', {
      operation: 'checkUserExists',
      email,
      timestamp: new Date().toISOString(),
    });

    try {
      // 1. 验证邮箱格式
      if (!email || !this.isValidEmail(email)) {
        this.logger.warn('邮箱格式无效', {
          operation: 'checkUserExists',
          email,
        });
        return false;
      }

      // 2. 获取用户列表
      const usersResult = await this.getAllUsers();
      if (!usersResult.success) {
        this.logger.warn('获取用户列表失败', {
          operation: 'checkUserExists',
          email,
          error: usersResult.error,
        });
        return false;
      }

      // 3. 检查用户是否存在
      const userExists = usersResult.users?.some(user => 
        user.email.toLowerCase() === email.toLowerCase()
      ) || false;

      const duration = Date.now() - startTime;
      
      this.logger.log('用户存在性检查完成', {
        operation: 'checkUserExists',
        email,
        exists: userExists,
        duration,
        timestamp: new Date().toISOString(),
      });

      return userExists;

    } catch (error) {
      const err = error as Error;
      const duration = Date.now() - startTime;
      
      this.logger.error('检查用户存在性失败', {
        operation: 'checkUserExists',
        email,
        error: err.message,
        duration,
        timestamp: new Date().toISOString(),
      }, err.stack);

      return false;
    }
  }

  /**
   * 获取用户详细信息
   * 
   * 功能描述：
   * 根据邮箱获取用户的详细信息
   * 
   * @param request 用户查询请求
   * @returns Promise<UserInfoResponse>
   */
  async getUserInfo(request: UserQueryRequest): Promise<UserInfoResponse> {
    const startTime = Date.now();
    
    this.logger.log('开始获取用户信息', {
      operation: 'getUserInfo',
      email: request.email,
      timestamp: new Date().toISOString(),
    });

    try {
      // 1. 验证请求参数
      if (!request.email || !this.isValidEmail(request.email)) {
        return {
          success: false,
          error: '邮箱格式无效',
        };
      }

      // 2. 获取用户列表
      const usersResult = await this.getAllUsers();
      if (!usersResult.success) {
        return {
          success: false,
          error: usersResult.error || '获取用户列表失败',
        };
      }

      // 3. 查找指定用户
      const user = usersResult.users?.find(u => 
        u.email.toLowerCase() === request.email.toLowerCase()
      );

      if (!user) {
        return {
          success: false,
          error: '用户不存在',
        };
      }

      const duration = Date.now() - startTime;
      
      this.logger.log('用户信息获取完成', {
        operation: 'getUserInfo',
        email: request.email,
        userId: user.userId,
        duration,
        timestamp: new Date().toISOString(),
      });

      return {
        success: true,
        userId: user.userId,
        email: user.email,
        fullName: user.fullName,
        isActive: user.isActive,
        isAdmin: user.isAdmin,
        isBot: user.isBot,
      };

    } catch (error) {
      const err = error as Error;
      const duration = Date.now() - startTime;
      
      this.logger.error('获取用户信息失败', {
        operation: 'getUserInfo',
        email: request.email,
        error: err.message,
        duration,
        timestamp: new Date().toISOString(),
      }, err.stack);

      return {
        success: false,
        error: '系统错误，请稍后重试',
      };
    }
  }

  /**
   * 验证用户凭据
   * 
   * 功能描述：
   * 验证用户的API Key是否有效
   * 
   * @param request 用户验证请求
   * @returns Promise<UserValidationResponse>
   */
  async validateUserCredentials(request: UserValidationRequest): Promise<UserValidationResponse> {
    const startTime = Date.now();
    
    this.logger.log('开始验证用户凭据', {
      operation: 'validateUserCredentials',
      email: request.email,
      hasApiKey: !!request.apiKey,
      timestamp: new Date().toISOString(),
    });

    try {
      // 1. 验证请求参数
      if (!request.email || !this.isValidEmail(request.email)) {
        return {
          success: false,
          error: '邮箱格式无效',
        };
      }

      if (!request.apiKey) {
        return {
          success: false,
          error: 'API Key不能为空',
        };
      }

      // 2. 使用用户的API Key测试连接
      const isValid = await this.testUserApiKey(request.email, request.apiKey);
      
      // 3. 如果API Key有效，获取用户ID
      let userId = undefined;
      if (isValid) {
        const userInfo = await this.getUserInfo({ email: request.email });
        if (userInfo.success) {
          userId = userInfo.userId;
        }
      }

      const duration = Date.now() - startTime;
      
      this.logger.log('用户凭据验证完成', {
        operation: 'validateUserCredentials',
        email: request.email,
        isValid,
        userId,
        duration,
        timestamp: new Date().toISOString(),
      });

      return {
        success: true,
        isValid,
        userId,
      };

    } catch (error) {
      const err = error as Error;
      const duration = Date.now() - startTime;
      
      this.logger.error('验证用户凭据失败', {
        operation: 'validateUserCredentials',
        email: request.email,
        error: err.message,
        duration,
        timestamp: new Date().toISOString(),
      }, err.stack);

      return {
        success: false,
        error: '系统错误，请稍后重试',
      };
    }
  }

  /**
   * 获取所有用户列表
   * 
   * 功能描述：
   * 从Zulip服务器获取所有用户的列表
   * 
   * @returns Promise<UsersListResponse>
   */
  async getAllUsers(): Promise<UsersListResponse> {
    this.logger.debug('开始获取用户列表', {
      operation: 'getAllUsers',
      timestamp: new Date().toISOString(),
    });

    try {
      // 获取Zulip配置
      const config = this.configService.getZulipConfig();
      
      // 构建API URL
      const apiUrl = `${config.zulipServerUrl}/api/v1/users`;
      
      // 构建认证头
      const auth = Buffer.from(`${config.zulipBotEmail}:${config.zulipBotApiKey}`).toString('base64');
      
      // 发送请求
      const response = await fetch(apiUrl, {
        method: 'GET',
        headers: {
          'Authorization': `Basic ${auth}`,
          'Content-Type': 'application/json',
        },
      });

      if (!response.ok) {
        this.logger.warn('获取用户列表失败', {
          operation: 'getAllUsers',
          status: response.status,
          statusText: response.statusText,
        });
        
        return {
          success: false,
          error: `API调用失败: ${response.status} ${response.statusText}`,
        };
      }

      const data: ZulipUsersResponse = await response.json();
      
      // 转换数据格式
      const users = data.members?.map(user => ({
        userId: user.user_id,
        email: user.email,
        fullName: user.full_name,
        isActive: user.is_active,
        isAdmin: user.is_admin,
        isBot: user.is_bot,
      })) || [];

      this.logger.debug('用户列表获取完成', {
        operation: 'getAllUsers',
        userCount: users.length,
        timestamp: new Date().toISOString(),
      });

      return {
        success: true,
        users,
        totalCount: users.length,
      };

    } catch (error) {
      const err = error as Error;
      this.logger.error('获取用户列表异常', {
        operation: 'getAllUsers',
        error: err.message,
        timestamp: new Date().toISOString(),
      }, err.stack);

      return {
        success: false,
        error: '系统错误，请稍后重试',
      };
    }
  }

  /**
   * 测试用户API Key是否有效
   * 
   * 功能描述：
   * 使用用户的API Key测试是否能够成功调用Zulip API
   * 
   * @param email 用户邮箱
   * @param apiKey 用户API Key
   * @returns Promise<boolean> 是否有效
   * @private
   */
  private async testUserApiKey(email: string, apiKey: string): Promise<boolean> {
    this.logger.debug('测试用户API Key', {
      operation: 'testUserApiKey',
      email,
    });

    try {
      // 获取Zulip配置
      const config = this.configService.getZulipConfig();
      
      // 构建API URL - 使用获取用户自己信息的接口
      const apiUrl = `${config.zulipServerUrl}/api/v1/users/me`;
      
      // 使用用户的API Key构建认证头
      const auth = Buffer.from(`${email}:${apiKey}`).toString('base64');
      
      // 发送请求
      const response = await fetch(apiUrl, {
        method: 'GET',
        headers: {
          'Authorization': `Basic ${auth}`,
          'Content-Type': 'application/json',
        },
      });

      const isValid = response.ok;
      
      this.logger.debug('API Key测试完成', {
        operation: 'testUserApiKey',
        email,
        isValid,
        status: response.status,
      });

      return isValid;

    } catch (error) {
      const err = error as Error;
      this.logger.error('测试API Key异常', {
        operation: 'testUserApiKey',
        email,
        error: err.message,
      });

      return false;
    }
  }

  /**
   * 验证邮箱格式
   * 
   * @param email 邮箱地址
   * @returns boolean 是否有效
   * @private
   */
  private isValidEmail(email: string): boolean {
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    return emailRegex.test(email);
  }
}