/**
 * API 客户端 - 与 FastAPI 后端通信
 * 使用 SuperJSON 处理序列化
 */

import { serialize, deserialize } from './superjson';
import { mcpTokenManager } from './mcp-token-manager';
import catalog from './catalog/catalog';

// 配置 - 使用 Next.js rewrites 反向代理到 FastAPI
const BACKEND_URL = '/api';

// 类型定义
export interface ChatMessage {
  role: 'user' | 'assistant';
  content: string;
}

export interface ChatRequest {
  message: string;
  history: ChatMessage[];
}

export interface ChatResponse {
  response: string;
  model: string;
  tool_calls: Array<{
    tool: string;
    result: unknown;
  }>;
  has_tools: boolean;
}

export interface MCPServer {
  id: string;
  name: string;
  url: string;
  auth_type: 'none' | 'jwt';
  enabled: boolean;
}

export interface MCPToolsResponse {
  tools: Array<{
    name: string;
    description: string;
    input_schema: Record<string, unknown>;
  }>;
  count: number;
}

export interface LoginRequest {
  email: string;
  password: string;
}

// 用户角色类型
export type UserRole = 'reader' | 'author' | 'admin';

// 用户信息接口
export interface UserInfo {
  id?: string;
  username: string;
  email?: string;
  role: UserRole;
}

export interface LoginResponse {
  success: boolean;
  session_id: string;
  username: string;
  server: string;
  role: UserRole;
  token?: string;
}

export interface RegisterRequest {
  email: string;
  username: string;
  password: string;
}

export interface AuthStatusResponse {
  authenticated: boolean;
  username?: string;
  server?: string;
  role?: string;
}

// API 客户端类
export class ApiClient {
  private baseUrl: string;
  private sessionId: string | null = null;
  private mcpTokens: Record<string, string> = {};
  private userInfo: UserInfo | null = null;

  constructor(baseUrl: string = BACKEND_URL) {
    this.baseUrl = baseUrl;
  }

  // 设置会话（同时持久化到 localStorage）
  setSession(sessionId: string) {
    this.sessionId = sessionId;
    // 持久化到 localStorage
    if (typeof window !== 'undefined') {
      localStorage.setItem('session_id', sessionId);
    }
  }

  // 设置用户信息
  setUserInfo(userInfo: UserInfo) {
    this.userInfo = userInfo;
    // 持久化到 localStorage
    if (typeof window !== 'undefined') {
      localStorage.setItem('userInfo', JSON.stringify(userInfo));
    }
  }

  // 获取用户信息
  getUserInfo(): UserInfo | null {
    return this.userInfo;
  }

  // 根据角色获取 MCP URL
  getMcpUrl(): string {
    if (!this.userInfo) {
      return '/mcp/'; // 默认使用 User MCP
    }
    // admin 使用 Admin MCP，其他角色使用 User MCP
    return this.userInfo.role === 'admin' ? '/admin-mcp/' : '/mcp/';
  }

  // 设置 MCP Tokens
  setMcpTokens(tokens: Record<string, string>) {
    this.mcpTokens = { ...tokens };
  }

  // 获取请求头
  private getHeaders(): HeadersInit {
    const headers: HeadersInit = {
      'Content-Type': 'application/json',
    };

    // 携带所有已登录的 MCP Token
    const allMcpTokens = mcpTokenManager.getAllTokens();
    if (Object.keys(allMcpTokens).length > 0) {
      headers['X-MCP-Tokens'] = JSON.stringify(allMcpTokens);
    }

    return headers;
  }

  // 通用请求方法
  private async request<T>(
    endpoint: string,
    options: RequestInit = {}
  ): Promise<T> {
    const url = `${this.baseUrl}${endpoint}`;
    const response = await fetch(url, {
      ...options,
      headers: {
        ...this.getHeaders(),
        ...options.headers,
      },
    });

    if (!response.ok) {
      const error = await response.json().catch(() => ({ error: response.statusText }));
      throw new Error(error.error || error.detail || 'API request failed');
    }

    return response.json();
  }

  // 健康检查
  async health(): Promise<{ status: string; model: string; mcp_servers: string[] }> {
    return this.request('/health');
  }

  // 聊天（非流式）
  async chat(message: string, history: ChatMessage[] = []): Promise<ChatResponse> {
    // 构建请求体（包含组件定义）
    const requestBody = {
      message,
      history,
      // 发送可用组件列表给后端，实现动态组件注册
      componentsPrompt: catalog.prompt({ mode: 'inline' })
    };

    return this.request<ChatResponse>('/chat', {
      method: 'POST',
      body: serialize(requestBody),
    });
  }

  // 聊天（流式）- 返回 EventSource
  chatStream(message: string, history: ChatMessage[] = []): any {
    const url = new URL(`${this.baseUrl}/chat/stream`);
    const headers: Record<string, string> = {};

    if (this.sessionId) {
      headers['X-Session-ID'] = this.sessionId;
    }

    if (Object.keys(this.mcpTokens).length > 0) {
      headers['X-MCP-Tokens'] = JSON.stringify(this.mcpTokens);
    }

    // 构建请求体（包含组件定义）
    const body = {
      message,
      history,
      // 发送可用组件列表给后端，实现动态组件注册
      componentsPrompt: catalog.prompt({ mode: 'inline' })
    };

    // 使用 fetch 创建流式连接
    const eventSource = new EventSourcePolyfill(url.toString(), {
      headers,
      method: 'POST',
      body: JSON.stringify(body),
    });

    return eventSource;
  }

  // 使用 fetch 的流式请求
  async chatStreamFetch(
    message: string,
    history: ChatMessage[] = [],
    onEvent: (event: MessageEvent) => void,
    onError?: (error: Error) => void,
    onComplete?: () => void
  ): Promise<() => void> {
    const url = `${this.baseUrl}/chat/stream`;
    const controller = new AbortController();

    try {
      // 构建请求体（包含组件定义和启用状态）
      const requestBody = {
        message,
        history,
        // 发送可用组件列表给后端，实现动态组件注册
        componentsPrompt: catalog.prompt({ mode: 'inline' }),
        // 发送已启用的 MCP 列表，后端只获取这些 MCP 的工具
        enabledMcpList: mcpTokenManager.getEnabledMcpList()
      };

      const response = await fetch(url, {
        method: 'POST',
        headers: this.getHeaders(),
        body: JSON.stringify(requestBody),
        signal: controller.signal,
      });

      if (!response.ok) {
        throw new Error(`HTTP error! status: ${response.status}`);
      }

      const reader = response.body?.getReader();
      const decoder = new TextDecoder();

      if (!reader) {
        throw new Error('Response body is null');
      }

      let buffer = '';
      let currentEvent = 'message';  // 默认事件类型

      while (true) {
        const { done, value } = await reader.read();

        if (done) {
          onComplete?.();
          break;
        }

        buffer += decoder.decode(value, { stream: true });

        // 处理 SSE 事件
        const lines = buffer.split('\n');
        buffer = lines.pop() || '';

        for (const line of lines) {
          if (line.startsWith('event: ')) {
            // 提取事件类型
            currentEvent = line.slice(7).trim();
          } else if (line.startsWith('data: ')) {
            // 提取数据并使用当前事件类型
            const data = line.slice(6);
            try {
              onEvent(new MessageEvent(currentEvent, { data }));
            } catch (e) {
              console.error('Error parsing SSE data:', e);
            }
            // 重置事件类型为默认值
            currentEvent = 'message';
          }
        }
      }
    } catch (error) {
      if (error instanceof Error && error.name !== 'AbortError') {
        onError?.(error);
      }
    }

    return () => controller.abort();
  }

  // 获取 MCP 服务器列表
  async listMcpServers(): Promise<{ servers: MCPServer[] }> {
    return this.request('/mcp/servers');
  }

  // 获取 MCP 工具列表
  async listMcpTools(): Promise<MCPToolsResponse> {
    return this.request('/mcp/tools');
  }

  // 用户登录
  async login(email: string, password: string): Promise<LoginResponse> {
    const response = await this.request<LoginResponse>('/auth/login', {
      method: 'POST',
      body: JSON.stringify({ email, password }),
    });
    if (response.session_id) {
      this.setSession(response.session_id);
      // 保存用户信息
      this.setUserInfo({
        username: response.username,
        role: response.role || 'reader',
      });
    }
    return response;
  }

  // 管理员登录
  async adminLogin(email: string, password: string): Promise<LoginResponse> {
    const response = await this.request<LoginResponse>('/auth/admin-login', {
      method: 'POST',
      body: JSON.stringify({ email, password }),
    });
    if (response.session_id) {
      this.setSession(response.session_id);
      // 保存用户信息
      this.setUserInfo({
        username: response.username,
        role: response.role || 'admin',
      });
    }
    return response;
  }

  // 用户注册
  async register(email: string, username: string, password: string): Promise<{ success: boolean; message: string; user: unknown }> {
    return this.request('/auth/register', {
      method: 'POST',
      body: JSON.stringify({ email, username, password }),
    });
  }

  // 登出（同时清除 localStorage）
  async logout(): Promise<{ success: boolean }> {
    const response = await this.request<{ success: boolean }>('/auth/logout', {
      method: 'POST',
      body: JSON.stringify({ session_id: this.sessionId }),
    });
    this.sessionId = null;
    this.mcpTokens = {};
    this.userInfo = null;
    // 清除 localStorage
    if (typeof window !== 'undefined') {
      localStorage.removeItem('session_id');
      localStorage.removeItem('username');
      localStorage.removeItem('userInfo');
    }
    return response;
  }

  // 检查认证状态
  async authStatus(): Promise<AuthStatusResponse> {
    return this.request('/auth/status');
  }
}

// EventSource polyfill for POST requests
class EventSourcePolyfill {
  private url: string;
  private headers: Record<string, string>;
  private onmessage: ((event: MessageEvent) => void) | null = null;
  private onerror: ((event: Event) => void) | null = null;
  private eventSource: EventSource | null = null;

  constructor(url: string, options: { headers: Record<string, string>; method?: string; body?: string }) {
    this.url = url;
    this.headers = options.headers;
    // 简化实现 - 实际应用中需要更完整的 polyfill
    // 这里仅作为类型占位
  }

  addEventListener(type: string, listener: (event: MessageEvent) => void) {
    if (type === 'message') {
      this.onmessage = listener;
    }
  }

  close() {
    this.eventSource?.close();
  }
}

// 单例实例
export const apiClient = new ApiClient();