import { ApiError } from '@typings/api';

const BASE_URL = '/api';
const DEFAULT_TIMEOUT = 30000;

interface RequestOptions {
  method?: 'GET' | 'POST' | 'PUT' | 'DELETE';
  body?: any;
  headers?: Record<string, string>;
  timeout?: number;
}

class ApiClient {
  private baseUrl: string;

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

  private async handleResponse<T>(response: Response): Promise<T> {
    if (!response.ok) {
      let errorMessage = '请求失败';

      if (response.status === 401) {
        errorMessage = '未授权，请重新登录';
      } else if (response.status === 403) {
        errorMessage = '没有权限执行此操作';
      } else if (response.status === 404) {
        errorMessage = '请求的资源不存在';
      } else if (response.status >= 500) {
        errorMessage = '服务器错误，请稍后重试';
      } else {
        try {
          const errorData = await response.json();
          errorMessage = errorData.detail || errorData.message || errorMessage;
        } catch {
          // 无法解析错误详情
        }
      }

      throw new ApiError(response.status, errorMessage);
    }

    const contentType = response.headers.get('content-type');
    if (contentType?.includes('application/json')) {
      return response.json();
    }
    return {} as T;
  }

  async request<T>(path: string, options: RequestOptions = {}): Promise<T> {
    const { method = 'GET', body, headers = {}, timeout = DEFAULT_TIMEOUT } = options;

    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), timeout);

    const config: RequestInit = {
      method,
      headers: {
        'Content-Type': 'application/json',
        ...headers,
      },
      signal: controller.signal,
    };

    if (body && method !== 'GET') {
      config.body = JSON.stringify(body);
    }

    try {
      const response = await fetch(`${this.baseUrl}${path}`, config);
      clearTimeout(timeoutId);
      return this.handleResponse<T>(response);
    } catch (error: any) {
      clearTimeout(timeoutId);

      if (error.name === 'AbortError') {
        throw new ApiError(0, '请求超时，请检查网络连接');
      }

      if (!error.status) {
        throw new ApiError(0, '网络错误，请检查网络连接');
      }

      throw error;
    }
  }

  async get<T>(path: string): Promise<T> {
    return this.request<T>(path);
  }

  async post<T>(path: string, body?: any): Promise<T> {
    return this.request<T>(path, { method: 'POST', body });
  }

  async put<T>(path: string, body?: any): Promise<T> {
    return this.request<T>(path, { method: 'PUT', body });
  }

  async delete<T>(path: string): Promise<T> {
    return this.request<T>(path, { method: 'DELETE' });
  }

  async upload<T>(path: string, formData: FormData): Promise<T> {
    const response = await fetch(`${this.baseUrl}${path}`, {
      method: 'POST',
      body: formData,
    });

    return this.handleResponse<T>(response);
  }
}

export const apiClient = new ApiClient();