import axios, { AxiosInstance, AxiosRequestConfig, AxiosResponse, AxiosError } from 'axios'
import { ElMessage } from 'element-plus'
import router from '@/router'
import { getEnvConfig } from '@/config/env'

// 获取环境配置
const envConfig = getEnvConfig()

// 创建 axios 实例
const service: AxiosInstance = axios.create({
  baseURL: envConfig.baseURL,
  timeout: envConfig.timeout,
  headers: {
    'Content-Type': 'application/json;charset=UTF-8'
  }
})

// 请求拦截器
service.interceptors.request.use(
  (config) => {
    // 从 localStorage 获取 token
    const token = localStorage.getItem('token')
    if (token) {
      config.headers.Authorization = `Bearer ${token}`
    }
    return config
  },
  (error: AxiosError) => {
    console.error('请求错误：', error)
    return Promise.reject(error)
  }
)

// 响应拦截器
service.interceptors.response.use(
  (response: AxiosResponse) => {
    const res = response.data

    // 根据后端返回的状态码进行处理
    // 这里假设后端返回格式为 { code: number, data: any, message: string }
    if (res.code !== undefined && res.code !== 200 && res.code !== 0) {
      ElMessage.error(res.message || '请求失败')
      
      // 401: 未授权，跳转到登录页
      if (res.code === 401) {
        localStorage.removeItem('token')
        router.push('/login')
      }
      
      return Promise.reject(new Error(res.message || '请求失败'))
    }
    
    return res
  },
  (error: AxiosError) => {
    console.error('响应错误：', error)
    
    if (error.response) {
      const status = error.response.status
      
      switch (status) {
        case 401:
          ElMessage.error('未授权，请重新登录')
          localStorage.removeItem('token')
          router.push('/login')
          break
        case 403:
          ElMessage.error('拒绝访问')
          break
        case 404:
          ElMessage.error('请求的资源不存在')
          break
        case 500:
          ElMessage.error('服务器内部错误')
          break
        case 502:
          ElMessage.error('网关错误')
          break
        case 503:
          ElMessage.error('服务不可用')
          break
        case 504:
          ElMessage.error('网关超时')
          break
        default:
          ElMessage.error(error.message || '请求失败')
      }
    } else if (error.request) {
      ElMessage.error('网络错误，请检查网络连接')
    } else {
      ElMessage.error('请求配置错误')
    }
    
    return Promise.reject(error)
  }
)

// 通用请求方法
export interface ResponseData<T = unknown> {
  code: number
  data: T
  message: string
}

// GET 请求
export function get<T = unknown>(
  url: string,
  params?: unknown,
  config?: AxiosRequestConfig
): Promise<ResponseData<T>> {
  return service.get(url, { params, ...config })
}

// POST 请求
export function post<T = unknown>(
  url: string,
  data?: unknown,
  config?: AxiosRequestConfig
): Promise<ResponseData<T>> {
  return service.post(url, data, config)
}

// PUT 请求
export function put<T = unknown>(
  url: string,
  data?: unknown,
  config?: AxiosRequestConfig
): Promise<ResponseData<T>> {
  return service.put(url, data, config)
}

// DELETE 请求
export function del<T = unknown>(
  url: string,
  params?: unknown,
  config?: AxiosRequestConfig
): Promise<ResponseData<T>> {
  return service.delete(url, { params, ...config })
}

// 导出 axios 实例
export default service