import axios from 'axios'
import { ElMessage } from 'element-plus'
import { authStore } from '@/utils/auth'

const api = axios.create({
  baseURL: '/api/v1',
  timeout: 30000,
  headers: {
    'Content-Type': 'application/json'
  }
})

// 请求拦截器：自动带 Authorization header
api.interceptors.request.use(
  config => {
    const token = authStore.getAccessToken()
    if (token) {
      config.headers = config.headers || {}
      config.headers.Authorization = `Bearer ${token}`
    }
    return config
  },
  error => Promise.reject(error)
)

// 标记正在刷新 token，防止并发 401 触发多次刷新
let isRefreshing = false
let pendingQueue = []

function flushQueue(newToken) {
  pendingQueue.forEach(cb => cb(newToken))
  pendingQueue = []
}

function queueRefresh(cb) {
  pendingQueue.push(cb)
}

// 响应拦截器：401 时尝试 refresh token；refresh 失败就跳登录
api.interceptors.response.use(
  response => {
    return response.data
  },
  async error => {
    const originalRequest = error.config || {}
    const status = error.response?.status
    const detail = error.response?.data?.detail

    // 401 且不是 login/refresh 本身：尝试刷新 token
    if (status === 401 && !originalRequest._retry && !originalRequest.url?.includes('/auth/')) {
      const refreshToken = authStore.getRefreshToken()
      if (!refreshToken) {
        authStore.clear()
        redirectToLogin()
        return Promise.reject(error)
      }

      if (isRefreshing) {
        // 已有刷新请求在进行，等它完成后再重试
        return new Promise(resolve => {
          queueRefresh(newToken => {
            if (newToken) {
              originalRequest._retry = true
              originalRequest.headers.Authorization = `Bearer ${newToken}`
              resolve(api(originalRequest))
            } else {
              redirectToLogin()
              resolve(Promise.reject(error))
            }
          })
        })
      }

      originalRequest._retry = true
      isRefreshing = true
      try {
        const formBody = new URLSearchParams()
        formBody.append('refresh_token', refreshToken)
        const resp = await axios.post('/api/v1/auth/refresh', formBody, {
          headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
        })
        const newToken = resp.data?.access_token
        if (newToken) {
          authStore.setAccessToken(newToken)
          if (resp.data?.refresh_token) {
            authStore.setRefreshToken(resp.data.refresh_token)
          }
          isRefreshing = false
          flushQueue(newToken)
          originalRequest.headers.Authorization = `Bearer ${newToken}`
          return api(originalRequest)
        } else {
          throw new Error('refresh 响应缺少 access_token')
        }
      } catch (refreshErr) {
        isRefreshing = false
        flushQueue(null)
        authStore.clear()
        redirectToLogin()
        return Promise.reject(refreshErr)
      }
    }

    // 非 401 或 refresh 后仍失败的：弹 toast（保持原行为，避免 view 重复弹）
    console.error('API Error:', error)
    ElMessage.error(typeof detail === 'string' ? detail : '请求失败')
    return Promise.reject(error)
  }
)

function redirectToLogin() {
  if (typeof window !== 'undefined' && window.location.pathname !== '/login') {
    const next = encodeURIComponent(window.location.pathname + window.location.search)
    window.location.href = `/login?next=${next}`
  }
}

export default api