import axios from 'axios'
import { useAuthStore } from '../store/auth'

export const api = axios.create({
  baseURL: '/',
  paramsSerializer: (params) => {
    const sp = new URLSearchParams()
    for (const [key, val] of Object.entries(params)) {
      if (val === undefined || val === null) continue
      if (Array.isArray(val)) {
        val.forEach((v) => sp.append(key, String(v)))
      } else {
        sp.append(key, String(val))
      }
    }
    return sp.toString()
  },
})

// Inject access token on every request
api.interceptors.request.use((config) => {
  const token = useAuthStore.getState().accessToken
  if (token) config.headers.Authorization = `Bearer ${token}`
  return config
})

// On 401 — try refresh once, then logout
let refreshing: Promise<string> | null = null

api.interceptors.response.use(
  (r) => r,
  async (error) => {
    const original = error.config
    if (error.response?.status !== 401 || original._retried) {
      return Promise.reject(error)
    }
    original._retried = true

    const { refreshToken, setTokens, clearTokens, username } = useAuthStore.getState()
    if (!refreshToken) {
      clearTokens()
      return Promise.reject(error)
    }

    if (!refreshing) {
      refreshing = axios
        .post('/api/v1/auth/refresh', { refresh_token: refreshToken })
        .then((r) => {
          setTokens(r.data.access_token, r.data.refresh_token, username ?? '')
          return r.data.access_token
        })
        .catch(() => {
          clearTokens()
          throw new Error('Session expired')
        })
        .finally(() => { refreshing = null })
    }

    const newToken = await refreshing
    original.headers.Authorization = `Bearer ${newToken}`
    return api(original)
  }
)