import axios, { type InternalAxiosRequestConfig } from 'axios'
import { parseApiJsonResponse } from '@chongchong/shared'
import { refreshAuthenticatedSession } from './http'

interface CachedOverseasToken {
  accessToken: string
  refreshAfter: number
}

type RetryableOverseasRequestConfig = InternalAxiosRequestConfig & { _overseasAuthRetry?: boolean }

const TOKEN_REFRESH_SAFETY_WINDOW_MS = 30_000

let cachedToken: CachedOverseasToken | null = null

export const overseasHttp = axios.create({
  baseURL: import.meta.env.VITE_OVERSEAS_API_BASE_URL || '/overseas-api',
  timeout: 15_000,
  transformResponse: [(data: unknown) => parseApiJsonResponse(data)],
})

function currentOverseasAccessToken() {
  return cachedToken && cachedToken.refreshAfter > Date.now() ? cachedToken.accessToken : ''
}

async function requireOverseasAccessToken() {
  const current = currentOverseasAccessToken()
  if (current) return current
  await refreshAuthenticatedSession()
  const refreshed = currentOverseasAccessToken()
  if (!refreshed) throw new Error('当前环境未签发海外访问令牌')
  return refreshed
}

export function replaceOverseasAccessToken(accessToken: string | null, expiresIn: number) {
  if (!accessToken && expiresIn === 0) {
    cachedToken = null
    return
  }
  if (!accessToken || !Number.isFinite(expiresIn) || expiresIn <= 0) {
    throw new Error('海外访问令牌响应无效')
  }
  cachedToken = {
    accessToken,
    refreshAfter: Date.now() + Math.max(0, expiresIn * 1000 - TOKEN_REFRESH_SAFETY_WINDOW_MS),
  }
}

export function clearOverseasAccessToken() {
  cachedToken = null
}

overseasHttp.interceptors.request.use(async (config) => {
  const accessToken = await requireOverseasAccessToken()
  config.headers.Authorization = `Bearer ${accessToken}`
  return config
})

overseasHttp.interceptors.response.use(
  (response) => response.data,
  async (error) => {
    const config = error.config as RetryableOverseasRequestConfig | undefined
    if (error.response?.status !== 401 || !config || config._overseasAuthRetry) {
      return Promise.reject(error)
    }
    config._overseasAuthRetry = true
    clearOverseasAccessToken()
    try {
      await refreshAuthenticatedSession()
      const accessToken = await requireOverseasAccessToken()
      config.headers.Authorization = `Bearer ${accessToken}`
      return overseasHttp.request(config)
    } catch {
      return Promise.reject(error)
    }
  },
)