import axios, { AxiosError, AxiosHeaders, type AxiosInstance, type AxiosResponse, type InternalAxiosRequestConfig } from 'axios'
import { jwtDecode } from 'jwt-decode'
import Cookies from 'js-cookie'

import type { UserStorageData, DecodedToken } from '@/types'
import { buildGuestLoginRedirect, CONSUMER_SESSION_EXPIRED_EVENT } from '@/lib/authRouting'
import { reportBrowserEvent } from '@/lib/observability/client'
import { parseRefreshExpiry } from '@/lib/refreshTokenExpiry'
import { localizeApiErrorPayload } from '@/services/apiErrorLocalization'
import { setAccountSuspended } from '@/lib/accountSuspension'
import { applyFormDataRequestDefaults } from '@/lib/formDataRequest'
import { expireRefreshSessionOnThisOrigin } from '@/lib/expireRefreshSession'

const resolveApiBaseUrl = (raw?: string): string | undefined => {
  if (!raw) return undefined

  const trimmed = raw.replace(/\/+$/, '')

  if (trimmed.endsWith('/api/v1')) return `${trimmed}/`

  return `${trimmed}/api/v1/`
}

const AUTH_CONFIG = {
  baseURL: resolveApiBaseUrl(process.env.NEXT_PUBLIC_API_URL),
  cookieName: 'accessToken',
  /** Legacy JS-readable cookie from the abandoned body-token model — remove only. */
  legacyRefreshCookieName: 'refreshToken',
  localStorageKey: 'user',
  refreshPath: 'auth/refresh',
}

const TOKEN_MESSAGES = {
  accessInvalid: new Set(['ACCESS_TOKEN_INVALID', 'ACCESS_TOKEN_EXPIRED', 'UNAUTHORIZED']),
  refreshInvalid: new Set(['REFRESH_TOKEN_INVALID', 'REFRESH_TOKEN_EXPIRED', 'UNAUTHORIZED']),
}

type RequestConfigWithRetry = InternalAxiosRequestConfig & { _retry?: boolean }

interface RefreshApiResponse {
  success: boolean
  data?: {
    accessToken: string
    sessionId?: string
    expiresAt?: string
  }
  body?: {
    accessToken: string
    sessionId?: string
    expiresAt?: string
  }
  message?: string
  code?: string
}

const isClient = typeof window !== 'undefined'
let refreshPromise: Promise<string | null> | null = null
let sessionExpiryInFlight = false

/**
 * صفر کردن state ماژول‌سطح axios (مثلاً بین تست‌ها، یا بعد از ورود مجدد نرم
 * بدون hard navigation که ماژول را از نو لود کند).
 */
export const resetAxiosAuthModuleState = (): void => {
  refreshPromise = null
  sessionExpiryInFlight = false
}

const isTokenExpired = (expireTime: number): boolean => Date.now() >= expireTime

const redirectToLogin = (): void => {
  if (!isClient) return

  // Admin session expiry → `/auth`. Consumer/host → home + AuthGate modal.
  const target = buildGuestLoginRedirect(window.location.origin, window.location.pathname, window.location.search)
  const targetUrl = `${target.pathname}${target.search}`

  if (target.pathname === '/auth' || target.pathname.startsWith('/auth/')) {
    window.location.replace(targetUrl)

    return
  }

  window.dispatchEvent(new CustomEvent(CONSUMER_SESSION_EXPIRED_EVENT, { detail: { targetUrl } }))
}

const clearAuthData = (): void => {
  if (!isClient) return
  localStorage.removeItem(AUTH_CONFIG.localStorageKey)
  Cookies.remove(AUTH_CONFIG.cookieName)
  Cookies.remove(AUTH_CONFIG.legacyRefreshCookieName)
  Cookies.remove('userStatus')
  Cookies.remove('userRole')
}

const handleSessionExpired = async (): Promise<never> => {
  if (sessionExpiryInFlight) {
    throw new AxiosError('نشست منقضی شده است')
  }

  sessionExpiryInFlight = true
  try {
    clearAuthData()
    window.dispatchEvent(new Event('userChanged'))
    await expireRefreshSessionOnThisOrigin()
    redirectToLogin()
    throw new AxiosError('نشست منقضی شده است')
  } finally {
    // بعد از اتمام این دور، ورود مجدد نرم (AuthGate بدون reload) باید بتواند
    // دوباره مسیر expiry را طی کند؛ تست‌ها هم به همین دلیل flaky بودند.
    sessionExpiryInFlight = false
  }
}

const tryRefreshAccessToken = async (): Promise<string | null> => {
  try {
    return await getOrRefreshAccessToken()
  } catch {
    return null
  }
}

const createStorageData = (
  accessToken: string,
  decodedAccess: DecodedToken,
  refreshExpireTime: number,
  sessionId?: string
): UserStorageData => ({
  accessToken,
  userId: decodedAccess.sub,
  role: decodedAccess.role,
  sessionId,
  AccessTokenExpireTime: decodedAccess.exp * 1000,
  refreshTokenExpireTime: refreshExpireTime,
})

const persistUserStorage = (next: UserStorageData & Record<string, unknown>): void => {
  const { refreshToken: _legacyRefreshToken, ...sanitized } = next as UserStorageData & {
    refreshToken?: unknown
  }

  void _legacyRefreshToken
  localStorage.setItem(AUTH_CONFIG.localStorageKey, JSON.stringify(sanitized))
}

const setAccessCookie = (token: string, cookieExpiryTime: number): void => {
  const expireInSeconds = Math.floor((cookieExpiryTime - Date.now()) / 1000)

  if (expireInSeconds <= 0) return
  Cookies.set(AUTH_CONFIG.cookieName, token, { expires: expireInSeconds / 86400, sameSite: 'lax' })
}

const getStoredUser = (): (UserStorageData & Record<string, unknown>) | null => {
  if (!isClient) return null
  const raw = localStorage.getItem(AUTH_CONFIG.localStorageKey)

  if (!raw) return null

  try {
    return JSON.parse(raw) as UserStorageData & Record<string, unknown>
  } catch {
    return null
  }
}

/**
 * Refresh sends the Nest httpOnly cookie via `withCredentials` — JS cannot
 * read that cookie. Guests (no stored session and no access cookie) must
 * never hit `auth/refresh`. Do not gate on `refreshTokenExpireTime`; the
 * httpOnly cookie is the source of truth.
 */
const canAttemptTokenRefresh = (): boolean => {
  if (!isClient) return false

  const userData = getStoredUser()

  if (userData?.accessToken || userData?.userId) return true

  return Boolean(Cookies.get(AUTH_CONFIG.cookieName))
}

const isTransientRefreshFailure = (error: unknown): boolean => axios.isAxiosError(error) && !error.response

const refreshAccessToken = async (): Promise<string | null> => {
  if (!canAttemptTokenRefresh()) return null

  const userData = getStoredUser()
  const url = new URL(AUTH_CONFIG.refreshPath, AUTH_CONFIG.baseURL)
  let data: RefreshApiResponse

  const requestRefresh = () =>
    axios.post<RefreshApiResponse>(
      url.href,
      {},
      {
        withCredentials: true,
        headers: {
          'Content-Type': 'application/json',
        },
      }
    )

  try {
    data = (await requestRefresh()).data
  } catch (error) {
    // A VPN reconnect can drop the response after the server has already
    // rotated the httpOnly cookie. The API permits one device-bound recovery
    // retry in that short window; never retry HTTP responses.
    if (isTransientRefreshFailure(error)) {
      data = (await requestRefresh()).data
    } else {
      if (
        axios.isAxiosError(error) &&
        error.response?.status === 403 &&
        (error.response.data as { code?: string } | undefined)?.code === 'ACCOUNT_SUSPENDED'
      ) {
        setAccountSuspended(true)
      }

      throw error
    }
  }

  const tokens = data.success ? (data.data ?? data.body) : null

  if (!tokens?.accessToken) {
    throw new Error(data.message ?? 'پاسخ تمدید نشست معتبر نیست')
  }

  const decodedAccess = jwtDecode<DecodedToken>(tokens.accessToken)
  const refreshExpireTime = parseRefreshExpiry(tokens.expiresAt)

  const tokenStorage = createStorageData(tokens.accessToken, decodedAccess, refreshExpireTime, tokens.sessionId)

  persistUserStorage({ ...userData, ...tokenStorage })
  setAccessCookie(tokens.accessToken, decodedAccess.exp * 1000)

  // `localStorage.setItem` only fires the native `storage` event in *other*
  // tabs, not this one — AuthContext's `user` state (and anything derived
  // from it, e.g. the chat WebSocket's auth token in useChatSocket) would
  // otherwise stay stale until a full page reload. See docs/prompt/_shared.md.
  if (isClient) window.dispatchEvent(new Event('userChanged'))

  return tokens.accessToken
}

/**
 * Exported so `AuthContext` can call this proactively (before the short-lived
 * access token expires) instead of only reactively on a 401. See the
 * scheduler in AuthContext.tsx for why that matters — proxy.ts checks the
 * `accessToken` cookie and the Nest httpOnly refresh cookie on every
 * navigation, including soft ones, and a stale access cookie there forces a
 * full-page reload.
 *
 * Never rejects: refresh failures resolve to `null` so fire-and-forget callers
 * cannot leak `unhandledrejection` (Sentry). Use
 * `refreshAccessTokenProactively` when a failed rotation should soft-expire
 * the session instead of only returning null.
 */
export const getOrRefreshAccessToken = async (): Promise<string | null> => {
  refreshPromise ??= refreshAccessToken()
    .catch(() => null)
    .finally(() => {
      refreshPromise = null
    })

  return refreshPromise
}

/**
 * Proactive access-token rotation for the AuthContext expiry timer.
 * On failure runs the same soft session-expiry path as a 401 interceptor
 * (clear local auth, expire refresh cookie, open AuthGate / `/auth`).
 * Never rejects — safe for `void refreshAccessTokenProactively()`.
 */
export const refreshAccessTokenProactively = async (): Promise<void> => {
  const token = await getOrRefreshAccessToken()

  if (token) return

  try {
    await handleSessionExpired()
  } catch {
    // handleSessionExpired always throws after cleanup; swallow for timers.
  }
}

const axiosInstance: AxiosInstance = axios.create({
  baseURL: AUTH_CONFIG.baseURL,
  withCredentials: true,
})

function attachAuthorization(config: InternalAxiosRequestConfig, token: string, cookieExpiryTime?: number): InternalAxiosRequestConfig {
  const headers = AxiosHeaders.from(config.headers)

  headers.set('Authorization', `Bearer ${token}`)
  config.headers = headers
  if (cookieExpiryTime) setAccessCookie(token, cookieExpiryTime)

  return config
}

/**
 * Relative `url` values resolve against our API `baseURL` and are always
 * treated as same-origin backend requests (JWT attached). Absolute URLs are
 * only same-backend when their origin matches `NEXT_PUBLIC_API_URL` — used so
 * bearer tokens are never sent to unrelated hosts.
 */
function isSameBackendRequest(config: { url?: string }): boolean {
  const url = config.url ?? ''

  if (!/^https?:\/\//i.test(url)) return true

  const apiBaseUrl = AUTH_CONFIG.baseURL

  if (!apiBaseUrl) return false

  try {
    return new URL(url).origin === new URL(apiBaseUrl).origin
  } catch {
    return false
  }
}

async function handleUserWithStorageToken(config: InternalAxiosRequestConfig): Promise<InternalAxiosRequestConfig> {
  const userData = getStoredUser()

  if (!userData?.accessToken) return config

  const { accessToken, AccessTokenExpireTime } = userData

  // Queue new requests while token refresh is in flight (including 401 path)
  if (refreshPromise) {
    const refreshedToken = await tryRefreshAccessToken()

    if (!refreshedToken) {
      return handleSessionExpired()
    }

    return attachAuthorization(config, refreshedToken)
  }

  if (!isTokenExpired(AccessTokenExpireTime)) {
    return attachAuthorization(config, accessToken, AccessTokenExpireTime)
  }

  const newToken = await tryRefreshAccessToken()

  if (!newToken) {
    return handleSessionExpired()
  }

  axiosInstance.defaults.headers.Authorization = `Bearer ${newToken}`

  return attachAuthorization(config, newToken)
}

async function handleUserWithCookieToken(
  config: InternalAxiosRequestConfig,
  accessTokenCookie: string
): Promise<InternalAxiosRequestConfig> {
  try {
    const decodedAccessToken = jwtDecode<DecodedToken>(accessTokenCookie)

    if (!isTokenExpired(decodedAccessToken.exp * 1000)) {
      return attachAuthorization(config, accessTokenCookie, decodedAccessToken.exp * 1000)
    }
  } catch {
    // Fall through to refresh when the cookie JWT is malformed/expired.
  }

  // Cookie-only sessions (no localStorage user yet) must still rotate via
  // the httpOnly refresh cookie before clearing auth — otherwise an expired
  // access cookie logs the user out even when refresh is still valid.
  if (!canAttemptTokenRefresh()) {
    return handleSessionExpired()
  }

  const newToken = await tryRefreshAccessToken()

  if (!newToken) {
    return handleSessionExpired()
  }

  axiosInstance.defaults.headers.Authorization = `Bearer ${newToken}`

  return attachAuthorization(config, newToken)
}

axiosInstance.interceptors.request.use(
  async (config: InternalAxiosRequestConfig) => {
    if (!isSameBackendRequest(config)) {
      config.withCredentials = false

      return config
    }
    config.withCredentials = true
    applyFormDataRequestDefaults(config)
    if (!isClient) return config

    const userData = getStoredUser()

    if (userData?.accessToken) return handleUserWithStorageToken(config)

    const accessTokenCookie = Cookies.get(AUTH_CONFIG.cookieName)

    if (accessTokenCookie) return handleUserWithCookieToken(config, accessTokenCookie)

    return config
  },
  (error: AxiosError) => Promise.reject(error)
)

const isRefreshTokenRequest = (config?: InternalAxiosRequestConfig): boolean => (config?.url ?? '').includes('auth/refresh')

const getErrorMessage = (error: AxiosError): string => {
  const data = error.response?.data as { message?: string; code?: string } | undefined

  return data?.code ?? data?.message ?? ''
}

const shouldTryRefreshFor401 = (error: AxiosError, config: RequestConfigWithRetry): boolean => {
  if (isRefreshTokenRequest(config)) return false
  if (config._retry) return false
  if (!canAttemptTokenRefresh()) return false

  const message = getErrorMessage(error)

  if (TOKEN_MESSAGES.refreshInvalid.has(message) && isRefreshTokenRequest(config)) return false
  if (!message) return true

  return TOKEN_MESSAGES.accessInvalid.has(message) || message === 'Unauthorized'
}

async function handle401Response(error: AxiosError): Promise<AxiosResponse> {
  const config = error.config as RequestConfigWithRetry | undefined

  if (!config) {
    return Promise.reject(error)
  }

  if (isRefreshTokenRequest(config)) {
    return handleSessionExpired()
  }

  if (!shouldTryRefreshFor401(error, config)) {
    return Promise.reject(error)
  }

  config._retry = true

  try {
    const newToken = await tryRefreshAccessToken()

    if (!newToken) throw new Error('تمدید نشست ناموفق بود')

    config.headers = AxiosHeaders.from(config.headers).set('Authorization', `Bearer ${newToken}`)

    return await axiosInstance.request(config)
  } catch (_refreshError) {
    return handleSessionExpired()
  }
}

axiosInstance.interceptors.response.use(
  (response: AxiosResponse) => {
    const path = (response.config.url ?? '').split('?')[0]

    // A successful authenticated profile request is authoritative: the
    // account has been reactivated since the suspension was first observed.
    if (/\/?users\/me\/?$/.test(path)) setAccountSuspended(false)

    return response
  },
  async (error: AxiosError) => {
    const rawPath = (error.config?.url ?? 'unknown').split('?')[0]
    const endpoint = rawPath.replace(/\b[0-9a-f]{8}-[0-9a-f-]{27,}\b/gi, ':id').replace(/\/\d+(?=\/|$)/g, '/:id')

    const status = error.response?.status ?? 0

    if (status === 403 && getErrorMessage(error) === 'ACCOUNT_SUSPENDED') {
      setAccountSuspended(true)
    }

    // Only surface server/network failures to Sentry — expected 4xx (auth,
    // validation, not-found) would otherwise flood Issues.
    if (!error.response || status >= 500) {
      reportBrowserEvent({
        name: 'api_failure',
        level: 'error',
        attributes: {
          endpoint: endpoint.slice(0, 160),
          method: error.config?.method?.toUpperCase() ?? 'UNKNOWN',
          status,
        },
      })
    }

    if (error.response?.status === 401 && isSameBackendRequest(error.config ?? {})) {
      try {
        return await handle401Response(error)
      } catch (refreshError) {
        if (refreshError instanceof AxiosError && refreshError.response) {
          refreshError.response.data = localizeApiErrorPayload(refreshError.response.data, refreshError.response.status)
        }

        return Promise.reject(refreshError instanceof Error ? refreshError : new Error('تمدید نشست ناموفق بود'))
      }
    }

    if (error.response) {
      error.response.data = localizeApiErrorPayload(error.response.data, error.response.status)
    }

    return Promise.reject(error)
  }
)

export default axiosInstance