import {
  buildSsoRedirectUrl,
  isJwtExpired,
  isReturnToAllowed,
  readJwtPayload,
  type LoginResponse,
  type MeResponse,
} from '@authportal/shared'

const TOKEN_KEY = 'authportal_token'

/** Fallback if /api/v1/auth/config unavailable (dev). Includes `private` for LAN SSO. */
export const DEFAULT_RETURN_TO_ALLOWLIST =
  '.shnt.top,localhost,private,http://localhost:5173'

let returnToAllowlist: string | null = null
let returnToAllowlistPromise: Promise<string> | null = null

export async function ensureReturnToAllowlist(): Promise<string> {
  if (returnToAllowlist) return returnToAllowlist
  if (returnToAllowlistPromise) return returnToAllowlistPromise

  returnToAllowlistPromise = (async () => {
    const fromVite = import.meta.env.VITE_RETURN_TO_ALLOWLIST as
      | string
      | undefined
    try {
      const res = await fetch('/api/v1/auth/config')
      if (res.ok) {
        const data = (await res.json()) as { return_to_allowlist?: string }
        if (data.return_to_allowlist) {
          returnToAllowlist = data.return_to_allowlist
          return returnToAllowlist
        }
      }
    } catch {
      /* ignore */
    }
    returnToAllowlist = fromVite || DEFAULT_RETURN_TO_ALLOWLIST
    return returnToAllowlist
  })().finally(() => {
    returnToAllowlistPromise = null
  })

  return returnToAllowlistPromise
}

export function getToken(): string | null {
  const token = localStorage.getItem(TOKEN_KEY)
  if (!token) return null
  if (isJwtExpired(token)) {
    localStorage.removeItem(TOKEN_KEY)
    return null
  }
  return token
}

export function setToken(token: string) {
  localStorage.setItem(TOKEN_KEY, token)
}

export function clearToken() {
  localStorage.removeItem(TOKEN_KEY)
}

/** True when stored JWT claims disagree with live /me (DB). */
export function jwtClaimsStaleVsMe(token: string, me: MeResponse): boolean {
  const payload = readJwtPayload(token)
  if (!payload) return true
  if (Boolean(payload.is_admin) !== Boolean(me.is_admin)) return true
  const claimApps = Array.isArray(payload.apps)
    ? payload.apps.map(String).sort().join(',')
    : ''
  const meApps = [...me.apps].map(String).sort().join(',')
  if (claimApps !== meApps) return true
  const claimPerms = Array.isArray(payload.permissions)
    ? payload.permissions.map(String).sort().join(',')
    : ''
  const mePerms = [...me.permissions].map(String).sort().join(',')
  if (claimPerms !== mePerms) return true
  return false
}

/**
 * Re-mint access token from API (current DB rights) and store it.
 * Always use before SSO handoff so apps never get a stale user JWT.
 */
export async function reissueAccessToken(): Promise<LoginResponse> {
  const token = getToken()
  if (!token) {
    throw new Error('Нет сессии')
  }
  const res = await fetch('/api/v1/auth/reissue', {
    method: 'POST',
    headers: {
      Authorization: `Bearer ${token}`,
      Accept: 'application/json',
    },
  })
  if (!res.ok) {
    clearToken()
    throw new Error('Не удалось обновить сессию')
  }
  const body = (await res.json()) as LoginResponse
  setToken(body.access_token)
  return body
}

/** SSO open: fresh JWT → app /auth/callback. */
export async function ssoOpenApp(appBaseUrl: string): Promise<void> {
  const base = appBaseUrl.replace(/\/$/, '')
  const issued = await reissueAccessToken()
  const callback = `${base}/auth/callback`
  window.location.href = buildSsoRedirectUrl(
    callback,
    issued.access_token,
    issued.expires_at,
  )
}

/** SSO return_to handoff with fresh JWT. */
export async function ssoHandoffReturnTo(returnTo: string): Promise<boolean> {
  const allowlist = await ensureReturnToAllowlist()
  if (!isReturnToAllowed(returnTo, allowlist)) return false
  const issued = await reissueAccessToken()
  window.location.href = buildSsoRedirectUrl(
    returnTo,
    issued.access_token,
    issued.expires_at,
  )
  return true
}