import { ApiException, type ApiError } from './types'

const BASE = '' // 同源；dev 走 vite proxy
const DEFAULT_TIMEOUT_MS = 30_000

interface RequestOptions {
  method?: 'GET' | 'POST' | 'PATCH' | 'DELETE'
  body?: unknown
  signal?: AbortSignal
}

let authTokenProvider: () => string | null = () => null
let onUnauthorized: () => void = () => {}

export function configure(opts: {
  tokenProvider: () => string | null
  onUnauthorized: () => void
}) {
  authTokenProvider = opts.tokenProvider
  onUnauthorized = opts.onUnauthorized
}

export async function request<T>(path: string, opts: RequestOptions = {}): Promise<T> {
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    'X-Client-Request-ID': crypto.randomUUID(),
  }
  const token = authTokenProvider()
  if (token) headers['Authorization'] = `Bearer ${token}`

  const controller = new AbortController()
  const timer = setTimeout(() => controller.abort(), DEFAULT_TIMEOUT_MS)
  if (opts.signal) {
    if (opts.signal.aborted) {
      controller.abort()
    } else {
      opts.signal.addEventListener('abort', () => controller.abort(), { once: true })
    }
  }

  try {
    const resp = await fetch(BASE + path, {
      method: opts.method || 'GET',
      headers,
      body: opts.body !== undefined ? JSON.stringify(opts.body) : undefined,
      signal: controller.signal,
    })

    if (resp.status === 401) {
      onUnauthorized()
    }

    if (resp.status === 204) {
      return undefined as T
    }

    const text = await resp.text()
    const data = text ? JSON.parse(text) : null

    if (!resp.ok) {
      throw new ApiException(
        resp.status,
        (data as ApiError) || { code: 'unknown', message: resp.statusText },
      )
    }
    return data as T
  } finally {
    clearTimeout(timer)
  }
}