/**
 * 共享 HTTP 客户端(公开站 + Admin 统一)
 *
 * 特性:
 *   - 统一超时(默认 30s,可覆盖)
 *   - 统一错误处理(ApiError)
 *   - 401 自动广播(Admin 场景)
 *   - JSON/HTML 容错解析
 *   - 请求竞态防护(可选 signal)
 */

import { UNAUTHORIZED_EVENT } from '../admin/api'

const API_BASE = '/api/v1'
const DEFAULT_TIMEOUT = 30_000

export class ApiError extends Error {
  constructor(
    message: string,
    public status: number,
    public data?: unknown,
  ) {
    super(message)
    this.name = 'ApiError'
  }
}

interface RequestOptions {
  timeoutMs?: number
  skipAuthHandling?: boolean
  signal?: AbortSignal
  method?: string
  body?: string
}

async function request<T>(path: string, options: RequestOptions = {}): Promise<T> {
  const url = path.startsWith('http') ? path : path.startsWith('/') ? path : `${API_BASE}${path}`
  const { timeoutMs = DEFAULT_TIMEOUT, skipAuthHandling, signal } = options

  const controller = new AbortController()
  const timer = setTimeout(() => controller.abort(), timeoutMs)

  // 如果外部传了 signal,也关联到内部 controller
  if (signal) {
    signal.addEventListener('abort', () => controller.abort(), { once: true })
  }

  try {
    const res = await fetch(url, {
      signal: controller.signal,
      headers: { 'Content-Type': 'application/json' },
    })

    if (!res.ok) {
      const rawText = await res.text()
      let detail: unknown = rawText
      try {
        detail = JSON.parse(rawText)
      } catch {
        // 非 JSON(如 HTML 错误页),保留原始文本
      }
      let message =
        detail && typeof detail === 'object' && detail !== null && 'detail' in detail
          ? String((detail as { detail: unknown }).detail)
          : `HTTP ${res.status}: ${res.statusText}`

      if (res.status === 401 && !skipAuthHandling) {
        message += '\n登录已过期,请重新登录。'
        window.dispatchEvent(new CustomEvent(UNAUTHORIZED_EVENT))
      }
      throw new ApiError(message, res.status, detail)
    }

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

    return res.json() as Promise<T>
  } catch (err) {
    if (err instanceof ApiError) throw err
    if (err instanceof DOMException && err.name === 'AbortError') {
      throw new ApiError('请求超时,请稍后重试', 0)
    }
    throw new ApiError(
      err instanceof Error ? err.message : '网络错误,请检查连接',
      0,
    )
  } finally {
    clearTimeout(timer)
  }
}

export const http = {
  get: <T>(path: string, opts?: RequestOptions) => request<T>(path, { ...opts }),
  post: <T>(path: string, body?: unknown, opts?: RequestOptions) =>
    request<T>(path, { ...opts, method: 'POST', body: body ? JSON.stringify(body) : undefined }),
  put: <T>(path: string, body?: unknown, opts?: RequestOptions) =>
    request<T>(path, { ...opts, method: 'PUT', body: body ? JSON.stringify(body) : undefined }),
  delete: <T>(path: string, opts?: RequestOptions) => request<T>(path, { ...opts, method: 'DELETE' }),
}