import { ref } from 'vue'
import { SseClient } from './SseClient.ts'
import type { SseEvents } from './sseBus.ts'
import { sseBus } from './sseBus.ts'
import { useAccountStore } from '@/stores'

/** SSE 连接 URL */
const SSE_URL = '/api/sse/subscribe'

/** 是否正在刷新 token（防并发） */
let isRefreshing = false

// ==================== 模块级单例 ====================

const isConnected = ref(false)

const client = new SseClient(SSE_URL, () => useAccountStore().accessToken, {
  onConnected() {
    isConnected.value = true
    sseBus.emit('connected', undefined)
  },
  onMessage(event: string, data: string) {
    try {
      const payload = JSON.parse(data)
      sseBus.emit(event as keyof SseEvents, payload)
    } catch {
      console.warn('[SSE] 事件数据解析失败:', event, data)
    }
  },
  onError(message: string) {
    sseBus.emit('error', { message, retryCount: 0 })
  },
  onUnauthorized() {
    void refreshTokenAndReconnect()
  }
})

// ==================== Token 刷新 ====================

async function refreshTokenAndReconnect(): Promise<void> {
  if (isRefreshing) return

  const accountStore = useAccountStore()
  if (!accountStore.refreshToken) {
    sseBus.emit('error', { message: '登录已过期，请重新登录', retryCount: 0 })
    return
  }

  isRefreshing = true
  try {
    const newToken = await accountStore.refreshAccessToken()
    if (newToken) {
      await client.connect()
    }
  } catch {
    sseBus.emit('error', { message: '实时连接异常，请刷新页面', retryCount: 0 })
  } finally {
    isRefreshing = false
  }
}

// ==================== Composable ====================

/**
 * 全局 SSE 连接管理
 *
 * SseClient 只管连接生命周期，业务消息通过 sseBus 分发。
 * 组件只需 `useSse().connect()` / `useSse().disconnect()`。
 */
export function useSse() {
  return {
    isConnected,
    connect: () => client.connect(),
    disconnect: () => {
      client.disconnect()
      isConnected.value = false
    }
  }
}