import { useEffect, useRef, useState, useCallback } from 'react'
import * as SecureStore from 'expo-secure-store'
import { API_BASE } from '../constants/Config'

const WS_BASE = API_BASE.replace('https://', 'wss://').replace('http://', 'ws://')

export interface WSEvent {
  event_type: string
  data:       Record<string, unknown>
  timestamp:  string
}

export function useWebSocket(channels: string[] = []) {
  const [connected,   setConnected]   = useState(false)
  const [lastEvent,   setLastEvent]   = useState<WSEvent | null>(null)
  const [events,      setEvents]      = useState<WSEvent[]>([])
  const ws = useRef<WebSocket | null>(null)
  const retry = useRef<ReturnType<typeof setTimeout> | null>(null)

  const connect = useCallback(async () => {
    const token = await SecureStore.getItemAsync('grd_token')
    if (!token) return

    const url = `${WS_BASE}/ws/events?token=${token}`
    try {
      ws.current = new WebSocket(url)

      ws.current.onopen = () => {
        setConnected(true)
        // 채널 구독 메시지 전송
        if (channels.length > 0 && ws.current) {
          ws.current.send(JSON.stringify({ subscribe: channels }))
        }
      }

      ws.current.onmessage = (e) => {
        try {
          const evt: WSEvent = JSON.parse(e.data)
          setLastEvent(evt)
          setEvents(prev => [evt, ...prev].slice(0, 50)) // 최근 50개 유지
        } catch {}
      }

      ws.current.onclose = () => {
        setConnected(false)
        // 5초 후 재연결
        retry.current = setTimeout(connect, 5000)
      }

      ws.current.onerror = () => {
        ws.current?.close()
      }
    } catch {}
  }, [])

  useEffect(() => {
    connect()
    return () => {
      if (retry.current) clearTimeout(retry.current)
      ws.current?.close()
    }
  }, [connect])

  const send = useCallback((data: object) => {
    if (ws.current?.readyState === WebSocket.OPEN) {
      ws.current.send(JSON.stringify(data))
    }
  }, [])

  return { connected, lastEvent, events, send }
}