"use client"

import { useCallback, useEffect, useRef, useState } from "react"
import { useQueryClient } from "@tanstack/react-query"

export interface WsNotification {
  id: string
  type: string
  title: string
  message: string
  link: string
  read: boolean
  createdAt: string
}

interface UseNotificationsOptions {
  userId?: string
  enabled?: boolean
}

/**
 * WebSocket hook for real-time notifications via STOMP over SockJS.
 * Connects to /ws, subscribes to /user/queue/notifications.
 * Falls back gracefully if WebSocket is unavailable.
 */
export function useNotifications({
  userId,
  enabled = true,
}: UseNotificationsOptions) {
  const [connected, setConnected] = useState(false)
  const [lastNotification, setLastNotification] =
    useState<WsNotification | null>(null)
  const stompClientRef = useRef<unknown>(null)
  const queryClient = useQueryClient()

  const connect = useCallback(async () => {
    if (!userId || !enabled) return

    try {
      // Dynamic import to avoid SSR issues
      const { Client } = await import("@stomp/stompjs")
      const SockJS = (await import("sockjs-client")).default

      const backendUrl =
        process.env.NEXT_PUBLIC_WS_URL || "http://localhost:8080"

      const client = new Client({
        webSocketFactory: () => new SockJS(`${backendUrl}/ws`),
        reconnectDelay: 5000,
        heartbeatIncoming: 10000,
        heartbeatOutgoing: 10000,
        onConnect: () => {
          setConnected(true)

          client.subscribe(`/user/${userId}/queue/notifications`, (message) => {
            try {
              const notification: WsNotification = JSON.parse(message.body)
              setLastNotification(notification)
              // Invalidate notifications query to refresh badge count
              queryClient.invalidateQueries({ queryKey: ["notifications"] })
            } catch {
              console.error("Failed to parse notification message")
            }
          })
        },
        onDisconnect: () => {
          setConnected(false)
        },
        onStompError: (frame) => {
          console.error("STOMP error:", frame.headers["message"])
          setConnected(false)
        },
      })

      client.activate()
      stompClientRef.current = client
    } catch {
      // WebSocket libraries not available (SSR or missing deps) — fail silently
      console.warn("WebSocket connection unavailable, falling back to polling")
    }
  }, [userId, enabled, queryClient])

  const disconnect = useCallback(() => {
    const client = stompClientRef.current as { deactivate?: () => void } | null
    if (client?.deactivate) {
      client.deactivate()
    }
    stompClientRef.current = null
    setConnected(false)
  }, [])

  useEffect(() => {
    connect()
    return () => disconnect()
  }, [connect, disconnect])

  return {
    connected,
    lastNotification,
    disconnect,
  }
}