// UserActivityTracker.tsx

'use client'

import { useEffect, useRef } from 'react'
import { useSession } from 'next-auth/react'

type Presence = 'online' | 'away' | 'offline'

export default function UserActivityTracker() {
  const { data: session } = useSession()
  const lastActivityRef = useRef<number>(Date.now())
  const prevStatusRef   = useRef<Presence>('offline')
  const intervalRef     = useRef<ReturnType<typeof setInterval> | null>(null)

  useEffect(() => {
    if (!session?.user?.steamId) return

    const markActive = () => { lastActivityRef.current = Date.now() }

    const tick = () => {
      const diffMs = Date.now() - lastActivityRef.current
      const nextStatus: Presence = diffMs < 30_000 ? 'online' : 'away'

      if (nextStatus !== prevStatusRef.current) {
        prevStatusRef.current = nextStatus
        fetch(nextStatus === 'online' ? '/api/user/activity' : '/api/user/away', { method: 'POST' })
          .catch(() => {})
      }
    }

    // Initial online
    prevStatusRef.current = 'away'
    markActive()
    tick()

    intervalRef.current = setInterval(tick, 5_000)

    // Activity Events
    window.addEventListener('mousemove', markActive)
    window.addEventListener('keydown', markActive)
    window.addEventListener('touchstart', markActive)
    document.addEventListener('visibilitychange', () => {
      if (!document.hidden) markActive()
    })

    return () => {
      window.removeEventListener('mousemove', markActive)
      window.removeEventListener('keydown', markActive)
      window.removeEventListener('touchstart', markActive)
      document.removeEventListener('visibilitychange', () => {
        if (!document.hidden) markActive()
      })

      if (intervalRef.current) clearInterval(intervalRef.current)
    }
  }, [session?.user?.steamId])

  return null
}