import { useCallback, useState } from 'react'

const SESSION_START_KEY = 'inventory_audit_session_start'
const LAST_LOCATION_KEY = 'inventory_audit_last_location'

function readSessionStart(): number {
  const raw = sessionStorage.getItem(SESSION_START_KEY)
  if (raw) return Number(raw)
  const now = Date.now()
  sessionStorage.setItem(SESSION_START_KEY, String(now))
  return now
}

/** Tracks the current audit walk: when it started (for the found/not-found split) and the
 *  last location typed in, so the next scanned object can default to the same location. */
export function useAuditSession() {
  const [sessionStart, setSessionStart] = useState<number>(readSessionStart)
  const [lastLocation, setLastLocationState] = useState<string | null>(() =>
    sessionStorage.getItem(LAST_LOCATION_KEY),
  )

  const restart = useCallback(() => {
    const now = Date.now()
    sessionStorage.setItem(SESSION_START_KEY, String(now))
    sessionStorage.removeItem(LAST_LOCATION_KEY)
    setSessionStart(now)
    setLastLocationState(null)
  }, [])

  const setLastLocation = useCallback((location: string | null) => {
    if (location) sessionStorage.setItem(LAST_LOCATION_KEY, location)
    else sessionStorage.removeItem(LAST_LOCATION_KEY)
    setLastLocationState(location)
  }, [])

  return { sessionStart, restart, lastLocation, setLastLocation }
}