"use client"

type Point = { x: number; y: number }

const listeners = new Set<() => void>()
let latest: Point = { x: 0, y: 0 }
let rafId: number | null = null

function emit() {
  rafId = null
  for (const cb of listeners) cb()
}

/** Throttle pointer notifications to at most once per animation frame. */
export function notifyDragPointerMove(x: number, y: number) {
  latest = { x, y }
  if (rafId !== null) return
  rafId = globalThis.requestAnimationFrame(emit)
}

export function getDragPointerSnapshot(): Point {
  return latest
}

export function subscribeDragPointer(cb: () => void) {
  listeners.add(cb)
  return () => {
    listeners.delete(cb)
  }
}

export function resetDragPointer(x: number, y: number) {
  if (rafId !== null) {
    globalThis.cancelAnimationFrame(rafId)
    rafId = null
  }
  latest = { x, y }
  for (const cb of listeners) cb()
}