import { ref, watch, type Ref } from 'vue'

type RouteLike = { fullPath?: string; name?: string } & Record<string, unknown>

/**
 * Simple per-route scroll position helper.
 *
 * - Stores `window.scrollY` for the route we leave
 * - Restores it when we navigate back to the same route
 *
 * Intended to be used with a reactive current route ref:
 *   useRouteScrollPositions(currentRouteRef)
 */
export function useRouteScrollPositions(currentRoute: Ref<RouteLike | undefined>) {
  const scrollPositions = ref<Record<string, number>>({})
  watch(
    currentRoute,
    (to, from) => {
      // Spara position för route vi lämnar
      const fromKey = from?.fullPath ?? (typeof from?.name === 'string' ? (from.name as string) : undefined)
      if (fromKey) {
        scrollPositions.value[fromKey] = window.scrollY ?? 0
      }

      // Återställ position för route vi går till, om sparad
      const toKey = to?.fullPath ?? (typeof to?.name === 'string' ? (to.name as string) : undefined)
      if (toKey && scrollPositions.value[toKey] !== undefined) {
        const y = scrollPositions.value[toKey]
        setTimeout(() => {
          window.scrollTo({ top: y, behavior: 'auto' })
        }, 1000)
      }
    },
    { flush: 'post' },
  )

  return { scrollPositions }
}