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

export type SortOrder = 'asc' | 'desc'

export function nextSortState(
  currentField: string | null,
  currentOrder: SortOrder | null,
  prop: string,
  order: SortOrder
): { sortField: string | null; sortOrder: SortOrder | null } {
  if (currentField === prop && currentOrder === order) {
    return { sortField: null, sortOrder: null }
  }
  return { sortField: prop, sortOrder: order }
}

export function useColumnSort(options?: { onChange?: () => void }) {
  const sortField = ref<string | null>(null)
  const sortOrder = ref<SortOrder | null>(null)

  const hasActiveSort = computed(() => Boolean(sortField.value && sortOrder.value))

  function setSort(prop: string, order: SortOrder) {
    const next = nextSortState(sortField.value, sortOrder.value, prop, order)
    sortField.value = next.sortField
    sortOrder.value = next.sortOrder
    options?.onChange?.()
  }

  function clearSort() {
    if (!sortField.value && !sortOrder.value) return
    sortField.value = null
    sortOrder.value = null
    options?.onChange?.()
  }

  function isSortActive(prop: string, order?: SortOrder) {
    if (!sortField.value || sortField.value !== prop) return false
    if (order == null) return true
    return sortOrder.value === order
  }

  function toQueryParams(): Record<string, string> {
    if (!sortField.value || !sortOrder.value) return {}
    return { sortField: sortField.value, sortOrder: sortOrder.value }
  }

  function onColumnHidden(prop: string) {
    if (sortField.value === prop) clearSort()
  }

  function watchVisibleColumns(visibleProps: Ref<string[]>) {
    watch(
      visibleProps,
      (next, prev) => {
        if (!prev) return
        const nextSet = new Set(next || [])
        for (const p of prev) {
          if (!nextSet.has(p)) onColumnHidden(p)
        }
      },
      { deep: true }
    )
  }

  return {
    sortField,
    sortOrder,
    hasActiveSort,
    setSort,
    clearSort,
    isSortActive,
    toQueryParams,
    onColumnHidden,
    watchVisibleColumns
  }
}