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


export function usePagination(totalItems: number | Ref<number>, itemsPerPage = 20) {
  const pageNum = ref(1)

  const total = computed(() => {
    return typeof totalItems === 'number' ? totalItems : totalItems.value
  })

  const offset = computed(() => (pageNum.value - 1) * itemsPerPage)
  const firstResult = computed(() => (total.value === 0 ? 0 : offset.value + 1))
  const lastResult = computed(() => {
    const last = offset.value + itemsPerPage
    return last > total.value ? total.value : last
  })

  const totalPages = computed(() => Math.ceil(total.value / itemsPerPage))

  function goToPage(page: number) {
    if (page < 1) pageNum.value = 1
    else if (page > totalPages.value) pageNum.value = totalPages.value
    else pageNum.value = page
  }

  function nextPage() {
    goToPage(pageNum.value + 1)
  }

  function prevPage() {
    goToPage(pageNum.value - 1)
  }

  return {
    pageNum,
    offset,
    firstResult,
    lastResult,
    total,
    totalPages,
    goToPage,
    nextPage,
    prevPage,
  }
}