import {
  nextTick,
  onBeforeUnmount,
  onMounted,
  ref,
  unref,
  watch,
  type Ref
} from 'vue'
import { useEventListener, useResizeObserver } from '@vueuse/core'
import {
  LIST_TABLE_VIEWPORT_BOTTOM_GAP,
  LIST_TABLE_VIEWPORT_MIN_HEIGHT,
  calcListTableViewportHeight
} from '@/composables/listTableViewportHeight'

export type UseListTableViewportHeightOptions = {
  /** 表格锚点（包住 ListTable/el-table 的元素，不含分页） */
  tableEl: Ref<HTMLElement | null | undefined> | (() => HTMLElement | null | undefined)
  /** 分页条根节点；无分页可省略 */
  pagerEl?: Ref<HTMLElement | null | undefined> | (() => HTMLElement | null | undefined)
  /** 可选：ListTable / el-table 组件实例，高度变化后调用 doLayout */
  tableRef?: Ref<any>
  minHeight?: number
  bottomGap?: number
  /** 主内容滚动根；默认 #app-content */
  scrollRootSelector?: string
  /** 为 false 时不自动监听（隐藏 Tab 可用） */
  enabled?: Ref<boolean> | boolean
}

function resolveEl(
  source?: Ref<HTMLElement | null | undefined> | (() => HTMLElement | null | undefined)
): HTMLElement | null {
  if (!source) return null
  if (typeof source === 'function') return source() ?? null
  return unref(source) ?? null
}

export function useListTableViewportHeight(options: UseListTableViewportHeightOptions) {
  const tableHeight = ref(LIST_TABLE_VIEWPORT_MIN_HEIGHT)
  const minHeight = options.minHeight ?? LIST_TABLE_VIEWPORT_MIN_HEIGHT
  const bottomGap = options.bottomGap ?? LIST_TABLE_VIEWPORT_BOTTOM_GAP
  const scrollRootSelector = options.scrollRootSelector ?? '#app-content'

  const isEnabled = () => {
    const e = options.enabled
    if (e === undefined) return true
    return !!unref(e)
  }

  const recalc = () => {
    if (!isEnabled()) return
    if (typeof window === 'undefined') return

    const table = resolveEl(options.tableEl)
    if (!table) return

    const root =
      (document.querySelector(scrollRootSelector) as HTMLElement | null) ?? null
    const contentViewportBottom = root
      ? root.getBoundingClientRect().bottom
      : window.innerHeight

    const tableTop = table.getBoundingClientRect().top
    const pager = resolveEl(options.pagerEl)
    const pagerHeight = pager ? Math.ceil(pager.getBoundingClientRect().height) : 0

    const next = calcListTableViewportHeight({
      contentViewportBottom,
      tableTop,
      pagerHeight,
      minHeight,
      bottomGap
    })

    if (next !== tableHeight.value) {
      tableHeight.value = next
    }

    nextTick(() => {
      const inst = options.tableRef ? unref(options.tableRef) : null
      if (inst && typeof inst.doLayout === 'function') {
        inst.doLayout()
      }
    })
  }

  let raf = 0
  const scheduleRecalc = () => {
    if (raf) cancelAnimationFrame(raf)
    raf = requestAnimationFrame(() => {
      raf = 0
      recalc()
    })
  }

  onMounted(() => {
    nextTick(scheduleRecalc)
  })

  onBeforeUnmount(() => {
    if (raf) cancelAnimationFrame(raf)
  })

  useEventListener(window, 'resize', scheduleRecalc)

  // 观察表锚点与分页尺寸变化（筛选展开会改变 tableTop）
  useResizeObserver(
    () => resolveEl(options.tableEl),
    () => scheduleRecalc()
  )
  useResizeObserver(
    () => resolveEl(options.pagerEl),
    () => scheduleRecalc()
  )
  useResizeObserver(
    () => document.querySelector(scrollRootSelector) as HTMLElement | null,
    () => scheduleRecalc()
  )

  if (options.enabled !== undefined && typeof options.enabled !== 'boolean') {
    watch(options.enabled, () => scheduleRecalc())
  }

  return { tableHeight, recalc: scheduleRecalc }
}