import { ref, onMounted } from 'vue'
import { showToast } from 'vant'
import { expenseItemApi } from '@/api'

export interface ExpenseItem {
  id: string
  parentId: string
  itemName: string
  itemCode: string
  level: number
  sortOrder: number
  status: number | string
  childCount: number
  children?: ExpenseItem[]
}

function normalizeItem(raw: any): ExpenseItem {
  const children = Array.isArray(raw?.children) ? raw.children.map(normalizeItem) : undefined
  return {
    id: String(raw?.id ?? ''),
    parentId: raw?.parentId == null || raw?.parentId === '' ? '0' : String(raw.parentId),
    itemName: raw?.itemName ?? '',
    itemCode: raw?.itemCode ?? '',
    level: Number(raw?.level ?? 0),
    sortOrder: Number(raw?.sortOrder ?? 0),
    status: raw?.status,
    childCount: Number(raw?.childCount ?? children?.length ?? 0),
    children,
  }
}

export function useExpenseItemTree() {
  const expenseTree = ref<ExpenseItem[]>([])
  const loading = ref(false)
  const flatList = ref<ExpenseItem[]>([])

  async function load() {
    loading.value = true
    try {
      const res: any = await expenseItemApi.tree()
      const tree: ExpenseItem[] = (res.data ?? []).map(normalizeItem)
      expenseTree.value = tree
      flatList.value = flattenTree(tree)
    } catch (e: any) {
      showToast(e?.message || '加载费用项目失败')
    } finally {
      loading.value = false
    }
  }

  onMounted(load)

  return { expenseTree, flatList, loading, load }
}

function flattenTree(tree: ExpenseItem[]): ExpenseItem[] {
  const result: ExpenseItem[] = []
  for (const node of tree) {
    result.push(node)
    if (node.children?.length) result.push(...flattenTree(node.children))
  }
  return result
}

export function formatExpenseName(
  id: string | number | null | undefined,
  flatList: ExpenseItem[],
): string {
  if (id == null || id === '') return '-'
  const sid = String(id)
  const parts: string[] = []
  let cur: ExpenseItem | undefined = flatList.find((i) => String(i.id) === sid)
  const guard = new Set<string>()
  while (cur && !guard.has(cur.id)) {
    guard.add(cur.id)
    parts.unshift(cur.itemName)
    const pid = cur.parentId
    cur =
      pid != null && pid !== '' && pid !== '0' ? flatList.find((i) => String(i.id) === pid) : undefined
  }
  return parts.length ? parts.join('/') : '-'
}

/** 从列表/详情行上常见的 camel/snake 字段取费用项 ID */
export function pickExpenseItemId(row: Record<string, any> | null | undefined): string | null {
  if (!row || typeof row !== 'object') return null
  const raw = row.expenseId ?? row.expense_id ?? row.expenseItemId ?? row.expense_item_id
  if (raw == null || raw === '') return null
  return String(raw)
}

/**
 * 优先用费用树拼出「一级/二级」；无 ID 或树未加载时用接口返回的 expenseName。
 */
export function resolveExpenseDisplay(
  row: Record<string, any> | null | undefined,
  flatList: ExpenseItem[],
): string {
  if (!row) return '-'
  const id = pickExpenseItemId(row)
  const nameFb = row.expenseName ?? row.expense_name
  if (id != null && flatList.length) {
    const p = formatExpenseName(id, flatList)
    if (p && p !== '-') return p
  }
  const fb = nameFb != null ? String(nameFb).trim() : ''
  return fb || '-'
}