/**
 * 树形业务数据：全路径展示文案（与 Fresh Mint 规范一致）
 * 扁平列表沿 parentId 回溯，或树结构 DFS 预计算 id → 路径
 */

export const DEFAULT_TREE_PATH_SEPARATOR = ' / '

export type TreePathFlatNode = Record<string, unknown>

/** 从扁平列表（含 parentId / parent_id、name）解析「根 → 当前」路径文案 */
export function buildTreePathLabelFromFlat(
  nodeId: string | null | undefined,
  flatList: TreePathFlatNode[] | null | undefined,
  separatorOrOpts?: string | { separator?: string; nameKey?: string }
): string {
  const separator =
    typeof separatorOrOpts === 'string'
      ? separatorOrOpts
      : (separatorOrOpts?.separator ?? DEFAULT_TREE_PATH_SEPARATOR)
  const nameKey =
    typeof separatorOrOpts === 'string' ? 'name' : (separatorOrOpts?.nameKey ?? 'name')
  const cid = String(nodeId ?? '').trim()
  if (!cid) return ''
  const byId = new Map<string, TreePathFlatNode>()
  for (const c of flatList || []) {
    const id = String(c?.id ?? '').trim()
    if (id) byId.set(id, c)
  }
  const names: string[] = []
  let cur: string | null = cid
  const seen = new Set<string>()
  while (cur && byId.has(cur) && !seen.has(cur)) {
    seen.add(cur)
    const cat: TreePathFlatNode = byId.get(cur)!
    const nm = String(cat?.[nameKey] ?? '').trim()
    if (nm) names.unshift(nm)
    const pid: string = String(cat?.parentId ?? cat?.parent_id ?? '').trim()
    cur = pid || null
  }
  return names.length ? names.join(separator) : ''
}

/** 从树形根列表预计算 id → 全路径（用于列表/卡片等高频展示） */
export function buildPathLabelMapFromTreeRoots(
  roots: unknown[] | null | undefined,
  options?: {
    idKey?: string
    nameKey?: string
    childrenKey?: string
    separator?: string
  }
): Map<string, string> {
  const idKey = options?.idKey ?? 'id'
  const nameKey = options?.nameKey ?? 'name'
  const childrenKey = options?.childrenKey ?? 'children'
  const sep = options?.separator ?? DEFAULT_TREE_PATH_SEPARATOR
  const map = new Map<string, string>()
  const walk = (nodes: unknown[], pathNames: string[]) => {
    for (const raw of nodes || []) {
      const n = raw as Record<string, unknown>
      const id = n?.[idKey] != null ? String(n[idKey]).trim() : ''
      const curName = String(n?.[nameKey] ?? '').trim()
      const nextPath = curName ? [...pathNames, curName] : [...pathNames]
      if (id) map.set(id, nextPath.join(sep))
      const ch = n?.[childrenKey]
      if (Array.isArray(ch) && ch.length) walk(ch as unknown[], nextPath)
    }
  }
  walk(roots || [], [])
  return map
}

/** 优先全路径；无法解析时用接口给的 fallback（多为末级名）；皆无则占位符 */
export function resolveTreePathDisplay(
  nodeId: unknown,
  flatList: TreePathFlatNode[] | null | undefined,
  fallbackName?: unknown,
  separator: string = DEFAULT_TREE_PATH_SEPARATOR,
  emptyPlaceholder = '—',
  nameKey?: string
): string {
  const path = buildTreePathLabelFromFlat(String(nodeId ?? '').trim() || undefined, flatList, {
    separator,
    nameKey
  })
  if (path) return path
  const fb = String(fallbackName ?? '').trim()
  if (fb) return fb
  return emptyPlaceholder
}

/** `el-tree-select` 的 data 节点上按 value 查找本级 label（扁平列表缺父链时的回退） */
export function findTreeSelectShortLabel(
  nodes: Array<{ value?: unknown; label?: unknown; children?: unknown[] }> | null | undefined,
  nodeId: string | null | undefined
): string {
  const id = String(nodeId ?? '').trim()
  if (!id) return ''
  const walk = (arr: typeof nodes): string => {
    for (const n of arr || []) {
      if (!n) continue
      if (String(n.value ?? '') === id) return String(n.label ?? '').trim()
      const hit = walk(n.children as typeof nodes)
      if (hit) return hit
    }
    return ''
  }
  return walk(nodes)
}