export type DeptNode = {
  id: string;
  name: string;
  code?: string | null;
  parentId?: string | null;
};

function companyRootId(depts: DeptNode[]) {
  const roots = depts.filter((d) => !d.parentId);
  const named = roots.find((d) => d.name?.includes('公司') || d.code === 'ROOT' || d.code === 'OA_1');
  return named?.id || roots[0]?.id;
}

export function isTopLevelDept(depts: DeptNode[], dept: DeptNode) {
  const rootId = companyRootId(depts);
  if (!rootId) return !dept.parentId;
  if (dept.id === rootId) return false;
  return dept.parentId === rootId || !dept.parentId;
}

export function topLevelDepartments(depts: DeptNode[]) {
  return depts.filter((d) => isTopLevelDept(depts, d)).sort((a, b) => a.name.localeCompare(b.name, 'zh'));
}

export function topLevelOf(depts: DeptNode[], deptId?: string | null): DeptNode | undefined {
  if (!deptId) return undefined;
  const byId = new Map(depts.map((d) => [d.id, d]));
  const rootId = companyRootId(depts);
  let cur = byId.get(deptId);
  const seen = new Set<string>();
  while (cur && !seen.has(cur.id)) {
    seen.add(cur.id);
    if (isTopLevelDept(depts, cur)) return cur;
    if (!cur.parentId || cur.parentId === rootId) return cur.id === rootId ? undefined : cur;
    cur = byId.get(cur.parentId);
  }
  return undefined;
}

export function topLevelNameOf(depts: DeptNode[], deptId?: string | null, fallback?: string | null) {
  return topLevelOf(depts, deptId)?.name || fallback || '';
}

export function topLevelNameByLeafName(depts: DeptNode[], name?: string | null) {
  if (!name) return '';
  const leaf = depts.find((d) => d.name === name);
  if (!leaf) return name;
  return topLevelOf(depts, leaf.id)?.name || name;
}

export function descendantIds(depts: DeptNode[], root?: string) {
  if (!root) return null;
  const kids = new Map<string, string[]>();
  for (const d of depts) {
    if (!d.parentId) continue;
    const arr = kids.get(d.parentId) || [];
    arr.push(d.id);
    kids.set(d.parentId, arr);
  }
  const out = new Set<string>([root]);
  const stack = [root];
  while (stack.length) {
    const id = stack.pop()!;
    for (const c of kids.get(id) || []) {
      if (!out.has(c)) {
        out.add(c);
        stack.push(c);
      }
    }
  }
  return out;
}

export function topLevelSelectOptions(depts: DeptNode[]) {
  return topLevelDepartments(depts).map((d) => ({ value: d.id, label: d.name }));
}