import type { Metadata } from 'next';
import { publicApi } from '@/lib/services';
import { ManualLayout } from '@/components/front/ManualLayout';
import type { Manual, ManualTreeNode } from '@/lib/types';

export const revalidate = 60;

export const metadata: Metadata = {
  title: '使用手册',
  description: '产品使用手册与文档',
};

/** 扁平化树为「仅文档」节点，用于查找第一篇可显示的文档 */
function flattenDocIds(nodes: ManualTreeNode[]): number[] {
  const out: number[] = [];
  const walk = (list: ManualTreeNode[]) => {
    for (const n of list) {
      if (n.type === 1) out.push(n.id);
      if (n.children.length > 0) walk(n.children);
    }
  };
  walk(nodes);
  return out;
}

export default async function ManualIndexPage() {
  const tree = await publicApi.getManualTree().catch(() => [] as ManualTreeNode[]);
  const docIds = flattenDocIds(tree);

  // 优先展示第一篇文档的内容；树中无文档节点时显示空态
  const firstDoc: Manual | null = docIds[0]
    ? await publicApi.getManualDetail(docIds[0]).catch(() => null)
    : null;

  return <ManualLayout tree={tree} doc={firstDoc} />;
}