const fs = require('fs');
const path = require('path');
const md = require('markdown-it')({ html: false, breaks: false, linkify: false });

const TOC_GROUPS = [
  { group: '快速开始', nums: [1, 2] },
  { group: '业务操作', nums: [3, 4, 5, 6, 7, 8] },
  { group: '设置与答疑', nums: [9, 10] },
];

module.exports = function() {
  const raw = fs.readFileSync(path.join(__dirname, '../content/docs.md'), 'utf8');
  const lines = raw.split('\n');

  // Split into chapters by "## {n}. {title}" headings
  const chapters = [];
  let current = null;

  for (const line of lines) {
    const match = line.match(/^## (\d+)\. (.+)/);
    if (match) {
      if (current) chapters.push(current);
      const num = parseInt(match[1], 10);
      current = { num, id: 'ch-' + num, title: match[2].trim(), bodyLines: [] };
    } else if (current) {
      current.bodyLines.push(line);
    }
  }
  if (current) chapters.push(current);

  // Render each chapter's body to HTML
  const rendered = chapters.map(ch => ({
    num: ch.num,
    id: ch.id,
    title: ch.title,
    html: md.render(ch.bodyLines.join('\n')),
  }));

  // Build TOC
  const chapterMap = {};
  rendered.forEach(ch => { chapterMap[ch.num] = ch; });

  const toc = TOC_GROUPS.map(g => ({
    group: g.group,
    items: g.nums
      .filter(n => chapterMap[n])
      .map(n => ({ id: chapterMap[n].id, num: n, title: chapterMap[n].title })),
  }));

  return { toc, chapters: rendered };
};