const MarkdownIt = require('markdown-it');
const markdownItAnchor = require('markdown-it-anchor');
const markdownItFootnote = require('markdown-it-footnote');
const markdownItAttrs = require('markdown-it-attrs');
const Prism = require('prismjs');
require('prismjs/components/prism-bash');
require('prismjs/components/prism-json');
require('prismjs/components/prism-yaml');
require('prismjs/components/prism-python');
require('prismjs/components/prism-go');
require('prismjs/components/prism-docker');
require('prismjs/components/prism-sql');
require('prismjs/components/prism-typescript');
require('prismjs/components/prism-markdown');

function slugifyHeading(s) {
  return encodeURIComponent(String(s).trim().toLowerCase().replace(/\s+/g, '-'));
}

function createMarkdownRenderer(pluginManager) {
  const md = new MarkdownIt({
    html: true,
    linkify: true,
    typographer: true,
    highlight: function (str, lang) {
      if (lang && Prism.languages[lang]) {
        try {
          return `<pre class="language-${lang}"><code class="language-${lang}">${Prism.highlight(str, Prism.languages[lang], lang)}</code></pre>`;
        } catch (__) {}
      }
      const escaped = md.utils.escapeHtml(str);
      return `<pre class="language-text"><code class="language-text">${escaped}</code></pre>`;
    }
  });

  md.use(markdownItAnchor, {
    slugify: slugifyHeading,
    permalink: markdownItAnchor.permalink.linkInsideHeader({
      symbol: '#',
      placement: 'after',
      ariaHidden: true
    })
  });

  md.use(markdownItFootnote);
  md.use(markdownItAttrs);

  // Disable indented code blocks (4 spaces) so indented HTML elements don't get converted to <pre><code>
  md.disable('code');

  if (pluginManager) {
    pluginManager.applyMarkdownHooks(md);
  }

  return md;
}

function extractToc(markdownContent) {
  const headings = [];
  const lines = markdownContent.split(/\r?\n/);
  let inCodeBlock = false;

  for (const line of lines) {
    if (line.trim().startsWith('```')) {
      inCodeBlock = !inCodeBlock;
      continue;
    }
    if (inCodeBlock) continue;

    const match = line.match(/^(#{1,6})\s+(.+)$/);
    if (match) {
      const level = match[1].length;
      // Strip markdown links/formatting from heading text for TOC display
      const title = match[2].replace(/\[([^\]]+)\]\([^)]+\)/g, '$1').replace(/[*_`]/g, '').trim();
      const id = slugifyHeading(title);
      headings.push({ level, title, id });
    }
  }

  // Build hierarchical tree if needed or flat list with levels
  return headings;
}

module.exports = {
  createMarkdownRenderer,
  extractToc,
  slugifyHeading
};