const fs = require('fs/promises')
const path = require('path')
const marked = require('marked')
const fm = require('front-matter')
const { highlight } = require('highlight.js')

marked.use({
  highlight: (code, lang) => {
    if (lang) {
      return highlight(lang, code).value
    }

    return code
  }
})

function tocHTML (toc) {
  let html = '<ul>\n'
  for (const li of toc) {
    html += '<li>\n'
    html += `<div>\n<a href="#${li.slug}">${li.text}</a>\n</div>\n`
    if (li.children && li.children.length > 0) {
      html += tocHTML(li.children)
    }
    html += '</li>\n'
  }
  html += '</ul>\n'

  return html
}

function markdownTOC (markdown) {
  const tokens = marked.lexer(markdown)
  const slugger = new marked.Slugger()
  const toc = []
  let currentHeading
  let ignoreFirst = true
  for (const token of tokens) {
    if (token.type === 'heading') {
      if (token.depth === 1) {
        if (ignoreFirst) {
          ignoreFirst = false
          continue
        }
        currentHeading = {
          text: token.text,
          slug: slugger.slug(token.text),
          children: []
        }
        toc.push(currentHeading)
      } else if (token.depth === 2) {
        if (!currentHeading) {
          continue
        }
        currentHeading.children.push({
          text: token.text,
          slug: slugger.slug(token.text)
        })
      }
    }
  }

  return {
    toc: tocHTML(toc),
    html: marked.parser(tokens)
  }
}

function createHTML (header, footer, text) {
  const { attributes, body } = fm(text)
  for (const prop in attributes) {
    header = header.replace(new RegExp(`%\\(${prop}\\)s`, 'ig'), attributes[prop])
    footer = footer.replace(new RegExp(`%\\(${prop}\\)s`, 'ig'), attributes[prop])
  }

  const { toc, html } = markdownTOC(body)

  header = header.replace(/%\(toc_html\)s/ig, toc)

  return header + html + footer
}

async function createDocs () {
  const docs = path.resolve(__dirname, '..', 'docs')
  const dist = path.resolve(__dirname, '..', 'public')
  const branding = path.join(docs, 'branding')

  await fs.rmdir(dist, { recursive: true })
  await fs.mkdir(dist)

  const header = await fs.readFile(path.join(branding, 'header.html.in'), { encoding: 'utf8' })
  const footer = await fs.readFile(path.join(branding, 'footer.html.in'), { encoding: 'utf8' })
  const files = await fs.readdir(docs)
  for (const file of files) {
    if (!file.endsWith('.md')) {
      continue
    }
    const text = await fs.readFile(path.join(docs, file), { encoding: 'utf8' })
    const html = createHTML(header, footer, text)

    await fs.writeFile(path.join(dist, file.replace(/md$/, 'html')), html)
  }

  const dest = path.join(dist, 'media')
  const src = path.join(branding, 'media')
  const highlightjsStyles = path.resolve(__dirname, '..', 'node_modules', 'highlight.js', 'styles')
  await fs.mkdir(dest)
  await fs.mkdir(path.join(dest, 'css'))
  await fs.mkdir(path.join(dest, 'js'))
  await fs.mkdir(path.join(dest, 'img'))
  await fs.copyFile(path.join(src, 'css', 'style.css'), path.join(dest, 'css', 'style.css'))
  await fs.copyFile(path.join(highlightjsStyles, 'default.css'), path.join(dest, 'css', 'highlight.css'))
  await fs.copyFile(path.join(src, 'js', 'script.js'), path.join(dest, 'js', 'script.js'))
  await fs.copyFile(path.join(src, 'img', 'logo.svg'), path.join(dest, 'img', 'logo.svg'))
  await fs.copyFile(path.join(branding, 'CNAME'), path.join(dist, 'CNAME'))
}

createDocs().catch(ex => {
  console.error(ex)
  process.exit(1)
})