import { mkdir, readFile, writeFile } from 'node:fs/promises'
import { join } from 'node:path'
import { escapeHtml, h, raw, render } from './html.js'
import { dateFor, readPages } from './content.js'
import { renderFeed, renderSitemap, toSitemapDate } from './feed.js'
import { createOutput, discardOutput, publishOutput } from './output.js'
import { renderMarkdownPage } from './markdown.js'
import {
  contentDirectories,
  generatedRoot,
  navLabels,
  siteName,
  siteUrl,
  standalonePages,
} from './site.config.js'

const includeDrafts = process.argv.includes('--drafts')
const output = await createOutput(generatedRoot)

const pageShell = (title, body, path = '/', navTitle = '', { draft = false } = {}) =>
  `<!DOCTYPE html>${render(
    h('html', { lang: 'en-US' }, [
      h('head', {}, [
        h('meta', { charset: 'utf-8' }),
        h('meta', {
          name: 'viewport',
          content: 'width=device-width, initial-scale=1',
        }),
        draft ? h('meta', { name: 'robots', content: 'noindex, nofollow' }) : undefined,
        h('title', {}, [title ? `${title} | ${siteName}` : siteName]),
        h('link', { rel: 'icon', href: '/favicon.ico' }),
        h('link', {
          rel: 'alternate',
          type: 'application/rss+xml',
          title: `${siteName} feed`,
          href: '/feed.xml',
        }),
        h('link', { rel: 'stylesheet', href: '/src/global.css' }),
        h('script', { type: 'module', src: '/src/main.js' }),
      ]),
      h('body', {}, [raw(body), h('nav', { 'aria-label': 'Breadcrumb' }, [raw(nav(path, navTitle))])]),
    ]),
  )}`

const nav = (path, currentTitle = '') => {
  if (path === '/') {
    if (!currentTitle) return render(h('span', {}, [siteName]))
    return render([h('a', { href: '/' }, [siteName]), ' / ', currentTitle])
  }
  const parts = path.split('/').filter(Boolean)
  const children = [h('a', { href: '/' }, [siteName])]
  let href = ''
  for (const [index, part] of parts.entries()) {
    href += `/${part}`
    const isLast = index === parts.length - 1
    const label = isLast && currentTitle ? currentTitle : (navLabels[part] ?? part)
    children.push(' / ', isLast ? label : h('a', { href: `${href}/` }, [label]))
  }
  return render(children)
}

const writePage = async (path, html) => {
  const directory = join(output, path)
  await mkdir(directory, { recursive: true })
  await writeFile(join(directory, 'index.html'), html)
}

const titleHeading = (title, className = '') => `
  <header class="page-heading${className ? ` ${className}` : ''}">
    <h1 class="title">${escapeHtml(title)}</h1>
  </header>`

const renderHome = (externalLinks, sectionLinks, recentLinks) =>
  pageShell(
    '',
    `
  ${titleHeading(siteName)}
  <main class="container">
    <section class="block">${sectionLinks}${externalLinks}</section>
    <section class="block recent">
      <h2>Recent</h2>
      <ul>${recentLinks || '<li>Nothing to show yet.</li>'}</ul>
    </section>
  </main>`,
  )

const renderNotesTable = (pages, directory) => {
  const rows = pages
    .map(
      (page) => `
    <tr>
      <td><a href="/${directory}/${page.name}/">${escapeHtml(page.title)}</a></td>
      <td>${page.date ? `<time class="table-last-updated" datetime="${escapeHtml(page.date)}" data-value="${escapeHtml(page.date)}">${escapeHtml(page.date)}</time>` : ''}</td>
    </tr>`,
    )
    .join('')
  return `<table class="${directory}-table"><caption class="visually-hidden">${escapeHtml(directory)} pages</caption><thead><tr><th scope="col">Page</th><th scope="col">Last updated</th></tr></thead><tbody>${rows}</tbody></table>`
}

const renderPostsList = (pages, directory) => {
  const items = pages
    .map(
      (page) => `
    <li>
      <a href="/${directory}/${page.name}/">${escapeHtml(page.title)}</a>
      ${page.date ? `<time datetime="${escapeHtml(page.date)}" data-value="${escapeHtml(page.date)}">${escapeHtml(page.date)}</time>` : ''}
    </li>`,
    )
    .join('')
  return `<ul class="posts-list">${items}</ul>`
}

const renderEmptySection = () => `
  <div class="text center">
    <p><strong>crickets</strong></p>
    <p>Nothing to list...</p>
    <a class="link button back" href="/">Go Home</a>
  </div>`

const renderNotFound = () =>
  pageShell(
    'Page not found',
    `${titleHeading('404: Page Not Found')}<main class="container"><section class="block text center"><p><strong>Uh oh! The page you are looking for does not exist...</strong></p><a class="link button back" href="/">Go Home</a><a class='button blue link extern' href='https://en.wikipedia.org/wiki/HTTP_404'>More on 404</a></section></main>`,
    '/',
    ' ... ??? / 404: Page Not Found',
  )

const renderSection = (directory, pages) => {
  const title = directory[0].toUpperCase() + directory.slice(1)
  const listing =
    pages.length === 0
      ? renderEmptySection()
      : directory === 'posts'
        ? renderPostsList(pages, directory)
        : renderNotesTable(pages, directory)

  return pageShell(
    title,
    `${titleHeading(title)}<main class="container"><section class="block">${listing}</section></main>`,
    `/${directory}`,
    title,
  )
}

const renderArticle = (directory, page, navigationPath = `/${directory}/${page.name}`) => {
  const updated = page.date
    ? `<time class="last-updated" datetime="${escapeHtml(page.date)}" data-value="${escapeHtml(page.date)}">Last updated: ${escapeHtml(page.date)}</time>`
    : ''
  const heading = titleHeading(page.title, `${directory}-heading`)
  const draftNotice = page.draft
    ? `<p class="draft-banner" role="status">Draft — rename <code>.${escapeHtml(page.name)}.md</code> to <code>${escapeHtml(page.name)}.md</code> to publish.</p>`
    : ''
  const tableOfContents = page.markdown.toc
  const contents = tableOfContents
    ? `<section class="block toc"><details open><summary>Contents</summary>${tableOfContents}</details></section><hr>`
    : ''
  const article = `<section class="block">${page.markdown.html}</section>`
  const body = `${heading}<main class="article-page ${directory}-page container">${draftNotice}${updated}${contents}${article}</main>`

  return pageShell(page.title, body, navigationPath, page.title, { draft: Boolean(page.draft) })
}

try {
const sections = Object.fromEntries(await Promise.all(contentDirectories.map(async (dir) => [dir, await readPages(dir, { includeDrafts })])))
for (const pages of Object.values(sections)) {
  for (const page of pages) page.markdown = renderMarkdownPage(page.source)
}

const external = JSON.parse(await readFile('external.json', 'utf8'))

const externalLinks = Object.entries(external)
  .map(([text, href]) => `<a class="button blue link extern" href="${escapeHtml(href)}">${escapeHtml(text)}</a>`)
  .join('')

const sectionLinks = contentDirectories
  .map((dir) => `<a class="button link" href="/${dir}/">${dir[0].toUpperCase() + dir.slice(1)}</a>`)
  .join('')

const standaloneLinks = standalonePages
  .filter((page) => page.path !== 'licenses')
  .map((page) => `<a class="button link" href="/${page.path}/">${page.title}</a>`)
  .join('')

const recentPages = contentDirectories
  .flatMap((dir) => sections[dir].filter((page) => !page.draft).map((page) => ({ ...page, dir })))
  .sort((a, b) => b.date.localeCompare(a.date))
  .slice(0, 5)

const recentLinks = recentPages
  .map(
    (page) =>
      `<li>${page.date ? `<time class="recent-date" datetime="${escapeHtml(page.date)}" data-value="${escapeHtml(page.date)}" data-tooltip="${escapeHtml(page.date)}">${escapeHtml(page.date)}</time>` : ''}<span class="recent-gap" aria-hidden="true"></span><span class="recent-type">${page.dir}</span><a href="/${page.dir}/${page.name}/">${escapeHtml(page.title)}</a></li>`,
  )
  .join('')
await writeFile(join(output, 'index.html'), renderHome(externalLinks, sectionLinks + standaloneLinks, recentLinks))
await writeFile(join(output, '404.html'), renderNotFound())

for (const dir of contentDirectories) {
  const pages = sections[dir]
  await writePage(
    dir,
    renderSection(
      dir,
      pages.filter((page) => !page.draft),
    ),
  )

  for (const page of pages) {
    await writePage(join(dir, page.name), renderArticle(dir, page))
  }
}

const generatedStandalone = []
for (const page of standalonePages) {
  const source = await readFile(page.source, 'utf8')
  const generatedPage = {
    name: page.path,
    title: page.title,
    source,
    markdown: renderMarkdownPage(source),
    date: await dateFor(page.source),
  }
  generatedStandalone.push(generatedPage)
  await writePage(page.path, renderArticle(page.path, generatedPage, '/'))
}

const feedItems = contentDirectories
  .flatMap((dir) => sections[dir].filter((page) => !page.draft).map((page) => ({ ...page, dir })))
  .sort((a, b) => b.date.localeCompare(a.date))

for (const item of feedItems) item.description = item.markdown.excerpt

await writeFile(join(output, 'feed.xml'), renderFeed(feedItems))

const sitemapUrls = [
  {
    loc: `${siteUrl}/`,
    lastmod: toSitemapDate(feedItems[0]?.date),
  },
  ...contentDirectories.map((dir) => ({
    loc: `${siteUrl}/${dir}/`,
    lastmod: toSitemapDate(
      [...sections[dir]].filter((page) => !page.draft).sort((a, b) => b.date.localeCompare(a.date))[0]?.date,
    ),
  })),
  ...generatedStandalone.map((page) => ({
    loc: `${siteUrl}/${page.name}/`,
    lastmod: toSitemapDate(page.date),
  })),
  ...feedItems.map((page) => ({
    loc: `${siteUrl}/${page.dir}/${page.name}/`,
    lastmod: toSitemapDate(page.date),
  })),
  { loc: `${siteUrl}/feed.xml`, lastmod: toSitemapDate(feedItems[0]?.date) },
]

await writeFile(join(output, 'sitemap.xml'), renderSitemap(sitemapUrls))
await publishOutput(output, generatedRoot)
} catch (error) {
  await discardOutput(output)
  throw error
}