import { unified } from 'unified'
import markdown from 'remark-parse-no-trim'
import markdownNext from 'remark-parse'
import gfm from 'remark-gfm'
import emoji from 'remark-gemoji-to-emoji'
import remark2rehype from 'remark-rehype'
import raw from 'rehype-raw'
import slug from 'rehype-slug'
import highlight from 'rehype-highlight'
import dockerfile from 'highlight.js/lib/languages/dockerfile'
import http from 'highlight.js/lib/languages/http'
import groovy from 'highlight.js/lib/languages/groovy'
import erb from 'highlight.js/lib/languages/erb'
import powershell from 'highlight.js/lib/languages/powershell'
import graphql from 'highlight.js/lib/languages/graphql'
import html from 'rehype-stringify'
import remarkCodeExtra from 'remark-code-extra'
import codeHeader from './plugins/code-header.js'
import rewriteLocalLinks from './plugins/rewrite-local-links.js'
import rewriteImgSources from './plugins/rewrite-asset-urls.js'
import rewriteAssetImgTags from './plugins/rewrite-asset-img-tags.js'
import useEnglishHeadings from './plugins/use-english-headings.js'
import wrapInElement from './plugins/wrap-in-element.js'
import headingLinks from './plugins/heading-links.js'

// plugins aren't designed to be used more than once,
// this workaround lets us do that
// see https://github.com/unifiedjs/unified/issues/79
const wrapperForImages = () =>
  wrapInElement({ selector: 'ol > li img', wrapper: 'span.procedural-image-wrapper' })

const wrapperForTheadThScope = () =>
  wrapInElement({
    selector: 'thead th',
    wrapper: 'th',
    // This moves what it finds in the selector inside the wrapper.
    rewrite: true,
    wrapperAdditionalAttributes: {
      scope: 'col',
    },
  })

const wrapperForTbodyThScope = () =>
  wrapInElement({
    selector: 'thead th',
    wrapper: 'th',
    // This moves what it finds in the selector inside the wrapper.
    rewrite: true,
    wrapperAdditionalAttributes: {
      scope: 'col',
    },
  })

const wrapperForRowheadersTbody = () =>
  wrapInElement({
    selector: '.rowheaders tbody tr td:first-child',
    wrapper: 'th',
    // This moves what it finds in the selector inside the wrapper.
    rewrite: true,
    wrapperAdditionalAttributes: {
      scope: 'row',
    },
  })

export default function createProcessor(context) {
  return unified()
    .use(process.env.COMMONMARK ? markdownNext : markdown)
    .use(process.env.COMMONMARK ? gfm : null)
    .use(remarkCodeExtra, { transform: codeHeader })
    .use(emoji)
    .use(remark2rehype, { allowDangerousHtml: true })
    .use(slug)
    .use(useEnglishHeadings, context)
    .use(headingLinks)
    .use(highlight, {
      languages: { graphql, dockerfile, http, groovy, erb, powershell },
      subset: false,
    })
    .use(raw)
    .use(wrapperForImages)
    .use(wrapperForTheadThScope)
    .use(wrapperForTbodyThScope)
    .use(wrapperForRowheadersTbody)
    .use(rewriteImgSources)
    .use(rewriteAssetImgTags)
    .use(rewriteLocalLinks, context)
    .use(html)
}

export function createMinimalProcessor(context) {
  return unified()
    .use(process.env.COMMONMARK ? markdownNext : markdown)
    .use(process.env.COMMONMARK ? gfm : null)
    .use(remark2rehype, { allowDangerousHtml: true })
    .use(slug)
    .use(raw)
    .use(rewriteLocalLinks, context)
    .use(html)
}