import { unified } from 'unified'
import remarkParse from 'remark-parse'
import remarkRehype from 'remark-rehype'
import rehypeRaw from 'rehype-raw'
import rehypeExtractExcerpt from 'rehype-extract-excerpt'
import rehypeStringify from 'rehype-stringify'
// TODO: this breaks the side base somehow
// import rehypePresetMinify from 'rehype-preset-minify'
// import * as shiki from 'shiki'

import remarkGfm from 'remark-gfm'
import remarkGithub from 'remark-github'
import remarkGithubAdmonitions from 'remark-github-beta-blockquote-admonitions'
import remarkDirective from 'remark-directive'

// @ts-ignore
// import remarkAbbr from 'remark-abbr'
import remarkCode from './remark-code'
import rehypeSlug from 'rehype-slug'
import rehypeAutolinkHeadings from 'rehype-autolink-headings'
import rehypeToc from 'rehype-toc'
// https://github.com/GaiAma/Coding4GaiAma/tree/HEAD/packages/rehype-accessible-emojis
// https://github.com/mrzmmr/rehype-partials
// https://github.com/kamranayub/remark-typedoc-symbol-links

import { h } from 'hastscript'
import { visit } from 'unist-util-visit'
import { findAfter } from 'unist-util-find-after'
import { visitParents } from 'unist-util-visit-parents'
import { headingRank } from 'hast-util-heading-rank'
import { toString } from 'hast-util-to-string'
import { hasProperty } from 'hast-util-has-property'

import { consume, cx } from '$lib/twind'

import tokyoNightLight from './themes/tokyo-night-light.json'
import tokyoNightDark from './themes/tokyo-night-storm.json'

import QuickLRU from 'quick-lru'
import { readFile } from './read-cache'

const cache = new QuickLRU<string, string>({ maxSize: 500 })

const base = ({ noCode }: { noCode?: boolean } = {}) => {
  let processor = unified()
    .use(remarkParse)
    // TODO: https://github.com/sergioramos/remark-hint with custom classes
    // TODO: .use(remarkAbbr)
    // TODO: remarkA11yEmoji,
    // https://learn.microsoft.com/en-us/contribute/markdown-reference#alerts-note-tip-important-caution-warning
    .use(remarkGithubAdmonitions, {
      classNameMaps: {
        block: (title: string) =>
          `relative rounded-md drop-shadow border-l-4 border-${getAdmonitionColor(
            title,
          )}-7 text-${getAdmonitionColor(title)}-12 bg-${getAdmonitionColor(
            title,
          )}-3 hover:bg-${getAdmonitionColor(
            title,
          )}-4 mb-5 p-4 pl-10 pb-0.5 before:absolute before:left-2 before:top-4 before:content-['${getAdmonitionIcon(
            title,
          )}'])`,
        title: (title: string) => `font-medium text-${getAdmonitionColor(title)}-11 m-0 -mb-2`,
      },
      titleFilter: ['note', 'tip', 'hint', 'important', 'caution', 'warning'],
      titleTextMap: (title: string) => {
        const parts = title.split('/')
        const checkedTitle = parts.shift()
        return {
          checkedTitle: checkedTitle?.toLocaleLowerCase(),
          displayTitle: parts.join(':').trim() || checkedTitle,
        }
      },
      titleLift: true,
      titleUnwrap: true,
      dataMaps: {
        block: (data) => ({ ...data, hName: 'div' }),
        title: (data) => ({ ...data, hName: 'div' }),
      },
    })
    .use(remarkGfm)
    .use(remarkGithub, {
      repository: 'https://github.com/tw-in-js/twind.git',
      buildUrl(values, defaultBuildUrl) {
        // prevent @scope/package to be interpreted as a user mention
        return values.type === 'mention' && values.user.includes('/')
          ? false
          : defaultBuildUrl(values)
      },
    })

  if (!noCode) {
    processor = processor.use(remarkCode, {
      themes: {
        light: tokyoNightLight as any,
        dark: tokyoNightDark as any,
      },
    })
  }

  // TODO: https://github.com/kevin940726/remark-codesandbox
  return processor
    .use(remarkDirective)
    .use(function cols() {
      return (tree) => {
        visit(tree, (node) => {
          // if (
          //   node.type === 'textDirective' ||
          //   node.type === 'leafDirective' ||
          //   node.type === 'containerDirective'
          // ) {
          //   console.debug(node)
          // }

          if (node.type === 'containerDirective' && node.name.startsWith('cols-')) {
            const data = node.data || (node.data = {})

            data.hName = 'div'
            data.hProperties = {
              className: `md:grid grid-cols-${node.name.slice('cols-'.length)} ${
                node.attributes?.class || ''
              }`,
            }

            const children = []
            let currentChild

            try {
              for (const child of node.children) {
                if (child.type === 'leafDirective' && child.name.startsWith('col-span-')) {
                  children.push(child)
                  child.data ||= {}
                  child.data.hName = 'div'
                  child.data.hProperties = {
                    className: `${child.name} ${child.attributes?.class || ''}`,
                  }
                  currentChild = child
                } else if (currentChild) {
                  currentChild.children.push(child)
                }
              }
            } catch (error) {
              console.debug(error)
            }

            node.children = children
          }
        })
      }
    })
    .use(remarkRehype, { allowDangerousHtml: true })
    .use(rehypeRaw) // *Parse* the raw HTML strings embedded in the tree
    .use(rehypeSlug)
}

const processor = base()
  .use(rehypeAutolinkHeadings, {
    behavior: 'wrap',
    properties: {
      class: `flex items-center no-underline before:(invisible -ml-5 pr-3 text-brand-12 text-sm content-['#']) hover:before:visible`,
    },
  })
  .use(rehypeToc, {
    headings: ['h2', 'h3'],
    customizeTOC(toc) {
      if (!toc) return toc

      if (!toc.children[0].children.length) {
        return { type: 'text', value: '' }
      }

      toc.properties.role = 'directory'
      toc.properties['aria-label'] = 'Table of contents'

      for (const node of walk([toc])) {
        if (node.properties?.className) {
          const kind = node.properties.className.split(' ')[0]
          const level = node.properties.className.slice(-1)

          node.properties.className =
            {
              toc: `not-prose w-64 py-10 hidden xl:block fixed top-16 bottom-0 right-[max(0px,calc(50%-45rem))] overflow-y-auto text-sm leading-6 before:(block content-['On_this_page'] text-accent-12 font-semibold mb-4)`,
              'toc-level': level == '1' ? `list-none` : `ml-${level == '2' ? 4 : 2} list-['›']`,
              'toc-item': level == '2' ? 'font-medium' : 'pl-2',
              'toc-link': `block py-1 mr-4 hover:text-brand-12 transition-colors duration-300 ease-in-out`,
            }[kind] || kind
        }
      }

      function* walk(nodes) {
        for (const node of nodes) {
          yield node

          if (node.children) {
            yield* walk(node.children)
          }
        }
      }
    },
  })
  // TODO: configure https://github.com/rehypejs/rehype-external-links
  // mdsvex already includes it?
  // [rehypeExternalLinks, { target: "_blank" }],

  .use(rehypeStringify)

function getAdmonitionColor(title: string) {
  switch (title) {
    case 'note': // 🧚
      return 'brand'
    case 'tip': // 💡
      return 'success'
    case 'hint': // ✨
      return 'info'
    case 'important': // 📣 💥
      return 'accent'
    case 'caution': // 🧨
      return 'error'
    case 'warning': // 🚨
      return 'warning'
  }

  return 'neutral'
}

function getAdmonitionIcon(title: string) {
  switch (title) {
    case 'note':
      return '🧚'
    case 'tip':
      return '💡'
    case 'hint':
      return '✨'
    case 'important':
      return '📣'
    case 'caution':
      return '🧨'
    case 'warning':
      return '🚨'
  }

  return '💥'
}

export function extractExcerpt(content: string): Promise<string | undefined> {
  return base()
    .use(rehypeExtractExcerpt)
    .use(rehypeStringify)
    .process(content)
    .then((vfile) => (vfile.data.excerpt ? String(vfile.data.excerpt) : undefined))
}

export function sectionize(
  content: string,
): Promise<{ anchor: string; rank: number; title: string; content: string }[] | undefined> {
  return base({ noCode: true })
    .use(function sectionize() {
      return (tree, vfile) => {
        const sections = (vfile.data['sections'] = [])

        visitParents(
          tree,
          (node) => [1, 2, 3].includes(headingRank(node)) && hasProperty(node, 'id'),
          (node, ancestors) => {
            const start = node
            const parent = ancestors[ancestors.length - 1]

            const end = findAfter(parent, start, (node) => !!headingRank(node))

            const startIndex = parent.children.indexOf(start)
            const endIndex = parent.children.indexOf(end)

            const between = parent.children.slice(
              startIndex + 1,
              endIndex > 0 ? endIndex : undefined,
            )

            sections.push({
              anchor: node.properties.id,
              rank: headingRank(node),
              title: toString(node).trim().replace(/\n+/g, ' '),
              content: toString(h('section', between)).trim().replace(/\n+/g, ' '),
            })
          },
        )
      }
    })
    .use(rehypeStringify)
    .process(content)
    .then((vfile) => vfile.data.sections)
}

export async function transform(content: string): Promise<string> {
  // console.log({ id, frontmatter })
  let cached = cache.get(content)

  if (!cached) {
    // consum will expand all groupings within the html and replace certain escapings
    cache.set(content, (cached = consume(String(await processor.process(content)), cx)))
  }

  return cached
}

export async function transformFile(file: string): Promise<string> {
  const { content } = await readFile(file)
  return transform(content)
}