micromark-extension-lemmy-spoiler/dev/lib/spoiler.js

micromark extension to support lemmy spoiler format

/**
 * @typedef {import('micromark-util-types').Construct} Construct
 * @typedef {import('micromark-util-types').State} State
 * @typedef {import('micromark-util-types').Token} Token
 * @typedef {import('micromark-util-types').TokenizeContext} TokenizeContext
 * @typedef {import('micromark-util-types').Tokenizer} Tokenizer
 */

import {ok as assert} from 'devlop'
import {factorySpace} from 'micromark-factory-space'
import {markdownLineEnding, markdownSpace} from 'micromark-util-character'
import {codes, constants, types} from 'micromark-util-symbol'

/** @type {Construct} */
export const spoiler = {
  tokenize: tokenizeSpoiler,
  concrete: true
}

const nonLazyLine = {tokenize: tokenizeNonLazyLine, partial: true}

const spoilerKeyword = 'spoiler'

/**
 * @this {TokenizeContext}
 * @type {Tokenizer}
 */
function tokenizeSpoiler(effects, ok, nok) {
  const self = this
  const tail = self.events[self.events.length - 1]
  const initialSize =
    tail && tail[1].type === types.linePrefix
      ? tail[2].sliceSerialize(tail[1], true).length
      : 0
  let sizeOpen = 0
  /** @type {Token} */
  let previous

  let sizeKeyword = 0

  return start

  /** @type {State} */
  function start(code) {
    assert(code === codes.colon, 'expected `:`')
    effects.enter('spoiler')
    effects.enter('spoilerFence')
    effects.enter('spoilerSequence')
    return sequenceOpen(code)
  }

  /** @type {State} */
  function sequenceOpen(code) {
    if (code === codes.colon) {
      effects.consume(code)
      sizeOpen++
      return sequenceOpen
    }

    if (sizeOpen < constants.codeFencedSequenceSizeMin) {
      return nok(code)
    }

    effects.exit('spoilerSequence')

    return afterSequenceOpen(code)
  }

  /** @type {State} */
  function afterSequenceOpen(code) {
    return factorySpace(effects, keywordStart, types.whitespace)(code)
  }

  /** @type {State} */
  function keywordStart(code) {
    if (sizeKeyword === 0) {
      effects.enter('spoilerKeyword')
    }

    if (code === spoilerKeyword.codePointAt(sizeKeyword)) {
      effects.consume(code)
      sizeKeyword++
      return keywordStart
    }

    if (sizeKeyword < spoilerKeyword.length) return nok(code)

    effects.exit('spoilerKeyword')

    return afterKeyword(code)
  }

  /** @type {State} */
  function afterKeyword(code) {
    if (!markdownSpace(code)) {
      return nok(code)
    }

    return factorySpace(effects, nameStart, types.whitespace)(code)
  }

  /** @type {State} */
  function nameStart(code) {
    effects.enter('spoilerName')
    effects.enter(types.chunkText, {
      contentType: constants.contentTypeText
    })

    if (markdownLineEnding(code) || code === codes.eof) {
      return nok(code)
    }

    return parseName(code)
  }

  /** @type {State} */
  function parseName(code) {
    if (markdownLineEnding(code) || code === codes.eof) {
      effects.exit(types.chunkText)
      effects.exit('spoilerName')
      return openAfter(code)
    }

    effects.consume(code)
    return parseName
  }

  /** @type {State} */
  function openAfter(code) {
    effects.exit('spoilerFence')

    if (code === codes.eof) {
      return afterOpening(code)
    }

    assert(
      markdownLineEnding(code),
      'openAfter must be called with eof or line ending'
    )

    if (self.interrupt) {
      return ok(code)
    }

    return effects.attempt(nonLazyLine, contentStart, afterOpening)(code)
  }

  /** @type {State} */
  function afterOpening(code) {
    effects.exit('spoiler')
    return ok(code)
  }

  /** @type {State} */
  function contentStart(code) {
    if (code === codes.eof) {
      effects.exit('spoiler')
      return ok(code)
    }

    effects.enter('spoilerContent')
    return lineStart(code)
  }

  /** @type {State} */
  function lineStart(code) {
    if (code === codes.eof) {
      return after(code)
    }

    return effects.attempt(
      {tokenize: tokenizeClosingFence, partial: true},
      after,
      initialSize
        ? factorySpace(effects, chunkStart, types.linePrefix, initialSize + 1)
        : chunkStart
    )(code)
  }

  /** @type {State} */
  function chunkStart(code) {
    if (code === codes.eof) {
      return after(code)
    }

    const token = effects.enter(types.chunkDocument, {
      contentType: constants.contentTypeDocument,
      previous
    })
    if (previous) previous.next = token
    previous = token
    return contentContinue(code)
  }

  /** @type {State} */
  function contentContinue(code) {
    if (code === codes.eof) {
      const t = effects.exit(types.chunkDocument)
      self.parser.lazy[t.start.line] = false
      return after(code)
    }

    if (markdownLineEnding(code)) {
      return effects.check(nonLazyLine, nonLazyLineAfter, lineAfter)(code)
    }

    effects.consume(code)
    return contentContinue
  }

  /** @type {State} */
  function nonLazyLineAfter(code) {
    effects.consume(code)
    const t = effects.exit(types.chunkDocument)
    self.parser.lazy[t.start.line] = false
    return lineStart
  }

  /** @type {State} */
  function lineAfter(code) {
    const t = effects.exit(types.chunkDocument)
    self.parser.lazy[t.start.line] = false
    return after(code)
  }

  /** @type {State} */
  function after(code) {
    effects.exit('spoilerContent')
    effects.exit('spoiler')
    return ok(code)
  }

  /**
   * @this {TokenizeContext}
   * @type {Tokenizer}
   */
  function tokenizeClosingFence(effects, ok, nok) {
    let size = 0

    return factorySpace(
      effects,
      closingPrefixAfter,
      types.linePrefix,
      constants.tabSize
    )

    /** @type {State} */
    function closingPrefixAfter(code) {
      effects.enter('spoilerFence')
      effects.enter('spoilerSequence')
      return closingSequence(code)
    }

    /** @type {State} */
    function closingSequence(code) {
      if (code === codes.colon) {
        effects.consume(code)
        size++
        return closingSequence
      }

      if (size < sizeOpen) return nok(code)
      effects.exit('spoilerSequence')
      return factorySpace(effects, closingSequenceEnd, types.whitespace)(code)
    }

    /** @type {State} */
    function closingSequenceEnd(code) {
      if (code === codes.eof || markdownLineEnding(code)) {
        effects.exit('spoilerFence')
        return ok(code)
      }

      return nok(code)
    }
  }
}

/**
 * @this {TokenizeContext}
 * @type {Tokenizer}
 */
function tokenizeNonLazyLine(effects, ok, nok) {
  const self = this

  return start

  /** @type {State} */
  function start(code) {
    assert(markdownLineEnding(code), 'expected eol')
    effects.enter(types.lineEnding)
    effects.consume(code)
    effects.exit(types.lineEnding)
    return lineStart
  }

  /** @type {State} */
  function lineStart(code) {
    return self.parser.lazy[self.now().line] ? nok(code) : ok(code)
  }
}