webapp/src/components/Editor/prosemirror/extension/markdown.ts

import {
  inputRules,
  textblockTypeInputRule,
  wrappingInputRule,
  smartQuotes,
  emDash,
  ellipsis
} from 'prosemirror-inputrules'
import type { NodeType, Schema } from 'prosemirror-model'
import type { ProseMirrorExtension } from '../helpers'

const blockQuoteRule = (nodeType: NodeType) => wrappingInputRule(/^\s*>\s$/, nodeType)

const orderedListRule = (nodeType: NodeType) =>
  wrappingInputRule(
    /^(\d+)\.\s$/,
    nodeType,
    (match) => ({ order: +match[1] }),
    (match, node) => node.childCount + node.attrs.order === +match[1]
  )

const bulletListRule = (nodeType: NodeType) => wrappingInputRule(/^\s*([*+-])\s$/, nodeType)

const headingRule = (nodeType: NodeType, maxLevel: number) =>
  textblockTypeInputRule(new RegExp('^(#{1,' + maxLevel + '})\\s$'), nodeType, (match) => ({
    level: match[1].length
  }))

const markdownRules = (schema: Schema) => {
  const rules = [...smartQuotes, ellipsis, emDash]
  if (schema.nodes.blockquote) rules.push(blockQuoteRule(schema.nodes.blockquote))
  if (schema.nodes.ordered_list) rules.push(orderedListRule(schema.nodes.ordered_list))
  if (schema.nodes.bullet_list) rules.push(bulletListRule(schema.nodes.bullet_list))
  if (schema.nodes.heading) rules.push(headingRule(schema.nodes.heading, 6))
  return rules
}

export default (): ProseMirrorExtension => ({
  plugins: (prev, schema) => [...prev, inputRules({ rules: markdownRules(schema) })]
})