import { canUseRegexLookbehind, type PlainExtension } from '@prosekit/core'

import { defineMarkInputRule } from '../input-rule/index.ts'

/**
 * @internal
 */
export function defineItalicInputRule(): PlainExtension {
  return defineMarkInputRule({
    regex: canUseRegexLookbehind()
      ? /(?<=\s|^)\*([^\s*]|[^\s*][^*]*[^\s*])\*$/
      : /\*([^\s*]|[^\s*][^*]*[^\s*])\*$/,
    type: 'italic',
  })
}