import type { LexicalVisitor, MdastImportVisitor } from '@mdxeditor/editor'
import type { ElementNode } from 'lexical'
import type * as Mdast from 'mdast'

import { $createMentionNode, $isMentionNode } from './MentionNode'
import {
  MENTION_MARKDOWN_PROTOCOL,
  MENTION_NAME_SANITIZE_REGEX,
  MENTION_URL_PATH_SANITIZE_REGEX,
} from './constants'
import { stripMentionProtocol } from './utils'

export const MdastMentionLinkVisitor: MdastImportVisitor<Mdast.Nodes> = {
  testNode: (node) =>
    node.type === 'link' &&
    typeof node.url === 'string' &&
    node.url.startsWith(MENTION_MARKDOWN_PROTOCOL),
  priority: 1,
  visitNode: ({ mdastNode, lexicalParent }) => {
    const link = mdastNode as Mdast.Link
    const profileId = stripMentionProtocol(link.url)
    const urlPath = typeof link.title === 'string' ? link.title : ''
    const firstChild = link.children?.[0]
    const textValue = firstChild && firstChild.type === 'text' ? firstChild.value : ''
    const name = textValue.startsWith('@') ? textValue.slice(1) : textValue
    // MentionNode is a leaf (token-mode TextNode subclass) — append directly
    // and DON'T step into it. Using `addAndStepInto` would make mdxeditor try
    // to recurse into the link's text children with our MentionNode as the
    // parent, but it has no `.append` (it's not an ElementNode) → crash.
    ;(lexicalParent as ElementNode).append($createMentionNode({ profileId, urlPath, name }))
  },
}

// Defensive sanitization on export so a hostile or unusual name/urlPath
// can't break out of the `[@…](… "…")` form `MENTION_MARKDOWN_LINK_REGEX` parses.
const sanitizeName = (name: string): string => name.replace(MENTION_NAME_SANITIZE_REGEX, '')
const sanitizeUrlPath = (urlPath: string): string =>
  urlPath.replace(MENTION_URL_PATH_SANITIZE_REGEX, '')

export const LexicalMentionVisitor: LexicalVisitor = {
  testLexicalNode: $isMentionNode,
  priority: 1,
  visitLexicalNode: ({ lexicalNode, mdastParent, actions }) => {
    if (!$isMentionNode(lexicalNode)) return
    const link: Mdast.Link = {
      type: 'link',
      url: `${MENTION_MARKDOWN_PROTOCOL}${lexicalNode.getProfileId()}`,
      title: sanitizeUrlPath(lexicalNode.getUrlPath()),
      children: [{ type: 'text', value: `@${sanitizeName(lexicalNode.getName())}` }],
    }
    actions.appendToParent(mdastParent, link as Mdast.RootContent)
  },
}