/**
 * The CodeTabs directive supports displaying a set of sequential code blocks
 * as tabbed files.
 *
 * The syntax is:
 *
 * ````mdx
 * <$CodeTabs>
 *
 * ```js name=a.js
 * console.log('file a')
 * ```
 *
 * ```js name=b.js
 * console.log('file b')
 * ```
 *
 * <$/CodeTabs>
 * ````
 */

import { type Parent, type Code, type Root } from 'mdast'
import type { MdxJsxFlowElement } from 'mdast-util-mdx-jsx'
import { SKIP, visitParents } from 'unist-util-visit-parents'

import { isCodeSampleWrapper } from './CodeSample'

export function codeTabsRemark() {
  return function transform(tree: Root) {
    rewriteNodes(tree)
    return tree
  }
}

function rewriteNodes(tree: Root) {
  visitParents(
    tree,
    ['mdxJsxFlowElement', 'code'],
    (node: MdxJsxFlowElement | Code, ancestors: Array<Parent>) => {
      if (node.type === 'mdxJsxFlowElement') {
        if (node.name !== '$CodeTabs') {
          return
        } else {
          replaceCodeTabs(node, ancestors)
          // Code blocks inside CodeTabs are handled with CodeTabs, so ignore
          // them here
          return SKIP
        }
      } else {
        nameCodeBlock(node, ancestors)
      }
    }
  )
}

function replaceCodeTabs(node: MdxJsxFlowElement, ancestors: Array<Parent>) {
  if (node.children.some((child) => child.type !== 'code' && !isCodeSampleWrapper(child))) {
    throw new Error(
      `CodeTabs must contain only code blocks and code sample wrappers, found:\n\n${JSON.stringify(node.children, null, 2)}`
    )
  }

  const parent = ancestors[ancestors.length - 1]
  const remappedChildren = node.children.map(
    (code: Code | MdxJsxFlowElement, idx): MdxJsxFlowElement => {
      const file = getFileName(code)
      return {
        type: 'mdxJsxFlowElement',
        name: 'TabPanel',
        attributes: [
          {
            type: 'mdxJsxAttribute',
            name: 'id',
            value: file || `File ${idx + 1}`,
          },
          {
            type: 'mdxJsxAttribute',
            name: 'label',
            value: file || `File ${idx + 1}`,
          },
        ],
        children: [code],
      }
    }
  )
  const tabsWrapper: MdxJsxFlowElement = {
    type: 'mdxJsxFlowElement',
    name: 'Tabs',
    attributes: [
      {
        type: 'mdxJsxAttribute',
        name: 'listClassNames',
        value: 'flex-nowrap overflow-x-auto -mb-6',
      },
    ],
    children: remappedChildren,
  }

  parent.children.splice(parent.children.indexOf(node), 1, tabsWrapper)
}

function nameCodeBlock(node: Code, ancestors: Array<Parent>) {
  const file = getFileName(node)
  if (!file) return

  const parent = ancestors[ancestors.length - 1]
  const codeBlockWrapper: MdxJsxFlowElement = {
    type: 'mdxJsxFlowElement',
    name: 'NamedCodeBlock',
    attributes: [
      {
        type: 'mdxJsxAttribute',
        name: 'name',
        value: file,
      },
    ],
    children: [node],
  }
  parent.children.splice(parent.children.indexOf(node), 1, codeBlockWrapper)
}

function getFileName(node: Code | MdxJsxFlowElement): string | undefined {
  const code = node.type === 'code' ? node : (node.children[0] as Code)
  return code?.meta
    ?.split(/\s+/)
    .find((meta) => meta.startsWith('name='))
    ?.split('=')[1]
}