---
import DocsCard from './DocsCard.astro'
import docs from '@data/docs.json'
import Icon from '@ui/Icon.astro'
import { getDocsChildren } from '@lib/docs-pages'
import type { DocsPage } from '@lib/docs-pages'

interface MenuLeaf {
  title: string
  url: string
}

interface MenuNode {
  title: string
  url?: string
  children?: MenuNode[]
}

interface Props {
  /** Page URL in the docs namespace, e.g. "/ui/components/alert". */
  url: string
  /**
   * Which half to render. The child cards of an index page are content and stay
   * inside the article panel; the prev/next nav sits on the page canvas below
   * it. Omitted renders both.
   */
  only?: 'children' | 'pagination'
}

const { url, only } = Astro.props

const children = await getDocsChildren(url)

type Pagination = {
  prev: MenuLeaf | null
  next: MenuLeaf | null
  found: boolean
}

function findPage(nodes: MenuNode[]): Pagination | null {
  const index = nodes.findIndex((item) => item.url === url)

  if (index !== -1) {
    const previousNode = index > 0 ? nodes[index - 1] : null
    const nextNode = index < nodes.length - 1 ? nodes[index + 1] : null

    return {
      prev: previousNode?.url ? { title: previousNode.title, url: previousNode.url } : null,
      next: nextNode?.url ? { title: nextNode.title, url: nextNode.url } : null,
      found: true,
    }
  }

  for (const node of nodes) {
    const result = node.children ? findPage(node.children) : null
    if (result) return result
  }

  return null
}

const { prev, next, found } = findPage(docs.menu as MenuNode[]) ?? {
  prev: null,
  next: null,
  found: false,
}
---

<!-- BEGIN DOCS PAGINATION -->{
  only !== 'pagination' && children.length > 0 && (
    <div class="mt-6 pt-6">
      <div class="row row-deck row-cards">
        {children.map((child: DocsPage) => (
          <DocsCard href={child.url} title={child.title} description={child.description} icon={child.icon} />
        ))}
      </div>
    </div>
  )
}

{
  only !== 'children' && children.length === 0 && found && (prev || next) && (
    <nav class="docs-pagination" aria-label="Pagination">
      {prev && (
        <a class="docs-pagination-link" href={prev.url} rel="prev">
          <span class="docs-pagination-label">
            <Icon name="chevron-left" /> Previous
          </span>
          <span class="docs-pagination-title">{prev.title}</span>
        </a>
      )}
      {next && (
        <a class="docs-pagination-link docs-pagination-next" href={next.url} rel="next">
          <span class="docs-pagination-label">
            Next <Icon name="chevron-right" />
          </span>
          <span class="docs-pagination-title">{next.title}</span>
        </a>
      )}
    </nav>
  )
}
<!-- END DOCS PAGINATION -->