---
import { ScrollArea } from '@/components/ui/scroll-area'
import { cn } from '@/lib/utils'
import type { MarkdownHeading } from 'astro'
import { Icon } from 'astro-icon/components'

type Props = {
  headings: MarkdownHeading[]
}

const { headings } = Astro.props

function getHeadingMargin(depth: number): string {
  const margins: Record<number, string> = {
    3: 'ml-4',
    4: 'ml-8',
    5: 'ml-12',
    6: 'ml-16',
  }
  return margins[depth] || ''
}
---

<details
  open
  class="group col-start-2 rounded-xl border p-4 xl:sticky xl:top-20 xl:col-start-1 xl:mr-8 xl:ml-auto xl:h-[calc(100vh-5rem)] xl:max-w-fit xl:rounded-none xl:border-none xl:p-0"
>
  <summary
    class="flex cursor-pointer items-center justify-between text-xl font-medium group-open:pb-4 xl:hidden"
  >
    <span>Table of Contents</span>
    <Icon
      name="lucide:chevron-down"
      class="size-5 shrink-0 transition-transform group-open:rotate-180"
    />
  </summary>

  <ScrollArea
    client:load
    className="flex max-h-64 flex-col overflow-y-auto xl:max-h-[calc(100vh-8rem)]"
    type="always"
  >
    <ul
      class="flex list-none flex-col gap-y-2 px-4 xl:mr-8"
      id="table-of-contents"
    >
      <li class="hidden text-lg font-medium xl:block">Table of Contents</li>
      {
        headings.map((heading) => (
          <li
            class={cn(
              'text-foreground/60 px-4 text-sm xl:p-0',
              getHeadingMargin(heading.depth),
            )}
          >
            <a
              href={`#${heading.slug}`}
              class="marker:text-foreground/30 list-item list-disc underline decoration-transparent underline-offset-[3px] transition-colors duration-200 hover:decoration-inherit xl:list-none"
            >
              {heading.text}
            </a>
          </li>
        ))
      }
    </ul>
  </ScrollArea>
</details>

<script>
  function setupToc() {
    const header = document.querySelector('header')
    const headerHeight = header ? header.offsetHeight : 0

    const observer = new IntersectionObserver(
      (sections) => {
        sections.forEach((section) => {
          const heading = section.target.querySelector('h2, h3, h4, h5, h6')
          if (!heading) return

          const id = heading.getAttribute('id')
          const link = document.querySelector(
            `#table-of-contents li a[href="#${id}"]`,
          )
          if (!link) return

          const addRemove = section.isIntersecting ? 'add' : 'remove'
          link.classList[addRemove]('text-foreground')
        })
      },
      {
        rootMargin: `-${headerHeight}px 0px 0px 0px`,
      },
    )

    const sections = document.querySelectorAll('.prose section')
    sections.forEach((section) => {
      observer.observe(section)
    })
  }

  document.addEventListener('astro:page-load', setupToc)
  document.addEventListener('astro:after-swap', setupToc)
</script>