"use client"

/**
 * ScrollRegion — keyboard-accessible overflow container.
 *
 * Satisfies axe `scrollable-region-focusable` (Safari keyboard scroll parity)
 * **only while content overflows**. Non-overflowing regions stay out of the
 * Tab order so short breadcrumbs / fitting tables do not take a full-width
 * focus stop before their real controls.
 *
 * Use for any clipped `overflow-*` region that is not already a DS primitive
 * (`HorizontalScrollRegion`, `ScrollArea`, `Table`, `CardScrollRegion`).
 */

import * as React from "react"

import { useScrollOverflow } from "../../hooks/use-scroll-overflow"
import { composeRefs } from "../../lib/compose-refs"
import { cn } from "../../lib/utils"

export type ScrollRegionProps = React.ComponentProps<"div"> & {
  /** Accessible name for the scroll viewport. */
  label: string
}

export const ScrollRegion = React.forwardRef<HTMLDivElement, ScrollRegionProps>(
  function ScrollRegion({ label, className, children, tabIndex, ...props }, ref) {
    const { ref: localRef, overflowing } = useScrollOverflow<HTMLDivElement>()

    const resolvedTabIndex =
      tabIndex !== undefined ? tabIndex : overflowing ? 0 : undefined

    return (
      <div
        ref={composeRefs(localRef, ref)}
        data-slot="scroll-region"
        role="region"
        tabIndex={resolvedTabIndex}
        aria-label={label}
        className={cn(
          "outline-none",
          // Inset, because a scroll region is a full-bleed box: it fills a table
          // shell, a card, or a toolbar row, all of which clip. An offset ring
          // paints in whatever is outside the region and came back as four cut
          // stubs. Drawn inside, the ring also reads as what it is — the edge of
          // the thing that scrolls.
          overflowing &&
            "focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-inset",
          className,
        )}
        {...props}
      >
        {children}
      </div>
    )
  },
)

ScrollRegion.displayName = "ScrollRegion"