Collapsible

"use client"

import * as React from "react"
import { Collapsible as CollapsiblePrimitive } from "@base-ui/react/collapsible"
import { ChevronDownIcon } from "lucide-react"

import { cn } from "@/registry/lib/utils"

// Disclosure reveal timings. Exit is faster than the entrance so closing feels
// crisp, not sluggish; both stay under the 300ms UI ceiling.
const OPEN_MS = 200
const CLOSE_MS = 150
// The divider fades out fast and front-loaded on close (well under CLOSE_MS) so a
// 1px line never sits crisp while the panel collapses behind it.
const BORDER_MS = 75
// A strong ease-out - punchy start, smooth settle - mirrors the site's
// --ease-out-quart token. Inlined so the registry item stays self-contained.
const EASE_OUT = "cubic-bezier(0.165, 0.84, 0.44, 1)"

function Collapsible({
  className,
  ...props
}: React.ComponentProps<typeof CollapsiblePrimitive.Root>) {
  // Ships its own surface so a bare disclosure looks finished: a bordered,
  // clipped box the padded trigger sits flush against. When Collapsible is used
  // headlessly to wrap content already inside another surface (e.g. a Card),
  // pass `className="contents"` to drop the box (border/overflow/radius no-op)
  // while keeping the open/close context. When `render`-ing onto a Card, pass
  // `border-0` on the Card: Card's edge is now a `shadow-ring` hairline, not a
  // `border`, so this `border` won't dedupe against it and you'd get a double edge.
  return (
    <CollapsiblePrimitive.Root
      data-slot="collapsible"
      className={cn(
        "overflow-hidden rounded-lg border border-border bg-card",
        className
      )}
      {...props}
    />
  )
}

function CollapsibleTrigger({
  className,
  children,
  ...props
}: React.ComponentProps<typeof CollapsiblePrimitive.Trigger>) {
  return (
    <CollapsiblePrimitive.Trigger
      data-slot="collapsible-trigger"
      className={cn(
        "group flex w-full cursor-pointer items-center justify-between gap-2 px-4 py-3 text-sm font-medium text-muted-foreground ring-inset transition-colors ease-out outline-none hover:bg-muted hover:text-foreground focus-visible:ring-ring-focus focus-visible:ring-[3px] disabled:pointer-events-none disabled:opacity-50 pointer-coarse:min-h-9",
        className
      )}
      {...props}
    >
      {children}
      <ChevronDownIcon className="size-4 shrink-0 transition-transform motion-reduce:transition-none duration-200 ease-out group-data-[panel-open]:rotate-180" />
    </CollapsiblePrimitive.Trigger>
  )
}

function CollapsibleContent({
  className,
  children,
  ...props
}: React.ComponentProps<typeof CollapsiblePrimitive.Panel>) {
  const ref = React.useRef<HTMLDivElement>(null)

  // Single clean reveal, driven in JS by measuring the content's own height -
  // the same proven mechanism the kit's animate-height Card uses. We deliberately
  // DON'T lean on Base UI's height keyframe: with a measured var it hitches on
  // open (the keyframe captures --collapsible-panel-height before Base UI sets
  // it), and Base UI only defers its exit for a *keyframe*, not a JS transition.
  //
  // Instead we pass `keepMounted` so the panel node never unmounts (Base UI then
  // treats us as animation-type "none" and just toggles the `hidden` attribute),
  // and we own both `height` and `display`: on each open/close we pin the current
  // height, force a reflow, then transition to the target (measured height, or 0).
  // Forcing `display: block` before measuring overrides Base UI's `hidden` so the
  // content stays laid out through a close, and it also survives an interrupted
  // toggle (we read the live height each time, so mid-flight reversals are smooth).
  // On settle we release the inline styles: open -> natural `auto` height; closed
  // -> `hidden` resumes (display:none), so collapsed content leaves the a11y tree.
  React.useEffect(() => {
    const node = ref.current
    if (!node) return

    // A panel that is already open (no reveal to clip) must not keep the clip:
    // it would shear the focus rings of any field inside. Covers both an
    // open-on-mount disclosure and the reduced-motion path below, neither of
    // which ever runs a transition that could release it.
    const syncOverflow = () => {
      node.style.overflow = node.hasAttribute("data-open") ? "visible" : ""
    }
    syncOverflow()

    // Reduced motion: let Base UI show/hide instantly via `hidden`, no animation.
    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
      const reducedObserver = new MutationObserver(syncOverflow)
      reducedObserver.observe(node, {
        attributes: true,
        attributeFilter: ["data-open", "data-closed", "hidden"],
      })
      return () => reducedObserver.disconnect()
    }

    let wasOpen = node.hasAttribute("data-open")

    const settle = (e: TransitionEvent) => {
      if (e.target !== node || e.propertyName !== "height") return
      node.style.transition = ""
      node.style.height = ""
      node.style.display = ""
      node.style.borderTopColor = ""
      // The clip is only needed *during* the height reveal. Once an open panel
      // settles, release it so focus rings on the fields inside aren't sheared
      // at their edges (every control rings 1px outside its border box).
      node.style.overflow = node.hasAttribute("data-open") ? "visible" : ""
    }

    const animate = (open: boolean) => {
      const s = node.style
      s.overflow = "" // re-arm the clip for the reveal (settle releases it again)
      s.display = "block" // lay out through the animation, overriding `hidden`
      // Live start height: 0 for a fresh open, otherwise the current rendered
      // (possibly mid-transition) height so reversals don't jump.
      const from = s.height ? node.offsetHeight : open ? 0 : node.offsetHeight
      s.height = "auto"
      const to = open ? node.offsetHeight : 0
      s.transition = "none"
      s.height = `${from}px`
      void node.getBoundingClientRect() // reflow so the next assignment animates
      // Both directions ease-out (the panel is entering/leaving), but the exit is
      // quicker than the entrance - a disclosure should snap shut with less
      // ceremony than it opens (Emil Kowalski: exits can be faster than entrances).
      if (open) {
        s.borderTopColor = "" // divider is crisp on the way in, no fade
        s.transition = `height ${OPEN_MS}ms ${EASE_OUT}`
        s.height = `${to}px`
      } else {
        // Fade any divider border out fast alongside the collapse (a no-op when
        // the panel has no border), then run the shorter height exit.
        s.transition = `height ${CLOSE_MS}ms ${EASE_OUT}, border-top-color ${BORDER_MS}ms ease-out`
        s.height = `${to}px`
        s.borderTopColor = "transparent"
      }
    }

    const observer = new MutationObserver(() => {
      const isOpen = node.hasAttribute("data-open")
      if (isOpen === wasOpen) return
      wasOpen = isOpen
      animate(isOpen)
    })
    observer.observe(node, {
      attributes: true,
      attributeFilter: ["data-open", "data-closed", "hidden"],
    })
    node.addEventListener("transitionend", settle)
    return () => {
      observer.disconnect()
      node.removeEventListener("transitionend", settle)
    }
  }, [])

  // overflow-hidden clips the content during the height reveal. `className` lands
  // on the panel (e.g. a divider `border-t` the demos add).
  return (
    <CollapsiblePrimitive.Panel
      ref={ref}
      keepMounted
      data-slot="collapsible-content"
      className={cn("overflow-hidden", className)}
      {...props}
    >
      {children}
    </CollapsiblePrimitive.Panel>
  )
}

export { Collapsible, CollapsibleTrigger, CollapsibleContent }