Notification Stack

// Shared motion tokens. Easing curves mirror the CSS custom properties in
// globals.css; springs are the canonical physics used across components.
// Strong custom variants — defaults like `ease-in`/`ease-out` feel weak.

export const EASE_OUT = [0.16, 1, 0.3, 1] as const;
export const EASE_IN_OUT = [0.77, 0, 0.175, 1] as const;
export const EASE_DRAWER = [0.32, 0.72, 0, 1] as const;

/** CSS string form of EASE_OUT for inline style transitions. */
export const EASE_OUT_CSS = "cubic-bezier(0.16, 1, 0.3, 1)";

/** Press feedback on buttons and other tappable surfaces. */
export const SPRING_PRESS = {
  type: "spring",
  stiffness: 500,
  damping: 30,
  mass: 0.6,
} as const;

/** Content swaps — label/icon slots trading places inside a control. */
export const SPRING_SWAP = {
  type: "spring",
  stiffness: 460,
  damping: 30,
  mass: 0.55,
} as const;

/** Overlay panel entrances — modals and sheets summoned by pointer. */
export const SPRING_PANEL = {
  type: "spring",
  stiffness: 420,
  damping: 40,
  mass: 0.5,
} as const;

/** Shared-layout glides — pills, indicators and panels morphing between positions. */
export const SPRING_LAYOUT = {
  type: "spring",
  stiffness: 360,
  damping: 32,
  mass: 0.6,
} as const;

/** Cursor-follow physics for decorative mouse tracking (magnetic, tilt, dock). */
export const SPRING_MOUSE = {
  stiffness: 200,
  damping: 15,
  mass: 0.3,
} as const;

/** Dragged handles and fills (sliders) — critically damped `useSpring` config,
 * so the value follows the pointer butterily and never rebounds off an end. */
export const SPRING_GLIDE = {
  stiffness: 700,
  damping: 50,
  mass: 0.5,
} as const;

"use client";

import { type RefObject, useEffect } from "react";

/**
 * What the dismissing gesture does to the control it landed on.
 *
 * `"pass-through"` is the platform norm (native popover light-dismiss): the
 * tap closes the overlay *and* activates whatever was under it. Use
 * `"consume"` where the open overlay sits over or beside controls that would
 * be costly to trigger by accident — the dismissal then swallows the
 * activation too, so the gesture only closes.
 */
export type DismissBehavior = "pass-through" | "consume";

export interface DismissOptions {
  /** Default `"pass-through"`. */
  behavior?: DismissBehavior;
  /** Dismiss on Escape as well. Default true. */
  escape?: boolean;
  /** Return true for an outside target that should *not* dismiss. Must be stable. */
  ignore?: (target: Element) => boolean;
}

/**
 * What every currently open dismiss scope counts as inside itself. A consumed
 * dismissal reads this to tell a stray gesture from one that belongs to an
 * overlay in front of it: overlays have no shared z-order to consult, but the
 * one the gesture landed in has said as much by registering it.
 */
const openScopes = new Set<(target: Element) => boolean>();

function claimedByAnotherScope(
  self: (target: Element) => boolean,
  target: Element,
) {
  for (const scope of openScopes) {
    if (scope !== self && scope(target)) return true;
  }
  return false;
}

// preventDefault on pointerdown does not suppress the click that follows, so
// consuming a gesture means swallowing that click itself. The swallower
// deliberately outlives the effect that installed it — the dismissal it
// belongs to has already unmounted or re-rendered by the time the click lands.
// It releases on that click, or on the next gesture if the pointer is dragged
// away and no click ever arrives, so it can never eat a later one. A keydown
// releases it too: a gesture that ends with neither a click nor a cancel would
// otherwise leave it armed, and the click Enter synthesizes on some focused
// control is not the one this dismissal was owed.
function consumeActivation(source: Event) {
  const swallow = (event: MouseEvent) => {
    event.preventDefault();
    event.stopPropagation();
    release();
  };
  const restart = (event: Event) => {
    if (event !== source) release();
  };
  const release = () => {
    window.removeEventListener("click", swallow, true);
    window.removeEventListener("pointerdown", restart, true);
    window.removeEventListener("pointercancel", restart, true);
    window.removeEventListener("keydown", release, true);
  };
  window.addEventListener("click", swallow, true);
  window.addEventListener("pointerdown", restart, true);
  window.addEventListener("pointercancel", restart, true);
  window.addEventListener("keydown", release, true);
}

/**
 * Close an open overlay on Escape or a pointerdown outside `ref`. Pass `null`
 * for `ref` when what counts as inside isn't one element, and say so with
 * `ignore` instead.
 *
 * The pointerdown listener is capture-phase: a bubble-phase one is blinded by
 * any handler in between that stops propagation, and an overlay cannot know
 * what it is layered over. `onDismiss` and `ignore` must be stable (wrap in
 * useCallback) so the listeners aren't re-bound every render while open.
 */
export function useDismiss(
  open: boolean,
  onDismiss: () => void,
  ref: RefObject<HTMLElement | SVGElement | null> | null,
  {
    behavior = "pass-through",
    escape: dismissOnEscape = true,
    ignore,
  }: DismissOptions = {},
) {
  useEffect(() => {
    if (!open) return;
    const inside = (target: Element) =>
      Boolean(ref?.current?.contains(target)) || Boolean(ignore?.(target));
    const onKey = (event: KeyboardEvent) => {
      if (dismissOnEscape && event.key === "Escape") onDismiss();
    };
    const onPointer = (event: PointerEvent) => {
      const target = event.target as Element | null;
      if (!target || inside(target)) return;
      // Outside this overlay, but inside one that is also open: the gesture is
      // that overlay's to answer, and swallowing its click from behind would
      // cost the user the control they actually aimed at.
      if (behavior === "consume" && !claimedByAnotherScope(inside, target)) {
        consumeActivation(event);
      }
      onDismiss();
    };
    openScopes.add(inside);
    window.addEventListener("keydown", onKey);
    window.addEventListener("pointerdown", onPointer, true);
    return () => {
      openScopes.delete(inside);
      window.removeEventListener("keydown", onKey);
      window.removeEventListener("pointerdown", onPointer, true);
    };
  }, [open, onDismiss, ref, behavior, dismissOnEscape, ignore]);
}

"use client";

import { useMemo, useRef } from "react";
import { isHoveringPointer } from "@/lib/touch";

interface BoundaryEvent {
  pointerId: number;
  pointerType: string;
  buttons: number;
}

export interface HoverGesture {
  /** True when this enter starts a hover: the pointer arrived resting, not pressing. */
  enter: (event: BoundaryEvent) => boolean;
  /** True when this leave ends a hover that entered as one. */
  leave: (event: BoundaryEvent) => boolean;
}

/**
 * Pairs a surface's enter with its leave, per pointer.
 *
 * `isHoveringPointer` answers the question the *enter* asks — is this pointer
 * resting on the surface or pressing it — and both boundary cases go wrong if
 * the leave is asked the same question again:
 *
 * - A pen with no hover never rests. It arrives in contact, taps, and the spec
 *   then requires its boundary events after `pointerup`, so the leave carries
 *   `buttons: 0` and reads as a mouse gliding off. Hover teardown then undid
 *   the tap — the panel the pen had just opened closed under it.
 * - A mouse pressed on the surface and dragged off leaves with `buttons: 1`.
 *   Skipping teardown there strands the surface open: the release happens
 *   outside, and no second leave ever comes.
 *
 * So the state a hover holds is released by the pointer that took it, whatever
 * the buttons say at the boundary, and a pointer that arrived in contact never
 * took it in the first place. Contact is the exception tracked here, not
 * hover: a leave from a pointer this surface never saw enter — mounted under
 * the cursor, say — still counts, since the alternative is state with no way
 * out.
 */
export function useHoverGesture(): HoverGesture {
  const contact = useRef(new Set<number>());

  return useMemo(
    () => ({
      enter: (event) => {
        if (isHoveringPointer(event)) {
          contact.current.delete(event.pointerId);
          return true;
        }
        contact.current.add(event.pointerId);
        return false;
      },
      leave: (event) => {
        const arrivedInContact = contact.current.delete(event.pointerId);
        return !arrivedInContact && event.pointerType !== "touch";
      },
    }),
    [],
  );
}

"use client";

import { useMemo, useRef } from "react";

/** What a pointerdown recorded, read back by the click that ends its gesture. */
export interface TapRecord<S> {
  /** Which input started the gesture. */
  pointerType: string;
  /** What the surface was showing when it started. */
  state: S;
}

export interface TapGesture<S> {
  /** Record the gesture a pointerdown starts, with the state it starts in. */
  start: (event: { pointerType: string }, state: S) => void;
  /** Read the record and clear it. `null` when no pointer is behind this click. */
  take: () => TapRecord<S> | null;
  /** Drop the record: this gesture will never spend it on a click. */
  drop: () => void;
}

/**
 * The pointer gesture behind a click, recorded where the click cannot report
 * it. A `click` carries no `pointerType` in the engines that matter, so the
 * `pointerdown` before it is the only thing that says which input activated
 * the control — and whether one did at all, since keyboard activation
 * synthesizes a click with no pointer behind it.
 *
 * State goes in with the record because a click reports that no better: a
 * browser that focuses a control on contact can open the very panel the tap
 * was meant to open, and reading "is it open" at click time then undoes it.
 * What the gesture started against is what it acts on.
 *
 * The record is spent by one click and dropped by everything else, because a
 * record that outlives its gesture is worse than none:
 *
 * - A scroll or an OS gesture takes the touch away — `pointercancel`, no click
 *   ever — and the finger would sit in the record until some later click.
 * - That later click is often `Enter` on a keyboard, which arrives with no
 *   pointerdown of its own and would inherit the abandoned finger. A keydown
 *   is the start of a keyboard activation and never part of a tap, so it drops
 *   the record too.
 *
 * Both ends have to be wired by the surface: `drop` on `onPointerCancel` and
 * on `onKeyDown`.
 */
export function useTapGesture<S>(): TapGesture<S> {
  const record = useRef<TapRecord<S> | null>(null);

  return useMemo(
    () => ({
      start: (event, state) => {
        record.current = { pointerType: event.pointerType, state };
      },
      take: () => {
        const spent = record.current;
        record.current = null;
        return spent;
      },
      drop: () => {
        record.current = null;
      },
    }),
    [],
  );
}

import { clsx, type ClassValue } from "clsx"
import { twMerge } from "tailwind-merge"

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}

// Shared touch primitives. iOS and iPadOS run their own gestures on top of the
// page — the long-press selection callout and the selection it drags in with
// it — and they win: once the platform claims a touch it cancels ours
// mid-gesture, so a press-and-hold or a drag simply dies. Surfaces that own
// their gesture have to opt out.
//
// What the two classes below cover, precisely:
// - `-webkit-touch-callout: none` stops iOS's long-press callout. WebKit-only:
//   it is not a property other engines have, so it is inert everywhere else.
// - `user-select: none` stops the long-press selection on every engine,
//   Android included, and stops a drag from painting a selection under the
//   cursor. It is inherited, so it reaches every descendant — which is why the
//   two classes differ only in whether they apply it unconditionally.
// What neither covers:
// - Chrome for Android's long-press menu on a link or an image. No CSS
//   suppresses it; a gesture surface that wraps one needs its own
//   `onContextMenu` with `preventDefault()`.
// - The native drag of an `<img>` or `<a>` descendant. `-webkit-user-drag` is
//   not inherited and plain divs and buttons are not drag sources, so setting
//   it on the surface does nothing — the child itself needs `draggable={false}`.

/**
 * Classes for a surface that *is* the control: a thumb, a drum, a stage, a
 * handle, a hold button. Selection is suppressed on every input, because a
 * drag that highlights the control's own label is wrong on a mouse too.
 * Compose with `touch-none` when the surface also owns the scroll axis — leave
 * it off when the page must still scroll from there.
 */
export const TOUCH_GESTURE_CLASS = "select-none [-webkit-touch-callout:none]";

/**
 * The same opt-out for a gesture surface that wraps content the consumer owns:
 * a scroller, a context-menu trigger, a sheet header, a list row. Selection is
 * suppressed only where the platform runs its own press gestures — a coarse
 * pointer — so a mouse user can still select and copy that content. If the
 * gesture itself would paint a selection under the cursor, add `select-none`
 * for the duration of the gesture rather than reaching for
 * `TOUCH_GESTURE_CLASS`.
 *
 * `pointer: coarse` describes the *primary* pointer and nothing else, so a
 * hybrid machine reads it wrong in both directions: a tablet with a mouse
 * plugged in keeps touch as primary and loses mouse selection, and a laptop
 * with a touchscreen keeps the mouse as primary and leaves selection live
 * under a finger. No media query can answer per interaction — the query is
 * about the device, and the question is about the gesture in progress. The
 * default stays here because it is right on the machines that are one thing or
 * the other, and losing a selection is a nuisance; where the miss costs a
 * *gesture* instead, the surface pairs it with `holdSelection` on the press.
 */
export const TOUCH_GESTURE_CONTENT_CLASS =
  "[-webkit-touch-callout:none] pointer-coarse:select-none";

/**
 * Suppress selection on `element` for as long as a gesture is running on it,
 * whatever the primary pointer of the machine happens to be. Returns the
 * release. Inline, so it wins over the class above and is gone again the
 * moment the gesture ends.
 *
 * For the press gestures a native selection would otherwise steal — a
 * long-press that opens a menu. Elsewhere prefer the classes: a surface that
 * takes selection away for the whole session is a surface whose text nobody
 * can copy.
 */
export function holdSelection(element: HTMLElement) {
  element.style.setProperty("user-select", "none");
  element.style.setProperty("-webkit-user-select", "none");
  return () => {
    element.style.removeProperty("user-select");
    element.style.removeProperty("-webkit-user-select");
  };
}

/**
 * Pointer capture, best effort. WebKit throws `NotFoundError` when the pointer
 * is already gone by the time the handler runs — routine on iOS, where the
 * system can claim the touch first — and an uncaught throw takes the rest of
 * the handler, the gesture included, down with it. Touch pointers carry
 * implicit capture anyway, so losing it is never fatal.
 */
export function capturePointer(element: Element, pointerId: number) {
  try {
    element.setPointerCapture(pointerId);
  } catch {
    // Pointer is no longer active — implicit capture still applies on touch.
  }
}

/** Release a capture taken with `capturePointer`, ignoring a stale pointer. */
export function releasePointer(element: Element, pointerId: number) {
  try {
    if (element.hasPointerCapture(pointerId)) {
      element.releasePointerCapture(pointerId);
    }
  } catch {
    // Capture was already dropped by the browser.
  }
}

/**
 * Whether this event came from a pointer that is *hovering*: not a touch, and
 * not currently pressed. Which input the user is holding right now is not
 * something a device capability can answer — a touchscreen laptop hovers and
 * taps, and iPadOS reports a fine hovering pointer for a finger — so both
 * paths stay live and each handler branches on the event it was given.
 *
 * A pen resting on the glass is making contact, not hovering: `buttons` is the
 * tell, and it sends a pen tap down the same route a finger takes.
 *
 * This answers what an *enter* asks. A leave is the other half of a pair and
 * has to be read against the enter that started it — `useHoverGesture` in
 * `lib/hooks/use-hover-gesture` does that, and hover surfaces should use it
 * rather than asking this question twice.
 */
export const isHoveringPointer = (event: {
  pointerType: string;
  buttons: number;
}) => event.pointerType !== "touch" && event.buttons === 0;

"use client";
// beui.dev/components/blocks/notification-stack

import { ArrowUpRight, BellOff } from "lucide-react";
import { motion, type Transition, useReducedMotion } from "motion/react";
import {
  type FocusEvent,
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  useCallback,
  useRef,
  useState,
} from "react";
import { ActionSwapText } from "@/components/motion/action-swap";
import { EASE_OUT, SPRING_LAYOUT } from "@/lib/ease";
import { useDismiss } from "@/lib/hooks/use-dismiss";
import { useHoverGesture } from "@/lib/hooks/use-hover-gesture";
import { useTapGesture } from "@/lib/hooks/use-tap-gesture";
import { cn } from "@/lib/utils";

export type NotificationStackItem = {
  id: string;
  title: ReactNode;
  description?: ReactNode;
  trailing?: ReactNode;
};

export type NotificationStackClassNames = {
  stack?: string;
  card?: string;
  content?: string;
  title?: string;
  description?: string;
  trailing?: string;
  footer?: string;
  count?: string;
};

export interface NotificationStackProps {
  items: NotificationStackItem[];
  expanded?: boolean;
  defaultExpanded?: boolean;
  onExpandedChange?: (expanded: boolean) => void;
  onViewAll?: () => void;
  maxVisible?: number;
  collapsedLabel?: string;
  expandedLabel?: string;
  emptyLabel?: string;
  className?: string;
  classNames?: NotificationStackClassNames;
}

const STACK_PEEK = 8;
const STACK_INSET = 12;

function useControllableExpanded({
  expanded,
  defaultExpanded,
  onExpandedChange,
}: {
  expanded?: boolean;
  defaultExpanded: boolean;
  onExpandedChange?: (expanded: boolean) => void;
}) {
  const [internalExpanded, setInternalExpanded] = useState(defaultExpanded);
  const isControlled = expanded !== undefined;
  const value = expanded ?? internalExpanded;

  const setValue = useCallback(
    (next: boolean) => {
      if (!isControlled) setInternalExpanded(next);
      onExpandedChange?.(next);
    },
    [isControlled, onExpandedChange],
  );

  return [value, setValue] as const;
}

function NotificationCardContent({
  item,
  classNames,
}: {
  item: NotificationStackItem;
  classNames?: NotificationStackClassNames;
}) {
  return (
    <span
      className={cn(
        "flex min-w-0 flex-col gap-1.5 py-4",
        classNames?.content,
      )}
    >
      <span className="flex min-w-0 items-start justify-between gap-3">
        <span
          className={cn(
            "min-w-0 text-sm font-medium leading-snug",
            classNames?.title,
          )}
        >
          {item.title}
        </span>
        {item.trailing ? (
          <span
            className={cn("shrink-0 text-xs", classNames?.trailing)}
          >
            {item.trailing}
          </span>
        ) : null}
      </span>
      {item.description ? (
        <span
          className={cn(
            "text-xs leading-relaxed text-muted-foreground",
            classNames?.description,
          )}
        >
          {item.description}
        </span>
      ) : null}
    </span>
  );
}

export function NotificationStack({
  items,
  expanded,
  defaultExpanded = false,
  onExpandedChange,
  onViewAll,
  maxVisible = 3,
  collapsedLabel = "Notifications",
  expandedLabel = "View all",
  emptyLabel = "All caught up",
  className,
  classNames,
}: NotificationStackProps) {
  const reduce = useReducedMotion();
  const hasFocus = useRef(false);
  const rootRef = useRef<HTMLButtonElement>(null);
  const hover = useHoverGesture();
  // What the last gesture on the stack was, and whether it was already
  // expanded when that gesture started. A click reports neither.
  const tap = useTapGesture<boolean>();
  const [isExpanded, setIsExpanded] = useControllableExpanded({
    expanded,
    defaultExpanded,
    onExpandedChange,
  });
  // Set by the tap that expands the stack, and the reason the outside-tap
  // dismisser exists at all — a hovering pointer has its own way out.
  const [tapExpanded, setTapExpanded] = useState(false);

  const collapse = useCallback(() => {
    setTapExpanded(false);
    setIsExpanded(false);
  }, [setIsExpanded]);

  // A pointer leaving the stack is what collapses it, and a finger never
  // leaves: without this the stack stays open for good once tapped, and when
  // `onViewAll` is set the next tap follows the link instead of closing. The
  // tap that lands somewhere else stands in for the pointer leaving, and it is
  // consumed rather than passed through — the expanded stack covers the page,
  // so the tap that dismisses it is aimed at nothing else.
  useDismiss(tapExpanded && isExpanded, collapse, rootRef, {
    behavior: "consume",
  });

  const visibleItems = items.slice(0, Math.max(1, maxVisible));
  const primaryItem = visibleItems[0];
  const transition: Transition = reduce ? { duration: 0 } : SPRING_LAYOUT;
  const cardTransition: Transition = reduce
    ? { duration: 0 }
    : { duration: 0.32, ease: EASE_OUT };
  const backgroundTransition: Transition = reduce
    ? { duration: 0 }
    : { duration: 0.26, ease: EASE_OUT };

  if (!primaryItem) {
    return (
      <div
        className={cn(
          "flex w-full max-w-[22rem] items-center justify-center gap-2 rounded-3xl bg-muted/70 px-5 py-8 text-sm font-medium text-muted-foreground",
          className,
        )}
      >
        <BellOff className="h-4 w-4" aria-hidden="true" />
        {emptyLabel}
      </div>
    );
  }

  const handleBlur = (event: FocusEvent<HTMLButtonElement>) => {
    if (event.currentTarget.contains(event.relatedTarget)) return;
    hasFocus.current = false;
    collapse();
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLButtonElement>) => {
    // A key press is the start of a keyboard activation, never part of a tap:
    // whatever a taken-away gesture left behind must not be read as one.
    tap.drop();
    if (event.key !== "Escape") return;
    event.preventDefault();
    collapse();
    // Focus stays where the keyboard put it. Blurring here collapsed the stack
    // *and* threw the user back to the top of the document.
  };

  const handleClick = () => {
    const gesture = tap.take();
    // Read from where the gesture started, not from now: a browser that
    // focuses the stack on contact expands it mid-tap, and the first tap would
    // then follow `onViewAll` instead of opening the list it was meant to.
    const wasExpanded = gesture ? gesture.state : isExpanded;

    if (!wasExpanded) {
      setIsExpanded(true);
      if (gesture && gesture.pointerType !== "mouse") setTapExpanded(true);
      return;
    }

    if (onViewAll) {
      onViewAll();
      return;
    }

    collapse();
  };

  return (
    <motion.button
      ref={rootRef}
      type="button"
      initial={false}
      aria-expanded={isExpanded}
      aria-label={
        isExpanded
          ? `${items.length} notifications. ${expandedLabel}.`
          : `${items.length} notifications. Expand notifications.`
      }
      // A tap reports as a hover on its way past — enter, leave, then click —
      // so an unfiltered hover path expands, collapses and expands again in
      // the space of one tap, springs and all. The tap has its own route
      // through `handleClick`.
      onPointerEnter={(event: PointerEvent<HTMLButtonElement>) => {
        if (hover.enter(event)) setIsExpanded(true);
      }}
      onPointerLeave={(event: PointerEvent<HTMLButtonElement>) => {
        if (hover.leave(event) && !hasFocus.current) collapse();
      }}
      onPointerDown={(event: PointerEvent<HTMLButtonElement>) => {
        tap.start(event, isExpanded);
      }}
      // The platform can take the gesture away mid-press — a scroll, a system
      // swipe — and no click follows it.
      onPointerCancel={tap.drop}
      onFocus={() => {
        hasFocus.current = true;
        setIsExpanded(true);
      }}
      onBlur={handleBlur}
      onKeyDown={handleKeyDown}
      onClick={handleClick}
      className={cn(
        "relative z-10 block w-full max-w-[22rem] cursor-pointer rounded-3xl text-left text-foreground outline-none",
        "focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background",
        className,
      )}
    >
      {/* This invisible first card gives the button its compact intrinsic footprint. */}
      <span aria-hidden="true" className="invisible block p-3">
        <span className="block">
          <span
            className={cn(
              "block rounded-2xl border border-transparent px-4",
              classNames?.card,
            )}
          >
            <NotificationCardContent
              item={primaryItem}
              classNames={classNames}
            />
          </span>
        </span>
        <span className="mt-2 block h-9" />
      </span>

      <span className="absolute inset-x-0 bottom-0 block p-3">
        <motion.span
          aria-hidden="true"
          layout
          initial={false}
          transition={backgroundTransition}
          className="absolute inset-0 rounded-3xl bg-muted"
        />
        <span
          className={cn(
            "relative z-10 grid gap-1",
            !isExpanded && "pb-2",
            classNames?.stack,
          )}
        >
          {visibleItems.map((item, index) => {
            const isPrimary = index === 0;

            return (
              <motion.span
                key={item.id}
                layout="position"
                initial={false}
                animate={{
                  y: isExpanded ? 0 : index * STACK_PEEK,
                  clipPath: isExpanded
                    ? "inset(0px 0px round 16px)"
                    : `inset(0px ${index * STACK_INSET}px round 16px)`,
                }}
                transition={cardTransition}
                className={cn(
                  "block rounded-2xl border border-border/60 bg-background px-4",
                  classNames?.card,
                )}
                style={{
                  zIndex: visibleItems.length - index,
                  gridColumn: 1,
                  gridRow: isExpanded ? index + 1 : 1,
                }}
              >
                <span
                  className={cn(
                    "block",
                    !isPrimary && !isExpanded && "invisible",
                  )}
                >
                  <NotificationCardContent
                    item={item}
                    classNames={classNames}
                  />
                </span>
              </motion.span>
            );
          })}
        </span>

        <motion.span
          layout="position"
          transition={transition}
          className={cn(
            "relative z-10 mt-2 flex min-h-9 items-center gap-2 px-1",
            classNames?.footer,
          )}
        >
          <span
            className={cn(
              "grid size-7 shrink-0 place-items-center rounded-full bg-orange-600 text-xs font-medium text-white shadow-[inset_0_1px_2px_rgb(0_0_0/0.2),inset_0_-1px_0_rgb(255_255_255/0.16)] dark:bg-orange-500",
              classNames?.count,
            )}
          >
            {items.length}
          </span>
          <span className="flex items-center text-sm font-medium">
            <ActionSwapText
              value={isExpanded ? "expanded" : "collapsed"}
              animation="roll"
            >
              {isExpanded ? (
                <span className="inline-flex items-center gap-1">
                  {expandedLabel}
                  <ArrowUpRight className="size-4" aria-hidden="true" />
                </span>
              ) : (
                collapsedLabel
              )}
            </ActionSwapText>
          </span>
        </motion.span>
      </span>
    </motion.button>
  );
}

"use client";

import { AnimatePresence, motion, useReducedMotion, type HTMLMotionProps, type Variants } from "motion/react";
import { useState } from "react";
import type { ReactNode } from "react";
import { EASE_OUT, SPRING_PRESS, SPRING_SWAP } from "@/lib/ease";
import { cn } from "@/lib/utils";

export type ActionSwapItem = {
  id: string;
  label: ReactNode;
  icon?: ReactNode;
  ariaLabel?: string;
};

export type ActionSwapButtonVariant = "primary" | "secondary" | "outline" | "ghost";
export type ActionSwapButtonSize = "sm" | "md" | "lg" | "icon";
export type ActionSwapAnimation = "blur" | "roll" | "cascade";

/** Animations with a single-element variant set (cascade animates per letter). */
type CoreAnimation = "blur" | "roll";

export interface ActionSwapButtonProps extends Omit<
  HTMLMotionProps<"button">,
  "children" | "onChange"
> {
  items: ActionSwapItem[];
  value?: string;
  defaultValue?: string;
  onValueChange?: (value: string, item: ActionSwapItem) => void;
  variant?: ActionSwapButtonVariant;
  size?: ActionSwapButtonSize;
  animation?: ActionSwapAnimation;
  iconOnly?: boolean;
  cycle?: boolean;
}

export interface ActionSwapTextProps {
  value: string;
  children: ReactNode;
  animation?: ActionSwapAnimation;
  className?: string;
}

export interface ActionSwapIconProps {
  value: string;
  children: ReactNode;
  animation?: ActionSwapAnimation;
  className?: string;
}

const BLUR_TRANSITION = { duration: 0.2, ease: "easeInOut" } as const;
const ROLL_TRANSITION = SPRING_SWAP;
const ROLL_EXIT_TRANSITION = { duration: 0.14, ease: EASE_OUT } as const;
const SWAP_BLUR = "blur(8px)";
const ROLL_BLUR = "blur(3px)";

// Cascade rolls the label one letter at a time, left to right. The leaving
// and landing strings overlap as independent layers (no shared cells), so
// proportional glyph widths never jitter. Exits cascade at half the enter
// stagger so the tail of the old label lingers briefly.
const CASCADE_STAGGER = 0.025;

const CASCADE_LETTER_VARIANTS: Variants = {
  initial: { opacity: 0, y: "105%", filter: ROLL_BLUR },
  animate: (delay: number = 0) => ({
    opacity: 1,
    y: "0%",
    filter: "blur(0px)",
    transition: { ...SPRING_SWAP, delay },
  }),
  exit: (delay: number = 0) => ({
    opacity: 0,
    y: "-105%",
    filter: ROLL_BLUR,
    transition: { duration: 0.16, ease: EASE_OUT, delay: delay * 0.5 },
  }),
};

const TEXT_VARIANTS: Record<CoreAnimation, Variants> = {
  blur: {
    initial: { opacity: 0, scale: 0.94, filter: SWAP_BLUR },
    animate: {
      opacity: 1,
      scale: 1,
      filter: "blur(0px)",
      transition: BLUR_TRANSITION,
    },
    exit: {
      opacity: 0,
      scale: 0.94,
      filter: SWAP_BLUR,
      transition: BLUR_TRANSITION,
    },
  },
  roll: {
    initial: { opacity: 0, y: "90%", filter: ROLL_BLUR },
    animate: {
      opacity: 1,
      y: "0%",
      filter: "blur(0px)",
      transition: ROLL_TRANSITION,
    },
    exit: {
      opacity: 0,
      y: "-90%",
      filter: ROLL_BLUR,
      transition: ROLL_EXIT_TRANSITION,
    },
  },
};

const ICON_VARIANTS: Record<CoreAnimation, Variants> = {
  blur: {
    initial: { opacity: 0, scale: 0.25, filter: SWAP_BLUR },
    animate: {
      opacity: 1,
      scale: 1,
      filter: "blur(0px)",
      transition: BLUR_TRANSITION,
    },
    exit: {
      opacity: 0,
      scale: 0.25,
      filter: SWAP_BLUR,
      transition: BLUR_TRANSITION,
    },
  },
  roll: {
    initial: { opacity: 0, y: 12, filter: ROLL_BLUR },
    animate: {
      opacity: 1,
      y: 0,
      filter: "blur(0px)",
      transition: ROLL_TRANSITION,
    },
    exit: {
      opacity: 0,
      y: -12,
      filter: ROLL_BLUR,
      transition: ROLL_EXIT_TRANSITION,
    },
  },
};

const VARIANT_CLASS: Record<ActionSwapButtonVariant, string> = {
  primary: "bg-primary text-primary-foreground hover:bg-primary/90",
  secondary: "border border-border bg-card text-foreground hover:border-border",
  outline: "border border-border bg-transparent text-foreground hover:bg-muted/60",
  ghost: "text-muted-foreground hover:bg-muted/60 hover:text-foreground",
};

const SIZE_CLASS: Record<ActionSwapButtonSize, string> = {
  sm: "h-8 gap-1.5 rounded-full px-3 text-xs",
  md: "h-10 gap-2 rounded-full px-4 text-sm",
  lg: "h-12 gap-2.5 rounded-full px-5 text-base",
  icon: "h-10 w-10 rounded-full",
};

export function ActionSwapText({
  value,
  children,
  animation = "blur",
  className,
}: ActionSwapTextProps) {
  const reduce = useReducedMotion();

  // Cascade needs a plain string to split into letters; non-string content
  // and reduced motion fall back to the closest single-element animation.
  const label = typeof children === "string" ? children : null;
  const cascade = animation === "cascade" && label !== null && !reduce;
  const coreAnimation: CoreAnimation =
    animation === "cascade" ? "roll" : animation;

  return (
    <span
      className={cn(
        "relative -my-[0.08em] inline-block max-w-full whitespace-nowrap py-[0.08em] align-bottom",
        className,
      )}
      style={{
        clipPath: "inset(0 -999px)",
        WebkitClipPath: "inset(0 -999px)",
      }}
    >
      <span
        aria-hidden
        className="invisible inline-block whitespace-nowrap"
      >
        {cascade
          ? label.split("").map((char, index) => (
              <span
                // biome-ignore lint/suspicious/noArrayIndexKey: position is the slot identity.
                key={index}
                className="inline-block whitespace-pre"
              >
                {char}
              </span>
            ))
          : children}
      </span>
      {cascade ? (
        <>
          {/* Letters are decorative fragments; readers get the whole label. */}
          <span className="sr-only">{label}</span>
          <AnimatePresence initial={false}>
            <motion.span
              key={`cascade-${value}`}
              aria-hidden
              initial="initial"
              animate="animate"
              exit="exit"
              className="absolute left-0 top-[0.08em] inline-block whitespace-pre"
            >
              {label.split("").map((char, i) => (
                <motion.span
                  // biome-ignore lint/suspicious/noArrayIndexKey: position is the slot identity — the letter at a position is exactly what rolls.
                  key={i}
                  custom={i * CASCADE_STAGGER}
                  variants={CASCADE_LETTER_VARIANTS}
                  className="inline-block whitespace-pre will-change-[opacity,filter,transform]"
                >
                  {char}
                </motion.span>
              ))}
            </motion.span>
          </AnimatePresence>
        </>
      ) : (
        <AnimatePresence initial={false}>
          <motion.span
            key={`${animation}-${value}`}
            variants={TEXT_VARIANTS[coreAnimation]}
            initial={reduce ? false : "initial"}
            animate={reduce ? { opacity: 1, filter: "blur(0px)", scale: 1, y: 0 } : "animate"}
            exit={reduce ? undefined : "exit"}
            // Truncation lives on the layer that holds the text — the layer
            // moves as a whole, so clipping it never eats the roll.
            className="absolute left-0 top-[0.08em] inline-block max-w-full truncate will-change-[opacity,filter,transform]"
          >
            {children}
          </motion.span>
        </AnimatePresence>
      )}
    </span>
  );
}

export function ActionSwapIcon({
  value,
  children,
  animation = "blur",
  className,
}: ActionSwapIconProps) {
  const reduce = useReducedMotion();
  // Icons are single elements — cascade maps to its closest motion, roll.
  const coreAnimation: CoreAnimation =
    animation === "cascade" ? "roll" : animation;

  return (
    <span className={cn("relative inline-grid shrink-0 place-items-center overflow-hidden", className)}>
      <AnimatePresence mode="popLayout" initial={false}>
        <motion.span
          key={`${animation}-${value}`}
          aria-hidden
          variants={ICON_VARIANTS[coreAnimation]}
          initial={reduce ? false : "initial"}
          animate={reduce ? { opacity: 1, filter: "blur(0px)", scale: 1, y: 0 } : "animate"}
          exit={reduce ? undefined : "exit"}
          className="col-start-1 row-start-1 inline-flex items-center justify-center will-change-[opacity,filter,transform]"
        >
          {children}
        </motion.span>
      </AnimatePresence>
    </span>
  );
}

export function ActionSwapButton({
  items,
  value,
  defaultValue,
  onValueChange,
  variant = "secondary",
  size = "md",
  animation = "blur",
  iconOnly = size === "icon",
  cycle = true,
  className,
  disabled,
  onClick,
  ...rest
}: ActionSwapButtonProps) {
  const reduce = useReducedMotion();
  const [internalValue, setInternalValue] = useState(defaultValue ?? items[0]?.id);
  const currentValue = value ?? internalValue;
  const activeIndex = Math.max(0, items.findIndex((item) => item.id === currentValue));
  const activeItem = items[activeIndex] ?? items[0];
  const hasIcon = items.some((item) => item.icon);
  const nextItem = cycle && items.length > 0 ? items[(activeIndex + 1) % items.length] : undefined;

  if (!activeItem) return null;

  const accessibleLabel = activeItem.ariaLabel ?? (iconOnly && typeof activeItem.label === "string" ? activeItem.label : undefined);

  return (
    <motion.button
      type="button"
      disabled={disabled}
      whileTap={reduce || disabled ? undefined : { scale: 0.97 }}
      transition={SPRING_PRESS}
      className={cn(
        "inline-flex items-center justify-center overflow-hidden font-medium transition-colors",
        "disabled:pointer-events-none disabled:opacity-50",
        VARIANT_CLASS[variant],
        SIZE_CLASS[size],
        className,
      )}
      aria-label={accessibleLabel}
      onClick={(event) => {
        onClick?.(event);
        if (event.defaultPrevented || disabled || !cycle || !nextItem) return;
        if (value === undefined) setInternalValue(nextItem.id);
        onValueChange?.(nextItem.id, nextItem);
      }}
      {...rest}
    >
      {hasIcon ? (
        <ActionSwapIcon value={activeItem.id} animation={animation} className="h-4 w-4">
          {activeItem.icon ?? null}
        </ActionSwapIcon>
      ) : null}
      {!iconOnly ? (
        <ActionSwapText value={activeItem.id} animation={animation}>
          {activeItem.label}
        </ActionSwapText>
      ) : null}
    </motion.button>
  );
}