Popover

"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 | 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;

// 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 { useEffect, useState } from "react";

/**
 * Returns true only on devices that have a true hover (mouse / trackpad).
 * Touch devices fire phantom `:hover` on tap that sticks until tap-elsewhere
 * — gate hover-only effects (scale lifts, magnetic pulls) behind this.
 */
export function useHoverCapable() {
  const [canHover, setCanHover] = useState(false);

  useEffect(() => {
    if (typeof window === "undefined" || !window.matchMedia) return;
    const mq = window.matchMedia("(hover: hover) and (pointer: fine)");
    const update = () => setCanHover(mq.matches);
    update();
    mq.addEventListener?.("change", update);
    return () => mq.removeEventListener?.("change", update);
  }, []);

  return canHover;
}

"use client";
// beui.dev/components/motion/popover

import {
  animate,
  type MotionValue,
  useMotionValue,
  useMotionValueEvent,
  useReducedMotion,
} from "motion/react";
import {
  cloneElement,
  createContext,
  isValidElement,
  type ReactElement,
  type ReactNode,
  type Ref,
  useCallback,
  useContext,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { createPortal } from "react-dom";
import { usePopoverPortalPosition } from "@/components/motion/popover-position";
import { useDismiss } from "@/lib/hooks/use-dismiss";
import {
  type HoverGesture,
  useHoverGesture,
} from "@/lib/hooks/use-hover-gesture";
import { useTapGesture } from "@/lib/hooks/use-tap-gesture";
import { cn } from "@/lib/utils";

type Side = "top" | "bottom";
type Align = "start" | "center" | "end";
type TriggerMode = "click" | "hover";

// This morph needs less bounce than layout motion: too much overshoot makes
// the liquid neck balloon past the final panel edges.
const GOO_OPEN_SPRING = {
  type: "spring",
  visualDuration: 0.3,
  bounce: 0.15,
} as const;
const GOO_CLOSE_SPRING = {
  type: "spring",
  visualDuration: 0.21,
  bounce: 0.15,
} as const;
const HOVER_CLOSE_DELAY = 120;
const CIRCLE_KAPPA = 0.5523;

// `onPointerEnter`/`onPointerLeave` rather than the mouse pair: a tap fires
// compatibility mouseenter/mouseleave that carry no pointerType at all, and
// they are what made the panel flicker open and shut under a finger. The
// gesture pairs the two, so the panel a pen tap opened is not closed again by
// the boundary event that ends the same tap.
function makeHoverHandlers(
  hover: HoverGesture,
  enter: () => void,
  leave: () => void,
) {
  return {
    onPointerEnter: (event: React.PointerEvent) => {
      if (hover.enter(event)) enter();
    },
    onPointerLeave: (event: React.PointerEvent) => {
      if (hover.leave(event)) leave();
    },
  };
}

const lerp = (a: number, b: number, t: number) => a + (b - a) * t;

interface Rect {
  x: number;
  y: number;
  w: number;
  h: number;
  r: number;
}
interface Geo {
  layerW: number;
  layerH: number;
  left: number;
  top: number;
  trigger: Rect;
  panel: Rect;
}

// Trigger rect and panel rect in a shared local coordinate box.
function buildGeo(
  tW: number,
  tH: number,
  cW: number,
  cH: number,
  side: Side,
  align: Align,
  gap: number,
  panelRadius: number,
): Geo {
  const py = side === "bottom" ? tH + gap : -(gap + cH);
  const px = align === "start" ? 0 : align === "end" ? tW - cW : (tW - cW) / 2;

  const left = Math.min(0, px);
  const top = Math.min(0, py);
  const layerW = Math.max(tW, px + cW) - left;
  const layerH = Math.max(tH, py + cH) - top;

  const triggerRadius = Math.min(tH / 2, panelRadius);

  return {
    layerW,
    layerH,
    left,
    top,
    trigger: { x: -left, y: -top, w: tW, h: tH, r: triggerRadius },
    panel: { x: px - left, y: py - top, w: cW, h: cH, r: panelRadius },
  };
}

function rectAtProgress(geo: Geo, progress: number): Rect {
  const trigger = geo.trigger;
  const panel = geo.panel;

  return {
    x: lerp(trigger.x, panel.x, progress),
    y: lerp(trigger.y, panel.y, progress),
    w: lerp(trigger.w, panel.w, progress),
    h: lerp(trigger.h, panel.h, progress),
    r: lerp(trigger.r, panel.r, progress),
  };
}

function insetFor(rect: Rect, layerW: number, layerH: number) {
  const top = rect.y;
  const right = layerW - (rect.x + rect.w);
  const bottom = layerH - (rect.y + rect.h);
  const left = rect.x;
  return `inset(${top}px ${right}px ${bottom}px ${left}px round ${rect.r}px)`;
}

function roundedRectShape(rect: Rect) {
  const radius = Math.max(0, Math.min(rect.r, rect.w / 2, rect.h / 2));
  const control = radius * CIRCLE_KAPPA;
  const x1 = rect.x;
  const y1 = rect.y;
  const x2 = rect.x + rect.w;
  const y2 = rect.y + rect.h;
  const px = (value: number) => `${value.toFixed(3)}px`;

  return (
    `shape(from ${px(x1 + radius)} ${px(y1)}, ` +
    `line to ${px(x2 - radius)} ${px(y1)}, ` +
    `curve to ${px(x2)} ${px(y1 + radius)} with ${px(x2 - radius + control)} ${px(y1)} / ${px(x2)} ${px(y1 + radius - control)}, ` +
    `line to ${px(x2)} ${px(y2 - radius)}, ` +
    `curve to ${px(x2 - radius)} ${px(y2)} with ${px(x2)} ${px(y2 - radius + control)} / ${px(x2 - radius + control)} ${px(y2)}, ` +
    `line to ${px(x1 + radius)} ${px(y2)}, ` +
    `curve to ${px(x1)} ${px(y2 - radius)} with ${px(x1 + radius - control)} ${px(y2)} / ${px(x1)} ${px(y2 - radius + control)}, ` +
    `line to ${px(x1)} ${px(y1 + radius)}, ` +
    `curve to ${px(x1 + radius)} ${px(y1)} with ${px(x1)} ${px(y1 + radius - control)} / ${px(x1 + radius - control)} ${px(y1)}, ` +
    "close)"
  );
}

function clipForProgress(geo: Geo, progress: number, supportsShape: boolean) {
  const rect = rectAtProgress(geo, progress);
  return supportsShape
    ? roundedRectShape(rect)
    : insetFor(rect, geo.layerW, geo.layerH);
}

function roundedRectPath(rect: Rect) {
  const radius = Math.max(0, Math.min(rect.r, rect.w / 2, rect.h / 2));
  const n = (value: number) => value.toFixed(3);
  const x1 = rect.x;
  const y1 = rect.y;
  const x2 = rect.x + rect.w;
  const y2 = rect.y + rect.h;
  const arc = `A${n(radius)} ${n(radius)} 0 0 1`;

  // A zero radius makes every arc degenerate to a line, so this also draws
  // plain rectangles.
  return (
    `M${n(x1 + radius)} ${n(y1)}` +
    `H${n(x2 - radius)}${arc} ${n(x2)} ${n(y1 + radius)}` +
    `V${n(y2 - radius)}${arc} ${n(x2 - radius)} ${n(y2)}` +
    `H${n(x1 + radius)}${arc} ${n(x1)} ${n(y2 - radius)}` +
    `V${n(y1 + radius)}${arc} ${n(x1 + radius)} ${n(y1)}Z`
  );
}

// The goo layer is portalled above the page, so its copy of the trigger pill
// would cover the real trigger's label and focus ring. Punching the trigger
// back out keeps the real one visible and clips the blur to the layer box.
// This is a clip path rather than a CSS mask on purpose: WebKit silently
// ignores `mask: url(#id)` pointing at an SVG <mask> element, which left the
// label hidden behind the goo in Safari.
function triggerCutout(geo: Geo) {
  const layer = { x: 0, y: 0, w: geo.layerW, h: geo.layerH, r: 0 };
  return `path(evenodd, "${roundedRectPath(layer)} ${roundedRectPath(geo.trigger)}")`;
}

interface PopoverContextValue {
  open: boolean;
  setOpen: (open: boolean) => void;
  toggle: () => void;
  openHover: () => void;
  scheduleClose: () => void;
  triggerMode: TriggerMode;
  side: Side;
  align: Align;
  gap: number;
  panelRadius: number;
  gooStrength: number;
  reduce: boolean;
  gooId: string;
  contentId: string;
  progress: MotionValue<number>;
  triggerRef: React.MutableRefObject<HTMLElement | null>;
  contentRef: React.MutableRefObject<HTMLDivElement | null>;
}

const PopoverContext = createContext<PopoverContextValue | null>(null);

function usePopoverContext(component: string) {
  const ctx = useContext(PopoverContext);
  if (!ctx) throw new Error(`${component} must be used within <Popover>`);
  return ctx;
}

export interface PopoverProps {
  children: ReactNode;
  /** Controlled open state. */
  open?: boolean;
  /** Uncontrolled initial open state. */
  defaultOpen?: boolean;
  onOpenChange?: (open: boolean) => void;
  /** How the popover is summoned. Default "click". */
  trigger?: TriggerMode;
  /** Which side of the trigger the panel oozes out of. Default "bottom". */
  side?: Side;
  /** Alignment along the trigger's edge. Default "center". */
  align?: Align;
  /** Gap between trigger and panel, in px — the length of the gooey neck. Default 14. */
  sideOffset?: number;
  /** Corner radius of the open panel, in px. Default 16. */
  panelRadius?: number;
  /** Blur radius feeding the goo filter — higher melts more. Default 8. */
  gooStrength?: number;
  className?: string;
}

export function Popover({
  children,
  open: controlledOpen,
  defaultOpen = false,
  onOpenChange,
  trigger = "click",
  side = "bottom",
  align = "center",
  sideOffset = 14,
  panelRadius = 16,
  gooStrength = 8,
  className,
}: PopoverProps) {
  const reduce = useReducedMotion() ?? false;
  const gooId = useId().replace(/:/g, "");
  const contentId = useId();
  const rootRef = useRef<HTMLDivElement>(null);
  const triggerRef = useRef<HTMLElement | null>(null);
  const contentRef = useRef<HTMLDivElement | null>(null);
  const closeTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const rootHover = useHoverGesture();
  const progress = useMotionValue(defaultOpen ? 1 : 0);

  const [internalOpen, setInternalOpen] = useState(defaultOpen);
  const controlled = controlledOpen !== undefined;
  const open = controlled ? controlledOpen : internalOpen;

  const setOpen = useCallback(
    (next: boolean) => {
      if (!controlled) setInternalOpen(next);
      onOpenChange?.(next);
    },
    [controlled, onOpenChange],
  );

  const cancelClose = useCallback(() => {
    if (closeTimer.current) {
      clearTimeout(closeTimer.current);
      closeTimer.current = null;
    }
  }, []);

  const openHover = useCallback(() => {
    cancelClose();
    setOpen(true);
  }, [cancelClose, setOpen]);

  const scheduleClose = useCallback(() => {
    cancelClose();
    closeTimer.current = setTimeout(() => setOpen(false), HOVER_CLOSE_DELAY);
  }, [cancelClose, setOpen]);

  const toggle = useCallback(() => setOpen(!open), [setOpen, open]);

  useEffect(() => () => cancelClose(), [cancelClose]);

  useEffect(() => {
    const animation = animate(
      progress,
      open ? 1 : 0,
      reduce
        ? { duration: 0 }
        : open
          ? GOO_OPEN_SPRING
          : GOO_CLOSE_SPRING,
    );
    return () => animation.stop();
  }, [open, progress, reduce]);

  // The panel is a `role="dialog"` and goes inert the moment it closes, so
  // focus cannot be left sitting inside it: Escape hands it back to the
  // trigger, the way the ARIA dialog pattern asks. A pointer dismissal takes
  // the focus onward itself when it lands on something focusable — this only
  // catches the case where it would otherwise be stranded.
  const close = useCallback(() => {
    setOpen(false);
    const focused = document.activeElement;
    const inPanel =
      focused instanceof HTMLElement && contentRef.current?.contains(focused);
    if (inPanel) triggerRef.current?.focus();
  }, [setOpen]);
  // The panel is portalled, so both trees participate in outside detection.
  const ignoreContent = useCallback(
    (target: Element) => Boolean(contentRef.current?.contains(target)),
    [],
  );
  // A hover trigger opens on tap as well now, so it needs the same outside
  // dismissal the click trigger always had. The gesture passes through to
  // whatever it landed on, which is the light-dismiss bargain the platform's
  // own popovers strike.
  useDismiss(open, close, rootRef, { ignore: ignoreContent });

  const ctx = useMemo<PopoverContextValue>(
    () => ({
      open,
      setOpen,
      toggle,
      openHover,
      scheduleClose,
      triggerMode: trigger,
      side,
      align,
      gap: sideOffset,
      panelRadius,
      gooStrength,
      reduce,
      gooId,
      contentId,
      progress,
      triggerRef,
      contentRef,
    }),
    [
      open,
      setOpen,
      toggle,
      openHover,
      scheduleClose,
      trigger,
      side,
      align,
      sideOffset,
      panelRadius,
      gooStrength,
      reduce,
      gooId,
      contentId,
      progress,
    ],
  );

  const hoverHandlers =
    trigger === "hover"
      ? makeHoverHandlers(rootHover, openHover, scheduleClose)
      : {};

  return (
    <PopoverContext.Provider value={ctx}>
      <div
        ref={rootRef}
        className={cn("relative inline-flex isolate", className)}
        {...hoverHandlers}
      >
        {children}
      </div>
    </PopoverContext.Provider>
  );
}

function mergeRefs<T>(...refs: Array<Ref<T> | undefined>) {
  return (node: T | null) => {
    for (const ref of refs) {
      if (typeof ref === "function") ref(node);
      else if (ref && typeof ref === "object")
        (ref as React.MutableRefObject<T | null>).current = node;
    }
  };
}

export interface PopoverTriggerProps {
  /** A single focusable element (e.g. a Button) that opens the popover. */
  children: ReactElement;
}

export function PopoverTrigger({ children }: PopoverTriggerProps) {
  const ctx = usePopoverContext("PopoverTrigger");
  // What the last gesture on the trigger was, and whether the panel was
  // already open when it started. A click reports neither.
  const tap = useTapGesture<boolean>();

  if (!isValidElement(children)) return children;

  const child = children as ReactElement<Record<string, unknown>>;
  const childProps = child.props;
  const childRef = (childProps as { ref?: Ref<HTMLElement> }).ref;

  const compose =
    <E extends { defaultPrevented?: boolean }>(
      name: string,
      handler: (event: E) => void,
    ) =>
    (event: E) => {
      (childProps[name] as ((e: unknown) => void) | undefined)?.(event);
      if (!event.defaultPrevented) handler(event);
    };

  // Observation, not action. `compose` steps aside for a child that handled
  // the event itself, which is right for anything that *does* something — but
  // a child preventing the pointerdown default (to hold focus, say) has not
  // said the gesture didn't happen. Skipping the record there left the panel
  // reading whatever the gesture before it had put in.
  const observe =
    <E,>(name: string, handler: (event: E) => void) =>
    (event: E) => {
      (childProps[name] as ((e: unknown) => void) | undefined)?.(event);
      handler(event);
    };

  // The hover trigger keeps its hover path and *adds* a tap one, rather than
  // swapping mode on a device that reports a touchscreen: a touchscreen laptop
  // has both inputs and the mouse must keep working. A hovering pointer has
  // already opened the panel on its way in, and a keyboard press arrives with
  // no pointerdown behind it, so only a tap toggles here. Which panel state
  // the tap acts on is read from the gesture's start, because a browser that
  // focuses the trigger on contact would otherwise open it mid-gesture and let
  // the click close it again.
  const handlers: Record<string, unknown> =
    ctx.triggerMode === "hover"
      ? {
          onFocus: compose("onFocus", ctx.openHover),
          onBlur: compose("onBlur", ctx.scheduleClose),
          onPointerDown: observe<React.PointerEvent>(
            "onPointerDown",
            (event) => tap.start(event, ctx.open),
          ),
          onPointerCancel: observe("onPointerCancel", tap.drop),
          onKeyDown: observe("onKeyDown", tap.drop),
          onClick: compose("onClick", () => {
            const gesture = tap.take();
            if (!gesture || gesture.pointerType === "mouse") return;
            ctx.setOpen(!gesture.state);
          }),
        }
      : { onClick: compose("onClick", ctx.toggle) };

  return cloneElement(child, {
    ...handlers,
    ref: mergeRefs(childRef, (node: HTMLElement | null) => {
      ctx.triggerRef.current = node;
    }),
    // Above the goo layer (z-[-1]) so the neck reads behind it.
    className: cn("relative z-0", childProps.className as string | undefined),
    "aria-haspopup": "dialog",
    "aria-expanded": ctx.open,
    "aria-controls": ctx.open ? ctx.contentId : undefined,
    "data-state": ctx.open ? "open" : "closed",
  });
}

const ALIGN_ORIGIN: Record<Align, string> = {
  start: "left",
  center: "center",
  end: "right",
};

export interface PopoverContentProps {
  children: ReactNode;
  className?: string;
}

export function PopoverContent({ children, className }: PopoverContentProps) {
  const ctx = usePopoverContext("PopoverContent");
  const [portalReady, setPortalReady] = useState(false);
  const {
    side,
    align,
    gap,
    panelRadius,
    gooStrength,
    reduce,
    gooId,
    contentId,
    progress,
    triggerRef,
    contentRef,
    open,
    triggerMode,
    openHover,
    scheduleClose,
  } = ctx;

  const measureRef = contentRef;
  const panelHover = useHoverGesture();
  const blobRef = useRef<HTMLDivElement>(null);
  const clipRef = useRef<HTMLDivElement>(null);
  const geoRef = useRef<Geo | null>(null);
  const supportsShapeRef = useRef(false);
  const layout = usePopoverPortalPosition(
    triggerRef,
    measureRef,
    portalReady,
  );

  useEffect(() => setPortalReady(true), []);

  const geo = useMemo(
    () =>
      buildGeo(
        layout?.trigger.width ?? 0,
        layout?.trigger.height ?? 0,
        layout?.content.width ?? 0,
        layout?.content.height ?? 0,
        side,
        align,
        gap,
        panelRadius,
      ),
    [layout, side, align, gap, panelRadius],
  );

  // Morph the same clip on the goo body and the content, so the whole popover
  // oozes as one and the text reveals with it.
  const render = useCallback((g: Geo | null, p: number) => {
    if (!g || g.layerW === 0) return;
    const clip = clipForProgress(g, p, supportsShapeRef.current);
    if (blobRef.current) blobRef.current.style.clipPath = clip;
    if (clipRef.current) clipRef.current.style.clipPath = clip;
  }, []);

  useLayoutEffect(() => {
    supportsShapeRef.current =
      typeof CSS !== "undefined" &&
      typeof CSS.supports === "function" &&
      CSS.supports(
        "clip-path",
        "shape(from 0px 0px, line to 1px 1px, close)",
      );
    geoRef.current = geo;
    render(geo, progress.get());
  }, [geo, progress, render]);

  useMotionValueEvent(progress, "change", (p) => render(geoRef.current, p));

  const hoverHandlers =
    triggerMode === "hover"
      ? makeHoverHandlers(panelHover, openHover, scheduleClose)
      : {};

  // Match the server and first client render, then attach the portal after
  // hydration. This preserves SSR without regenerating the page on the client.
  if (!portalReady) return null;

  return createPortal(
    <div
      data-popover-portal=""
      className="pointer-events-none fixed left-0 top-0 z-[9999] isolate size-0"
      style={{
        visibility: layout ? "visible" : "hidden",
        transform: `translate3d(${layout?.trigger.left ?? 0}px, ${layout?.trigger.top ?? 0}px, 0)`,
      }}
    >
      {/* Goo filter: blur, sharpen the alpha back into solid shapes, then lay
          the crisp original on top so blobs merge with liquid edges. */}
      <svg aria-hidden width="0" height="0" className="absolute">
        <title>Popover visual effects</title>
        <defs>
          <filter id={gooId} x="-50%" y="-50%" width="200%" height="200%">
            <feGaussianBlur
              in="SourceGraphic"
              stdDeviation={gooStrength}
              result="blur"
            />
            <feColorMatrix
              in="blur"
              mode="matrix"
              values="1 0 0 0 0  0 1 0 0 0  0 0 1 0 0  0 0 0 22 -10"
              result="goo"
            />
            <feComposite in="SourceGraphic" in2="goo" operator="atop" />
          </filter>
        </defs>
      </svg>

      {/* Goo body: static trigger pill + morphing blob. */}
      <div
        aria-hidden
        className="pointer-events-none absolute z-[-1]"
        style={{
          left: geo.left,
          top: geo.top,
          width: geo.layerW,
          height: geo.layerH,
          filter: reduce ? undefined : `url(#${gooId})`,
          clipPath: triggerCutout(geo),
        }}
      >
        <div
          className="absolute bg-popover"
          style={{
            left: geo.trigger.x,
            top: geo.trigger.y,
            width: geo.trigger.w,
            height: geo.trigger.h,
            borderRadius: geo.trigger.r,
          }}
        />
        <div
          ref={blobRef}
          className="absolute inset-0 bg-popover"
          style={{
            clipPath: clipForProgress(geo, progress.get(), false),
          }}
        />
      </div>

      {/* Content is clipped by the same morph. The portal wrapper stays
          pointer-transparent; only the fully open panel accepts interaction. */}
      <div
        className="pointer-events-none absolute z-10"
        style={{
          left: geo.left,
          top: geo.top,
          width: geo.layerW,
          height: geo.layerH,
        }}
      >
        <div
          ref={clipRef}
          inert={!open}
          className="absolute inset-0"
          style={{
            clipPath: clipForProgress(geo, progress.get(), false),
            pointerEvents: open ? "auto" : "none",
          }}
        >
          <div
            ref={measureRef}
            id={contentId}
            role="dialog"
            {...hoverHandlers}
            style={{
              position: "absolute",
              left: geo.panel.x,
              top: geo.panel.y,
              transformOrigin: `${ALIGN_ORIGIN[align]} ${side === "bottom" ? "top" : "bottom"}`,
            }}
            className={cn(
              "w-max max-w-[min(92vw,20rem)] p-4 text-popover-foreground outline-none",
              className,
            )}
          >
            {children}
          </div>
        </div>
      </div>
    </div>,
    document.body,
  );
}