Order Book

// 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;

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

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

"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/charts/order-book

import { motion, useReducedMotion } from "motion/react";
import { createContext, useContext, type ReactNode } from "react";
import { SPRING_PANEL } from "@/lib/ease";
import { OrderBookDepthRow } from "./order-book/depth-row";
import { cn } from "@/lib/utils";
import { buildOrderBook } from "./order-book/model";

export type OrderBookLevel = { price: number; size: number };

export interface OrderBookProps {
  /** Snapshot of buy levels. Equal prices are combined; invalid and zero sizes are omitted. */
  bids: readonly OrderBookLevel[];
  /** Snapshot of sell levels. Supply new arrays when the book changes. */
  asks: readonly OrderBookLevel[];
  /** Number of nearest levels to show on each side. */
  levels?: number;
  /** Last traded price. Omit to show the midpoint of the best bid and ask. */
  lastPrice?: number;
  label?: string;
  baseSymbol?: string;
  quoteSymbol?: string;
  formatPrice?: (value: number) => string;
  formatSize?: (value: number) => string;
  children?: ReactNode;
  className?: string;
}

const priceFormatter = new Intl.NumberFormat("en-US", {
  minimumFractionDigits: 2,
  maximumFractionDigits: 2,
});
const sizeFormatter = new Intl.NumberFormat("en-US", {
  notation: "compact",
  maximumFractionDigits: 1,
});
const defaultPrice = (value: number) => priceFormatter.format(value);
const defaultSize = (value: number) => sizeFormatter.format(value);

function useOrderBookModel({
  bids,
  asks,
  levels = 9,
  lastPrice,
  baseSymbol = "",
  quoteSymbol = "USD",
  formatPrice = defaultPrice,
  formatSize = defaultSize,
}: OrderBookProps) {
  const book = buildOrderBook(bids, asks, levels);
  return {
    ...book,
    price:
      lastPrice != null && Number.isFinite(lastPrice) && lastPrice > 0 ? lastPrice : book.midpoint,
    baseSymbol,
    quoteSymbol,
    formatPrice,
    formatSize,
    reduce: useReducedMotion(),
  };
}
const OrderBookContext = createContext<ReturnType<typeof useOrderBookModel> | null>(null);

export function useOrderBook() {
  const context = useContext(OrderBookContext);
  if (!context) throw new Error("Order book parts must be rendered inside OrderBook.");
  return context;
}

/** A snapshot-driven depth ladder. No timers or invented market data live in the chart. */
export function OrderBook({ children, className, label = "Order book", ...props }: OrderBookProps) {
  const model = useOrderBookModel(props);
  return (
    <OrderBookContext.Provider value={model}>
      <section
        aria-label={label}
        className={cn(
          "w-full max-w-[560px] overflow-hidden rounded-2xl border border-border bg-background font-mono text-xs tabular-nums",
          className,
        )}
      >
        {children === undefined ? (
          <>
            <OrderBookHeader />
            <OrderBookSide side="ask" />
            <OrderBookSpread />
            <OrderBookSide side="bid" />
            <OrderBookBalance />
          </>
        ) : (
          children
        )}
      </section>
    </OrderBookContext.Provider>
  );
}

export function OrderBookHeader({ className }: { className?: string }) {
  const { baseSymbol, quoteSymbol } = useOrderBook();
  return (
    <div
      aria-hidden="true"
      className={cn(
        "grid grid-cols-3 py-3 text-[10px] uppercase tracking-wider text-muted-foreground",
        className,
      )}
    >
      <span className="px-4">Price{quoteSymbol && ` (${quoteSymbol})`}</span>
      <span className="px-4 text-right">Size{baseSymbol && ` (${baseSymbol})`}</span>
      <span className="px-4 text-right">Total</span>
    </div>
  );
}

export function OrderBookSide({ side, className }: { side: "bid" | "ask"; className?: string }) {
  const { bids, asks, maxTotal, formatPrice, formatSize, reduce, baseSymbol, quoteSymbol } =
    useOrderBook();
  const rows = side === "ask" ? [...asks].reverse() : bids;
  const color =
    side === "ask" ? "text-rose-600 dark:text-rose-400" : "text-emerald-700 dark:text-emerald-400";
  return (
    <table
      aria-label={side === "ask" ? "Asks · sell orders" : "Bids · buy orders"}
      className={cn("w-full table-fixed border-separate border-spacing-0", className)}
    >
      <thead className="sr-only">
        <tr>
          <th scope="col">Price {quoteSymbol}</th>
          <th scope="col">Size {baseSymbol}</th>
          <th scope="col">Cumulative total {baseSymbol}</th>
        </tr>
      </thead>
      <tbody>
        {rows.length === 0 ? (
          <tr>
            <td colSpan={3} className="px-4 py-6 text-center text-muted-foreground">
              No {side === "ask" ? "asks" : "bids"}
            </td>
          </tr>
        ) : (
          rows.map((row, index) => (
            <OrderBookDepthRow
              key={row.price}
              row={row}
              fraction={maxTotal ? row.total / maxTotal : 0}
              entranceIndex={side === "ask" ? rows.length - 1 - index : index}
              color={color}
              formatPrice={formatPrice}
              formatSize={formatSize}
              reduce={!!reduce}
            />
          ))
        )}
      </tbody>
    </table>
  );
}

export function OrderBookSpread({ className }: { className?: string }) {
  const { price, spread, midpoint, formatPrice } = useOrderBook();
  return (
    <div
      className={cn(
        "my-1 flex flex-wrap items-baseline justify-between gap-x-4 gap-y-1 border-y border-border bg-muted/40 px-4 py-3",
        className,
      )}
    >
      <span className="text-base font-medium tracking-tight">
        <span className="sr-only">Reference price: </span>
        {price == null ? "—" : formatPrice(price)}
      </span>
      <span className="text-[10px] text-muted-foreground">
        {spread == null || midpoint == null
          ? "Spread unavailable"
          : spread < 0
            ? "Crossed book"
            : `Spread ${formatPrice(spread)} · ${((spread / midpoint) * 100).toFixed(3)}%`}
      </span>
    </div>
  );
}

/** Balance of the displayed depth, not the entire exchange order book. */
export function OrderBookBalance({ className }: { className?: string }) {
  const { bidTotal, askTotal, reduce } = useOrderBook();
  const total = bidTotal + askTotal;
  const ratio = total ? bidTotal / total : 0.5;
  return (
    <div className={cn("space-y-2 border-t border-border px-4 pb-3 pt-3", className)}>
      <div className="flex justify-between text-[10px]">
        <span className="text-emerald-700 dark:text-emerald-400">
          Bids {total ? `${(ratio * 100).toFixed(1)}%` : "—"}
        </span>
        <span className="text-muted-foreground">Visible depth</span>
        <span className="text-rose-600 dark:text-rose-400">
          Asks {total ? `${((1 - ratio) * 100).toFixed(1)}%` : "—"}
        </span>
      </div>
      <div aria-hidden="true" className="relative h-1 overflow-hidden rounded-full bg-rose-500/25">
        <motion.div
          initial={false}
          animate={{ transform: `scaleX(${ratio})` }}
          transition={reduce ? { duration: 0 } : SPRING_PANEL}
          className="absolute inset-0 origin-left bg-emerald-500/60"
        />
      </div>
    </div>
  );
}

"use client";

import { animate, motion, useMotionValue } from "motion/react";
import { useEffect, useRef } from "react";
import { EASE_OUT, SPRING_PANEL } from "@/lib/ease";
import { cn } from "@/lib/utils";
import type { DepthLevel } from "./model";

export function OrderBookDepthRow({
  row,
  fraction,
  entranceIndex,
  color,
  formatPrice,
  formatSize,
  reduce,
}: {
  row: DepthLevel;
  fraction: number;
  entranceIndex: number;
  color: string;
  formatPrice: (value: number) => string;
  formatSize: (value: number) => string;
  reduce: boolean;
}) {
  const highlight = useMotionValue(0);
  const previousSize = useRef(row.size);
  const entered = useRef(false);
  useEffect(() => {
    entered.current = true;
  }, []);

  useEffect(() => {
    const changed = previousSize.current !== row.size;
    previousSize.current = row.size;
    if (!changed || reduce) {
      highlight.set(0);
      return;
    }

    // A soft full-row tint identifies changed quantities. Retarget from
    // the current opacity when another snapshot interrupts the fade.
    let fade: ReturnType<typeof animate> | undefined;
    const rise = animate(highlight, 0.1, {
      duration: 0.08,
      ease: EASE_OUT,
      onComplete: () => {
        fade = animate(highlight, 0, { duration: 0.2, ease: EASE_OUT });
      },
    });
    return () => {
      rise.stop();
      fade?.stop();
    };
  }, [row.size, reduce, highlight]);

  return (
    <motion.tr
      initial={{ opacity: 0 }}
      animate={{ opacity: 1 }}
      transition={{
        duration: 0.18,
        ease: EASE_OUT,
        delay: reduce || entered.current ? 0 : Math.min(entranceIndex, 8) * 0.025,
      }}
      className={cn("group", color)}
    >
      <td className="relative h-8 px-4 py-0">
        <div
          aria-hidden="true"
          className="pointer-events-none absolute left-1 inset-y-px w-[calc(300%-8px)] overflow-hidden rounded-sm"
        >
          <motion.div
            initial={reduce ? false : { transform: `scaleX(${fraction * 0.85})`, opacity: 0 }}
            animate={{ transform: `scaleX(${fraction})`, opacity: 1 }}
            transition={
              reduce
                ? { duration: 0 }
                : {
                    ...SPRING_PANEL,
                    delay: entered.current ? 0 : Math.min(entranceIndex, 8) * 0.025,
                  }
            }
            className="absolute inset-0 origin-right overflow-hidden rounded-sm"
          >
            <div className="absolute inset-0 bg-current opacity-[0.12]" />
          </motion.div>
          <motion.div style={{ opacity: highlight }} className="absolute inset-0 bg-current" />
          <div className="absolute inset-0 bg-current opacity-0 transition-opacity duration-150 group-hover:opacity-[0.05]" />
        </div>
        <span className="relative">{formatPrice(row.price)}</span>
      </td>
      <td className="relative px-4 py-0 text-right text-foreground">
        {formatSize(row.size)}
      </td>
      <td className="relative px-4 py-0 text-right text-muted-foreground">
        {formatSize(row.total)}
      </td>
    </motion.tr>
  );
}

export type DepthLevel = { price: number; size: number; total: number };
type Level = { price: number; size: number };

function prepare(levels: readonly Level[], side: "bid" | "ask", limit: number): DepthLevel[] {
  const prices = new Map<number, number>();
  for (const { price, size } of levels) {
    if (!Number.isFinite(price) || !Number.isFinite(size) || price <= 0 || size <= 0) continue;
    prices.set(price, (prices.get(price) ?? 0) + size);
  }
  let total = 0;
  return [...prices]
    .sort(([a], [b]) => (side === "bid" ? b - a : a - b))
    .slice(0, limit)
    .map(([price, size]) => {
      total += size;
      return { price, size, total };
    });
}

/** Accumulate from the best quote outward before reversing asks for display. */
export function buildOrderBook(bids: readonly Level[], asks: readonly Level[], levels: number) {
  const limit = Number.isFinite(levels) ? Math.max(0, Math.floor(levels)) : 9;
  const buy = prepare(bids, "bid", limit);
  const sell = prepare(asks, "ask", limit);
  const bidTotal = buy.at(-1)?.total ?? 0;
  const askTotal = sell.at(-1)?.total ?? 0;
  const bestBid = buy[0]?.price;
  const bestAsk = sell[0]?.price;
  const midpoint = bestBid == null || bestAsk == null ? null : (bestBid + bestAsk) / 2;
  const spread = bestBid == null || bestAsk == null ? null : bestAsk - bestBid;
  return {
    bids: buy,
    asks: sell,
    bidTotal,
    askTotal,
    maxTotal: Math.max(bidTotal, askTotal),
    midpoint,
    spread,
  };
}

export type {
  ButtonLinkProps,
  ButtonProps,
  ButtonSize,
  ButtonVariant,
} from "./base";
export { Button, ButtonLink } from "./base";
export type { MagneticButtonProps } from "./magnetic";
export { MagneticButton } from "./magnetic";
export type { MetallicButtonProps } from "./metallic";
export { MetallicButton } from "./metallic";
export type { ButtonState, StatefulButtonProps } from "./stateful";
export { StatefulButton } from "./stateful";

"use client";

import {
  AnimatePresence,
  type HTMLMotionProps,
  motion,
  useReducedMotion,
} from "motion/react";
import {
  forwardRef,
  type PointerEvent,
  type ReactNode,
  useCallback,
  useRef,
  useState,
} from "react";
import { EASE_OUT, SPRING_PRESS } from "@/lib/ease";
import { useHoverCapable } from "@/lib/hooks/use-hover-capable";
import { cn } from "@/lib/utils";

export type ButtonVariant = "primary" | "secondary" | "ghost" | "outline";
export type ButtonSize = "sm" | "md" | "lg" | "icon";

export interface ButtonProps extends Omit<
  HTMLMotionProps<"button">,
  "children"
> {
  variant?: ButtonVariant;
  size?: ButtonSize;
  pressScale?: number;
  /** Spawn a Material-style ripple from the press point. Off by default. */
  ripple?: boolean;
  children?: ReactNode;
}

export interface ButtonLinkProps extends Omit<
  HTMLMotionProps<"a">,
  "children"
> {
  variant?: ButtonVariant;
  size?: ButtonSize;
  pressScale?: number;
  children?: ReactNode;
}

type Ripple = { id: number; x: number; y: number; size: number };

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

const SIZE_CLASS: Record<ButtonSize, string> = {
  sm: "h-8 px-3 text-xs gap-1.5 rounded-full",
  md: "h-10 px-5 text-sm gap-2 rounded-full",
  lg: "h-12 px-6 text-base gap-2 rounded-full",
  icon: "h-8 w-8 rounded-lg",
};

export const Button = forwardRef<HTMLButtonElement, ButtonProps>(
  function Button(
    {
      variant = "primary",
      size = "md",
      pressScale = 0.93,
      ripple = false,
      className,
      children,
      onPointerDown,
      ...rest
    },
    ref,
  ) {
    const reduce = useReducedMotion();
    const canHover = useHoverCapable();
    const [ripples, setRipples] = useState<Ripple[]>([]);
    const nextId = useRef(0);

    const handlePointerDown = useCallback(
      (event: PointerEvent<HTMLButtonElement>) => {
        if (ripple && !reduce) {
          const rect = event.currentTarget.getBoundingClientRect();
          const size = Math.max(rect.width, rect.height) * 2;
          const id = nextId.current++;
          setRipples((prev) => [
            ...prev,
            {
              id,
              x: event.clientX - rect.left,
              y: event.clientY - rect.top,
              size,
            },
          ]);
        }
        onPointerDown?.(event);
      },
      [ripple, reduce, onPointerDown],
    );

    return (
      <motion.button
        ref={ref}
        type="button"
        whileTap={reduce ? undefined : { scale: pressScale }}
        whileHover={reduce || !canHover ? undefined : { scale: 1.02 }}
        transition={SPRING_PRESS}
        onPointerDown={handlePointerDown}
        className={cn(
          "inline-flex items-center justify-center font-medium select-none",
          "transition-colors",
          "disabled:pointer-events-none disabled:opacity-50",
          ripple && "relative overflow-hidden",
          VARIANT_CLASS[variant],
          SIZE_CLASS[size],
          className,
        )}
        {...rest}
      >
        {ripple && !reduce ? (
          <span className="pointer-events-none absolute inset-0 overflow-hidden rounded-[inherit]">
            <AnimatePresence>
              {ripples.map((r) => (
                <motion.span
                  key={r.id}
                  className="absolute rounded-full bg-current"
                  style={{
                    left: r.x,
                    top: r.y,
                    width: r.size,
                    height: r.size,
                    x: "-50%",
                    y: "-50%",
                  }}
                  initial={{ scale: 0.05, opacity: 0.3 }}
                  animate={{ scale: 1, opacity: 0 }}
                  exit={{ opacity: 0 }}
                  transition={{ duration: 1.6, ease: EASE_OUT }}
                  onAnimationComplete={() =>
                    setRipples((prev) => prev.filter((x) => x.id !== r.id))
                  }
                />
              ))}
            </AnimatePresence>
          </span>
        ) : null}
        {children}
      </motion.button>
    );
  },
);

export const ButtonLink = forwardRef<HTMLAnchorElement, ButtonLinkProps>(
  function ButtonLink(
    {
      variant = "primary",
      size = "md",
      pressScale = 0.93,
      className,
      children,
      ...rest
    },
    ref,
  ) {
    const reduce = useReducedMotion();
    const canHover = useHoverCapable();

    return (
      <motion.a
        ref={ref}
        whileTap={reduce ? undefined : { scale: pressScale }}
        whileHover={reduce || !canHover ? undefined : { scale: 1.02 }}
        transition={SPRING_PRESS}
        className={cn(
          "inline-flex items-center justify-center font-medium select-none",
          "transition-colors",
          VARIANT_CLASS[variant],
          SIZE_CLASS[size],
          className,
        )}
        {...rest}
      >
        {children}
      </motion.a>
    );
  },
);

"use client";

import { forwardRef } from "react";
import { Magnetic } from "../magnetic";
import { Button, type ButtonProps } from "./base";

export interface MagneticButtonProps extends ButtonProps {
  /** Magnetic pull strength. Default 0.25. */
  strength?: number;
  /** Class applied to the magnetic wrapper. */
  magneticClassName?: string;
}

export const MagneticButton = forwardRef<HTMLButtonElement, MagneticButtonProps>(function MagneticButton(
  { strength = 0.25, magneticClassName, children, ...rest },
  ref,
) {
  return (
    <Magnetic strength={strength} className={magneticClassName}>
      <Button ref={ref} {...rest}>
        {children}
      </Button>
    </Magnetic>
  );
});

"use client";

import { motion, useReducedMotion } from "motion/react";
import { forwardRef, useState } from "react";
import { EASE_IN_OUT } from "@/lib/ease";
import { cn } from "@/lib/utils";
import { Button, type ButtonProps } from "./base";

export interface MetallicButtonProps extends Omit<
  ButtonProps,
  "ripple" | "variant"
> {
  /** Stops the traveling reflection while preserving the chrome rim. */
  paused?: boolean;
}

// The rim and highlight drift separately so the material stays quiet and reflective.
const SILVER_DRIFT = {
  duration: 8,
  ease: EASE_IN_OUT,
  repeat: Infinity,
};

const CHROME_SHIMMER = {
  duration: 2.4,
  ease: EASE_IN_OUT,
};

export const MetallicButton = forwardRef<
  HTMLButtonElement,
  MetallicButtonProps
>(function MetallicButton(
  {
    size = "md",
    paused = false,
    className,
    children,
    onHoverStart,
    onHoverEnd,
    ...rest
  },
  ref,
) {
  const reduce = useReducedMotion();
  const still = paused || Boolean(reduce);
  const [hovered, setHovered] = useState(false);

  return (
    <Button
      ref={ref}
      variant="ghost"
      size={size}
      onHoverStart={(event, info) => {
        setHovered(true);
        onHoverStart?.(event, info);
      }}
      onHoverEnd={(event, info) => {
        setHovered(false);
        onHoverEnd?.(event, info);
      }}
      className={cn(
        "group relative isolate overflow-hidden border-0 bg-transparent text-foreground",
        "hover:bg-transparent hover:text-foreground",
        "focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2",
        "shadow-[0_8px_22px_rgba(0,0,0,0.16)]",
        size === "icon" && "rounded-full",
        className,
      )}
      {...rest}
    >
      <motion.span
        aria-hidden="true"
        className="pointer-events-none absolute inset-y-0 left-[-18%] z-0 w-[136%] rounded-[inherit] bg-[linear-gradient(105deg,#111_0%,#737373_14%,#fafafa_26%,#525252_38%,#0a0a0a_50%,#a3a3a3_64%,#fff_75%,#404040_87%,#111_100%)]"
        animate={still ? undefined : { x: ["0%", "13%", "0%"] }}
        transition={still ? undefined : SILVER_DRIFT}
      />

      <motion.span
        aria-hidden="true"
        className="pointer-events-none absolute inset-y-0 left-[-58%] z-[1] w-[52%] -skew-x-12 bg-[linear-gradient(90deg,transparent,rgba(255,255,255,0.5)_48%,transparent)] opacity-50 blur-[3px] mix-blend-screen"
        animate={still ? undefined : { x: hovered ? "310%" : "0%" }}
        transition={still ? undefined : CHROME_SHIMMER}
      />

      <span
        aria-hidden="true"
        className="pointer-events-none absolute inset-[2px] z-[2] rounded-[inherit] bg-background transition-colors group-hover:bg-muted/40"
      />

      <span
        aria-hidden="true"
        className="pointer-events-none absolute inset-[2px] z-[3] rounded-[inherit] shadow-[inset_0_1px_0_rgba(255,255,255,0.28),inset_0_-1px_0_rgba(0,0,0,0.16)]"
      />

      <span className="relative z-10 inline-flex items-center justify-center gap-2">
        {children}
      </span>
    </Button>
  );
});

"use client";

import { Check, Loader2, X } from "lucide-react";
import {
  AnimatePresence,
  motion,
  useReducedMotion,
  type Variants,
} from "motion/react";
import {
  forwardRef,
  type ReactNode,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { EASE_OUT, SPRING_SWAP } from "@/lib/ease";
import { Button, type ButtonProps } from "./base";

export type ButtonState = "idle" | "loading" | "success" | "error";

export interface StatefulButtonProps extends Omit<ButtonProps, "children"> {
  state?: ButtonState;
  children: ReactNode;
  loadingText?: ReactNode;
  successText?: ReactNode;
  errorText?: ReactNode;
  icon?: ReactNode;
}

const CASCADE_STAGGER = 0.025;
const ROLL_BLUR = "blur(6px)";

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 ICON_VARIANTS: Variants = {
  // Width collapses too, so the icon adds/removes its own space smoothly
  // instead of popping the row width in a single frame.
  initial: { opacity: 0, width: 0, scale: 0.7, filter: ROLL_BLUR },
  animate: {
    opacity: 1,
    width: "1.5rem",
    scale: 1,
    filter: "blur(0px)",
    transition: SPRING_SWAP,
  },
  exit: {
    opacity: 0,
    width: 0,
    scale: 0.7,
    filter: ROLL_BLUR,
    transition: { duration: 0.16, ease: EASE_OUT },
  },
};

function IconSlot({ keyId, children }: { keyId: string; children: ReactNode }) {
  const reduce = useReducedMotion();
  return (
    <motion.span
      key={keyId}
      variants={ICON_VARIANTS}
      initial={reduce ? { opacity: 0 } : "initial"}
      animate={reduce ? { opacity: 1 } : "animate"}
      exit={reduce ? { opacity: 0 } : "exit"}
      transition={reduce ? { duration: 0.15 } : undefined}
      className="inline-grid shrink-0 place-items-center overflow-hidden"
    >
      {children}
    </motion.span>
  );
}

function TextSlot({
  value,
  children,
}: {
  value: string;
  children: ReactNode;
}) {
  const reduce = useReducedMotion();
  const measureRef = useRef<HTMLSpanElement>(null);
  const [width, setWidth] = useState<number>();
  const label = typeof children === "string" ? children : null;
  const cascade = label !== null && !reduce;

  // Measure strings with the same per-letter layout as the cascade. Measuring
  // the whole string preserves kerning, which can make it narrower than the
  // inline-block letters and clip the final glyph during the width animation.
  useLayoutEffect(() => {
    const nextWidth = measureRef.current?.offsetWidth;
    if (!nextWidth) return;
    setWidth((current) => (current === nextWidth ? current : nextWidth));
  });

  return (
    <motion.span
      initial={false}
      animate={{ width }}
      transition={reduce ? { duration: 0 } : SPRING_SWAP}
      className="relative inline-block overflow-hidden whitespace-nowrap align-bottom"
    >
      <span
        ref={measureRef}
        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 ? (
        <>
          <span className="sr-only">{label}</span>
          <AnimatePresence initial={false}>
            <motion.span
              key={`cascade-${value}`}
              aria-hidden
              initial="initial"
              animate="animate"
              exit="exit"
              className="absolute left-0 top-0 inline-block whitespace-pre"
            >
              {label.split("").map((char, index) => (
                <motion.span
                  // biome-ignore lint/suspicious/noArrayIndexKey: position is the slot identity.
                  key={index}
                  custom={index * CASCADE_STAGGER}
                  variants={CASCADE_LETTER_VARIANTS}
                  className="inline-block whitespace-pre will-change-[opacity,filter,transform]"
                >
                  {char}
                </motion.span>
              ))}
            </motion.span>
          </AnimatePresence>
        </>
      ) : (
        <AnimatePresence initial={false}>
          <motion.span
            key={`text-${value}`}
            initial={reduce ? { opacity: 0 } : { opacity: 0, y: 14, filter: ROLL_BLUR }}
            animate={reduce ? { opacity: 1 } : { opacity: 1, y: 0, filter: "blur(0px)" }}
            exit={reduce ? { opacity: 0 } : { opacity: 0, y: -14, filter: ROLL_BLUR }}
            transition={reduce ? { duration: 0.15 } : SPRING_SWAP}
            className="absolute left-0 top-0 inline-block will-change-[opacity,filter,transform]"
          >
            {children}
          </motion.span>
        </AnimatePresence>
      )}
    </motion.span>
  );
}

export const StatefulButton = forwardRef<HTMLButtonElement, StatefulButtonProps>(function StatefulButton(
  {
    state = "idle",
    children,
    loadingText = "Loading",
    successText = "Done",
    errorText = "Try again",
    icon,
    disabled,
    ...rest
  },
  ref,
) {
  const isBusy = state === "loading";
  const stateText =
    state === "loading"
      ? loadingText
      : state === "success"
        ? successText
        : state === "error"
        ? errorText
        : children;
  const textKey =
    typeof stateText === "string" ? `${state}-${stateText}` : state;

  return (
    <Button ref={ref} disabled={disabled || isBusy} aria-busy={isBusy} whileHover={undefined} {...rest}>
      <span
        aria-live="polite"
        className="relative inline-flex items-center justify-center overflow-hidden"
      >
        <AnimatePresence initial={false}>
          {state === "loading" ? (
            <IconSlot keyId="loading-icon">
              <Loader2 className="h-4 w-4 animate-spin" />
            </IconSlot>
          ) : null}
          {state === "success" ? (
            <IconSlot keyId="success-icon">
              <Check className="h-4 w-4" />
            </IconSlot>
          ) : null}
          {state === "error" ? (
            <IconSlot keyId="error-icon">
              <X className="h-4 w-4" />
            </IconSlot>
          ) : null}
        </AnimatePresence>

        <TextSlot value={textKey}>{stateText}</TextSlot>

        <AnimatePresence initial={false}>
          {state === "idle" && icon ? (
            <IconSlot keyId="idle-icon">{icon}</IconSlot>
          ) : null}
        </AnimatePresence>
      </span>
    </Button>
  );
});

"use client";

import { motion, useMotionValue, useReducedMotion, useSpring } from "motion/react";
import { useRef, type ReactNode } from "react";
import { SPRING_MOUSE } from "@/lib/ease";
import { useHoverCapable } from "@/lib/hooks/use-hover-capable";
import { cn } from "@/lib/utils";

export interface MagneticProps {
  children: ReactNode;
  strength?: number;
  className?: string;
}

export function Magnetic({ children, strength = 0.35, className }: MagneticProps) {
  const ref = useRef<HTMLDivElement>(null);
  const reduce = useReducedMotion();
  const canHover = useHoverCapable();
  // Decorative cursor-follow: skip on touch (phantom hover) and reduced motion.
  const enabled = !reduce && canHover;
  const x = useMotionValue(0);
  const y = useMotionValue(0);
  const sx = useSpring(x, SPRING_MOUSE);
  const sy = useSpring(y, SPRING_MOUSE);

  const onMove = (e: React.MouseEvent<HTMLDivElement>) => {
    const el = ref.current;
    if (!el || !enabled) return;
    const rect = el.getBoundingClientRect();
    x.set((e.clientX - rect.left - rect.width / 2) * strength);
    y.set((e.clientY - rect.top - rect.height / 2) * strength);
  };

  const onLeave = () => {
    x.set(0);
    y.set(0);
  };

  return (
    <motion.div
      ref={ref}
      onMouseMove={onMove}
      onMouseLeave={onLeave}
      style={{ x: sx, y: sy }}
      className={cn("inline-block", className)}
    >
      {children}
    </motion.div>
  );
}