主题切换按钮

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

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

// 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;

"use client";
// ui-lab-ten.vercel.app/components/motion/theme-toggle

import { Moon, Sun } from "lucide-react";
import { useTheme } from "next-themes";
import { useReducedMotion } from "motion/react";
import { useEffect, useState, type ComponentPropsWithoutRef } from "react";
import { ActionSwapIcon } from "@/components/motion/action-swap";
import { cn } from "@/lib/utils";

export type ThemeVariant = "rectangle" | "circle" | "circle-blur";

export type RectStart =
  | "top-left"
  | "top-right"
  | "bottom-left"
  | "bottom-right"
  | "center"
  | "bottom-up";

export interface ThemeToggleProps
  extends Omit<ComponentPropsWithoutRef<"button">, "children" | "onClick"> {
  /** Animation variant. Default: "rectangle". */
  variant?: ThemeVariant;
  /** Origin direction for the reveal. Default: "bottom-up". */
  start?: RectStart;
  iconClassName?: string;
}

const VT_STYLE_ID = "uilab-theme-toggle-vt";

// Duration/easing is component-specific: View Transition API uses CSS, not
// motion springs. 400ms + ease-out mirrors native OS mode-switch timing.
const VT_CSS = `
html[data-uilab-vt="rect"]::view-transition-old(root) {
  animation: none;
  mix-blend-mode: normal;
}
html[data-uilab-vt="rect"]::view-transition-new(root) {
  mix-blend-mode: normal;
  animation: uilab-rect-reveal 400ms ease-out;
}
html[data-uilab-vt="circle"]::view-transition-old(root),
html[data-uilab-vt="circle-blur"]::view-transition-old(root) {
  animation: none;
  mix-blend-mode: normal;
}
html[data-uilab-vt="circle"]::view-transition-new(root) {
  mix-blend-mode: normal;
  animation: uilab-circle-reveal 700ms cubic-bezier(0.4, 0, 0.2, 1);
}
html[data-uilab-vt="circle-blur"]::view-transition-new(root) {
  mix-blend-mode: normal;
  animation: uilab-circle-blur-reveal 700ms cubic-bezier(0.4, 0, 0.2, 1);
}
@keyframes uilab-rect-reveal {
  from { clip-path: var(--uilab-vt-from, inset(100% 0 0 0)); }
  to   { clip-path: inset(0 0 0 0); }
}
@keyframes uilab-circle-reveal {
  from { clip-path: circle(0% at var(--uilab-vt-origin, 50% 100%)); }
  to   { clip-path: circle(150% at var(--uilab-vt-origin, 50% 100%)); }
}
@keyframes uilab-circle-blur-reveal {
  from { clip-path: circle(0% at var(--uilab-vt-origin, 50% 100%)); filter: blur(8px); }
  to   { clip-path: circle(150% at var(--uilab-vt-origin, 50% 100%)); filter: blur(0px); }
}
`;

const RECT_FROM: Record<RectStart, string> = {
  "top-left":    "inset(0 100% 100% 0)",
  "top-right":   "inset(0 0 100% 100%)",
  "bottom-left": "inset(100% 100% 0 0)",
  "bottom-right":"inset(100% 0 0 100%)",
  center:        "inset(50% 50% 50% 50%)",
  "bottom-up":   "inset(100% 0 0 0)",
};

const CIRCLE_ORIGIN: Record<RectStart, string> = {
  "top-left":    "0% 0%",
  "top-right":   "100% 0%",
  "bottom-left": "0% 100%",
  "bottom-right":"100% 100%",
  center:        "50% 50%",
  "bottom-up":   "50% 100%",
};

export function useThemeToggle({
  variant = "rectangle",
  start = "bottom-up",
}: { variant?: ThemeVariant; start?: RectStart } = {}) {
  const { setTheme, resolvedTheme } = useTheme();
  const reduce = useReducedMotion() ?? false;
  const [mounted, setMounted] = useState(false);
  useEffect(() => setMounted(true), []);
  useEffect(() => {
    if (document.getElementById(VT_STYLE_ID)) return;
    const el = document.createElement("style");
    el.id = VT_STYLE_ID;
    el.textContent = VT_CSS;
    document.head.appendChild(el);
  }, []);
  const isDark = mounted && resolvedTheme === "dark";

  const toggle = () => {
    const next = isDark ? "light" : "dark";

    if (reduce || !("startViewTransition" in document)) {
      setTheme(next);
      return;
    }

    const root = document.documentElement;

    if (variant === "rectangle") {
      root.style.setProperty("--uilab-vt-from", RECT_FROM[start]);
      root.dataset.uilabVt = "rect";
    } else {
      root.style.setProperty("--uilab-vt-origin", CIRCLE_ORIGIN[start]);
      root.dataset.uilabVt = variant;
    }

    const vt = (
      document as Document & {
        startViewTransition(cb: () => void): { finished: Promise<void> };
      }
    ).startViewTransition(() => setTheme(next));

    vt.finished.finally(() => {
      delete root.dataset.uilabVt;
    });
  };

  return { isDark, mounted, toggle };
}

export function ThemeToggle({
  variant = "rectangle",
  start = "bottom-up",
  className,
  iconClassName,
  ...rest
}: ThemeToggleProps) {
  const { isDark, mounted, toggle } = useThemeToggle({ variant, start });

  return (
    <button
      type="button"
      aria-label={mounted && isDark ? "Switch to light mode" : "Switch to dark mode"}
      onClick={toggle}
      className={cn("flex items-center justify-center", className)}
      {...rest}
    >
      {mounted ? (
        <ActionSwapIcon
          value={isDark ? "dark" : "light"}
          animation="blur"
          className={iconClassName}
        >
          {isDark ? (
            <Sun className={iconClassName} />
          ) : (
            <Moon className={iconClassName} />
          )}
        </ActionSwapIcon>
      ) : (
        <span className={iconClassName} aria-hidden="true" />
      )}
    </button>
  );
}

"use client";

import { AnimatePresence, motion, useReducedMotion, type HTMLMotionProps, type Variants } from "motion/react";
import { useLayoutEffect, useRef, useState, type ReactNode } from "react";
import { EASE_OUT, EASE_OUT_CSS, 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 = { duration: 0.24, ease: EASE_OUT } as const;
const SWAP_BLUR = "blur(8px)";
const ROLL_BLUR = "blur(6px)";

// 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: "115%", filter: ROLL_BLUR },
    animate: {
      opacity: 1,
      y: "0%",
      filter: "blur(0px)",
      transition: ROLL_TRANSITION,
    },
    exit: {
      opacity: 0,
      y: "-115%",
      filter: ROLL_BLUR,
      transition: { duration: 0.18, ease: "easeInOut" },
    },
  },
};

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: 16, filter: ROLL_BLUR },
    animate: {
      opacity: 1,
      y: 0,
      filter: "blur(0px)",
      transition: ROLL_TRANSITION,
    },
    exit: {
      opacity: 0,
      y: -16,
      filter: ROLL_BLUR,
      transition: { duration: 0.18, ease: "easeInOut" },
    },
  },
};

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-primary/5",
  ghost: "text-muted-foreground hover:bg-primary/5 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();
  const measureRef = useRef<HTMLSpanElement>(null);
  const [width, setWidth] = useState<number>();

  useLayoutEffect(() => {
    const nextWidth = measureRef.current?.offsetWidth;
    if (!nextWidth) return;
    setWidth((currentWidth) => (currentWidth === nextWidth ? currentWidth : nextWidth));
  });

  // 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 inline-block overflow-hidden whitespace-nowrap align-bottom", className)}
      style={{
        width,
        transition: reduce ? undefined : `width 220ms ${EASE_OUT_CSS}`,
      }}
    >
      <span
        ref={measureRef}
        aria-hidden
        className="invisible inline-block whitespace-nowrap"
      >
        {children}
      </span>
      {cascade ? (
        <>
          {/* Letters are decorative fragments; readers get the whole label. */}
          <span className="sr-only">{label}</span>
          <AnimatePresence initial={false}>
            <motion.span
              key={`cascade-${value}`}
              aria-hidden
              initial="initial"
              animate="animate"
              exit="exit"
              className="absolute left-0 top-0 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"}
            className="absolute left-0 top-0 inline-block 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>
  );
}