Stacked Folder Card

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import { type ClassValue, clsx } from "clsx";
import { twMerge } from "tailwind-merge";
 
export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs));
}

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"use client";
 
import Image from "next/image";
import { forwardRef, useCallback, useState, type ComponentPropsWithoutRef } from "react";
 
import { cn } from "@/lib/cn";
 
type LayerIndex = 0 | 1 | 2;
type StackPosition = "front" | "middle" | "back";
 
const TRANSITION =
  "transition-[top,left,width,height,transform,box-shadow] duration-400 ease-[cubic-bezier(0.22,1,0.36,1)]";
 
const POSITION_LAYOUT: Record<StackPosition, string> = {
  front:
    "top-0 left-9 z-30 h-[17rem] w-[15.75rem] rotate-0 shadow-[0_20px_44px_-14px_rgba(0,0,0,0.38)]",
  middle:
    "top-4 left-4 z-20 h-[16rem] w-[15rem] -rotate-[3.5deg] shadow-[0_12px_28px_-10px_rgba(0,0,0,0.3)]",
  back:
    "top-9 left-0.5 z-10 h-[15.5rem] w-[14.5rem] -rotate-[7deg] shadow-[0_10px_24px_-10px_rgba(0,0,0,0.28)]",
};
 
// [front, middle, back] — hovered card goes front, previous front goes back, other stays middle.
const STACK_ORDER: Record<LayerIndex, readonly [LayerIndex, LayerIndex, LayerIndex]> = {
  0: [0, 1, 2],
  1: [1, 0, 2],
  2: [2, 1, 0],
};
 
function positionForLayer(layer: LayerIndex, active: LayerIndex): StackPosition {
  const [front, middle] = STACK_ORDER[active];
  if (layer === front) return "front";
  if (layer === middle) return "middle";
  return "back";
}
 
type LayerConfig = Readonly<{
  index: LayerIndex;
  src?: string;
  alt: string;
  surfaceClassName: string;
}>;
 
export type StackedFolderCardProps = Readonly<
  {
    imageSrc?: string;
    imageAlt?: string;
    backImageSrc?: string;
    middleImageSrc?: string;
    backClassName?: string;
    middleClassName?: string;
  } & ComponentPropsWithoutRef<"div">
>;
 
// Three-layer folder stack · fixed hit zones · hover rotates front → back.
export const StackedFolderCard = forwardRef<HTMLDivElement, StackedFolderCardProps>(
  function StackedFolderCard(
    {
      className,
      imageSrc = "/wallpaper-3.png",
      imageAlt = "Folder cover",
      backImageSrc,
      middleImageSrc,
      backClassName = "bg-[#e28a8a]",
      middleClassName = "bg-[#5a675e]",
      ...props
    },
    ref,
  ) {
    const [active, setActive] = useState<LayerIndex>(2);
 
    const [frontLayer, middleLayer, backLayer] = STACK_ORDER[active];
 
    const bringToFront = useCallback((layer: LayerIndex) => {
      setActive((current) => (current === layer ? current : layer));
    }, []);
 
    const layers: LayerConfig[] = [
      {
        index: 0,
        src: backImageSrc,
        alt: "",
        surfaceClassName: backClassName,
      },
      {
        index: 1,
        src: middleImageSrc,
        alt: "",
        surfaceClassName: middleClassName,
      },
      {
        index: 2,
        src: imageSrc,
        alt: imageAlt,
        surfaceClassName: "",
      },
    ];
 
    return (
      <div
        ref={ref}
        data-slot="stacked-folder-card"
        className={cn("relative h-[20rem] w-[19rem] font-sans", className)}
        {...props}
      >
        {layers.map((layer) => {
          const position = positionForLayer(layer.index, active);
 
          return (
            <div
              key={layer.index}
              aria-hidden
              className={cn(
                "pointer-events-none absolute overflow-hidden rounded-[2rem] border-[7px] border-white",
                TRANSITION,
                POSITION_LAYOUT[position],
                layer.surfaceClassName,
              )}
            >
              {layer.src ? (
                <Image
                  src={layer.src}
                  alt={layer.alt}
                  fill
                  sizes="280px"
                  className="object-cover"
                  draggable={false}
                />
              ) : null}
            </div>
          );
        })}
 
        <button
          type="button"
          tabIndex={-1}
          aria-label="Show back card"
          onMouseEnter={() => bringToFront(backLayer)}
          onFocus={() => bringToFront(backLayer)}
          className="absolute top-0 bottom-0 left-0 z-40 w-4 cursor-default border-0 bg-transparent p-0"
        />
 
        <button
          type="button"
          tabIndex={-1}
          aria-label="Show middle card"
          onMouseEnter={() => bringToFront(middleLayer)}
          onFocus={() => bringToFront(middleLayer)}
          className="absolute top-0 bottom-0 left-4 z-40 w-5 cursor-default border-0 bg-transparent p-0"
        />
 
        <button
          type="button"
          tabIndex={-1}
          aria-label="Show front card"
          onMouseEnter={() => bringToFront(frontLayer)}
          onFocus={() => bringToFront(frontLayer)}
          className="absolute top-0 right-0 bottom-0 left-9 z-40 cursor-default border-0 bg-transparent p-0"
        />
      </div>
    );
  },
);
 
StackedFolderCard.displayName = "StackedFolderCard";