Nested React Splitter

# Integrate this UI component

Add this component to my project.

1. Install any missing dependencies.
2. Make sure Tailwind CSS is set up and scans the new file.
3. Prefer passing props over editing the component source — changing the component itself may break it.
4. Adjust colors, size, and layout via props or wrapper classes to match my project. You know my codebase better than this snippet does.

## Component source

```tsx
'use client';

import {
  useId,
  useRef,
  useState,
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
} from 'react';

type Orientation = 'horizontal' | 'vertical';

type ResizablePanelsProps = {
  orientation: Orientation;
  firstPanel: ReactNode;
  secondPanel: ReactNode;
  defaultSize?: number;
  minSize?: number;
  ariaLabel?: string;
  showHandle?: boolean;
  className?: string;
};

function ResizablePanels({
  orientation,
  firstPanel,
  secondPanel,
  defaultSize = 50,
  minSize = 20,
  ariaLabel = 'Resize panels',
  showHandle = true,
  className = '',
}: ResizablePanelsProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const draggingRef = useRef(false);
  const [isActive, setIsActive] = useState(false);
  const firstPanelId = useId();
  const secondPanelId = useId();
  const isHorizontal = orientation === 'horizontal';
  const safeMinSize = Math.min(49, Math.max(0, minSize));
  const clamp = (value: number) =>
    Math.min(100 - safeMinSize, Math.max(safeMinSize, value));
  const [size, setSize] = useState(() => clamp(defaultSize));

  const resizeFromPointer = (clientX: number, clientY: number) => {
    const bounds = rootRef.current?.getBoundingClientRect();
    if (!bounds) return;

    const position = isHorizontal ? clientX - bounds.left : clientY - bounds.top;
    const total = isHorizontal ? bounds.width : bounds.height;
    setSize(clamp((position / total) * 100));
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    draggingRef.current = true;
    setIsActive(true);
    event.currentTarget.setPointerCapture(event.pointerId);
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    if (draggingRef.current) resizeFromPointer(event.clientX, event.clientY);
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>) => {
    draggingRef.current = false;
    setIsActive(false);
    if (event.currentTarget.hasPointerCapture(event.pointerId)) {
      event.currentTarget.releasePointerCapture(event.pointerId);
    }
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const decreaseKey = isHorizontal ? 'ArrowLeft' : 'ArrowUp';
    const increaseKey = isHorizontal ? 'ArrowRight' : 'ArrowDown';
    const step = event.shiftKey ? 10 : 2;

    if (event.key === decreaseKey || event.key === increaseKey) {
      event.preventDefault();
      setSize((value) =>
        clamp(value + (event.key === increaseKey ? step : -step)),
      );
    } else if (event.key === 'Home') {
      event.preventDefault();
      setSize(safeMinSize);
    } else if (event.key === 'End') {
      event.preventDefault();
      setSize(100 - safeMinSize);
    }
  };

  return (
    <div
      ref={rootRef}
      className={[
        'relative flex overflow-hidden rounded-2xl border border-gray-200 bg-white shadow-sm',
        isHorizontal ? 'flex-row' : 'flex-col',
        className,
      ]
        .filter(Boolean)
        .join(' ')}
    >
      <div
        id={firstPanelId}
        className='min-h-0 min-w-0 shrink-0 overflow-auto'
        style={{ flexBasis: `${size}%` }}
      >
        {firstPanel}
      </div>

      <div
        role='separator'
        tabIndex={0}
        aria-label={ariaLabel}
        aria-controls={`${firstPanelId} ${secondPanelId}`}
        aria-orientation={isHorizontal ? 'vertical' : 'horizontal'}
        aria-valuemin={safeMinSize}
        aria-valuemax={100 - safeMinSize}
        aria-valuenow={Math.round(size)}
        onDoubleClick={() => setSize(clamp(defaultSize))}
        onKeyDown={handleKeyDown}
        onPointerDown={handlePointerDown}
        onPointerMove={handlePointerMove}
        onPointerUp={handlePointerUp}
        onPointerCancel={handlePointerUp}
        onLostPointerCapture={() => {
          draggingRef.current = false;
          setIsActive(false);
        }}
        className={[
          'absolute z-10 touch-none bg-transparent outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-gray-300',
          isHorizontal
            ? 'bottom-0 top-0 w-3 -translate-x-1/2 cursor-col-resize'
            : 'left-0 right-0 h-3 -translate-y-1/2 cursor-row-resize',
        ].join(' ')}
        style={isHorizontal ? { left: `${size}%` } : { top: `${size}%` }}
      >
        <span
          aria-hidden='true'
          className={[
            isActive ? 'absolute bg-indigo-400' : 'absolute bg-gray-200',
            isHorizontal
              ? 'bottom-0 left-1/2 top-0 w-px -translate-x-1/2'
              : 'left-0 right-0 top-1/2 h-px -translate-y-1/2',
          ].join(' ')}
        />
        {showHandle ? (
          <span
            aria-hidden='true'
            className={[
              'absolute left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2 rounded-full border border-gray-200 bg-white',
              isHorizontal ? 'h-9 w-1.5' : 'h-1.5 w-9',
            ].join(' ')}
          />
        ) : null}
      </div>

      <div
        id={secondPanelId}
        className='min-h-0 min-w-0 shrink-0 overflow-auto'
        style={{ flexBasis: `${100 - size}%` }}
      >
        {secondPanel}
      </div>
    </div>
  );
}

function Placeholder({ label }: { label: string }) {
  return (
    <div className='flex h-full min-h-32 items-center justify-center bg-white p-6 text-sm font-medium text-gray-500'>
      {label}
    </div>
  );
}

export type HorizontalSplitterProps = {
  leftPanel?: ReactNode;
  rightPanel?: ReactNode;
  defaultSize?: number;
  minSize?: number;
  ariaLabel?: string;
  showHandle?: boolean;
  className?: string;
};

export function HorizontalSplitter({
  leftPanel = <Placeholder label='Left panel' />,
  rightPanel = <Placeholder label='Right panel' />,
  defaultSize = 36,
  minSize = 20,
  ariaLabel = 'Resize left and right panels',
  showHandle = true,
  className = '',
}: HorizontalSplitterProps) {
  return (
    <ResizablePanels
      orientation='horizontal'
      firstPanel={leftPanel}
      secondPanel={rightPanel}
      defaultSize={defaultSize}
      minSize={minSize}
      ariaLabel={ariaLabel}
      showHandle={showHandle}
      className={className}
    />
  );
}

export type VerticalSplitterProps = {
  topPanel?: ReactNode;
  bottomPanel?: ReactNode;
  defaultSize?: number;
  minSize?: number;
  ariaLabel?: string;
  showHandle?: boolean;
  className?: string;
};

export function VerticalSplitter({
  topPanel = <Placeholder label='Top panel' />,
  bottomPanel = <Placeholder label='Bottom panel' />,
  defaultSize = 58,
  minSize = 20,
  ariaLabel = 'Resize top and bottom panels',
  showHandle = true,
  className = '',
}: VerticalSplitterProps) {
  return (
    <ResizablePanels
      orientation='vertical'
      firstPanel={topPanel}
      secondPanel={bottomPanel}
      defaultSize={defaultSize}
      minSize={minSize}
      ariaLabel={ariaLabel}
      showHandle={showHandle}
      className={className}
    />
  );
}

export type NestedSplitterProps = {
  sidebar?: ReactNode;
  topPanel?: ReactNode;
  bottomPanel?: ReactNode;
  defaultSidebarSize?: number;
  defaultTopSize?: number;
  minSize?: number;
  showHandle?: boolean;
  className?: string;
};

export function NestedSplitter({
  sidebar = <Placeholder label='Navigation' />,
  topPanel = <Placeholder label='Workspace' />,
  bottomPanel = <Placeholder label='Console' />,
  defaultSidebarSize = 28,
  defaultTopSize = 64,
  minSize = 20,
  showHandle = true,
  className = '',
}: NestedSplitterProps) {
  return (
    <HorizontalSplitter
      leftPanel={sidebar}
      rightPanel={
        <VerticalSplitter
          topPanel={topPanel}
          bottomPanel={bottomPanel}
          defaultSize={defaultTopSize}
          minSize={minSize}
          showHandle={showHandle}
          className='h-full w-full rounded-none border-0 shadow-none'
        />
      }
      defaultSize={defaultSidebarSize}
      minSize={minSize}
      showHandle={showHandle}
      className={className}
    />
  );
}

export default HorizontalSplitter;

```