Switch for React

'use client';

import { useId, useState } from 'react';
import { cn } from '@/lib/kit';
import { Icon, type IconName } from '@/components/ui/icon';

export interface SwitchProps extends Omit<React.ButtonHTMLAttributes<HTMLButtonElement>, 'onChange' | 'value'> {
  checked?: boolean;
  defaultChecked?: boolean;
  onCheckedChange?: (checked: boolean) => void;
  label?: React.ReactNode;
  description?: React.ReactNode;
  size?: 'sm' | 'md';
  /** Where the switch sits next to the label. end is the settings-list look. */
  position?: 'start' | 'end';
  /** row: a bordered settings row, optionally with an icon */
  variant?: 'default' | 'row';
  icon?: IconName;
  /** Form name, a hidden input carries "on" when checked */
  name?: string;
  className?: string;
}

const SIZE = {
  sm: { track: 'h-5 w-9', thumb: 'size-4', on: 'translate-x-4', mark: 8 },
  md: { track: 'h-6 w-11', thumb: 'size-5', on: 'translate-x-5', mark: 10 },
};

/**
 * An on/off setting that applies right away. A button with role="switch" and aria-checked.
 *   <Switch label="Email digest" description="A summary every Monday" defaultChecked />
 */
export function Switch({ checked, defaultChecked, onCheckedChange, label, description, size = 'md', position = 'end', variant = 'default', icon, name, className, id, disabled, onClick, ...rest }: SwitchProps) {
  const auto = useId();
  const sid = id ?? auto;
  const [inner, setInner] = useState(defaultChecked ?? false);
  const on = checked ?? inner;
  const s = SIZE[size];

  const control = (
    <button
      type="button"
      role="switch"
      id={sid}
      aria-checked={on}
      aria-labelledby={label ? `${sid}-label` : undefined}
      aria-describedby={description ? `${sid}-desc` : undefined}
      disabled={disabled}
      {...rest}
      onClick={(e) => {
        onClick?.(e);
        setInner(!on);
        onCheckedChange?.(!on);
      }}
      className={cn(
        'group/switch relative inline-flex shrink-0 cursor-pointer items-center rounded-full p-0.5 outline-none transition-[background-color,box-shadow] duration-200 ease-[var(--ease-kit)]',
        'bg-[color-mix(in_oklab,var(--foreground)_14%,var(--background))] shadow-[inset_0_0_0_1px_color-mix(in_oklab,var(--foreground)_6%,transparent)] hover:bg-[color-mix(in_oklab,var(--foreground)_20%,var(--background))]',
        'aria-checked:bg-primary aria-checked:hover:bg-[color-mix(in_oklab,var(--primary)_88%,var(--background))]',
        'focus-visible:shadow-[0_0_0_3px_color-mix(in_oklab,var(--primary)_25%,transparent)]',
        'disabled:cursor-not-allowed disabled:opacity-50',
        // 44 px hit area
        'after:absolute after:-inset-x-1 after:-inset-y-3 after:content-[""]',
        s.track,
        !label && className,
      )}
    >
      {/* The knob travels on a spring: it overshoots a hair and settles. Held down it stretches. A small check draws itself on it. */}
      <span
        aria-hidden
        className={cn(
          'pointer-events-none grid place-items-center rounded-full shadow-[0_1px_3px_rgb(0_0_0/0.2),0_0_0_0.5px_rgb(0_0_0/0.04)] transition-[translate,scale,background-color] duration-[420ms] ease-[cubic-bezier(0.34,1.45,0.64,1)] group-active/switch:scale-x-[1.18] group-active/switch:duration-150 motion-reduce:transition-none',
          s.thumb,
          on ? cn(s.on, 'origin-right bg-primary-foreground') : 'origin-left bg-background dark:bg-[color-mix(in_oklab,var(--foreground)_88%,var(--background))]',
        )}
      >
        <svg viewBox="0 0 24 24" width={s.mark} height={s.mark} fill="none" className="text-primary">
          <path
            d="m5 12.5 4.5 4.5L19 7.5"
            pathLength={1}
            strokeDasharray="1 1"
            stroke="currentColor"
            strokeWidth="3.4"
            strokeLinecap="round"
            strokeLinejoin="round"
            className={cn('transition-[stroke-dashoffset,opacity] ease-[var(--ease-kit)] motion-reduce:transition-none', on ? 'opacity-100 delay-150 duration-300 [stroke-dashoffset:0]' : 'opacity-0 duration-150 [stroke-dashoffset:1]')}
          />
        </svg>
      </span>
    </button>
  );

  const hidden = name ? <input type="hidden" name={name} value={on ? 'on' : ''} /> : null;
  if (!label) return (
    <>
      {control}
      {hidden}
    </>
  );

  const text = (
    <span className="min-w-0 flex-1">
      <label id={`${sid}-label`} htmlFor={sid} className={cn('block cursor-pointer text-sm font-medium leading-5 text-foreground', disabled && 'cursor-not-allowed')}>
        {label}
      </label>
      {description && (
        <span id={`${sid}-desc`} className="mt-0.5 block text-[13px] leading-5 text-muted-foreground">
          {description}
        </span>
      )}
    </span>
  );

  return (
    <div
      className={cn(
        'flex items-start gap-3.5',
        variant === 'row' && 'items-center rounded-xl border border-border bg-card px-4 py-3.5 shadow-[var(--shadow-sm)]',
        disabled && 'opacity-60',
        className,
      )}
    >
      {variant === 'row' && icon && (
        <span
          className={cn(
            'grid size-9 shrink-0 place-items-center rounded-lg border bg-surface transition-[color,border-color,background-color] duration-300',
            on ? 'border-[color-mix(in_oklab,var(--primary)_35%,var(--border))] bg-[color-mix(in_oklab,var(--primary)_8%,var(--surface))] text-[color-mix(in_oklab,var(--primary)_85%,var(--foreground))]' : 'border-border text-muted-foreground',
          )}
        >
          <Icon name={icon} size={18} />
        </span>
      )}
      {position === 'start' && <span className={cn('flex items-center', size === 'md' ? 'h-6 -mt-0.5' : 'h-5')}>{control}</span>}
      {text}
      {position === 'end' && <span className={cn('flex items-center', variant === 'row' ? '' : size === 'md' ? 'h-6 -mt-0.5' : 'h-5')}>{control}</span>}
      {hidden}
    </div>
  );
}