Pill slider

'use client'

import { useState } from 'react'
import { sliderAria, sliderKeys, useTrackDrag, type SliderProps } from '../lib/slider'

// a tiny bar that swells on hover, fills as you drag and stretches past the ends
export function PillSlider(props: SliderProps & { width?: number }) {
  const { options, value, onChange, width = 72 } = props
  const count = options.length
  const [hover, setHover] = useState(false)
  const { ref, dragging, overshoot, handlers } = useTrackDrag(width, count, onChange)
  const open = hover || dragging
  const stretch = 1 + Math.min(Math.abs(overshoot), 40) / 260

  return (
    <div
      ref={ref}
      {...sliderAria(props)}
      onKeyDown={sliderKeys(value, count, onChange)}
      {...handlers}
      onPointerEnter={() => setHover(true)}
      onPointerLeave={() => setHover(false)}
      className="relative flex h-7 cursor-grab touch-none select-none items-center outline-none active:cursor-grabbing"
      style={{ width }}
    >
      <div
        className="relative w-full overflow-hidden rounded-full"
        style={{
          height: open ? 18 : 6,
          background: 'var(--curio-chip)',
          transform: `scaleX(${stretch}) scaleY(${2 - stretch})`,
          transformOrigin: overshoot < 0 ? 'right' : 'left',
          transition: dragging && overshoot ? 'height 200ms ease' : 'height 220ms cubic-bezier(.23,1,.32,1), transform 400ms cubic-bezier(.34,1.56,.64,1)',
        }}
      >
        <div
          className="absolute inset-y-0 left-0 rounded-full"
          style={{
            width: `${(value / (count - 1)) * 100}%`,
            minWidth: open ? 18 : 6,
            background: open ? 'var(--curio-accent)' : 'var(--curio-fg)',
            transition: 'width 280ms cubic-bezier(.23,1,.32,1), background-color 150ms',
          }}
        />
        {options.slice(1, -1).map((_, j) => {
          const i = j + 1
          return (
            <span
              key={i}
              className="absolute top-1/2 h-1 w-1 -translate-x-1/2 -translate-y-1/2 rounded-full transition-opacity"
              style={{ left: `${(i / (count - 1)) * 100}%`, background: 'var(--curio-muted)', opacity: open && i !== value ? 0.6 : 0 }}
            />
          )
        })}
      </div>
    </div>
  )
}

'use client'

import { useRef, useState } from 'react'
import type { ThemeOption } from './types'

export type SliderProps = {
  options: ThemeOption[]
  value: number
  onChange: (index: number) => void
  /** accessible name */
  label?: string
}

export const clampTo = (n: number, count: number) => Math.max(0, Math.min(count - 1, n))

// arrow keys / home / end
export function sliderKeys(value: number, count: number, onChange: (i: number) => void) {
  return (e: React.KeyboardEvent) => {
    const next =
      e.key === 'ArrowRight' || e.key === 'ArrowUp'
        ? value + 1
        : e.key === 'ArrowLeft' || e.key === 'ArrowDown'
          ? value - 1
          : e.key === 'Home'
            ? 0
            : e.key === 'End'
              ? count - 1
              : null
    if (next === null) return
    e.preventDefault()
    onChange(clampTo(next, count))
  }
}

export function sliderAria({ options, value, label = 'Theme' }: SliderProps) {
  return {
    role: 'slider' as const,
    tabIndex: 0,
    'aria-label': label,
    'aria-valuemin': 0,
    'aria-valuemax': options.length - 1,
    'aria-valuenow': value,
    'aria-valuetext': options[value]?.label,
  }
}

// drag along x; reports the nearest step and how far past either end you pulled
export function useTrackDrag(width: number, count: number, onStep: (i: number) => void) {
  const ref = useRef<HTMLDivElement>(null)
  const [dragging, setDragging] = useState(false)
  const [overshoot, setOvershoot] = useState(0)

  const update = (clientX: number) => {
    const rect = ref.current!.getBoundingClientRect()
    const x = clientX - rect.left
    setOvershoot(x < 0 ? x : x > width ? x - width : 0)
    onStep(clampTo(Math.round((x / width) * (count - 1)), count))
  }
  const stop = () => {
    setDragging(false)
    setOvershoot(0)
  }
  return {
    ref,
    dragging,
    overshoot,
    handlers: {
      onPointerDown: (e: React.PointerEvent) => {
        ;(e.currentTarget as HTMLElement).setPointerCapture(e.pointerId)
        setDragging(true)
        update(e.clientX)
      },
      onPointerMove: (e: React.PointerEvent) => dragging && update(e.clientX),
      onPointerUp: stop,
      onPointerCancel: stop,
    },
  }
}