'use client'
import { useEffect, useId, useRef, useState } from 'react'
/**
* An async autocomplete built on the ARIA combobox pattern: debounced
* queries, a stale-response guard, aria-activedescendant option tracking,
* and a polite live region announcing result counts.
*/
interface Typeface {
id: string
name: string
classification: string
year: number
}
const TYPEFACES: Typeface[] = [
{ id: 'akzidenz', name: 'Akzidenz-Grotesk', classification: 'Grotesque', year: 1898 },
{ id: 'futura', name: 'Futura', classification: 'Geometric sans', year: 1927 },
{ id: 'times', name: 'Times New Roman', classification: 'Transitional serif', year: 1932 },
{ id: 'palatino', name: 'Palatino', classification: 'Old-style serif', year: 1949 },
{ id: 'helvetica', name: 'Helvetica', classification: 'Neo-grotesque', year: 1957 },
{ id: 'univers', name: 'Univers', classification: 'Neo-grotesque', year: 1957 },
{ id: 'optima', name: 'Optima', classification: 'Humanist sans', year: 1958 },
{ id: 'eurostile', name: 'Eurostile', classification: 'Square sans', year: 1962 },
{ id: 'sabon', name: 'Sabon', classification: 'Old-style serif', year: 1967 },
{ id: 'avant', name: 'ITC Avant Garde', classification: 'Geometric sans', year: 1970 },
{ id: 'frutiger', name: 'Frutiger', classification: 'Humanist sans', year: 1976 },
{ id: 'bell', name: 'Bell Centennial', classification: 'Utility sans', year: 1978 },
{ id: 'chicago', name: 'Chicago', classification: 'Bitmap sans', year: 1984 },
{ id: 'lucida', name: 'Lucida Grande', classification: 'Humanist sans', year: 1985 },
{ id: 'rotis', name: 'Rotis', classification: 'Semi-serif', year: 1988 },
{ id: 'minion', name: 'Minion', classification: 'Old-style serif', year: 1990 },
{ id: 'georgia', name: 'Georgia', classification: 'Transitional serif', year: 1993 },
{ id: 'verdana', name: 'Verdana', classification: 'Humanist sans', year: 1996 },
{ id: 'gotham', name: 'Gotham', classification: 'Geometric sans', year: 2000 },
{ id: 'source', name: 'Source Sans', classification: 'Humanist sans', year: 2012 },
{ id: 'inter', name: 'Inter', classification: 'Neo-grotesque', year: 2017 },
{ id: 'fraunces', name: 'Fraunces', classification: 'Display serif', year: 2020 },
]
const DEBOUNCE_MS = 200
/** Simulated backend search with realistic latency. */
function searchTypefaces(query: string): Promise<Typeface[]> {
const q = query.trim().toLowerCase()
const results = TYPEFACES.filter(
(t) => t.name.toLowerCase().includes(q) || t.classification.toLowerCase().includes(q),
)
const latency = 250 + Math.random() * 450
return new Promise((resolve) => {
window.setTimeout(() => resolve(results), latency)
})
}
export default function AsyncCombobox() {
const [query, setQuery] = useState('')
const [results, setResults] = useState<Typeface[]>([])
const [open, setOpen] = useState(false)
const [loading, setLoading] = useState(false)
const [activeIndex, setActiveIndex] = useState(-1)
const [selected, setSelected] = useState<Typeface | null>(null)
const listboxId = useId()
const inputRef = useRef<HTMLInputElement>(null)
// Monotonic sequence number: responses that arrive for an older query are dropped.
const requestSeq = useRef(0)
const debounceTimer = useRef(0)
useEffect(() => {
return () => window.clearTimeout(debounceTimer.current)
}, [])
const onQueryChange = (value: string) => {
setQuery(value)
window.clearTimeout(debounceTimer.current)
const seq = ++requestSeq.current
if (value.trim() === '') {
setResults([])
setOpen(false)
setLoading(false)
setActiveIndex(-1)
return
}
setLoading(true)
debounceTimer.current = window.setTimeout(() => {
void searchTypefaces(value).then((found) => {
if (seq !== requestSeq.current) return // stale response, a newer query is in flight
setResults(found)
setActiveIndex(-1)
setOpen(true)
setLoading(false)
})
}, DEBOUNCE_MS)
}
const select = (face: Typeface) => {
window.clearTimeout(debounceTimer.current)
requestSeq.current++ // invalidate any in-flight search so it can't reopen the list
setSelected(face)
setQuery('')
setOpen(false)
setLoading(false)
setActiveIndex(-1)
inputRef.current?.focus()
}
const onKeyDown = (e: React.KeyboardEvent) => {
if (e.key === 'ArrowDown') {
e.preventDefault()
if (!open && results.length > 0) setOpen(true)
setActiveIndex((i) => Math.min(i + 1, results.length - 1))
} else if (e.key === 'ArrowUp') {
e.preventDefault()
if (!open && results.length > 0) {
setOpen(true)
setActiveIndex(results.length - 1)
return
}
setActiveIndex((i) => Math.max(i - 1, 0))
} else if (e.key === 'Enter') {
e.preventDefault()
const face = results[activeIndex]
if (open && face) select(face)
} else if (e.key === 'Escape') {
e.preventDefault()
setOpen(false)
setActiveIndex(-1)
}
}
const activeId =
activeIndex >= 0 && results[activeIndex]
? `${listboxId}-opt-${results[activeIndex].id}`
: undefined
return (
<div
className="mx-auto w-md max-w-full"
onBlurCapture={(e) => {
if (!e.currentTarget.contains(e.relatedTarget)) setOpen(false)
}}
>
<label
htmlFor={`${listboxId}-input`}
className="mb-2 block font-mono text-[10px] tracking-[0.14em] text-(--color-fg-subtle) uppercase"
>
Find a typeface
</label>
<div className="relative">
<div className="flex items-center gap-3 rounded-(--radius-card) border border-(--color-border-strong) bg-(--color-surface) px-4 py-3">
<input
ref={inputRef}
id={`${listboxId}-input`}
role="combobox"
aria-expanded={open}
aria-autocomplete="list"
aria-controls={listboxId}
aria-activedescendant={activeId}
type="text"
placeholder="Try “grotesque” or “Frutiger”…"
value={query}
onChange={(e) => onQueryChange(e.target.value)}
onKeyDown={onKeyDown}
className="w-full bg-transparent text-sm text-(--color-fg) placeholder:text-(--color-fg-subtle) focus:outline-none"
/>
{loading ? (
<span
aria-hidden="true"
className="size-3.5 shrink-0 animate-spin rounded-full border border-(--color-fg-subtle) border-t-transparent motion-reduce:animate-none"
/>
) : null}
</div>
<ul
id={listboxId}
role="listbox"
aria-label="Typefaces"
hidden={!open}
className="scrollbar-thin absolute inset-x-0 top-full z-10 mt-2 max-h-64 overflow-y-auto rounded-(--radius-card) border border-(--color-border-strong) bg-(--color-surface) py-1"
>
{results.length === 0 ? (
<li className="px-4 py-3 font-mono text-xs text-(--color-fg-subtle)">
No typefaces match.
</li>
) : (
results.map((face, i) => (
<li
key={face.id}
id={`${listboxId}-opt-${face.id}`}
role="option"
aria-selected={i === activeIndex}
onMouseEnter={() => setActiveIndex(i)}
onMouseDown={(e) => e.preventDefault()}
onClick={() => select(face)}
className={`flex cursor-default items-baseline justify-between gap-4 px-4 py-2.5 text-sm ${
i === activeIndex
? 'bg-(--color-surface-hover) text-(--color-fg)'
: 'text-(--color-fg-muted)'
}`}
>
<span className="min-w-0 truncate">{face.name}</span>
<span className="shrink-0 font-mono text-[10px] whitespace-nowrap text-(--color-fg-subtle)">
{face.classification} · {face.year}
</span>
</li>
))
)}
</ul>
</div>
{/* Result counts are announced here so screen reader users hear what typing produced. */}
<div aria-live="polite" className="sr-only">
{loading
? 'Searching…'
: open
? `${results.length} ${results.length === 1 ? 'result' : 'results'} available.`
: ''}
</div>
<div className="mt-4 flex h-8 items-center">
{selected ? (
<span className="inline-flex items-center gap-2 rounded-full border border-(--color-border) bg-(--color-surface) py-1 pr-1.5 pl-3 text-sm text-(--color-fg)">
{selected.name}
<button
type="button"
onClick={() => setSelected(null)}
aria-label={`Remove ${selected.name}`}
className="rounded-full px-1.5 font-mono text-xs text-(--color-fg-subtle) transition-colors hover:text-(--color-fg)"
>
✕
</button>
</span>
) : (
<span className="font-mono text-[10px] text-(--color-fg-subtle)">
nothing selected yet
</span>
)}
</div>
</div>
)
}