Transit Departures

'use client'

import { useEffect, useState } from 'react'
import './transit-departures.css'

export interface Departure { id: string; line: string; to: string; in: number; delay?: number; platform?: string }

export interface TransitDeparturesProps {
  departures: Departure[]
  stop?: string
  show?: 'min' | 'clock'
  now?: number
  fill?: 'dark' | 'light'
  className?: string
}

/** Live departure board with countdown and line filter. */
export function TransitDepartures({ departures, stop = 'Central Station', show = 'min', now = Date.now(), fill = 'dark', className }: TransitDeparturesProps) {
  const [left, setLeft] = useState(() => Object.fromEntries(departures.map((d) => [d.id, d.in])))
  const [line, setLine] = useState<string | null>(null)
  const [fav, setFav] = useState(false)
  const [t, setT] = useState(0)
  useEffect(() => { const i = setInterval(() => { setT((x) => x + 1); setLeft((l) => Object.fromEntries(Object.entries(l).map(([k, v]) => [k, v - 1]))) }, 1000); return () => clearInterval(i) }, [])
  const lines = Array.from(new Set(departures.map((d) => d.line)))
  const rows = departures.filter((d) => left[d.id] > -4 && (!line || d.line === line)).sort((a, b) => left[a.id] - left[b.id]).slice(0, 6)
  const clock = (s: number) => new Date(now + (t + s) * 1000).toLocaleTimeString('en-GB', { hour: '2-digit', minute: '2-digit' })
  return (
    <div className={['sd-trn', className].filter(Boolean).join(' ')} data-fill={fill}>
      <div className="sd-trn__h">
        <div><b>{stop}</b><small>Departures · {clock(0)}</small></div>
        <button type="button" className="sd-trn__star" aria-pressed={fav} aria-label={fav ? 'Remove from favourites' : 'Add to favourites'} onClick={() => setFav(!fav)}>
          <svg viewBox="0 0 20 20" aria-hidden><path d="m10 2.5 2.3 4.8 5.2.6-3.8 3.6 1 5.2L10 14.2l-4.7 2.5 1-5.2-3.8-3.6 5.2-.6z" /></svg>
        </button>
      </div>
      <div className="sd-trn__chips" role="group" aria-label="Lines">
        <button type="button" aria-pressed={!line} onClick={() => setLine(null)}>All</button>
        {lines.map((l) => <button key={l} type="button" aria-pressed={line === l} onClick={() => setLine(line === l ? null : l)}>{l}</button>)}
      </div>
      <ul className="sd-trn__list" aria-label="Next departures">
        {rows.map((d) => {
          const s = left[d.id], due = s <= 30, m = Math.max(0, Math.ceil(s / 60))
          return (
            <li key={d.id} className="sd-trn__r" data-gone={s <= 0 || undefined} aria-label={`Line ${d.line} to ${d.to}, ${due ? 'due' : `${m} minutes`}`}>
              <span className="sd-trn__ln" data-o={/^\d/.test(d.line) || undefined} aria-hidden>{d.line}</span>
              <span className="sd-trn__d">{d.to}<small>{d.delay ? <><s>{clock(s - d.delay)}</s> {clock(s)} · +{Math.round(d.delay / 60)} min</> : <>{d.platform ? `Platform ${d.platform}` : 'On time'}</>}</small></span>
              <span className="sd-trn__m" data-due={due || undefined} aria-hidden>{due ? 'Due' : show === 'clock' ? clock(s) : <>{m}<small>min</small></>}</span>
            </li>
          )
        })}
        {!rows.length && <li className="sd-trn__none">No more departures on this line</li>}
      </ul>
    </div>
  )
}

.sd-trn { --bg: #1c1c1c; --fg: #f6f6f6; --mute: #8e8e8e; --line: rgb(255 255 255 / 0.1); --soft: rgb(255 255 255 / 0.07); --strong: #fafafa; --on: #111; 
  color: var(--fg); font-size: 14px; line-height: 1.4; -webkit-tap-highlight-color: transparent; }
.sd-trn[data-fill='light'] { --bg: #fff; --fg: #121212; --mute: #6f6f6f; --line: rgb(0 0 0 / 0.09); --soft: rgb(0 0 0 / 0.05); --strong: #111; --on: #fff; }
.sd-trn :where(button) { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
.sd-trn :focus-visible { outline: 2px solid var(--fg); outline-offset: 2px; }
.sd-trn .sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
.sd-trn { width: min(100%, 330px); border-radius: 20px; background: var(--bg); box-shadow: inset 0 0 0 1px var(--line); overflow: hidden; }
.sd-trn__h { display: flex; align-items: center; gap: 10px; padding: 14px 14px 10px 16px; }
.sd-trn__h div { flex: 1; min-width: 0; }
.sd-trn__h b { display: block; font-size: 15px; }
.sd-trn__h small { font-size: 12px; color: var(--mute); font-variant-numeric: tabular-nums; }
.sd-trn__star { display: grid; place-items: center; width: 34px; height: 34px; border-radius: 10px; }
.sd-trn__star:hover { background: var(--soft); }
.sd-trn__star svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linejoin: round; transition: transform 220ms cubic-bezier(0.3, 1.8, 0.4, 1); }
.sd-trn__star[aria-pressed='true'] svg { fill: currentColor; transform: scale(1.12); }
.sd-trn__chips { display: flex; gap: 6px; padding: 0 14px 10px; }
.sd-trn__chips button { min-width: 32px; height: 28px; padding: 0 10px; border-radius: 8px; font-size: 12.5px; font-weight: 700; box-shadow: inset 0 0 0 1px var(--line); color: var(--mute) !important; }
.sd-trn__chips button[aria-pressed='true'] { background: var(--strong) !important; color: var(--on) !important; box-shadow: none; }
.sd-trn__list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); min-height: 260px; }
.sd-trn__r { display: grid; grid-template-columns: 34px 1fr auto; align-items: center; gap: 12px; padding: 11px 16px; border-bottom: 1px solid var(--line); animation: sd-trn-in 300ms ease-out; }
.sd-trn__r[data-gone] { animation: sd-trn-out 400ms ease-in forwards; }
.sd-trn__ln { display: grid; place-items: center; height: 26px; border-radius: 7px; background: var(--strong); color: var(--on); font-size: 13px; font-weight: 800; }
.sd-trn__ln[data-o] { background: transparent; color: var(--fg); box-shadow: inset 0 0 0 1.5px var(--fg); }
.sd-trn__d { min-width: 0; font-size: 14px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.sd-trn__d small { display: block; font-size: 12px; color: var(--mute); }
.sd-trn__d s { color: var(--mute); }
.sd-trn__m { text-align: right; font-size: 18px; font-weight: 700; font-variant-numeric: tabular-nums; }
.sd-trn__m small { font-size: 11px; font-weight: 500; color: var(--mute); margin-left: 2px; }
.sd-trn__m[data-due] { animation: sd-trn-blink 900ms steps(2, start) 2; font-size: 14px; }
.sd-trn__none { padding: 40px; text-align: center; color: var(--mute); font-size: 13px; }
@keyframes sd-trn-in { from { opacity: 0; transform: translateY(6px); } }
@keyframes sd-trn-out { to { opacity: 0; transform: translateX(-30px); } }
@keyframes sd-trn-blink { to { opacity: 0.2; } }
@media (prefers-reduced-motion: reduce) { .sd-trn *, .sd-trn *::before, .sd-trn *::after { animation: none !important; transition: none !important; } }