// One event's public page (EVENTS.md § API surface, Phase 14a).
//
// The storyline, its arc, what is live, what is next, what happened recently,
// and a results table once an occurrence has published one.
//
// **`?run=` is read from the URL and passed straight through**, because that is
// what an announcement's link carries. The page lives at the definition's slug —
// one stable address, so a link posted in Discord survives a retitle — and the
// occurrence has to be in the query string or a mail about last Friday's
// invasion would open next Friday's.
//
// **The error is checked before the form.** Phase 13 found the inverse of this
// on the admin editor: `if (loading || !form) return <Loading/>` above the error
// branch left a failed load spinning for ever with nothing on screen naming the
// problem. Order matters, and the order is error first.

import { useParams, useSearchParams, Link } from 'react-router-dom'
import PublicLayout from '../../components/PublicLayout.jsx'
import PageHeader from '../../components/PageHeader.jsx'
import { Loading, ErrorState, EmptyState } from '../../components/PageState.jsx'
import { useAsync } from '../../lib/useAsync.js'
import { api } from '../../api/client.js'
import { eventDateTime, statusWord } from '../../lib/eventCalendar.js'

export default function EventPage() {
  const { slug } = useParams()
  const [params] = useSearchParams()
  const run = params.get('run')
  const { loading, error, data } = useAsync(() => api.publicEvent(slug, run), [slug, run])

  if (error) {
    return (
      <PublicLayout section="website">
        <div className="shell-mid page-body">
          <ErrorState message="That event could not be found." />
          <p style={{ marginTop: 16 }}>
            <Link to="/site/events">Back to the calendar</Link>
          </p>
        </div>
      </PublicLayout>
    )
  }
  if (loading || !data) {
    return (
      <PublicLayout section="website">
        <div className="shell-mid page-body">
          <Loading />
        </div>
      </PublicLayout>
    )
  }

  const event = data.event
  const headline = event.current || event.next

  return (
    <PublicLayout section="website">
      <div className="shell-mid page-body">
        <PageHeader
          eyebrow={event.series ? event.series.name : 'Event'}
          title={event.title}
          lead={event.summary || ''}
        />

        {event.series && (
          <p className="sans" style={{ marginTop: -12 }}>
            <Link to={`/site/events/series/${event.series.slug}`}>Part of {event.series.name}</Link>
          </p>
        )}

        {/* The one fact a visitor came for, before the storyline rather than
            after it: whether it is happening now, and if not, when it next is. */}
        <div
          className="panel"
          style={{
            padding: '18px 22px',
            marginBottom: 24,
            borderColor: event.live ? '#8fc79a' : undefined,
          }}
        >
          {event.live ? (
            <>
              <div
                className="sans"
                style={{ color: '#8fc79a', fontWeight: 700, letterSpacing: '0.06em', textTransform: 'uppercase', fontSize: '0.74rem' }}
              >
                Happening now
              </div>
              <div style={{ marginTop: 6, color: 'var(--head)', fontSize: '1.1rem' }}>
                {/* The phase LABEL, and only while it is live. The plan behind
                    the event is never published. */}
                {event.current.phase || 'Under way'}
              </div>
            </>
          ) : event.next ? (
            <>
              <div className="sans dim" style={{ letterSpacing: '0.06em', textTransform: 'uppercase', fontSize: '0.74rem' }}>
                Next
              </div>
              <div style={{ marginTop: 6, color: 'var(--head)', fontSize: '1.1rem' }}>
                {eventDateTime(event.next.scheduledFor, event.next.timezone)}
              </div>
            </>
          ) : (
            <div className="dim">Nothing scheduled at the moment.</div>
          )}
        </div>

        {event.body && (
          <article
            className="panel"
            style={{ padding: 28, marginBottom: 24 }}
            // Sanitized on write, the treatment a wiki page and a forum post get.
            dangerouslySetInnerHTML={{ __html: event.body }}
          />
        )}

        {event.results && (
          <section style={{ marginBottom: 24 }}>
            <h2 className="display" style={{ fontSize: '1.3rem', color: 'var(--head)' }}>
              Results
            </h2>
            <p className="dim sans" style={{ marginTop: -6, fontSize: '0.85rem' }}>
              {eventDateTime(event.results.scheduledFor, event.timezone)}
            </p>
            {event.results.participants.length === 0 ? (
              <EmptyState>Results were published with nobody recorded.</EmptyState>
            ) : (
              <table className="table" style={{ width: '100%' }}>
                <thead>
                  <tr>
                    <th style={{ width: 60 }}>#</th>
                    <th>Who</th>
                    <th style={{ width: 120, textAlign: 'right' }}>Score</th>
                  </tr>
                </thead>
                <tbody>
                  {event.results.participants.map((p, i) => (
                    <tr key={`${p.name || 'anon'}-${i}`}>
                      <td>{p.rank ?? '—'}</td>
                      {/* A module supplies a display name in `meta` or it does
                          not; the member key is never published, so there is
                          genuinely nothing else to render. */}
                      <td>{p.name || <span className="dim">Unnamed</span>}</td>
                      <td style={{ textAlign: 'right' }}>{p.score}</td>
                    </tr>
                  ))}
                </tbody>
              </table>
            )}
          </section>
        )}

        <Occurrences title="Coming up" list={event.upcoming} slug={event.slug} timezone={event.timezone} />
        <Occurrences title="Previously" list={event.past} slug={event.slug} timezone={event.timezone} past />

        {!headline && event.past.length === 0 && (
          <EmptyState>This event has not been scheduled yet.</EmptyState>
        )}
      </div>
    </PublicLayout>
  )
}

function Occurrences({ title, list, slug, timezone, past = false }) {
  if (!list || list.length === 0) return null
  return (
    <section style={{ marginBottom: 24 }}>
      <h2 className="display" style={{ fontSize: '1.3rem', color: 'var(--head)' }}>
        {title}
      </h2>
      <ul style={{ listStyle: 'none', padding: 0, margin: 0, display: 'flex', flexDirection: 'column', gap: 8 }}>
        {list.map((o) => (
          <li key={o.runId} className="panel" style={{ padding: '12px 18px', display: 'flex', gap: 16, flexWrap: 'wrap' }}>
            <span style={{ flex: 1, minWidth: 220 }}>{eventDateTime(o.scheduledFor, o.timezone || timezone)}</span>
            <span className="dim sans" style={{ fontSize: '0.78rem' }}>{statusWord(o.status, o.scheduledFor)}</span>
            {/* Only a past occurrence gets its own link, and only when it has
                results: on any other, `?run=` would change nothing a reader
                could see. */}
            {past && o.resultsPublishedAt && (
              <Link className="sans" style={{ fontSize: '0.78rem' }} to={`/site/events/${slug}?run=${o.runId}`}>
                Results
              </Link>
            )}
          </li>
        ))}
      </ul>
    </section>
  )
}