// The public event calendar (EVENTS.md §I, Phase 14a).
//
// **A list, not a month grid.** The admin calendar draws a grid because an
// operator's question is "what does this month look like" — coverage, clashes,
// the gap on the third weekend. A visitor's question is "what is on, and when is
// the next one", which a chronological list answers in one glance and a grid
// answers by making them count squares. Same data, different question.
//
// **A projection is drawn differently from a run, and the reason is the
// operator's reason one tier along.** Past the materialisation horizon there is
// no row: nothing is committed to, nothing can be cancelled, and a forecast
// rendered identically to a booking would be the page promising something the
// server has not. It is dashed and labelled "expected".
//
// The date heading is the READER's day and the time beside each entry is the
// EVENT's own zone. That split is §I's: the shard's evening is what "8pm" means
// to everyone reading it, but "this month" is the month the reader is living in.

import { 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 { eventTime, readerDayLabel, statusWord } from '../../lib/eventCalendar.js'

export default function Events() {
  const { loading, error, data } = useAsync(() => api.publicEvents())
  const entries = data?.entries || []

  // Grouped by the reader's own day, in order. The server already sorted by
  // instant, so this preserves that order rather than re-sorting.
  const days = []
  for (const entry of entries) {
    const label = readerDayLabel(entry.scheduledFor)
    const last = days[days.length - 1]
    if (last && last.label === label) last.entries.push(entry)
    else days.push({ label, entries: [entry] })
  }

  return (
    <PublicLayout section="website">
      <div className="shell-mid page-body">
        <PageHeader
          eyebrow="What's on"
          title="Events"
          lead="Everything scheduled, live and recently finished. Times are shown in the shard's own timezone."
        />
        <section style={{ display: 'flex', flexDirection: 'column', gap: 28 }}>
          {loading && <Loading />}
          {error && <ErrorState message="Could not load the calendar right now." />}
          {!loading && !error && entries.length === 0 && (
            <EmptyState>Nothing on the calendar just yet — check back soon.</EmptyState>
          )}
          {days.map((day) => (
            <div key={day.label}>
              <h2
                className="sans"
                style={{
                  margin: '0 0 12px',
                  fontSize: '0.74rem',
                  letterSpacing: '0.08em',
                  textTransform: 'uppercase',
                  color: 'var(--muted)',
                }}
              >
                {day.label}
              </h2>
              <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
                {day.entries.map((entry) => (
                  <EventRow key={`${entry.slug}-${entry.scheduledFor}-${entry.kind}`} entry={entry} />
                ))}
              </div>
            </div>
          ))}
        </section>
      </div>
    </PublicLayout>
  )
}

function EventRow({ entry }) {
  const projected = entry.kind === 'projected'
  const body = (
    <div
      className="panel"
      style={{
        padding: '16px 20px',
        display: 'flex',
        alignItems: 'baseline',
        gap: 16,
        flexWrap: 'wrap',
        // The whole visual difference between a booking and a forecast, and it
        // is deliberately not subtle.
        borderStyle: projected ? 'dashed' : undefined,
        opacity: projected ? 0.72 : 1,
      }}
    >
      <span className="sans" style={{ fontWeight: 700, color: 'var(--accent)', minWidth: 96 }}>
        {eventTime(entry.scheduledFor, entry.timezone)}
      </span>
      <span style={{ flex: 1, minWidth: 200 }}>
        <span className="display" style={{ fontSize: '1.15rem', color: 'var(--head)' }}>
          {entry.title}
        </span>
        {entry.seriesName && (
          <span className="dim" style={{ marginLeft: 10, fontSize: '0.9rem' }}>
            {entry.seriesName}
          </span>
        )}
      </span>
      <span
        className="sans"
        style={{
          fontSize: '0.72rem',
          letterSpacing: '0.06em',
          textTransform: 'uppercase',
          color: entry.live ? '#8fc79a' : 'var(--muted)',
          fontWeight: entry.live ? 700 : 400,
        }}
      >
        {projected ? 'Expected' : statusWord(entry.status, entry.scheduledFor)}
      </span>
    </div>
  )

  // A projection has no page of its own worth linking to any differently — the
  // event page IS the definition's — so both link to the same place. It is the
  // OCCURRENCE that does not exist yet, not the event.
  return <Link to={`/site/events/${entry.slug}`} style={{ textDecoration: 'none' }}>{body}</Link>
}