radio-free-elsewhere/includes/broadcasts.php

<?php
// Broadcast and track-history logic shared by the poller, the CLI tools and the live page.

if (basename($_SERVER['SCRIPT_FILENAME'] ?? '') === basename(__FILE__)) {
    http_response_code(403);
    exit;
}

require_once __DIR__ . '/icecast.php';

// A live broadcast not seen for this long is considered ended (covers brief encoder drop-outs)
const BROADCAST_GRACE_MINUTES = 5;
// Tracks are cleared this long after their broadcast ends
const TRACK_RETENTION_MINUTES = 10;
// Show times are entered and displayed in the station's time zone; the database stores UTC
const STATION_TIMEZONE = 'America/New_York';
const STATION_TIMEZONE_LABEL = 'Eastern';

// A broadcast unseen for longer than the grace period is treated as over even before the poller marks it
// ended, so a stopped poller or a long status API outage can't leave a show showing as live.
function liveBroadcast(PDO $db): ?array {
    $row = $db->query(
        'SELECT * FROM broadcasts
         WHERE started_at IS NOT NULL AND ended_at IS NULL
           AND last_seen_at >= NOW() - INTERVAL ' . BROADCAST_GRACE_MINUTES . ' MINUTE
         ORDER BY started_at DESC LIMIT 1'
    )->fetch();
    return $row ?: null;
}

function pendingBroadcast(PDO $db): ?array {
    $row = $db->query(
        'SELECT * FROM broadcasts
         WHERE started_at IS NULL AND ended_at IS NULL
         ORDER BY created_at DESC LIMIT 1'
    )->fetch();
    return $row ?: null;
}

// The show for the live broadcast, or the queued one if nothing is live yet,
// with the broadcast's scheduled_at and started_at. Stale broadcasts are skipped as in liveBroadcast().
function currentShow(PDO $db): ?array {
    $row = $db->query(
        'SELECT s.*, b.scheduled_at, b.started_at FROM broadcasts b
         JOIN shows s ON s.id = b.show_id
         WHERE b.ended_at IS NULL
           AND (b.started_at IS NULL OR b.last_seen_at >= NOW() - INTERVAL ' . BROADCAST_GRACE_MINUTES . ' MINUTE)
         ORDER BY b.started_at IS NULL, b.started_at DESC, b.created_at DESC
         LIMIT 1'
    )->fetch();
    return $row ?: null;
}

// Converts a 'YYYY-MM-DD HH:MM' station time to a UTC DATETIME string, or null if it isn't a valid time
function stationTimeToUtc(string $local): ?string {
    $dt = DateTimeImmutable::createFromFormat('!Y-m-d H:i', $local, new DateTimeZone(STATION_TIMEZONE));
    // Reformatting catches overflowing dates (Feb 30) and times skipped by the DST change
    if ($dt === false || $dt->format('Y-m-d H:i') !== $local) return null;
    return $dt->setTimezone(new DateTimeZone('UTC'))->format('Y-m-d H:i:s');
}

function utcToStationTime(string $utc): DateTimeImmutable {
    return (new DateTimeImmutable($utc, new DateTimeZone('UTC')))->setTimezone(new DateTimeZone(STATION_TIMEZONE));
}

// Assigns a show to the live broadcast, or queues it for the next one if nothing is live.
// $scheduledAt (UTC) is the advertised start time of a queued show. Returns 'live' or 'queued'.
function setBroadcastShow(PDO $db, int $showId, ?string $scheduledAt = null): string {
    $live = liveBroadcast($db);
    if ($live !== null) {
        $db->prepare('UPDATE broadcasts SET show_id = ? WHERE id = ?')->execute([$showId, $live['id']]);
        return 'live';
    }
    clearQueuedShow($db);
    $db->prepare('INSERT INTO broadcasts (show_id, scheduled_at) VALUES (?, ?)')->execute([$showId, $scheduledAt]);
    return 'queued';
}

function clearQueuedShow(PDO $db): void {
    $db->exec('DELETE FROM broadcasts WHERE started_at IS NULL');
}

// Tracks from the most recent broadcast that has started, newest first
function recentTracks(PDO $db, int $limit = 100): array {
    $stmt = $db->prepare(
        'SELECT * FROM played_tracks
         WHERE broadcast_id = (SELECT id FROM broadcasts WHERE started_at IS NOT NULL ORDER BY started_at DESC LIMIT 1)
         ORDER BY played_at DESC, id DESC
         LIMIT ?'
    );
    $stmt->bindValue(1, $limit, PDO::PARAM_INT);
    $stmt->execute();
    return $stmt->fetchAll();
}

// Record one poll of the Icecast status. $track is the result of fetchCurrentTrack(): an array while
// streaming or null when offline. (Don't call this when the status API was unreachable.)
function recordPoll(PDO $db, ?array $track): void {
    $db->exec(
        'UPDATE broadcasts SET ended_at = last_seen_at
         WHERE started_at IS NOT NULL AND ended_at IS NULL
           AND last_seen_at < NOW() - INTERVAL ' . BROADCAST_GRACE_MINUTES . ' MINUTE'
    );
    $db->exec(
        'DELETE pt FROM played_tracks pt
         JOIN broadcasts b ON b.id = pt.broadcast_id
         WHERE b.ended_at < NOW() - INTERVAL ' . TRACK_RETENTION_MINUTES . ' MINUTE'
    );

    if ($track === null) return;

    $broadcast = liveBroadcast($db);
    if ($broadcast !== null) {
        $db->prepare('UPDATE broadcasts SET last_seen_at = NOW() WHERE id = ?')->execute([$broadcast['id']]);
        $broadcastId = (int)$broadcast['id'];
    } elseif (($pending = pendingBroadcast($db)) !== null) {
        $db->prepare('UPDATE broadcasts SET started_at = NOW(), last_seen_at = NOW() WHERE id = ?')->execute([$pending['id']]);
        $broadcastId = (int)$pending['id'];
    } else {
        // Nobody queued a show; record the broadcast anyway so track history still works
        $db->exec('INSERT INTO broadcasts (started_at, last_seen_at) VALUES (NOW(), NOW())');
        $broadcastId = (int)$db->lastInsertId();
    }

    if ($track['title'] === '') return;

    $stmt = $db->prepare('SELECT title, artist, album FROM played_tracks WHERE broadcast_id = ? ORDER BY played_at DESC, id DESC LIMIT 1');
    $stmt->execute([$broadcastId]);
    $last = $stmt->fetch();
    if ($last && $last['title'] === $track['title'] && $last['artist'] === $track['artist'] && $last['album'] === $track['album']) {
        return;
    }

    $db->prepare('INSERT INTO played_tracks (broadcast_id, title, artist, album, art_url) VALUES (?, ?, ?, ?, ?)')
       ->execute([
           $broadcastId,
           mb_substr($track['title'], 0, 255),
           mb_substr($track['artist'], 0, 255),
           mb_substr($track['album'], 0, 255),
           lookupAlbumArt($track['artist'], $track['album']),
       ]);
}