<?php define("VERSION", "0.0.1");
/* --- FEEDS - EDIT AS NEEDED --- */


$feeds["OTW News"]       ["url"] = "https://www.transformativeworks.org/category/announcement/feed/";
$feeds["Dreamwidth News"]["url"] = "https://dw-news.dreamwidth.org/data/rss";

/* --- CONFIG - EDIT AS NEEDED --- */


/// Directory to store RSS cache.
///
/// Multiple instances can share one dir.
$config["cache_dir"] = "/tmp/rss_dot_php";


/// Custom CSS
$config["custom_css"] = <<<'EOC'

/* custom CSS goes here! */

EOC;


/// Document Language
$config["lang"] = "en";


/// Date Format
///
/// Displayed under every article, see
/// <https://www.php.net/manual/en/datetime.format.php>
/// for documentation.
$config["date_fmt"] = "l, M jS, Y, H:i T";


/// Timezone
///
/// A value of type DateTimeZone, see
/// <https://www.php.net/manual/en/class.datetimezone.php>
/// for documentation.
$config["timezone"] = new DateTimeZone('UTC');


/* --- CODE - DO NOT TOUCH --- */

function load_rss(string $uri, string $linkrel = "alternate"): array {
  global $config;

  $xml = file_get_contents($uri);

  // if the file doesn't contain an encoding, attempt to read it from http headers and re-encode
  if (!preg_match("/^[^>]+encoding/", $xml) && str_starts_with($uri, "http")) {
    foreach ($http_response_header as $header) {
      if (!str_starts_with(strtolower($header), "content-type")) continue;
      if (preg_match("/(?<=charset=)[a-z0-9_-]+/i", $header, $matches)) {
        $xml = iconv($matches[0], "UTF-8", $xml);
        $doc = new DOMDocument(encoding: "UTF-8");
      }
      break;
    }
  }

  $doc ??= new DOMDocument();
  $doc->loadXML($xml);

  if ($doc->documentElement->nodeName == "rss") {
    // TODO: better rss / atom sniffing
    foreach ($doc->getElementsByTagName("item") as $node) {
      $data["title"] = $node->getElementsByTagName("title")
                            ?->item(0)?->textContent;
      $data["link"] ??= $node->getElementsByTagName("link")
                             ?->item(0)?->textContent;

      $data["date"] = new DateTime($node->getElementsByTagName("pubDate")
                                        ->item(0)->textContent);
      $data["date"]->setTimezone($config["timezone"]);

      $parsed[] = $data;
    }
  } else {
    // assume atom
    foreach ($doc->getElementsByTagName("entry") as $node) {
      $data["title"] = $node->getElementsByTagName("title")
                          ?->item(0)?->textContent;
      $data["links"] = [];
      foreach ($node->getElementsByTagName("link")->getIterator() as $link) {
        $date["links"][] = ["rel" => $link->getAttribute("rel"),
                          "href" => $link->getAttribute("href")];
        if ($link->getAttribute("rel") === $linkrel) {
          $data["link"] ??= $link->getAttribute("href");
        }
      }
      $data["link"] ??= @$data["links"][0];

      $data["date"] = $node->getElementsByTagName("published")
                           ?->item(0)?->textContent;
      $data["date"] ??= $node->getElementsByTagName("updated")
                             ?->item(0)?->textContent;
      $data["date"] = new DateTime($data["date"]);
      $data["date"]->setTimezone($config["timezone"]);

      $parsed[] = $data;
    }
  }

  return $parsed??[];
}

function load_cached(int $ttl, string $uri, string $linkrel = "alternate"): array {
  global $config;
  $path = $config["cache_dir"]."/".md5($uri);
//  echo $path."\n";
  if ((@filemtime($path) ?? 0) + $ttl < time()) {
//    echo "cache miss, loading over network\n";
    $data = load_rss($uri, $linkrel);
    file_put_contents($path, serialize($data));
    return $data;
  } else {
//    echo "cache hit, loading from file\n";
    return unserialize(file_get_contents($path));
  }
}

@mkdir($config["cache_dir"], recursive: true);

foreach ($_GET["disabled"]??[] as $idx => $feed) {
  if (!array_key_exists($feed, $feeds)) {
    unset($_GET["disabled"][$idx]);
    continue;
  }
  $off_feeds[$feed] = @$feeds[$feed];
  unset($feeds[$feed]);
}

$combined = [];
// Real Feed Processing Happens Here
foreach ($feeds as $name => $data) {
  if (!isset($data["url"])) {
    error_log("Feed \"$name\" missing url. Ignoring.");
    continue;
  }
  if (!isset($data["ttl"])) $data["ttl"] = 3600;
  if (!isset($data["linkrel"])) $data["linkrel"] = "alternate";

  foreach(load_cached($data["ttl"], $data["url"], $data["linkrel"]) as $entry) {
    $entry["source"] = $name;
    $combined[] = $entry;
  }
}

// reverse-chronological by default
usort($combined, fn($a, $b) => $b["date"]->getTimestamp() <=> $a["date"]->getTimestamp());

if (isset($_GET["reverse"]))
  $combined = array_reverse($combined);

$base = parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH);

?>
<!doctype html>
<html lang="<?= $config['lang'] ?>">
<head>
  <meta charset="utf-8">
  <style><?= $config['custom_css'] ?></style>
</head>
<body>
  <nav>
    <div>
      <b>Toggle Feeds</b>:
<?php foreach ($feeds??[] as $name => $data):
  $query = $_GET;
  $query["disabled"][] = $name;
  $uri = $base."?".http_build_query($query);
?>
        <span class="source" data-source="<?= htmlentities($name) ?>">
          <a href="<?= htmlentities($uri) ?>"><?= htmlentities($name) ?></a>
        </span>
<?php endforeach; ?>
<?php foreach ($off_feeds??[] as $name => $data):
  $query = $_GET;
  $query["disabled"] = array_filter($query["disabled"], fn($x) => $x !== $name);
  $uri = $base."?".http_build_query($query);
?>
        <span class="source disabled" data-source="<?= htmlentities($name) ?>">
          <a href="<?= htmlentities($uri) ?>"><?= htmlentities($name) ?></a>
        </span>
<?php endforeach; ?>
    </div>
  </nav>
  <main>
<?php if (!count($combined) && isset($_GET['disabled'])): ?>
<h1>Looks like you filtered out everything...</h1>
<p>Try unfiltering some feeds!</p>
<?php endif;
      foreach ($combined as $entry): ?>
    <article>
      <h1><a href="<?= htmlentities($entry['link']) ?>"><?= htmlentities($entry['title'] ?? "[[[No Title]]]") ?></a></h1>
      <span class="source" data-source="<?= htmlentities($entry['source']) ?>"><?= htmlentities($entry['source']) ?></span>
      &bullet;
      <time datetime="<?= htmlentities($entry['date']->format(DateTime::ISO8601)) ?>">
        <?= htmlentities($entry['date']->format($config['date_fmt'])) ?>
      </time>
    </article>
<?php endforeach; ?>
  </main>
  <!-- generated by rss_dot_php <?= VERSION ?>
       https://git.aleteoryx.me/cgit/rss_dot_php -->
</body>
</html>