rss_generator.php

<?php

// Set the content-type to XML
header("Content-Type: application/rss+xml; charset=UTF-8");

function extractValueFromPattern($filename, $pattern) {
    $markdownContent = file_get_contents("pages/posts/" . $filename . ".html");
    if (preg_match($pattern, $markdownContent, $matches)) {
        return trim($matches[1]);
    }
    return null;
}

// Function to get MIME type from file extension
function getMimeType($url) {
    $path = parse_url($url, PHP_URL_PATH); // strips query string and fragment
    $extension = strtolower(pathinfo($path, PATHINFO_EXTENSION));
    $mimeTypes = [
        'jpg'  => 'image/jpeg',
        'jpeg' => 'image/jpeg',
        'png'  => 'image/png',
        'gif'  => 'image/gif',
        'webp' => 'image/webp',
        // Add more extensions and MIME types as needed
    ];
    return $mimeTypes[$extension] ?? 'application/octet-stream';
}

// Define patterns for the metadata you want to extract
$patterns = [
    'pagetitle'   => '/<!--\s+pagetitle:(.*?)\s+-->/s',
    'pagedate'    => '/<!--\s+pagedate:(.*?)\s+-->/s',
    'pageexcerpt' => '/<!--\s+pageexcerpt:(.*?)\s+-->/s',
    'pageimage'   => '/<!--\s+pageimage:(.*?)\s+-->/s', // Image pattern
    'pagecategory' => '/<!--\s+pagecategory:(.*?)\s+-->/s' // Optional comma-separated categories. Untagged posts count as "uncategorized".
];

/* CATEGORY FEEDS */
// The ?rss parameter doubles as the category selector:
//   ?rss                  -> all posts (unchanged, backward compatible)
//   ?rss=all              -> all posts (explicit)
//   ?rss=tutorials        -> only posts in the "tutorials" category
//   ?rss=tutorials,seo    -> posts in ANY of the listed categories
//   ?rss=uncategorized    -> only posts with no pagecategory tag
// This works because index.php handles ?rss before top-cache.php is included,
// so RSS requests never touch the cache and query strings are safe here.
$rssFilterCategories = [];
if (!empty($_GET['rss']) && strtolower(trim($_GET['rss'])) !== 'all') {
    foreach (explode(',', $_GET['rss']) as $cat) {
        $cat = strtolower(trim($cat));
        // Same slug rules as category pages; also drops anything weird from the query string.
        if ($cat !== '' && preg_match('/^[a-z0-9\-]+$/', $cat)) {
            $rssFilterCategories[] = $cat;
        }
    }
}

// Site information
$siteTitle       = $WebsiteTitle;
$siteLink        = $WebsiteURL;
$siteDescription = $WebsiteDescription;
$defaultImage    = $WebsiteImage; // Default image URL

// Filtered feeds get the category name(s) in the channel title so subscribers
// can tell their feeds apart (e.g. "My Site – Tutorials").
if (!empty($rssFilterCategories)) {
    $prettyNames = array_map(function ($cat) {
        return ucwords(str_replace('-', ' ', $cat));
    }, $rssFilterCategories);
    $siteTitle .= ' – ' . implode(', ', $prettyNames);
}

// Initialize the RSS feed
echo '<?xml version="1.0" encoding="UTF-8" ?>' . "\n";
echo '<rss version="2.0">' . "\n";
echo '<channel>' . "\n";
echo '<title>' . htmlspecialchars($siteTitle) . '</title>' . "\n";
echo '<link>' . htmlspecialchars($siteLink) . '</link>' . "\n";
echo '<description>' . htmlspecialchars($siteDescription) . '</description>' . "\n";
echo '<language>en-us</language>' . "\n";

// Channel-wide image
echo '<image>' . "\n";
echo '<url>' . htmlspecialchars($WebsiteImage) . '</url>' . "\n";
echo '<title>' . htmlspecialchars($siteTitle) . '</title>' . "\n";
echo '<link>' . htmlspecialchars($siteLink) . '</link>' . "\n";
echo '</image>' . "\n";

// Collect all items
$items = [];
$postsDir = __DIR__ . '/pages/posts';

foreach (new DirectoryIterator($postsDir) as $fileInfo) {
    if ($fileInfo->isDot() || $fileInfo->getExtension() !== 'html') continue;

    $filename = $fileInfo->getBasename('.html');
    $pageData = [];

    // Extract metadata using the patterns
    foreach ($patterns as $variableName => $pattern) {
        $pageData[$variableName] = extractValueFromPattern($filename, $pattern);
    }

    if (empty($pageData['pagetitle']) || empty($pageData['pagedate'])) continue;

    // Parse the post's categories. Optional — untagged posts are "uncategorized".
    // Same parsing rules as the postarchives layouts.
    $postCategories = [];
    if (!empty($pageData['pagecategory'])) {
        foreach (explode(',', $pageData['pagecategory']) as $cat) {
            $cat = strtolower(trim($cat));
            if ($cat !== '') { $postCategories[] = $cat; }
        }
    }
    if (empty($postCategories)) { $postCategories = ['uncategorized']; }

    // Apply the category filter: keep the post if it's in ANY requested category.
    if (!empty($rssFilterCategories) && !array_intersect($rssFilterCategories, $postCategories)) continue;

    $url      = $siteLink . '/posts/' . $filename;
    $pubDate  = strtotime($pageData['pagedate']); // Use timestamp for sorting
    $imageUrl = !empty($pageData['pageimage']) ? $siteLink . '/' . $pageData['pageimage'] : $defaultImage;
    $mimeType = getMimeType($imageUrl);

    // Add the item to the array
    $items[] = [
        'title'       => htmlspecialchars($pageData['pagetitle']),
        'link'        => htmlspecialchars($url),
        'description' => htmlspecialchars($pageData['pageexcerpt']),
        'enclosure'   => '<enclosure url="' . htmlspecialchars($imageUrl) . '" type="' . htmlspecialchars($mimeType) . '" length="0" />',
        'pubDate'     => date(DATE_RSS, $pubDate),
        'timestamp'   => $pubDate // Store timestamp for sorting
    ];
}

// Sort items by date, latest first
usort($items, function($a, $b) {
    return $b['timestamp'] - $a['timestamp'];
});

// Output sorted items
foreach ($items as $item) {
    echo '<item>' . "\n";
    echo '<title>' . $item['title'] . '</title>' . "\n";
    echo '<link>' . $item['link'] . '</link>' . "\n";
    echo '<description>' . $item['description'] . '</description>' . "\n";
    echo $item['enclosure'] . "\n";
    echo '<pubDate>' . $item['pubDate'] . '</pubDate>' . "\n";
    echo '</item>' . "\n";
}

echo '</channel>' . "\n";
echo '</rss>' . "\n";
?>