hnreplies.php

<?php
# Call this script with the query parameter of your ID.
# So hnreplies.php?id=tn1

# Download from: https://sourceforge.net/projects/simplehtmldom/
include_once 'simplehtmldom/simple_html_dom.php';
include_once 'simplehtmldom/HtmlWeb.php';

$n = new simplehtmldom\HtmlWeb();
$url = "https://news.ycombinator.com/threads?id=" . $_GET['id'];
$doc = $n->load($url);

$items = [];

foreach ($doc->find(".athing") as $row) {
    if (!$row->find(".storyon a", 0)) {
        // find my comment
        $mycomment = $row->previousSibling();
        $depth = 1;
        while (!$mycomment->find(".storyon a", 0)) {
            $mycomment = $mycomment->previousSibling();
            $depth++;
        }

        $description = $row->find(".commtext", 0)->innertext;
        $description .= '<hr /><a href="';
        $description .= getAbsoluteUrl("https://news.ycombinator.com/", $mycomment->find(".age a", 0)->getAttribute("href"));
        $description .= '">My comment</a>';

        $pubDateStr = $row->find(".age", 0)->text();
        $pubDateTs = date_create($pubDateStr)->setTime(0, 0, 0, 0)->getTimestamp();

        $items[] = array(
            "title" => "Re^$depth: " . $mycomment->find(".storyon a", 0)->innertext,
            "description" => $description,
            "author" => $row->find(".hnuser", 0)->innertext,
            "pubDate" => gmdate(DATE_RFC2822, $pubDateTs),
            "link" => getAbsoluteUrl("https://news.ycombinator.com/", $row->find(".age a", 0)->getAttribute("href")),
            "guid" => $row->getAttribute("id"),
            "_sort" => $pubDateTs
        );
    }
}

// sort reverse chronologically
usort($items, function ($a, $b) {
    return $b['_sort'] - $a['_sort'];
});

// setup feed output
$rss = new SimpleXMLElement('<rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/"></rss>');
$rss->addAttribute('version', '2.0');

$channel = $rss->addChild('channel');

$channel->addChild('title', "HN Replies for " . $_GET['id']);
$channel->addChild('link', $url);

foreach ($items as $i) {
    unset($i['_sort']);

    $item = $channel->addChild("item");

    foreach ($i as $k => $v) {
        $x = $item->addChild($k, htmlentities($v, ENT_XML1 | ENT_DISALLOWED, "UTF-8"));
        if ($k == "guid") {
            $x->addAttribute('isPermaLink', 'false');
        }
    }
}


header('Content-Type: application/rss+xml; charset=utf-8', true);
echo $rss->asXML() . PHP_EOL;


function getAbsoluteUrl($baseUrl, $relativeUrl){

    // if already absolute URL
    if (parse_url($relativeUrl, PHP_URL_SCHEME) !== null){
        return $relativeUrl;
    }

    // queries and anchors
    if ($relativeUrl[0] === '#' || $relativeUrl[0] === '?'){
        return $baseUrl.$relativeUrl;
    }

    // parse base URL and convert to: $scheme, $host, $path, $query, $port, $user, $pass
    extract(parse_url($baseUrl));

    // if base URL contains a path remove non-directory elements from $path
    if (isset($path) === true){
        $path = preg_replace('#/[^/]*$#', '', $path);
    }
    else {
        $path = '';
    }

    // if realtive URL starts with //
    if (substr($relativeUrl, 0, 2) === '//'){
        return $scheme.':'.$relativeUrl;
    }

    // if realtive URL starts with /
    if ($relativeUrl[0] === '/'){
        $path = null;
    }

    $abs = null;

    // if realtive URL contains a user
    if (isset($user) === true){
        $abs .= $user;

        // if realtive URL contains a password
        if (isset($pass) === true){
            $abs .= ':'.$pass;
        }

        $abs .= '@';
    }

    $abs .= $host;

    // if realtive URL contains a port
    if (isset($port) === true){
        $abs .= ':'.$port;
    }

    $abs .= $path.'/'.$relativeUrl.(isset($query) === true ? '?'.$query : null);

    // replace // or /./ or /foo/../ with /
    $re = ['#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#'];
    for ($n = 1; $n > 0; $abs = preg_replace($re, '/', $abs, -1, $n)) {
    }

    // return absolute URL
    return $scheme.'://'.$abs;

}