A RSS feeds list using ARC components

rsslist.css

html, body {
    background: #EEE;
    height: 100%;
    overflow: auto;
    font-family: arial, helvetica, sans-serif;
    padding: 0;
}
section {
    background-color: white;
    border-radius: 3px;
    box-shadow: 0 0 3px #888;
    float: left;
  max-width: 300px;
    margin: 0 1em 1em 0;
}
section header {
    background-color: #EEE;
    overflow: hidden;
    position: relative;
}
section header h2 {
    margin: 0;
    padding: 10px;
    font-size: 1rem
}
section header button {
    position: absolute;
    right: 10px;
    top: 5px;
    width: 1em;
    text-indent: 2em;
    overflow: hidden;
    border: 0;
    background: transparent;
    font-size: 1.2em;
}
section header button::before {
    content: "X";
    display: block;
    position: absolute;
    left: -2em;
    top: 0;
}
.article-body {
    height: 400px;
    overflow: auto;
    color: #666;
}
article h3 {
    margin: 0;
    padding: 5px 10px 10px 10px;
}
article h3 a {
    text-decoration: none;
    color: #333;
}
section footer {
    background-color: #EEE;
    padding: 10px 
}
.body {
    padding: 0px 10px 10px 10px;
    border-bottom: 1px solid #ccc;
}
body > footer {
    position: absolute;
    left: 0;  
    bottom: 0;
    background-color: #AAA;
    padding: 10px;
  box-sizing: border-box;
    width: 100%;
}

rsslist.php

<?php
    /**
     * This is a simple demo showing how you can use different components from ARC together
     * You can get arc at https://github.com/Ariadne-CMS/arc-arc/ or with composer:
     *
     *     composer create-project arc/arc
     * 
     * See this gist for a simpler demo printing a single feed: 
     * https://gist.github.com/poef/dd977430dbf922d7555f
     */
     
    // load the composer autoloader
    require __DIR__ . '/vendor/autoload.php';

    // set shorter aliases for the html and xml writer/parser
    use \arc\html as h;
    use \arc\xml as x;

    // create a http proxy with caching based on the cache headers of each request
    $client = \arc\cache::proxy( \arc\http::client(), function($params) {
        return ( \arc\http\headers::parseCacheTime( $params['target']->responseHeaders ) );
    });

    // read a list of feeds
    $feeds = json_decode(file_get_contents('feeds.json'),true) ?: [];

    // create an adhoc object to render the html
    $agg = \arc\lambda::prototype();
    
    $agg->renderItem = function($item) {
        return h::article(
            h::h3( h::a( [ 'href' => $item->link->nodeValue ], $item->title->nodeValue ) ),
            h::div( [ 'class' => 'body' ], $item->description->nodeValue )
        );
    };
        
    $agg->renderItems = function($items) {
        $itemsString = '';
        if ( count($items) ) {
            foreach ($items as $item ) {
                $itemsString .= $this->renderItem($item);
            }   
        } else {
            $itemsString = h::div(['class' => 'warning'], 'No articles in this feed.');
        }
        // h::raw makes sure the $itemsString isn't encoded/escaped when printed later
        return h::raw($itemsString);
    };

    $agg->renderFeed = function($title, $link, $index, $items) {
        return h::section(['class' => 'feed'],
            h::header(
                h::h2( $title ),
                // this button removes this feed when pressed
                h::form(['class' => 'remove', 'method' => 'POST'],
                    h::button(['name' => 'removeFeed', 'value' => $index], 'Remove' )
                )
            ),
            h::div(['class' => 'article-body'], $this->renderItems($items) ),
            h::footer(
                h::a( ['href' => $link], $link )
            )
        );
    };

    // retrieves the contents and renders them, naming is hard...    
    $agg->getFeed = function($url, $index) use ($client) {
        $feed = $client->get($url);

        try {
            $rss = \arc\xml::parse($feed);
        } catch( \Exception $e ) {
            $rss = \arc\html::parse($feed);
        }

        $items = $rss->find('item');
        return $this->renderFeed(
            $rss->channel->title->nodeValue,
            $rss->channel->link->nodeValue,
            $index,
            $items
       );
    };
    
    // runs getFeed on all feeds and concatenates the results
    $agg->render = function($feeds) { 
        return implode(
            array_map(
                function($feed, $index) { 
                    return $this->getFeed($feed, $index);
                },
                $feeds,
                array_keys($feeds)
            )
        );
    };

    // check if a new feed is added
    $newFeed = \arc\hash::get('/newFeed/', $_POST);
    if ( isset($newFeed) ) {
        $feeds[] = $newFeed;
    }
    
    // check if a feed has been removed
    $removeFeed = \arc\hash::get('/removeFeed/', $_POST);
    if ( isset($removeFeed) ) {
        unset($feeds[ $removeFeed ]);
    }

    // if the feeds list has changed, write it to disk
    // this is a very unsafe way to do this, but it keeps this example short
    if ( isset($removeFeed) || isset($newFeed) ) {
        file_put_contents('data/feeds.json', json_encode($feeds,true));
    }

    // print the full html output
    echo h::doctype()
    .h::html(
        h::head(
            h::title('RSS Aggregator'),
            h::link(['href' => 'rsslist.css', 'rel' => 'stylesheet'])
        ),
        h::body(
            h::raw($aggregator->render($feeds)),
            h::footer(
                h::form(
                    ['method' => 'POST'],
                    h::input(['name' => 'newFeed']),
                    h::button(['ype' => 'submit'], 'Add feed')
                )
            )
        )
    );