snarfed.org custom theme functions.php, based on Ryu

functions.php

<?php
/*
 * Customizations for snarfed.org on top of the Ryu WordPress theme.
 * Not (yet) a full child theme.
 * Public domain.
 *
 * To log: dlog("xyz")
 * Defined below. Wraps error_log(). Writes to wp-content/debug.log
 *
 * Requires WP_DEBUG and WP_DEBUG_LOG to be true in wp-config.php. Details:
 * http://www.stumiller.me/sending-output-to-the-wordpress-debug-log/
 * http://codex.wordpress.org/Debugging_in_WordPress
 *
 * to fix semantic-linkbacks breakage until WP 4.2, do this:
 * update wp_comments set comment_type=NULL where comment_id=2586829;
 */

/* uncomment to turn on WP Super Cache debug log file in
 * wp-content/cache/supercache. */
/* global $wp_super_cache_debug; */
/* $wp_super_cache_debug = true; */

/* Max media upload size. */
@ini_set('upload_max_size', '128M');
@ini_set('post_max_size', '128M');

function dlog($msg) {
  if ( is_array( $msg ) || is_object( $msg ) ) {
    error_log( print_r( $msg, true ) );
  } else {
    error_log( $msg );
  }
}

/* Require WordPress.com login, which includes 2FA. */
add_filter( 'jetpack_remove_login_form', '__return_true' );

/* Change email address that WordPress emails me *from*. It defaults to
 * wordpress@snarfed.org, but when Google sees emails from a domain without
 * DKIM, SPF, etc set up, it eventually distrusts that domain and starts showing
 * "Suspicious link - This link leads to an untrusted site" whenever anyone
 * clicks on any link to that domain, which is obviously bad.
 *
 * https://gsuiteupdates.googleblog.com/2017/05/making-email-safer-with-Gmail-click-time-security-checks.html
 * https://productforums.google.com/forum/#!topic/gmail/qg7rTa5B7ZA
 * https://productforums.google.com/forum/#!topic/gmail/dK0da2oRnrE
 */
function snarfed_sender_email( $original_email_address ) {
    return 'wordpress@ryanbarrett.org';
}
add_filter( 'wp_mail_from', 'snarfed_sender_email' );

/* The Syndication Links plugin's stylesheet includes genericons etc, which I
 * already have, and I style the links myself, so ditch its style.
 */
remove_action('wp_enqueue_scripts', array('Syn_Config', 'enqueue_scripts'));

/* Disable XML-RPC. */
add_filter( 'xmlrpc_enabled', '__return_false' );
remove_action( 'wp_head', 'rsd_link' );

/* Jetpack Markdown: Enable by default for posts and pages.
 * https://jetpack.com/support/markdown/#using-the-markdown-block
 * https://jetpack.com/support/markdown/#cpt
 */
function snarfed_markdown_everywhere() {
    add_post_type_support( 'post', 'wpcom-markdown' );
    add_post_type_support( 'page', 'wpcom-markdown' );
}
add_action('init', 'snarfed_markdown_everywhere');

/* Jetpack Markdown: Don't make newlines meaningful. */
function wpautop_no_linebreaks( $content ) {
  $content = wpautop( $content, false );
  // maybe try to deal with trailing spaced newlines?
  return $content;
}
remove_filter( 'the_content', 'wpautop' );
add_filter( 'the_content', 'wpautop_no_linebreaks' );

/* Filter for normal comments. Just remove the dash before "via ..."
 */
function snarfed_cite($text) {
  return str_replace("<p><small>&mdash;&nbsp;<cite>", "<cite>",
    str_replace("</cite></small></p>", "</cite>", $text));
}
add_filter('semantic_linkbacks_cite', 'snarfed_cite');

/* Allow categories and tags on pages as well as posts.
 */
function snarfed_tags_categories_on_pages() {
  register_taxonomy_for_object_type( 'category', 'page' );
  register_taxonomy_for_object_type( 'post_tag', 'page' );
}
add_action( 'init', 'snarfed_tags_categories_on_pages' );

/* Clear a post/page's cache when it receives a webmention.
 */
function snarfed_webmention_clear_cache($comment_ID) {
  clean_post_cache(get_comment($comment_ID)->comment_post_ID);

  // wp_cache_post_change stores the last seen post ID in a static local var,
  // and short circuits if it's the same as last call. so set it to a different
  // id first. (417 is /2003-06-29_blogtastic on both snarfed and localhost.)
  $GLOBALS["super_cache_enabled"] = 1;
  wp_cache_post_change(417);
  wp_cache_post_change(get_comment($comment_ID)->comment_post_ID);
}
add_action('webmention_post', 'snarfed_webmention_clear_cache');

/* Don't let webmentions get marked as spam.
 */
function unspam_webmentions($approved, $commentdata) {
  return ($commentdata['comment_type'] == 'webmention' ||
		  get_comment_meta($commentdata['comment_ID'], 'semantic_linkbacks_type', true)
		  ) ? 1 : $approved;
}
add_filter('pre_comment_approved', 'unspam_webmentions', '99', 2);

/*
 * Don't show the "Send me a WebMention" form below the comment form.
 */
// function snarfed_nothing($template_file) {
//   return NULL;
// }
// add_filter('webmention_comment_form', 'snarfed_nothing');


/* Automatically mark comments that end in a 32-digit hex string as spam.
 *
 * https://snarfed.org/wordpress-mini-spam-filter-for-comments-ending-in-32-hex-characters
 */
function spam_32_hex_chars($approved, $commentdata) {
  $text = trim(wp_strip_all_tags($commentdata['comment_content'], true));
  return preg_match('|[0-9a-f]{32}$|', $text) ? 'spam' : $approved;
}

add_filter('pre_comment_approved', 'spam_32_hex_chars', '99', 2);

/* Capture the output from a PHP file in a string. Taken verbatim from the PHP
 * docs for include(). Used in header.php.
 *
 * If needed, we can use this to capture and process *all* output:
 * http://www.dagondesign.com/articles/wordpress-hook-for-entire-page-using-output-buffering/
 */
function get_include_contents($filename) {
  ob_start();
  include $filename;
  $contents = ob_get_contents();
  ob_end_clean();
  return $contents;
}

/* Make Jetpack's Publicize opt in per post, instead of automatic and opt out.
 */
add_filter('publicize_checkbox_default', '__return_false');

/* Make Jetpack's Photon image CDN (used in its Tiled Galleries feature) handle
 * connecting to us over SSL. Details:
 * https://wordpress.org/support/topic/tiled-gallery-fetching-full-size-images-resizing-in-browser?replies=3#post-7214361
 *
 * Theoretically no longer needed; Photon now supports HTTPS by default:
 * http://jetpack.me/2016/01/20/39-sitemaps-skype-sharing/
 *
 * ...but it broke on https://snarfed.org/2016-02-25_17194 when i tried removing it.
 */
add_filter( 'jetpack_photon_reject_https', '__return_false' );

/* Don't render featured images. I only use them for Twitter cards and Open
 * Graph (Facebook) tags.
 */
function snarfed_hide_featured_image ($html) {
    return ''; //preg_replace('/(width|height)="\d+"\s/', "", $html);
}
add_filter( 'post_thumbnail_html', 'snarfed_hide_featured_image' );

function snarfed_social_image_default ($url) {
	if ( is_singular() ) {
		global $post;

		$matches = [];
	    if ( preg_match( "/< *img *[^>]+src *= *[\"']([^\"']+)/",
						 $post->post_content, $matches ) ) {
			$url = $matches[1];
			if ( substr( $url, 0, 4 ) == 'http' ) {
				return $url;
			} else if ( substr( $url, 0, 2 ) == '//' ) {
				return 'https:' . $url;
			} else {
				return get_home_url( NULL, $url );
			}
	    }
	}

	// default
	return get_home_url( NULL, '/iraq_square.jpg' );
}
add_filter( 'jetpack_open_graph_image_default', 'snarfed_social_image_default' );
add_filter( 'jetpack_twitter_cards_image_default', 'snarfed_social_image_default' );

/* Don't put u-photo on Jetpack lazy loaded image placeholders.
 * https://jetpack.com/support/lazy-images/
 * https://developer.jetpack.com/hooks/jetpack_lazy_images_new_attributes/
 */
function snarfed_no_uphoto_lazy_images($attrs) {
	$classes = explode(' ', $attrs['class']);
	$attrs['class'] = implode(' ', array_filter($classes, function($cls) {
		return $cls != 'photo' && $cls != 'u-photo';
	}));
    // dlog($attrs);
	return $attrs;
}
add_filter( 'jetpack_lazy_images_new_attributes', 'snarfed_no_uphoto_lazy_images' );

/* WordPress 4.5 dropped the JPG quality of thumbnails to 82%, which makes them
 * look blurry. Bump that back up.
 * https://make.wordpress.org/core/2016/02/22/proposal-increase-the-default-image-compression-in-wordpress/
 */
function snarfed_better_quality_thumbnails($arg) {
	return 90;
}

add_filter('jpeg_quality', 'snarfed_better_quality_thumbnails');

/* Redirect image attachment pages to parent post.
 * https://www.wpexplorer.com/disable-image-page/
 */
function snarfed_redirect_attachment_page() {
	if ( is_attachment() ) {
		global $post;
		if ( $post && $post->post_parent ) {
			wp_redirect( esc_url( get_permalink( $post->post_parent ) ), 301 );
			exit;
		} else {
			wp_redirect( esc_url( home_url( '/' ) ), 301 );
			exit;
		}
	}
}
add_action( 'template_redirect', 'snarfed_redirect_attachment_page' );

/* Override and disable previous and next post links entirely. */
function ryu_content_nav($nav_id) {
}

/**
 * Override entry meta to add last modified time and microformats2 classes.
 *
 * Ryu doesn't have any filters or hooks for customizing this, so I had to copy
 * and modify ryu_[get_]entry_meta() from ryu/inc/template-tags.php. :/
 */
function ryu_entry_meta() {
  echo ryu_get_entry_meta();
}

function ryu_get_entry_meta() {
  $val = sprintf(__(
      '<span class="entry-date">' .
      '<a class="u-url" href="%1$s" title="%2$s" rel="bookmark">' .
      '<time class="dt-published" datetime="%3$s">%4$s</time></a>' .
      '%5$s</span>', 'ryu'),
         esc_url(get_permalink()),
         esc_attr(get_the_time()),
         /* 'c' is the ISO 8601 format specifier, but it ignores WordPress's
          * time zone and blindly uses GMT. DATE_W3C gets the time zone right.
          * http://freetheweb.tumblr.com/post/11431306520/wordpress-obtaining-timezone-accurate-iso-8601-strings
          */
         esc_attr(get_the_date(DATE_W3C)),
         esc_html(get_the_date()),
         function_exists('get_syndication_links') ? get_syndication_links( null ) : '');

  if ('page' == get_post_type() && get_the_date() != get_the_modified_date()) {
    $val = $val . sprintf(__(
        '<span class="entry-modified-date">updated ' .
        '<a class="u-url" href="%1$s" title="%2$s" rel="bookmark">' .
        '<time class="dt-updated" datetime="%3$s">%4$s' .
        '</time></a></span>', 'ryu'),
           esc_url(get_permalink()),
           esc_attr(get_the_modified_time()),
           esc_attr(get_the_modified_date(DATE_W3C)),
           esc_html(get_the_modified_date()));
  }

  $val = $val . sprintf(__(
      '<span class="author p-author h-card vcard"> %1$s' .
      '<a class="u-url url fn n p-name" href="%2$s" title="%3$s" rel="author">' .
      '%4$s</a></span>', 'ryu'),
         get_avatar(get_the_author_meta("ID"), 96, '', '', array( 'class' => 'u-photo' )),
         esc_url(get_the_author_meta('user_url')),
         esc_attr(get_the_author()),
         get_the_author());

  return $val;
}

/**
 * Suppress title (p-name) in replies etc so post type discovery thinks they're notes.
 */
function snarfed_no_title_in_notes($title) {
  if (is_singular() && !is_admin() &&
      (has_category('reply') ||
       has_category('like') ||
       has_category('repost') ||
       has_category('rsvp'))) {
    return NULL;
  }

  return $title;
}
add_filter('the_title', 'snarfed_no_title_in_notes');

/**
 * Override comment to tweak author and date.
 *
 * ...just like entry meta, above. Ryu doesn't have any filters or hooks for
 * customizing this, so I had to copy and modify ryu_comment() from
 * ryu/inc/template-tags.php. :/
 */
function ryu_comment( $comment, $args, $depth ) {
  $GLOBALS['comment'] = $comment;
  switch ( $comment->comment_type ) :
    case 'pingback' :
    case 'trackback' :
  ?>
  <li class="post pingback">
    <p><?php _e( 'Pingback:', 'ryu' ); ?> <?php comment_author_link(); ?></p>
  <?php
      break;
    default :
  ?>
  <li <?php comment_class(); ?> id="li-comment-<?php comment_ID(); ?>">
    <article id="comment-<?php comment_ID(); ?>" class="comment">
      <div class="comment-meta commentmetadata comment-author">
        <span class="comment-author-avatar"><?php echo get_avatar( $comment, 48 ); ?></span>
        <div class="vcard h-card p-author">
          <?php printf( '<cite class="fn theme-genericon">%s</cite>', get_comment_author_link() ); ?>
        </div><!-- .comment-author .vcard -->

        <div class="comment-date">
          <a href="<?php echo esc_url( get_comment_link( $comment->comment_ID ) ); ?>"
             title="<?php echo get_comment_time(); ?>">
            <time class="dt-published" datetime="<?php comment_time( 'c' ); ?>">
              <?php echo get_comment_date(); ?>
            </time>
          </a>
        </div><!-- .comment-date -->
      </div><!-- .comment-meta .commentmetadata -->

      <div class="comment-content">
        <?php comment_text(); ?>
      </div>
    </article><!-- #comment-## -->

  <?php
      break;
  endswitch;
}


/**
 * Remove some parts of wordpress-uf2 that I do myself above.
 */
remove_filter( 'the_author', 'uf2_the_author', 99, 1 );

/**
 * Load enqueued scripts in the footer to speed up page load.
 * Stolen from http://www.kevinleary.net/move-javascript-bottom-wordpress/
 *
 * Disabled because this includes stylesheets, and if they're in the footer, the
 * page initially loads with blank style (ie ugly) before the stylesheets load
 * and kick in.
 */
/*
function snarfed_footer_enqueue_scripts() {
  remove_action('wp_head', 'wp_print_scripts');
  remove_action('wp_head', 'wp_print_head_scripts', 9);
  remove_action('wp_head', 'wp_enqueue_scripts', 1);
  add_action('wp_footer', 'wp_print_scripts', 5);
  add_action('wp_footer', 'wp_enqueue_scripts', 1);
  add_action('wp_footer', 'wp_print_head_scripts', 9);
}
add_action('after_setup_theme', 'snarfed_footer_enqueue_scripts');
*/

/** Include my JavaScript files.
 */
function snarfed_scripts() {
  wp_enqueue_script('snarfed-fragmention',
                    get_stylesheet_directory_uri() . '/fragmention.js',
                    false, '1.0', true);
}
add_action('wp_enqueue_scripts', 'snarfed_scripts');

/** IndieWeb Press This tweaks.
 */
function snarfed_press_this_tweak() {
  ?>
<script type='text/javascript'>
function press_this_tweak() {
  /* map type to wordpress category id */
  var categories = {
    'like': '27',
    'reply': '23',
    'repost': '28',
    'rsvp': '29',
    // I currently show checkins on the front page.
    // 'checkin': 23
  };

  /* get 'type' query param. default to 'reply'. */
  var type = 'reply';
  var params = window.location.search.substr(1).split('&');
  for (var i = 0; i < params.length; i++) {
    var parts = params[i].split('=');
    if (parts[0] == 'type') {
      type = parts[1];
      break;
    }
  }

  var cats = document.getElementsByClassName('category');
  for (i = 0; i < cats.length; i++) {
    if (cats[i].attributes['data-term-id'].value == categories[type]) {
      cats[i].classList.add('selected');
    } else {
      cats[i].classList.remove('selected');
    }
  }

  var content = document.getElementById('pressthis');
  content.onchange = content.oninput = content.onfocus = function(event) {
	// Tag Gina in checkins by default.
    if (type == 'checkin') {
      content.value = content.value.replace(
          'with <a class="h-card" href=""></a>',
          'with <a class="h-card" href="https://www.facebook.com/gina.rossman.50">Gina Barrett</a>.');
    }

    // Use Bridgy Fed for Mastodon etc domains.
    for (const pattern of [
           '//counter.social/',
           '//friends.nico/',
           '//lgbt.io/',
           '//mastodon.',
           '//mstdn.',
           '//octodon.',
           '//pawoo.net/',
           '//toot.cafe/',
         ]) {
		console.log('examining ' + pattern);
      if (content.value.indexOf(pattern) >= 0 &&
		  content.value.indexOf('fed.brid.gy') == -1) {
          var text = (type == 'like' || type == 'repost') ? 'via Bridgy Fed' : '';
          content.value += ' <cite class="via">[' + text + '](https://fed.brid.gy/)</cite>';
          break;
      }
    }
  };

  content.onchange();

  // press-this.js's window.onload runs after onchange() above, and overwrites
  // our changes, and i can't find any other event handler that will trigger
  // after that automatically, so hack it with a timer. :/
  window.setTimeout(content.onchange, 1000);
}
window.addEventListener('load', press_this_tweak, false);
</script>
  <?php
}
add_action('admin_print_scripts-press-this.php', 'snarfed_press_this_tweak', 11);

/* Allow comments on pages by default. WordPress 4.3 switched the default off:
 * https://make.wordpress.org/core/2015/07/06/comments-are-now-turned-off-on-pages-by-default/
 */
function snarfed_comments_on_pages($status, $post_type, $comment_type) {
    return 'open';
}
add_filter('get_default_comment_status', 'snarfed_comments_on_pages', 10, 3);

/** Reply contexts via LinkPreview.
 */
function snarfed_embed_reply_context_script() {
  if (has_category('reply')) {
	$content = 'replying to:';
  } else if (has_category('repost')) {
	$content = '';
  } else {
    return;
  }

  ?>
<script type='text/javascript'>
function embed_reply_contexts() {
  var classes = ['u-in-reply-to', 'u-repost-of', 'u-quotation-of'];
  for (i in classes) {
	  var origs = document.getElementsByClassName(classes[i]);
	  for (j = 0; j < origs.length; j++) {
		  if (origs[j].href.indexOf("twitter.com/") >= 0 ||
			  origs[j].href.indexOf("facebook.com/") >= 0 ||
			  origs[j].href.indexOf("plus.google.com/") >= 0 ||
			  origs[j].href.indexOf("instagram.com/") >= 0) {
			  continue;
		  }
		  origs[j].insertAdjacentHTML('afterend', `
  <div class="box" style="margin-top: 1em">
    <a id="lp-url" href="">
      <img id="lp-image" style="float: right" src="">
      <div class="is-clipped">
        <h3 id="lp-title"></h3>
        <p><em id="lp-description"></em></p>
      </div>
    </a>
  </div>`);
		  fetch('https://api.linkpreview.net', {
            method: 'POST',
            mode: 'cors',
            body: JSON.stringify({
              key: '38cfb05179d598106ac12fe584811681',
              q: origs[j].href,
            }),
          })
            .then(res => res.json())
            .then(response => {
              document.getElementById('lp-title').innerHTML = response.title
              document.getElementById('lp-description').innerHTML = response.description
              document.getElementById('lp-image').src = response.image
              document.getElementById('lp-url').href = response.url
            });
	  }
  }
}
window.addEventListener('load', embed_reply_contexts, false);
</script>
  <?php
}
add_action('wp_footer', 'snarfed_embed_reply_context_script');

/* Used once on snarfed.org, 2017-11-20, to upgrade MySQL tables' charset and
 * collation from utf8 to utf8mb4 to fix showing emoji beyond BMP in comments.
 * From https://gist.github.com/FlorianBrinkmann/c3f57dd7c26328d7b4de04e696091eee
 * Background in https://make.wordpress.org/core/2015/04/02/the-utf8mb4-upgrade/
 * and etc/wordpress_emoji_mysql_utf8mb4.
 */
// function update_db_to_utf8mb4() {
// 	if (!isset($_GET['update-utf8bm4'])) {
// 		return;
// 	}

// 	require_once( ABSPATH . 'wp-admin/includes/upgrade.php');
// 	/** WordPress Administration API */
// 	require_once(ABSPATH . 'wp-admin/includes/admin.php');
// 	/** WordPress Schema API */
// 	require_once(ABSPATH . 'wp-admin/includes/schema.php');
// 	$tables = $wpdb->tables('all');
// 	if (!wp_should_upgrade_global_tables()) {
// 		$global_tables = $wpdb->tables('global');
// 		$tables = array_diff_assoc($tables, $global_tables);
// 	}
// 	foreach ($tables as $table) {
// 		maybe_convert_table_to_utf8mb4($table);
// 	}
// }
// add_action('wp_loaded', 'update_db_to_utf8mb4');

/* Return 404s appropriately. Don't redirect to a similar existing URL.
 */
add_filter('redirect_canonical', 'snarfed_no_redirect_on_404');
function snarfed_no_redirect_on_404($redirect_url)
{
    if (is_404()) {
        return false;
    }
    return $redirect_url;
}

?>