Basic social OG tag generation for WordPress

social.php

<?php
/**
 * Plugin Name: Social Test
 *
 * TODO: Output <meta name="twitter:site" content="@username" />? Needs custom option to read from.
 * TODO: Custom option for social fallback image instead of core image?
 */

/**
 * Adding the Open Graph schema definitions in the Language Attributes.
 *
 * @param  string $lang_attributes Language attributes set to output in head.
 * @return string                  Modified language attributes to output in head.
 */
function hd_add_opengraph_doctype( $lang_attributes ) {

	// Add schema definitions of they aren't present already.
	if ( false === stripos( $lang_attributes, 'prefix=' ) ) {
		$lang_attributes .= ' prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb#"';
	}

	return $lang_attributes;
}
add_filter( 'language_attributes', 'hd_add_opengraph_doctype' );




/**
 * Add Open Graph/meta tags to head.
 */
function hd_add_opengraph_tags() {

	/**
	 * Setup.
	 */

	// Bail if Yoast or AIOSEO is installed, since they will handle things.
	if ( class_exists( 'WPSEO_Options' ) || class_exists( 'All_in_One_SEO_Pack' ) ) {
		return;
	}

	// Set a post global on single posts. This avoids grabbing content from the first post on an archive page.
	if ( is_singular() ) {
		global $post;
	}

	/**
	 * Build the default values.
	 */

	$post_content             = ! empty( $post ) ? $post->post_content : ''; // Get the post content.
	$default_content          = ( $post_content ) ? wp_strip_all_tags( strip_shortcodes( $post_content ) ) : $post_content; // Strip all tags from the post content we just grabbed.
	$default_title            = get_bloginfo( 'name' ); // Set our default title.
	$default_url              = get_permalink(); // Set our default URL.
	$default_base_description = ( get_bloginfo( 'description' ) ) ? get_bloginfo( 'description' ) : esc_html__( 'Visit our website to learn more.', '_s' ); // Set our base description.
	$default_type             = 'article'; // Set the card type.
	// Get our custom logo URL. We'll use this on archives and when no featured image is found.
	$logo_id    = get_theme_mod( 'custom_logo' );
	$logo_image = ( $logo_id ) ? wp_get_attachment_image_src( $logo_id, 'full' ) : '';
	$logo_url   = ( $logo_id ) ? $logo_image[0] : '';

	// Set our final defaults.
	$card_locale           = get_locale();
	$card_title            = $default_title;
	$card_description      = $default_base_description;
	$card_long_description = $default_base_description;
	$card_url              = $default_url;
	$card_image            = $logo_url;
	$card_type             = $default_type;

	/**
	 * Start overrides.
	 */

	// All singles.
	if ( is_singular() ) {
		if ( has_post_thumbnail() ) {
			$card_image = get_the_post_thumbnail_url();
		}
	}
	// Single posts/pages that aren't the front page.
	if ( is_singular() && ! is_front_page() ) {
		$card_title            = get_the_title() . ' - ' . $default_title;
		$card_description      = ( $default_content ) ? wp_trim_words( $default_content, 53, '...' ) : $default_base_description;
		$card_long_description = ( $default_content ) ? wp_trim_words( $default_content, 140, '...' ) : $default_base_description;
	}
	// Categories, Tags, and Custom Taxonomies.
	if ( is_category() || is_tag() || is_tax() ) {
		$term_name      = single_term_title( '', false );
		$card_title     = $term_name . ' - ' . $default_title;
		$specify        = ( is_category() ) ? esc_html__( 'categorized in', '_s' ) : esc_html__( 'tagged with', '_s' );
		$queried_object = get_queried_object();
		$card_url       = get_term_link( $queried_object );
		$card_type      = 'website';
		// Translators: get the term name.
		$card_long_description = $card_description = sprintf( esc_html__( 'Posts %1$s %2$s.', '_s' ), $specify, $term_name );
	}
	// Search results.
	if ( is_search() ) {
		$search_term = get_search_query();
		$card_title  = $search_term . ' - ' . $default_title;
		$card_url    = get_search_link( $search_term );
		$card_type   = 'website';
		// Translators: get the search term.
		$card_long_description = $card_description = sprintf( esc_html__( 'Search results for %s.', '_s' ), $search_term );
	}
	if ( is_home() ) {
		$posts_page = get_option( 'page_for_posts' );
		$card_title = get_the_title( $posts_page ) . ' - ' . $default_title;
		$card_url   = get_permalink( $posts_page );
		$card_type  = 'website';
	}
	// Front page.
	if ( is_front_page() ) {
		$front_page = get_option( 'page_on_front' );
		$card_title = ( $front_page ) ? get_the_title( $front_page ) . ' - ' . $default_title : $default_title;
		$card_url   = get_home_url();
		$card_type  = 'website';
	}
	// Post type archives.
	if ( is_post_type_archive() ) {
		$post_type_name = get_post_type();
		$card_title     = $post_type_name . ' - ' . $default_title;
		$card_url       = get_post_type_archive_link( $post_type_name );
		$card_type      = 'website';
	}
	// Media page.
	if ( is_attachment() ) {
		$attachment_id = get_the_ID();
		$card_image    = ( wp_attachment_is_image( $attachment_id ) ) ? wp_get_attachment_image_url( $attachment_id, 'full' ) : $card_image;
	}
	?>
	<meta property="og:title" content="<?php echo esc_attr( $card_title ); ?>" />
	<meta property="og:type" content="<?php echo esc_attr( $card_type ); ?>" />
	<meta property="og:url" content="<?php echo esc_url( $card_url ); ?>" />
	<meta property="og:image" content="<?php echo esc_url( $card_image ); ?>" />
	<meta property="og:site_name" content="<?php echo esc_attr( $default_title ); ?>" />
	<meta property="og:description" content="<?php echo esc_attr( $card_description ); ?>" />
	<meta name="description" content="<?php echo esc_attr( $card_long_description ); ?>" />
	<meta property="og:locale" content="<?php echo esc_attr( $card_locale ); ?>" />
	<?php
}
add_action( 'wp_head', 'hd_add_opengraph_tags' );