UI Mastodon Verification Link plugin for ClassicPress and WordPress

ui-masto-verification-link.php

<?php
/**
 * Plugin Name: UI Mastodon Verification Link
 * Description: Adds mastodon rel=me profile link to the html head.
 * Version: 1.0
 * Author: Fabian Wolf
 * Author URI: https://usability-idealist.net/
 * License: GNU GPL v2
 */

/**
 * Adds mastodon rel=me profile link to the html head as a test.
 */

if( !class_exists( '_ui_Mastodon_Verification_Link' ) ) {
	
	class _ui_Mastodon_Verification_Link {
		
		public $plugin_prefix;
	
		public static function init() {
			new self();
		}
	
		function __construct() {
			$this->plugin_prefix = '_ui_mvl_';
			
			add_action( 'wp_head', array( $this, 'add_mastodon_verification_link' ), 9 );
			
			
			// Adding options to registered field
			add_action( 'admin_menu', array( $this, 'add_settings_to_admin_page' ) );
		}

		function add_mastodon_verification_link() {
		
			$verification_url = apply_filters( $this->plugin_prefix . 'get_verification_url',
				get_option( $this->plugin_prefix . 'verification_url', '' )
			);
			


			$link_template = apply_filters( $this->plugin_prefix . 'get_link_template', '<link type="href" rel="me" href="%s" />' );
			
			if( !empty( $verification_url ) && !empty( $link_template ) ) {
				// <link type="href" rel="me" href="https://kosmos.social/@ginsterbusch" />
				
				if( !is_array( $verification_url ) ) {
					$verification_url = explode("\n", trim( $verification_url ) );
					
					/**
					 * NOTE: NO duplicates wanted!
					 */
					
					$verification_url = array_unique( $verification_url );
					
				}
				
				$added_by = "\n" . '<!-- added by ' . basename( __FILE__, '.php' ) . ' v1.0 -->' . "\n";

				echo "\n" . $added_by;
				
				foreach( $verification_url as $url ) {
					echo "\n" . sprintf( $link_template, trim( $url ) );
				}
				
				echo "\n" . $added_by . "\n";
			}
		}
		
		function add_settings_to_admin_page() {
			
			$settings_page = 'general';
			$settings_page = 'discussion';
			
			register_setting( $settings_page, $this->plugin_prefix . 'verification_url' );
			
			
			add_settings_field( 
				sanitize_html_class( $this->plugin_prefix . 'verification-url' ),
				'Mastodon Profile URL(s)',
				array( $this, 'display_settings_field' ),
				$settings_page,
				'default',
				array(
					'id' => sanitize_html_class( $this->plugin_prefix . 'verification-url' ),
					'option_name' => $this->plugin_prefix . 'verification_url',
				)
			);
		}
		
		function display_settings_field( $input_data ) {
			$id = $input_data['id'];
			$option_name = $input_data['option_name'];
			$option_data = get_option( $option_name );
			
			?>
			<textarea name="<?php echo esc_attr( $option_name ); ?>" 
				id="<?php echo esc_attr( $id ); ?>" 
				cols="40" rows="4"><?php 
			if( !empty( $option_data ) ) {
				echo esc_attr( $option_data );
			} ?></textarea>
			<?php
		}
	}
	
	
	add_action( 'plugins_loaded', array( '_ui_Mastodon_Verification_Link', 'init' ) );
}