Metabox Second Editor 2

class sqpp_metabox_second_editor {

	public function __construct() {

		if ( is_admin() ) {
			add_action( 'load-post.php',     array( $this, 'init_metabox' ) );
			add_action( 'load-post-new.php', array( $this, 'init_metabox' ) );
		}

	}

	public function init_metabox() {

		add_action( 'add_meta_boxes',        array( $this, 'add_metabox' )         );
		add_action( 'save_post',             array( $this, 'save_metabox' ), 10, 2 );

	}

	public function add_metabox() {

		add_meta_box(
			'sqpp-mb-second-editor',
			__( 'Additional Editor', 'sqppcptmeta' ),
			array( $this, 'render_sqpp_metabox_second_editor' ),
			'page',
			'normal',
			'default'
		);

	}

	public function render_sqpp_metabox_second_editor( $post ) {

		// Add nonce for security and authentication.
		wp_nonce_field( 'nonce_action', 'nonce' );

		// Retrieve an existing value from the database.
		$sqpp_mb_second_editor_wysiwyg = get_post_meta( $post->ID, 'sqpp_mb_second_editor_wysiwyg', true );
		$sqpp_mb_second_editor_yn = get_post_meta( $post->ID, 'sqpp_mb_second_editor_yn', true );

		// Set default values.
		if( empty( $sqpp_mb_second_editor_wysiwyg ) ) $sqpp_mb_second_editor_wysiwyg = '';
		if( empty( $sqpp_mb_second_editor_yn ) ) $sqpp_mb_second_editor_yn = '';

		// Form fields.
		echo '<table class="form-table">';

		echo '	<tr>';
		echo '		<th><label for="sqpp_mb_second_editor_wysiwyg" class="sqpp_mb_second_editor_wysiwyg_label">' . __( '', 'sqppcptmeta' ) . '</label></th>';
		echo '		<td>';
		wp_editor( $sqpp_mb_second_editor_wysiwyg, 'sqpp_mb_second_editor_wysiwyg', array( 'media_buttons' => true ) );
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="sqpp_mb_second_editor_yn" class="sqpp_mb_second_editor_yn_label">' . __( 'Yes', 'sqppcptmeta' ) . '</label></th>';
		echo '		<td>';
		echo '			<label><input type="checkbox" id="sqpp_mb_second_editor_yn" name="sqpp_mb_second_editor_yn" class="sqpp_mb_second_editor_yn_field" value="checked" ' . checked( $sqpp_mb_second_editor_yn, 'checked', false ) . '> ' . __( '', 'sqppcptmeta' ) . '</label>';
		echo '			<span class="description">' . __( 'An additional editor can be activated below to add and edit content.', 'sqppcptmeta' ) . '</span>';
		echo '		</td>';
		echo '	</tr>';

		echo '</table>';

	}

	public function save_metabox( $post_id, $post ) {

		// Add nonce for security and authentication.
		$nonce_name   = isset( $_POST['nonce'] ) ? $_POST['nonce'] : '';
		$nonce_action = 'nonce_action';

		// Check if a nonce is set.
		if ( ! isset( $nonce_name ) )
			return;

		// Check if a nonce is valid.
		if ( ! wp_verify_nonce( $nonce_name, $nonce_action ) )
			return;

		// Check if the user has permissions to save data.
		if ( ! current_user_can( 'edit_post', $post_id ) )
			return;

		// Check if it's not an autosave.
		if ( wp_is_post_autosave( $post_id ) )
			return;

		// Check if it's not a revision.
		if ( wp_is_post_revision( $post_id ) )
			return;

		// Sanitize user input.
		$new_sqpp_mb_second_editor_wysiwyg = isset( $_POST[ 'sqpp_mb_second_editor_wysiwyg' ] ) ? wp_kses_post( $_POST[ 'sqpp_mb_second_editor_wysiwyg' ] ) : '';
		$new_sqpp_mb_second_editor_yn = isset( $_POST[ 'sqpp_mb_second_editor_yn' ] ) ? 'checked'  : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, 'sqpp_mb_second_editor_wysiwyg', $new_sqpp_mb_second_editor_wysiwyg );
		update_post_meta( $post_id, 'sqpp_mb_second_editor_yn', $new_sqpp_mb_second_editor_yn );

	}

}

new sqpp_metabox_second_editor;