Video Slider Metabox

class Video_Slider {

	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(
			'vslider',
			__( 'Video Slider Information', 'batachcreativeco_19' ),
			array( $this, 'render_metabox' ),
			'vslider',
			'advanced',
			'default'
		);

	}

	public function render_metabox( $post ) {

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

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

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

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

		echo '	<tr>';
		echo '		<th><label for="" class="_label">' . __( 'Video Link', 'batachcreativeco_19' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="url" id="" name="" class="_field" placeholder="' . esc_attr__( '', 'batachcreativeco_19' ) . '" value="' . esc_attr( $ ) . '">';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="" class="_label">' . __( 'Video Type', 'batachcreativeco_19' ) . '</label></th>';
		echo '		<td>';
		echo '			<select id="" name="" class="_field">';
		echo '			<option value="YouTube" ' . selected( $, 'YouTube', false ) . '> ' . __( '', 'batachcreativeco_19' ) . '</option>';
		echo '			<option value="Vimeo" ' . selected( $, 'Vimeo', false ) . '> ' . __( '', 'batachcreativeco_19' ) . '</option>';
		echo '			<option value="MP4" ' . selected( $, 'MP4', false ) . '> ' . __( '', 'batachcreativeco_19' ) . '</option>';
		echo '			</select>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="" class="_label">' . __( 'Video Author', 'batachcreativeco_19' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="" name="" class="_field" placeholder="' . esc_attr__( '', 'batachcreativeco_19' ) . '" value="' . esc_attr( $ ) . '">';
		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_ = isset( $_POST[ '' ] ) ? esc_url( $_POST[ '' ] ) : '';
		$new_ = isset( $_POST[ '' ] ) ? $_POST[ '' ] : '';
		$new_ = isset( $_POST[ '' ] ) ? sanitize_text_field( $_POST[ '' ] ) : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, '', $new_ );
		update_post_meta( $post_id, '', $new_ );
		update_post_meta( $post_id, '', $new_ );

	}

}

new Video_Slider;