RWB Showdates

class Showdate_Meta_box {

	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(
			'showdatesmeta',
			__( 'Show Dates Meta', 'text_domain' ),
			array( $this, 'render_metabox' ),
			'show_dates',
			'normal',
			'high'
		);

	}

	public function render_metabox( $post ) {

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

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

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

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

		echo '	<tr>';
		echo '		<th><label for="showvenue" class="showvenue_label">' . __( 'Venue', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="showvenue" name="showvenue" class="showvenue_field" placeholder="' . esc_attr__( '', 'text_domain' ) . '" value="' . esc_attr( $showvenue ) . '">';
		echo '			<p class="description">' . __( 'ex. Burdock', 'text_domain' ) . '</p>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="showplace" class="showplace_label">' . __( 'City, Country', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="showplace" name="showplace" class="showplace_field" placeholder="' . esc_attr__( '', 'text_domain' ) . '" value="' . esc_attr( $showplace ) . '">';
		echo '			<p class="description">' . __( 'Berlin, Germany', 'text_domain' ) . '</p>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="showurl" class="showurl_label">' . __( 'Event URL', 'text_domain' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="showurl" name="showurl" class="showurl_field" placeholder="' . esc_attr__( '', 'text_domain' ) . '" value="' . esc_attr( $showurl ) . '">';
		echo '			<p class="description">' . __( 'Ticket or Facebook Event Link', 'text_domain' ) . '</p>';
		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 it's not an autosave.
		if ( wp_is_post_autosave( $post_id ) )
			return;

		// Sanitize user input.
		$new_showvenue = isset( $_POST[ 'showvenue' ] ) ? sanitize_text_field( $_POST[ 'showvenue' ] ) : '';
		$new_showplace = isset( $_POST[ 'showplace' ] ) ? sanitize_text_field( $_POST[ 'showplace' ] ) : '';
		$new_showurl = isset( $_POST[ 'showurl' ] ) ? sanitize_text_field( $_POST[ 'showurl' ] ) : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, 'showvenue', $new_showvenue );
		update_post_meta( $post_id, 'showplace', $new_showplace );
		update_post_meta( $post_id, 'showurl', $new_showurl );

	}

}

new Showdate_Meta_box;