Getting notice functionality in the admin panel

admin/nmsp-admin-functions.php

@@ -0,0 +1,48 @@
+<?php
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * Show a notice on the admin panel.
+ *
+ * @since 1.0.0
+ *
+ * @param string $message      The message to show in the notice
+ * @param string $type         The 'type' of notice, e.g. info (default), success, warning, or error
+ * @param bool   $dismissible  Whether the notice should be dismissible
+ *
+ * @return string
+ */
+function nmsp_admin_notice( string $message, string $type = 'info', bool $dismissible = true ) {
+	$classes = 'notice';
+	switch ($type) {
+		case 'success':
+			$classes .= ' notice-success';
+			break;
+		case 'warning':
+			$classes .= ' notice-warning';
+			break;
+		case 'error':
+			$classes .= ' notice-error';
+			break;
+		case 'info':
+		default:
+			$classes .= ' notice-info';
+	}
+
+	if ( $dismissible ) {
+		$classes .= ' is-dismissible';
+	}
+
+	add_action( 'admin_notices', function () use ( $classes, $message ) {
+		ob_start();
+		?>
+		<div class="<?php echo $classes; ?>">
+			<p><?php _e( $message, 'nmsp-plugin-name-text-domain' ); ?></p>
+		</div>
+		<?php
+		echo ob_get_clean();
+	});
+}