WordPress plugin created by ChatGPT (https://i.wpfusion.com/8p22pV)

my-plugin.php

<?php

// Define a class for our plugin
class MyPlugin {
	// Define a static property to hold the single instance of the class
	private static $instance;

	// Define a private constructor to prevent the class from being instantiated directly
	private function __construct() {
		// Add the admin settings page to the WordPress admin menu
		add_action( 'admin_menu', array( $this, 'add_admin_menu' ) );

		// Register a callback function to save the plugin settings
		add_action( 'admin_post_my_plugin_save_settings', array( $this, 'save_settings' ) );
	}

	// Define a public static function to return the single instance of the class
	public static function get_instance() {
		if ( ! isset( self::$instance ) ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	// Define a function to add the admin settings page to the WordPress admin menu
	public function add_admin_menu() {
		add_options_page( 'My Plugin Settings', 'My Plugin', 'manage_options', 'my-plugin', array( $this, 'render_settings_page' ) );
	}

	// Define a function to render the admin settings page
	public function render_settings_page() {
		?>
		<div class="wrap">
			<h2>My Plugin Settings</h2>
			<form action="<?php echo admin_url( 'admin-post.php' ); ?>" method="post">
				<input type="hidden" name="action" value="my_plugin_save_settings">
				<table class="form-table">
					<tbody>
						<tr>
							<th scope="row">
								<label for="my-plugin-setting">My Setting</label>
							</th>
							<td>
								<input type="text" id="my-plugin-setting" name="my-plugin-setting" value="<?php echo get_option( 'my-plugin-setting' ); ?>">
							</td>
						</tr>
					</tbody>
				</table>
				<p class="submit">
					<input type="submit" name="submit" id="submit" class="button button-primary" value="Save Settings">
				</p>
			</form>
		</div>
		<?php
	}
	
	// Define a function to save the plugin settings
	public function save_settings() {
		// Check that the current user has permission to save plugin settings
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( 'Insufficient permissions' );
		}
		
		// Save the plugin setting
		update_option( 'my-plugin-setting', $_POST['my-plugin-setting'] );

		// Redirect the user back to the admin settings page
		wp_redirect( admin_url( 'options-general.php?page=my-plugin' ) );
		exit;
}
}

// Initialize the plugin by calling the get_instance() method of the singleton class
MyPlugin::get_instance();