class.mph-minify-notices.php

<?php

if ( ! class_exists( 'MPH_Admin_Notices' ) ) {

	/**
	 *	MPH Notices
	 *
	 * 	Abstraction for displaying admin notices across a site.
	 * 	Errors on the front end can easily be stored and displayed in the admin.
	 *
	 *	@param  $ID Unique id. Multiple instances of the class wishing to access the same data should use the same ID.
	 *
	 */
	class MPH_Admin_Notices {

		private $admin_notices = array();

		private $ID;

		function __construct( $ID = 'mph' ) {

			$this->ID = 'mphan_' . $ID;

			if ( ! get_option( $this->ID ) )
				add_option( $this->ID, array(), null, 'no' );
			else
				$this->admin_notices = get_option( $this->ID, array() );

			if ( isset( $_GET[ $this->ID . '_notice_dismiss' ] ) || isset( $_GET['_wpnonce'] ) )
				add_action( 'admin_init', array( $this, 'delete_notice_action' ) );

			add_action( 'admin_notices', array( $this, 'display_admin_notices' ) );

			add_action( 'shutdown', array( $this, '_update_notices' ) );

		}

		/**
		 * Creates an admin notice - saved in options to be shown in the admin, until dismissed.
		 *
		 * @param string $new_notice Message content
		 * @param string $type Message type - added as a class to the message when displayed. Reccommended to use: updated, error.
		 * @param bool $display_once Display message once, or require manual dismissal.
		 */
		public function add_notice( $message, $display_once = false, $type = 'updated' ) {

			$notice = array(
				'message' => $message,
				'type' => $type,
				'display_once' => $display_once
			);

			if ( ! in_array( $notice , $this->admin_notices ) )
				$this->admin_notices[uniqid()] = $notice;

		}

		public function _update_notices() {

			$this->admin_notices = array_filter( $this->admin_notices );

			if ( empty( $this->admin_notices ) ) {
				delete_option( $this->ID );
			} else {
				update_option( $this->ID, $this->admin_notices );
			}

		}

		/**
		 * Output all notices in the admin.
		 *
		 * @return null
		 */
		public function display_admin_notices() {

			// Display admin notices
			foreach ( array_keys( $this->admin_notices ) as $notice_id )
				$this->display_admin_notice( $notice_id );

		}

		/**
		 * Output an individual notice.
		 *
		 * @param  string $notice_id The notice id (or key)
		 * @return null
		 */
		private function display_admin_notice ( $notice_id ) {

			if ( ! $notice = $this->admin_notices[$notice_id] )
				return;

			?>

			<div class="<?php echo esc_attr( $notice['type'] ); ?> ' fade">

				<p>

					<?php echo $notice['message']; ?>

					<?php if ( empty( $notice['display_once'] ) ) : ?>
						<a class="button" style="margin-left: 10px; color: inherit; text-decoration: none;" href="<?php echo wp_nonce_url( add_query_arg( $this->ID . '_notice_dismiss', $notice_id ), $this->ID . '_notice_dismiss' ); ?>">Dismiss</a>
					<?php endif; ?>

				</p>

			</div>

			<?php

			if ( $notice['display_once'] )
				$this->unset_admin_notice( $notice_id );

		}

		/**
		 * Remove an admin notice by key from $this->admin_notices
		 *
		 * @param  string $notice_id Notice ID (or key)
		 * @return null
		 */
		private function unset_admin_notice( $notice_id ) {

			if ( array_key_exists( $notice_id, $this->admin_notices ) )
				unset( $this->admin_notices[$notice_id] );

		}

		/**
		 * Deletes an admin notice.
		 *
		 * Requirements:
		 * $this->ID . '_notice_dismiss' nonce verification
		 * value of $_GET[$this->ID . '_notice_dismiss'] si the ID of the notice to be deleted.
		 *
		 * @param null
		 * @return null
		 */
		public function delete_notice_action() {

			if ( ! wp_verify_nonce( $_GET['_wpnonce'], $this->ID . '_notice_dismiss' ) )
				return;

			$this->unset_admin_notice( $_GET[$this->ID . '_notice_dismiss'] );

		}

	}
}