Show GP Premium Elements by date range - Add CMB2 metabox to show a GP Premium Element in a chosen date range.

gp-elements-filter-by-date-range.php

<?php
/*
Plugin Name: Show GP Premium Elements by date range
Plugin URI: https://www.damiencarbery.com/2022/10/show-gp-premium-elements-by-date-range/
Description: Add CMB2 metabox to show a GP Premium Element in a chosen date range.
Author: Damien Carbery
Version: 0.1
*/


class ShowGPElementByDate {
	// Returns an instance of this class. 
	public static function get_instance() {
		if ( null == self::$instance ) {
			self::$instance = new self();
		} 
		return self::$instance;
	}


	// Initialize the plugin variables.
	public function __construct() {
		$this->init();
	}


	// Set up WordPress specfic actions.
	public function init() {
		// Verify that CMB2 plugin is active.
		add_action( 'admin_notices', array( $this, 'verify_cmb2_active' ) );

		// Add the CMB2 metabox.
		add_action( 'cmb2_admin_init', array( $this, 'gp_elements_metaboxes' ) );

		// Retrieve the postmeta to determine whether to display the Element.
		add_filter( 'generate_element_display', array( $this, 'generate_element_display' ), 10, 2 );
	}


	public function gp_elements_metaboxes() {
		$cmb = new_cmb2_box( array(
			'id'            => 'gpe_dates',
			'title'         => 'Show Date Range',
			'object_types'  => array( 'gp_elements', ), // GP Premium Elements
		) );
		$cmb->add_field( array(
			'name' => 'Enter start and end dates',
			'desc' => 'Set the date range to show this element. Clear the fields to always show the element (considering Display Rules).',
			'type' => 'title',
			'id'   => 'gpe_dates_title'
		) );
		$cmb->add_field( array(
			'name'        => 'Start Date',
			'desc'        => 'When to start showing this element',
			'id'          => 'element_start_date',
			'type'        => 'text_date_timestamp',
			'date_format' => 'j M Y',
		) );
		$cmb->add_field( array(
			'name'        => 'End Date',
			'desc'        => 'When to stop showing this element',
			'id'          => 'element_end_date',
			'type'        => 'text_date_timestamp',
			'date_format' => 'j M Y',
		) );
	}


	public function generate_element_display( $display, $post_id ) {
		//error_log( 'GED $post_id: ' . $post_id );
		//error_log( 'GED Element title: ' . get_the_title( $post_id ) );
		
		if ( is_admin() ) { return $display; }
		
		$start_date = get_post_meta( $post_id, 'element_start_date', true );
		$end_date = get_post_meta( $post_id, 'element_end_date', true );
		//error_log( 'Start date: ' . var_export( $start_date, true ) );
		//error_log( 'End date: ' . var_export( $end_date, true ) );

		// Show this GP Element between the two dates.
		if ( !is_null( $start_date ) && !is_null( $end_date ) ) {
			$now = time();
			//error_log( 'Now: ' . var_export( $now, true ) );

			if ( $now >= $start_date && $now <= $end_date ) {
				return true;
			}
			else {
				return false;
			}
		}

		return $display;
	}


	// Verify that CMB2 plugin is active.
	public function verify_cmb2_active() {
		if ( ! defined( 'CMB2_LOADED' ) ) {
			$plugin_data = get_plugin_data( __FILE__ );
			$plugin_name = $plugin_data['Name'];
	?>
	<div class="notice notice-warning is-dismissible"><p>Plugin <strong><?php echo $plugin_name; ?></strong> requires <a href="https://wordpress.org/plugins/cmb2/">CMB2 plugin</a>.</p></div>
	<?php
			//error_log( 'CMB2 is not active.' );
		}
	}
}


$ShowGPElementByDate = new ShowGPElementByDate();