Filter extension for the Event Post Widget: "Show only post from the current month and the current year"

functinos.php

<?php
/*
 * Filter extension for the Event Post Widget: "Show only post from the current month and the current year" 
 * @url https://wordpress.org/plugins/event-post/
 */

function cpwp_add_extensions_panel( $widget, $instance ) {

	$instance = wp_parse_args( ( array ) $instance, array(
		'use_current_month_filter' => ''
	) );
	$use_current_month_filter = $instance['use_current_month_filter'];
			
	echo '<p>'.
			'<label for="'.$widget->get_field_id('use_current_month_filter').'">'.
				'<input type="checkbox" class="checkbox" id="'.$widget->get_field_id('use_current_month_filter').'" name="'.$widget->get_field_name('use_current_month_filter').'" ';
	echo			checked( (bool) $instance["use_current_month_filter"], true ).' />';
	echo		_e( 'Use "Current month" filter extention','categorypostspro' ).
			'</label>'.
		'</p>';
}
add_filter('cpwp_bottom_mysettings_panel','cpwp_add_extensions_panel', 10, 2);


function cpwp_get_posts_of_current_month ( $query, $widget, $instance ) {
	if(isset($instance['use_current_month_filter'])&&$instance['use_current_month_filter']) {	
		
		$firstDay = date('Y-m-d',strtotime("first day of this month"));
		$lastDay = date('Y-m-d',strtotime("last day of this month"));
		
		$query['meta_query'] = array_merge( $query, array(
				'relation' => 'AND',
				array(
					'key' => 'event_end',
					'value' => $firstDay,
					'compare' => '>=',
					'type' => 'DATETIME'
				),
				array(
					'key' => 'event_begin',
					'value' => $lastDay,
					'compare' => '<=',
					'type' => 'DATETIME'
				)
			)
		);
	}
	return $query;
}
add_filter( 'cpwp_query_args', 'cpwp_get_posts_of_current_month', 10, 3 );