The Events Calendar Shortcode Month Attribute

<?php
/***
 Plugin Name: The Events Calendar Shortcode
 Plugin URI: http://dandelionwebdesign.com/downloads/shortcode-modern-tribe/
 Description: An addon to add shortcode functionality for <a href="http://wordpress.org/plugins/the-events-calendar/">The Events Calendar Plugin (Free Version) by Modern Tribe</a>.
 Version: 1.0.6
 Author: Dandelion Web Design Inc.
 Author URI: http://dandelionwebdesign.com
 License: GPL2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
*/

// Avoid direct calls to this file
if ( !defined( 'ABSPATH' ) ) {
    header( 'Status: 403 Forbidden' );
    header( 'HTTP/1.1 403 Forbidden' );
    exit();
}

/**
 * Events calendar shortcode addon main class
 *
 * @package events-calendar-shortcode
 * @author Dandelion Web Design Inc.
 * @version 1.0.0
 */
class Events_Calendar_Shortcode
{
    /**
     * Current version of the plugin.
     *
     * @since 1.0.0
     */
    const VERSION = '1.0.6';

    /**
     * Constructor. Hooks all interactions to initialize the class.
     *
     * @since 1.0.0
     * @access public
     *
     * @see  add_shortcode()
     */
    public function __construct()
    {
        add_shortcode('ecs-list-events', array($this, 'ecs_fetch_events') ); // link new function to shortcode name
    } // END __construct()

    /**
     * Fetch and return required events.
     * @param  array $atts  shortcode attributes
     * @return string   shortcode output
     */
    public function ecs_fetch_events( $atts )
    {
        /**
         * Check if events calendar plugin method exists
         */
        if ( !function_exists( 'tribe_get_events' ) ) {
            return;
        }

        global $wp_query, $post;
        $output = '';
        $ecs_event_tax = '';

        extract( shortcode_atts( array(
            'cat' => '',
            'limit' => 5,
            'eventdetails' => 'true',
            'venue' => 'false',
            'message' => 'There are no upcoming events at this time.',
            'order' => 'ASC',
            'viewall' => 'false',
            'excerpt' => 'false',
            'thumb' => 'false',
            'thumbwidth' => '',
            'thumbheight' => ''
        ), $atts, 'ecs-list-events' ), EXTR_PREFIX_ALL, 'ecs' );

        if ($ecs_cat) {
            $ecs_event_tax = array(
                array(
                    'taxonomy' => 'tribe_events_cat',
                    'field' => 'slug',
                    'terms' => $ecs_cat
                )
            );
        }

        $posts = get_posts( array(
                'post_type' => 'tribe_events',
                'posts_per_page' => $ecs_limit,
                'tax_query'=> $ecs_event_tax,
                'meta_key' => '_EventEndDate',
                'orderby' => 'meta_value',
                'order' => $ecs_order,
                'meta_query' => array(
                                    array(
                                        'key' => '_EventEndDate',
                                        'value' => date('Y-m-d'),
                                        'compare' => '>=',
                                        'type' => 'DATETIME'
                                    )
                                )
        ) );

        if ($posts) {

            $output .= '<ul class="ecs-event-list">';
            foreach( $posts as $post ) :
                setup_postdata( $post );
                $output .= '<li class="ecs-event">';
                    $output .= '<h4 class="entry-title summary">' .
                                    '<a href="' . tribe_get_event_link() . '" rel="bookmark">' . get_the_title() . '</a>
                                </h4>';

                    if( self::isValid($ecs_thumb) ) {
                        $thumbWidth = is_numeric($ecs_thumbwidth) ? $ecs_thumbwidth : '';
                        $thumbHeight = is_numeric($ecs_thumbheight) ? $ecs_thumbheight : '';
                        if( !empty($thumbWidth) && !empty($thumbHeight) ) {
                            $output .= get_the_post_thumbnail(get_the_ID(), array($thumbWidth, $thumbHeight) );
                        } else {
                            $output .= get_the_post_thumbnail(get_the_ID(), 'medium');
                        }
                    }

                    if( self::isValid($ecs_excerpt) ) {
                        $excerptLength = is_numeric($ecs_excerpt) ? $ecs_excerpt : 100;
                        $output .= '<p class="ecs-excerpt">' .
                                        self::get_excerpt($excerptLength) .
                                    '</p>';
                    }

                    if( self::isValid($ecs_eventdetails) ) {
                        $output .= '<span class="duration time">' . tribe_events_event_schedule_details() . '</span>';
                    }

                    if( self::isValid($ecs_venue) ) {
                        $output .= '<span class="duration venue"><em> at </em>' . tribe_get_venue() . '</span>';
                    }
                $output .= '</li>';
            endforeach;
            $output .= '</ul>';

            if( self::isValid($ecs_viewall) ) {
                $output .= '<span class="ecs-all-events"><a href="' . tribe_get_events_link() . '" rel="bookmark">' . translate( 'View All Events', 'tribe-events-calendar' ) . '</a></span>';
            }

        } else { //No Events were Found
            $output .= translate( $ecs_message, 'tribe-events-calendar' );
        } // endif

        wp_reset_query();

        return $output;
    }

    /**
     * Checks if the plugin attribute is valid
     *
     * @since 1.0.5
     *
     * @param string $prop
     * @return boolean
     */
    private function isValid( $prop )
    {
        return ($prop !== 'false');
    }

    /**
     * Fetch and trims the excerpt to specified length
     *
     * @param integer $limit Characters to show
     * @param string $source  content or excerpt
     *
     * @return string
     */
    private function get_excerpt( $limit, $source = null )
    {
        $excerpt = get_the_excerpt();
        if( $source == "content" ) {
            $excerpt = get_the_content();
        }

        $excerpt = preg_replace(" (\[.*?\])", '', $excerpt);
        $excerpt = strip_tags( strip_shortcodes($excerpt) );
        $excerpt = substr($excerpt, 0, $limit);
        $excerpt = trim(preg_replace( '/\s+/', ' ', $excerpt));
        $excerpt .= '...';

        return $excerpt;
    }
}

/**
 * Instantiate the main class
 *
 * @since 1.0.0
 * @access public
 *
 * @var object  $events_calendar_shortcode holds the instantiated class {@uses Events_Calendar_Shortcode}
 */
global $events_calendar_shortcode;
$events_calendar_shortcode = new Events_Calendar_Shortcode();