get_attendee_info()

function get_attendee_info( $attendees = false, $booking_info = false, $event_post_id = false ) {

    if ( false != $attendees ) {

        $allowed             = get_field( 'idf_allowed_categories', $event_post_id ) ? get_field( 'idf_allowed_categories', $event_post_id ) : false;
        $ice_name            = false;
        $ice_number          = false;
        $categories_array    = array();
        $category_categories = '';
        $shirt_size          = false;

        if ( 1 == $allowed ) { // if allowed classes is 1
            foreach ( $attendees as $key => $value ) {
                foreach ( $value as $key_attendee => $value_attendee ) {
                    // echo '<pre>'; var_dump($value_attendee); echo '</pre>'; exit;
                    $categories_array[] = $value_attendee[ 'attendee_categories' ];
                    if ( isset( $value_attendee[ 'attendee_shirt' ] ) ) {
                        $shirt_size = $value_attendee[ 'attendee_shirt' ];
                    }
                }
            }
        } elseif ( 2 == $allowed ) {
            foreach ( $attendees as $key => $value ) {
                foreach ( $value as $key_attendee => $value_attendee ) {
                    // echo '<pre>'; var_dump($value_attendee); echo '</pre>'; exit;
                    if ( is_array( $value_attendee[ 'attendee_categories' ] ) ) {
                        foreach ( $value_attendee[ 'attendee_categories' ] as $category ) {
                            $categories_array[] = $category;
                            if ( isset( $value_attendee[ 'attendee_shirt' ] ) ) {
                                $shirt_size = $value_attendee[ 'attendee_shirt' ];
                            }
                        }
                    } else {
                        $categories_array[] = $value_attendee[ 'attendee_categories' ];
                        if ( isset( $value_attendee[ 'attendee_shirt' ] ) ) {
                            $shirt_size = $value_attendee[ 'attendee_shirt' ];
                        }
                    }
                }
            }
        }

        if ( false == $shirt_size ) {
            $shirt_size = isset( $booking_info->booking_meta[ 'booking' ][ 'shirt_size' ] ) ? $booking_info->booking_meta[ 'booking' ][ 'shirt_size' ] : false;
            if ( false == $shirt_size ) {
                $shirt_size = isset( $booking_info->booking_meta[ 'booking' ][ 'tshirt_size' ] ) ? $booking_info->booking_meta[ 'booking' ][ 'tshirt_size' ] : false;
            }
        }
        $vegi_food  = isset( $booking_info->booking_meta[ 'booking' ][ 'vegi_food' ] ) ? $booking_info->booking_meta[ 'booking' ][ 'vegi_food' ] : false;
        if ( false == $ice_name ) {
            // $ice_name   = isset( $booking_info->booking_meta[ 'booking' ][ 'ice_name' ] ) ? $booking_info->booking_meta[ 'booking' ][ 'ice_name' ] : false;
            // $ice_number = isset( $booking_info->booking_meta[ 'booking' ][ 'ice_number' ] ) ? $booking_info->booking_meta[ 'booking' ][ 'ice_number' ] : false;
        }

        if ( 1 == count( $categories_array ) ) {
            $category_categories = 'Category: ';
        } elseif ( 2 == count( $categories_array ) ) {
            $category_categories = 'Categories: ';
        }

        $category_string     = implode( ' + ', $categories_array );
        $booking_info_output = '';
        if ( $categories_array ) {
            $booking_info_output .= $category_categories . ' ' . $category_string;
        }
        if ( false != $shirt_size ) {
            $booking_info_output .= '<br />';
            $booking_info_output .= 'Shirt size: ' . $shirt_size;
        }
        if ( false != $vegi_food ) {
            $booking_info_output .= '<br />';
            $booking_info_output .= 'Food: vegi';
        }
        if ( false != $ice_name ) {
            // $booking_info_output .= '<br />';
            // $booking_info_output .= 'ICE: ' . $ice_name;
        }

        return $booking_info_output;
    }

    return false;
}