Inventory_Presser_Plugin::modify_query_orderby( array $pieces )

		public function modify_query_orderby( $pieces ) {
			/**
			 * Count the number of meta fields we have added to the query by parsing
			 * the join piece of the query
			 */
			global $wpdb;
			$meta_field_count = count( explode( "INNER JOIN $wpdb->postmeta AS", $pieces['join'] ) ) - 1;

			// Parse out the ASC or DESC sort direction from the end of the ORDER BY clause.
			$direction             = $this->get_last_word( $pieces['orderby'] );
			$acceptable_directions = array( 'ASC', 'DESC' );
			$direction             = ( in_array( $direction, $acceptable_directions, true ) ? ' ' . $direction : '' );

			/**
			 * Build a string to replace the existing ORDER BY field name
			 * Essentially, we are going to turn 'wp_postmeta.meta_value' into
			 * 'mt1.meta_value ASC, mt2.meta_value ASC, mt3.meta_value ASC'
			 * where the number of meta values is what we calculated in $meta_field_count
			 */
			if ( 0 < $meta_field_count ) {
				$replacement = $pieces['orderby'] . ', ';
				for ( $m = 0; $m < $meta_field_count; $m++ ) {
					$replacement .= 'mt' . ( $m + 1 ) . '.meta_value';
					/**
					 * Determine if this meta field should be sorted as a number
					 * 1. Parse out the meta key name from $pieces['where']
					 * 2. Run it through INVP::meta_value_is_number
					 */
					$field_start = strpos( $pieces['where'], 'mt' . ( $m + 1 ) . '.meta_key = \'' ) + 16;
					$field_end   = strpos( $pieces['where'], "'", $field_start ) - $field_start;
					$field_name  = substr( $pieces['where'], $field_start, $field_end );
					if ( INVP::meta_value_is_number( $field_name ) ) {
						$replacement .= '+0';
					}

					$replacement .= $direction;
					if ( $m < ( $meta_field_count - 1 ) ) {
						$replacement .= ', ';
					}
				}

				$pieces['orderby'] = $replacement;
			}
			return $pieces;
		}