ed <= '$datetime_str'" );
			}
		}

		if ( isset( $query_args['after'] ) && '' !== $query_args['after'] ) {
			if ( is_a( $query_args['after'], 'WC_DateTime' ) ) {
				$datetime_str = $query_args['after']->date( TimeInterval::$sql_datetime_format );
			} else {
				$datetime_str = $query_args['after']->format( TimeInterval::$sql_datetime_format );
			}
			if ( isset( $this->subquery ) ) {
				$this->subquery->add_sql_clause( 'where_time', "AND {$table_name}.date_created >= '$datetime_str'" );
			} else {
				$this->add_sql_clause( 'where_time', "AND {$table_name}.date_created >= '$datetime_str'" );
			}
		}
	}

	/**
	 * Fills LIMIT clause of SQL request based on user supplied parameters.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_limit_sql_params( $query_args ) {
		global $wpdb;
		$params = $this->get_limit_params( $query_args );

		$this->clear_sql_clause( 'limit' );
		$this->add_sql_clause( 'limit', $wpdb->prepare( 'LIMIT %d, %d', $params['offset'], $params['per_page'] ) );
		return $params;
	}

	/**
	 * Fills LIMIT parameters of SQL request based on user supplied parameters.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_limit_params( $query_args = array() ) {
		if ( isset( $query_args['per_page'] ) && is_numeric( $query_args['per_page'] ) ) {
			$this->limit_parameters['per_page'] = (int) $query_args['per_page'];
		} else {
			$this->limit_parameters['per_page'] = get_option( 'posts_per_page' );
		}

		$this->limit_parameters['offset'] = 0;
		if ( isset( $query_args['page'] ) ) {
			$this->limit_parameters['offset'] = ( (int) $query_args['page'] - 1 ) * $this->limit_parameters['per_page'];
		}

		return $this->limit_parameters;
	}

	/**
	 * Generates a virtual table given a list of IDs.
	 *
	 * @param array $ids          Array of IDs.
	 * @param array $id_field     Name of the ID field.
	 * @param array $other_values Other values that must be contained in the virtual table.
	 * @return array
	 */
	protected function get_ids_table( $ids, $id_field, $other_values = array() ) {
		global $wpdb;
		$selects = array();
		foreach ( $ids as $id ) {
			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			$new_select = $wpdb->prepare( "SELECT %s AS {$id_field}", $id );
			foreach ( $other_values as $key => $value ) {
				$new_select .= $wpdb->prepare( ", %s AS {$key}", $value );
			}
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			array_push( $selects, $new_select );
		}
		return join( ' UNION ', $selects );
	}

	/**
	 * Returns a comma separated list of the fields in the `query_args`, if there aren't, returns `report_columns` keys.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_fields( $query_args ) {
		if ( isset( $query_args['fields'] ) && is_array( $query_args['fields'] ) ) {
			return $query_args['fields'];
		}
		return array_keys( $this->report_columns );
	}

	/**
	 * Returns a comma separated list of the field names prepared to be used for a selection after a join with `default_results`.
	 *
	 * @param array $fields                 Array of fields name.
	 * @param array $default_results_fields Fields to load from `default_results` table.
	 * @param array $outer_selections       Array of fields that are not selected in the inner query.
	 * @return string
	 */
	protected function format_join_selections( $fields, $default_results_fields, $outer_selections = array() ) {
		foreach ( $fields as $i => $field ) {
			foreach ( $default_results_fields as $default_results_field ) {
				if ( $field === $default_results_field ) {
					$field        = esc_sql( $field );
					$fields[ $i ] = "default_results.{$field} AS {$field}";
				}
			}
			if ( in_array( $field, $outer_selections, true ) && array_key_exists( $field, $this->report_columns ) ) {
				$fields[ $i ] = $this->report_columns[ $field ];
			}
		}
		return implode( ', ', $fields );
	}

	/**
	 * Fills ORDER BY clause of SQL request based on user supplied parameters.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 */
	protected function add_order_by_sql_params( $query_args ) {
		if ( isset( $query_args['orderby'] ) ) {
			$order_by_clause = $this->normalize_order_by( esc_sql( $query_args['orderby'] ) );
		} else {
			$order_by_clause = '';
		}

		$this->clear_sql_clause( 'order_by' );
		$this->add_sql_clause( 'order_by', $order_by_clause );
		$this->add_orderby_order_clause( $query_args, $this );
	}

	/**
	 * Fills FROM and WHERE clauses of SQL request for 'Intervals' section of data response based on user supplied parameters.
	 *
	 * @param array  $query_args Parameters supplied by the user.
	 * @param string $table_name Name of the db table relevant for the date constraint.
	 */
	protected function add_intervals_sql_params( $query_args, $table_name ) {
		$this->clear_sql_clause( array( 'from', 'where_time', 'where' ) );

		$this->add_time_period_sql_params( $query_args, $table_name );

		if ( isset( $query_args['interval'] ) && '' !== $query_args['interval'] ) {
			$interval = $query_args['interval'];
			$this->clear_sql_clause( 'select' );
			$this->add_sql_clause( 'select', TimeInterval::db_datetime_format( $interval, $table_name ) );
		}
	}

	/**
	 * Get join and where clauses for refunds based on user supplied parameters.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_refund_subquery( $query_args ) {
		global $wpdb;
		$table_name = $wpdb->prefix . 'wc_order_stats';
		$sql_query  = array(
			'where_clause' => '',
			'from_clause'  => '',
		);

		if ( ! isset( $query_args['refunds'] ) ) {
			return $sql_query;
		}

		if ( 'all' === $query_args['refunds'] ) {
			$sql_query['where_clause'] .= 'parent_id != 0';
		}

		if ( 'none' === $query_args['refunds'] ) {
			$sql_query['where_clause'] .= 'parent_id = 0';
		}

		if ( 'full' === $query_args['refunds'] || 'partial' === $query_args['refunds'] ) {
			$operator                   = 'full' === $query_args['refunds'] ? '=' : '!=';
			$sql_query['from_clause']  .= " JOIN {$table_name} parent_order_stats ON {$table_name}.parent_id = parent_order_stats.order_id";
			$sql_query['where_clause'] .= "parent_order_stats.status {$operator} '{$this->normalize_order_status( 'refunded' )}'";
		}

		return $sql_query;
	}

	/**
	 * Returns an array of products belonging to given categories.
	 *
	 * @param array $categories List of categories IDs.
	 * @return array|stdClass
	 */
	protected function get_products_by_cat_ids( $categories ) {
		$terms = get_terms(
			array(
				'taxonomy' => 'product_cat',
				'include'  => $categories,
			)
		);

		if ( is_wp_error( $terms ) || empty( $terms ) ) {
			return array();
		}

		$args = array(
			'category' => wc_list_pluck( $terms, 'slug' ),
			'limit'    => -1,
			'return'   => 'ids',
		);
		return wc_get_products( $args );
	}

	/**
	 * Get WHERE filter by object ids subquery.
	 *
	 * @param string $select_table Select table name.
	 * @param string $select_field Select table object ID field name.
	 * @param string $filter_table Lookup table name.
	 * @param string $filter_field Lookup table object ID field name.
	 * @param string $compare      Comparison string (IN|NOT IN).
	 * @param string $id_list      Comma separated ID list.
	 *
	 * @return string
	 */
	protected function get_object_where_filter( $select_table, $select_field, $filter_table, $filter_field, $compare, $id_list ) {
		global $wpdb;
		if ( empty( $id_list ) ) {
			return '';
		}

		$lookup_name = isset( $wpdb->$filter_table ) ? $wpdb->$filter_table : $wpdb->prefix . $filter_table;
		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		return " {$select_table}.{$select_field} {$compare} (
			SELECT
				DISTINCT {$filter_table}.{$select_field}
			FROM
				{$filter_table}
			WHERE
				{$filter_table}.{$filter_field} IN ({$id_list})
		)";
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
	}

	/**
	 * Returns an array of ids of allowed products, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_included_products_array( $query_args ) {
		$included_products = array();
		$operator          = $this->get_match_operator( $query_args );

		if ( isset( $query_args['category_includes'] ) && is_array( $query_args['category_includes'] ) && count( $query_args['category_includes'] ) > 0 ) {
			$included_products = $this->get_products_by_cat_ids( $query_args['category_includes'] );

			// If no products were found in the specified categories, we will force an empty set
			// by matching a product ID of -1, unless the filters are OR/any and products are specified.
			if ( empty( $included_products ) ) {
				$included_products = array( '-1' );
			}
		}

		if ( isset( $query_args['product_includes'] ) && is_array( $query_args['product_includes'] ) && count( $query_args['product_includes'] ) > 0 ) {
			if ( count( $included_products ) > 0 ) {
				if ( 'AND' === $operator ) {
					// AND results in an intersection between products from selected categories and manually included products.
					$included_products = array_intersect( $included_products, $query_args['product_includes'] );
				} elseif ( 'OR' === $operator ) {
					// OR results in a union of products from selected categories and manually included products.
					$included_products = array_merge( $included_products, $query_args['product_includes'] );
				}
			} else {
				$included_products = $query_args['product_includes'];
			}
		}

		return $included_products;
	}

	/**
	 * Returns comma separated ids of allowed products, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_included_products( $query_args ) {
		$included_products = $this->get_included_products_array( $query_args );
		return implode( ',', $included_products );
	}

	/**
	 * Returns comma separated ids of allowed variations, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_included_variations( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'variation_includes' );
	}

	/**
	 * Returns comma separated ids of excluded variations, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_excluded_variations( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'variation_excludes' );
	}

	/**
	 * Returns an array of ids of disallowed products, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return array
	 */
	protected function get_excluded_products_array( $query_args ) {
		$excluded_products = array();
		$operator          = $this->get_match_operator( $query_args );

		if ( isset( $query_args['category_excludes'] ) && is_array( $query_args['category_excludes'] ) && count( $query_args['category_excludes'] ) > 0 ) {
			$excluded_products = $this->get_products_by_cat_ids( $query_args['category_excludes'] );
		}

		if ( isset( $query_args['product_excludes'] ) && is_array( $query_args['product_excludes'] ) && count( $query_args['product_excludes'] ) > 0 ) {
			$excluded_products = array_merge( $excluded_products, $query_args['product_excludes'] );
		}

		return $excluded_products;
	}

	/**
	 * Returns comma separated ids of excluded products, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_excluded_products( $query_args ) {
		$excluded_products = $this->get_excluded_products_array( $query_args );
		return implode( ',', $excluded_products );
	}

	/**
	 * Returns comma separated ids of included categories, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_included_categories( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'category_includes' );
	}

	/**
	 * Returns comma separated ids of included coupons, based on query arguments from the user.
	 *
	 * @param array  $query_args Parameters supplied by the user.
	 * @param string $field      Field name in the parameter list.
	 * @return string
	 */
	protected function get_included_coupons( $query_args, $field = 'coupon_includes' ) {
		return $this->get_filtered_ids( $query_args, $field );
	}

	/**
	 * Returns comma separated ids of excluded coupons, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_excluded_coupons( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'coupon_excludes' );
	}

	/**
	 * Returns comma separated ids of included orders, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_included_orders( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'order_includes' );
	}

	/**
	 * Returns comma separated ids of excluded orders, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_excluded_orders( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'order_excludes' );
	}

	/**
	 * Returns comma separated ids of included users, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_included_users( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'user_includes' );
	}

	/**
	 * Returns comma separated ids of excluded users, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_excluded_users( $query_args ) {
		return $this->get_filtered_ids( $query_args, 'user_excludes' );
	}

	/**
	 * Returns order status subquery to be used in WHERE SQL query, based on query arguments from the user.
	 *
	 * @param array  $query_args Parameters supplied by the user.
	 * @param string $operator   AND or OR, based on match query argument.
	 * @return string
	 */
	protected function get_status_subquery( $query_args, $operator = 'AND' ) {
		global $wpdb;

		$subqueries        = array();
		$excluded_statuses = array();
		if ( isset( $query_args['status_is'] ) && is_array( $query_args['status_is'] ) && count( $query_args['status_is'] ) > 0 ) {
			$allowed_statuses = array_map( array( $this, 'normalize_order_status' ), esc_sql( $query_args['status_is'] ) );
			if ( $allowed_statuses ) {
				$subqueries[] = "{$wpdb->prefix}wc_order_stats.status IN ( '" . implode( "','", $allowed_statuses ) . "' )";
			}
		}

		if ( isset( $query_args['status_is_not'] ) && is_array( $query_args['status_is_not'] ) && count( $query_args['status_is_not'] ) > 0 ) {
			$excluded_statuses = array_map( array( $this, 'normalize_order_status' ), $query_args['status_is_not'] );
		}

		if ( ( ! isset( $query_args['status_is'] ) || empty( $query_args['status_is'] ) )
			&& ( ! isset( $query_args['status_is_not'] ) || empty( $query_args['status_is_not'] ) )
		) {
			$excluded_statuses = array_map( array( $this, 'normalize_order_status' ), $this->get_excluded_report_order_statuses() );
		}

		if ( $excluded_statuses ) {
			$subqueries[] = "{$wpdb->prefix}wc_order_stats.status NOT IN ( '" . implode( "','", $excluded_statuses ) . "' )";
		}

		return implode( " $operator ", $subqueries );
	}

	/**
	 * Add order status SQL clauses if included in query.
	 *
	 * @param array    $query_args Parameters supplied by the user.
	 * @param string   $table_name Database table name.
	 * @param SqlQuery $sql_query  Query object.
	 */
	protected function add_order_status_clause( $query_args, $table_name, &$sql_query ) {
		global $wpdb;
		$order_status_filter = $this->get_status_subquery( $query_args );
		if ( $order_status_filter ) {
			$sql_query->add_sql_clause( 'join', "JOIN {$wpdb->prefix}wc_order_stats ON {$table_name}.order_id = {$wpdb->prefix}wc_order_stats.order_id" );
			$sql_query->add_sql_clause( 'where', "AND ( {$order_status_filter} )" );
		}
	}

	/**
	 * Add order by SQL clause if included in query.
	 *
	 * @param array    $query_args Parameters supplied by the user.
	 * @param SqlQuery $sql_query  Query object.
	 * @return string Order by clause.
	 */
	protected function add_order_by_clause( $query_args, &$sql_query ) {
		$order_by_clause = '';

		$sql_query->clear_sql_clause( array( 'order_by' ) );
		if ( isset( $query_args['orderby'] ) ) {
			$order_by_clause = $this->normalize_order_by( esc_sql( $query_args['orderby'] ) );
			$sql_query->add_sql_clause( 'order_by', $order_by_clause );
		}

		// Return ORDER BY clause to allow adding the sort field(s) to query via a JOIN.
		return $order_by_clause;
	}

	/**
	 * Add order by order SQL clause.
	 *
	 * @param array    $query_args Parameters supplied by the user.
	 * @param SqlQuery $sql_query  Query object.
	 */
	protected function add_orderby_order_clause( $query_args, &$sql_query ) {
		if ( isset( $query_args['order'] ) ) {
			$sql_query->add_sql_clause( 'order_by', esc_sql( $query_args['order'] ) );
		} else {
			$sql_query->add_sql_clause( 'order_by', 'DESC' );
		}
	}

	/**
	 * Returns customer subquery to be used in WHERE SQL query, based on query arguments from the user.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_customer_subquery( $query_args ) {
		global $wpdb;

		$customer_filter = '';
		if ( isset( $query_args['customer_type'] ) ) {
			if ( 'new' === strtolower( $query_args['customer_type'] ) ) {
				$customer_filter = " {$wpdb->prefix}wc_order_stats.returning_customer = 0";
			} elseif ( 'returning' === strtolower( $query_args['customer_type'] ) ) {
				$customer_filter = " {$wpdb->prefix}wc_order_stats.returning_customer = 1";
			}
		}

		return $customer_filter;
	}

	/**
	 * Returns product attribute subquery elements used in JOIN and WHERE clauses,
	 * based on query arguments from the user.
	 *
	 * @param array  $query_args Parameters supplied by the user.
	 * @param string $table_name Database table name.
	 * @return array
	 */
	protected function get_attribute_subqueries( $query_args, $table_name ) {
		global $wpdb;

		$sql_clauses           = array(
			'join'  => array(),
			'where' => array(),
		);
		$match_operator        = $this->get_match_operator( $query_args );
		$post_meta_comparators = array(
			'='  => 'attribute_is',
			'!=' => 'attribute_is_not',
		);

		foreach ( $post_meta_comparators as $comparator => $arg ) {
			if ( ! isset( $query_args[ $arg ] ) || ! is_array( $query_args[ $arg ] ) ) {
				continue;
			}
			foreach ( $query_args[ $arg ] as $attribute_term ) {
				// We expect tuples.
				if ( ! is_array( $attribute_term ) || 2 !== count( $attribute_term ) ) {
					continue;
				}

				// If the tuple is numeric, assume these are IDs.
				if ( is_numeric( $attribute_term[0] ) && is_numeric( $attribute_term[1] ) ) {
					$attribute_id = intval( $attribute_term[0] );
					$term_id      = intval( $attribute_term[1] );

					// Invalid IDs.
					if ( 0 === $attribute_id || 0 === $term_id ) {
						continue;
					}

					// @todo: Use wc_get_attribute () instead ?
					$attr_taxonomy = wc_attribute_taxonomy_name_by_id( $attribute_id );
					// Invalid attribute ID.
					if ( empty( $attr_taxonomy ) ) {
						continue;
					}

					$attr_term = get_term_by( 'id', $term_id, $attr_taxonomy );
					// Invalid term ID.
					if ( false === $attr_term ) {
						continue;
					}

					$meta_key   = sanitize_title( $attr_taxonomy );
					$meta_value = $attr_term->slug;
				} else {
					// Assume these are a custom attribute slug/value pair.
					$meta_key   = esc_sql( $attribute_term[0] );
					$meta_value = esc_sql( $attribute_term[1] );
				}

				$join_alias = 'orderitemmeta1';

				if ( empty( $sql_clauses['join'] ) ) {
					$table_name            = esc_sql( $table_name );
					$sql_clauses['join'][] = "JOIN {$wpdb->prefix}woocommerce_order_items orderitems ON orderitems.order_id = {$table_name}.order_id";
				}

				// If we're matching all filters (AND), we'll need multiple JOINs on postmeta.
				// If not, just one.
				if ( 'AND' === $match_operator || 1 === count( $sql_clauses['join'] ) ) {
					$join_idx              = count( $sql_clauses['join'] );
					$join_alias            = 'orderitemmeta' . $join_idx;
					$sql_clauses['join'][] = "JOIN {$wpdb->prefix}woocommerce_order_itemmeta as {$join_alias} ON {$join_alias}.order_item_id = orderitems.order_item_id";
				}

				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
				$sql_clauses['where'][] = $wpdb->prepare( "( {$join_alias}.meta_key = %s AND {$join_alias}.meta_value {$comparator} %s )", $meta_key, $meta_value );
			}
		}

		// If we're matching multiple attributes and all filters (AND), make sure
		// we're matching attributes on the same product.
		$num_attribute_filters = count( $sql_clauses['join'] );

		for ( $i = 2; $i < $num_attribute_filters; $i++ ) {
			$join_alias            = 'orderitemmeta' . $i;
			$sql_clauses['join'][] = "AND orderitemmeta1.order_item_id = {$join_alias}.order_item_id";
		}

		return $sql_clauses;
	}

	/**
	 * Returns logic operator for WHERE subclause based on 'match' query argument.
	 *
	 * @param array $query_args Parameters supplied by the user.
	 * @return string
	 */
	protected function get_match_operator( $query_args ) {
		$operator = 'AND';

		if ( ! isset( $query_args['match'] ) ) {
			return $operator;
		}

		if ( 'all' === strtolower( $query_args['match'] ) ) {
			$operator = 'AND';
		} elseif ( 'any' === strtolower( $query_args['match'] ) ) {
			$operator = 'OR';
		}
		return $operator;
	}

	/**
	 * Returns filtered comma separated ids, based on query arguments from the user.
	 *
	 * @param array  $query_args Parameters supplied by the user.
	 * @param string $field      Query field to filter.
	 * @param string $separator  Field separator.
	 * @return string
	 */
	protected function get_filtered_ids( $query_args, $field, $separator = ',' ) {
		global $wpdb;

		$ids_str = '';
		$ids     = isset( $query_args[ $field ] ) && is_array( $query_args[ $field ] ) ? $query_args[ $field ] : array();

		/**
		 * Filter the IDs before retrieving report data.
		 *
		 * Allows filtering of the objects included or excluded from reports.
		 *
		 * @param array  $ids        List of object Ids.
		 * @param array  $query_args The original arguments for the request.
		 * @param string $field      The object type.
		 * @param string $context    The data store context.
		 */
		$ids = apply_filters( 'woocommerce_analytics_' . $field, $ids, $query_args, $field, $this->context );

		if ( ! empty( $ids ) ) {
			$placeholders = implode( $separator, array_fill( 0, count( $ids ), '%d' ) );
			/* phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared */
			$ids_str = $wpdb->prepare( "{$placeholders}", $ids );
			/* phpcs:enable */
		}
		return $ids_str;
	}

	/**
	 * Assign report columns once full table name has been assigned.
	 */
	protected function assign_report_columns() {}
}