<?php
/**
 * API\Reports\Orders\Stats\DataStore class file.
 */

namespace Automattic\WooCommerce\Admin\API\Reports\Orders\Stats;

defined( 'ABSPATH' ) || exit;

use Automattic\WooCommerce\Admin\API\Reports\DataStore as ReportsDataStore;
use Automattic\WooCommerce\Admin\API\Reports\DataStoreInterface;
use Automattic\WooCommerce\Internal\Fulfillments\FulfillmentUtils;
use Automattic\WooCommerce\Admin\API\Reports\TimeInterval;
use Automattic\WooCommerce\Admin\API\Reports\SqlQuery;
use Automattic\WooCommerce\Admin\API\Reports\Cache as ReportsCache;
use Automattic\WooCommerce\Admin\API\Reports\Customers\DataStore as CustomersDataStore;
use Automattic\WooCommerce\Utilities\OrderUtil;
use Automattic\WooCommerce\Admin\API\Reports\StatsDataStoreTrait;
use Automattic\WooCommerce\Utilities\FeaturesUtil;
use WC_Order;

/**
 * API\Reports\Orders\Stats\DataStore.
 */
class DataStore extends ReportsDataStore implements DataStoreInterface {
	use StatsDataStoreTrait;

	/**
	 * Option name to store whether the wc_order_stats table has a column `fulfillment_status`
	 *
	 * @var string
	 */
	const OPTION_ORDER_STATS_TABLE_HAS_COLUMN_ORDER_FULFILLMENT_STATUS = 'woocommerce_order_stats_has_fulfillment_column';

	/**
	 * Table used to get the data.
	 *
	 * @override ReportsDataStore::$table_name
	 *
	 * @var string
	 */
	protected static $table_name = 'wc_order_stats';

	/**
	 * Cron event name.
	 */
	const CRON_EVENT = 'wc_order_stats_update';

	/**
	 * Cache identifier.
	 *
	 * @override ReportsDataStore::$cache_key
	 *
	 * @var string
	 */
	protected $cache_key = 'orders_stats';

	/**
	 * Type for each column to cast values correctly later.
	 *
	 * @override ReportsDataStore::$column_types
	 *
	 * @var array
	 */
	protected $column_types = array(
		'orders_count'        => 'intval',
		'num_items_sold'      => 'intval',
		'gross_sales'         => 'floatval',
		'total_sales'         => 'floatval',
		'coupons'             => 'floatval',
		'coupons_count'       => 'intval',
		'refunds'             => 'floatval',
		'taxes'               => 'floatval',
		'shipping'            => 'floatval',
		'net_revenue'         => 'floatval',
		'avg_items_per_order' => 'floatval',
		'avg_order_value'     => 'floatval',
		'total_customers'     => 'intval',
		'products'            => 'intval',
		'segment_id'          => 'intval',
	);

	/**
	 * Data store context used to pass to filters.
	 *
	 * @override ReportsDataStore::$context
	 *
	 * @var string
	 */
	protected $context = 'orders_stats';

	/**
	 * Dynamically sets the date column name based on configuration
	 *
	 * @override ReportsDataStore::__construct()
	 */
	public function __construct() {
		$this->date_column_name = get_option( 'woocommerce_date_type', 'date_paid' );
		parent::__construct();
	}

	/**
	 * Assign report columns once full table name has been assigned.
	 *
	 * @override ReportsDataStore::assign_report_columns()
	 */
	protected function assign_report_columns() {
		$table_name = self::get_db_table_name();
		// Avoid ambiguous columns in SQL query.
		$refunds = "ABS( SUM( CASE WHEN {$table_name}.net_total < 0 THEN {$table_name}.net_total + {$table_name}.tax_total + {$table_name}.shipping_total ELSE 0 END ) )";
		if ( ! OrderUtil::uses_new_full_refund_data() ) {
			$refunds = "ABS( SUM( CASE WHEN {$table_name}.net_total < 0 THEN {$table_name}.net_total ELSE 0 END ) )";
		}
		$gross_sale_sum = "{$table_name}.total_sales - {$table_name}.tax_total - {$table_name}.shipping_total";
		$gross_sales    = "SUM( CASE WHEN {$table_name}.parent_id = 0 THEN {$gross_sale_sum} ELSE 0 END ) + COALESCE( SUM(discount_amount), 0 ) as gross_sales";

		$this->report_columns = array(
			'orders_count'        => "SUM( CASE WHEN {$table_name}.parent_id = 0 THEN 1 ELSE 0 END ) as orders_count",
			'num_items_sold'      => "SUM({$table_name}.num_items_sold) as num_items_sold",
			'gross_sales'         => $gross_sales,
			'total_sales'         => "SUM({$table_name}.total_sales) AS total_sales",
			'coupons'             => 'COALESCE( SUM(discount_amount), 0 ) AS coupons', // SUM() all nulls gives null.
			'coupons_count'       => 'COALESCE( coupons_count, 0 ) as coupons_count',
			'refunds'             => "{$refunds} AS refunds",
			'taxes'               => "SUM({$table_name}.tax_total) AS taxes",
			'shipping'            => "SUM({$table_name}.shipping_total) AS shipping",
			'net_revenue'         => "SUM({$table_name}.net_total) AS net_revenue",
			'avg_items_per_order' => "SUM( CASE WHEN {$table_name}.parent_id = 0 THEN {$table_name}.num_items_sold ELSE 0 END ) / SUM( CASE WHEN {$table_name}.parent_id = 0 THEN 1 ELSE 0 END ) AS avg_items_per_order",
			'avg_order_value'     => "SUM( CASE WHEN {$table_name}.parent_id = 0 THEN {$table_name}.net_total ELSE 0 END ) / SUM( CASE WHEN {$table_name}.parent_id = 0 THEN 1 ELSE 0 END ) AS avg_order_value",
			'total_customers'     => "COUNT( DISTINCT( {$table_name}.customer_id ) ) as total_customers",
		);
	}

	/**
	 * Set up all the hooks for maintaining and populating table data.
	 */
	public static function init() {
		add_action( 'woocommerce_before_delete_order', array( __CLASS__, 'delete_order' ) );
		add_action( 'delete_post', array( __CLASS__, 'delete_order' ) );
	}

	/**
	 * Updates the totals and intervals database queries with parameters used for Orders report: categories, coupons and order status.
	 *
	 * @param array $query_args      Query arguments supplied by the user.
	 */
	protected function orders_stats_sql_filter( $query_args ) {
		// phpcs:ignore Generic.Commenting.Todo.TaskFound
		// @todo Performance of all of this?
		global $wpdb;

		$from_clause        = '';
		$orders_stats_table = self::get_db_table_name();
		$product_lookup     = $wpdb->prefix . 'wc_order_product_lookup';
		$coupon_lookup      = $wpdb->prefix . 'wc_order_coupon_lookup';
		$tax_rate_lookup    = $wpdb->prefix . 'wc_order_tax_lookup';
		$operator           = $this->get_match_operator( $query_args );

		$where_filters = array();

		// Products filters.
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$product_lookup,
			'product_id',
			'IN',
			$this->get_included_products( $query_args )
		);
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$product_lookup,
			'product_id',
			'NOT IN',
			$this->get_excluded_products( $query_args )
		);

		// Variations filters.
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$product_lookup,
			'variation_id',
			'IN',
			$this->get_included_variations( $query_args )
		);
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$product_lookup,
			'variation_id',
			'NOT IN',
			$this->get_excluded_variations( $query_args )
		);

		// Coupons filters.
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$coupon_lookup,
			'coupon_id',
			'IN',
			$this->get_included_coupons( $query_args )
		);
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$coupon_lookup,
			'coupon_id',
			'NOT IN',
			$this->get_excluded_coupons( $query_args )
		);

		// Tax rate filters.
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$tax_rate_lookup,
			'tax_rate_id',
			'IN',
			implode( ',', $query_args['tax_rate_includes'] )
		);
		$where_filters[] = $this->get_object_where_filter(
			$orders_stats_table,
			'order_id',
			$tax_rate_lookup,
			'tax_rate_id',
			'NOT IN',
			implode( ',', $query_args['tax_rate_excludes'] )
		);

		// Product attribute filters.
		$attribute_subqueries = $this->get_attribute_subqueries( $query_args );
		if ( $attribute_subqueries['join'] && $attribute_subqueries['where'] ) {
			// Build a subquery for getting order IDs by product attribute(s).
			// Done here since our use case is a little more complicated than get_object_where_filter() can handle.
			$attribute_subquery = new SqlQuery();
			$attribute_subquery->add_sql_clause( 'select', "{$orders_stats_table}.order_id" );
			$attribute_subquery->add_sql_clause( 'from', $orders_stats_table );

			// JOIN on product lookup.
			$attribute_subquery->add_sql_clause( 'join', "JOIN {$product_lookup} ON {$orders_stats_table}.order_id = {$product_lookup}.order_id" );

			// Add JOINs for matching attributes.
			foreach ( $attribute_subqueries['join'] as $attribute_join ) {
				$attribute_subquery->add_sql_clause( 'join', $attribute_join );
			}
			// Add WHEREs for matching attributes.
			$attribute_subquery->add_sql_clause( 'where', 'AND (' . implode( " {$operator} ", $attribute_subqueries['where'] ) . ')' );

			// Generate subquery statement and add to our where filters.
			$where_filters[] = "{$orders_stats_table}.order_id IN (" . $attribute_subquery->get_query_statement() . ')';
		}

		$where_filters[] = $this->get_customer_subquery( $query_args );
		$refund_subquery = $this->get_refund_subquery( $query_args );
		$from_clause    .= $refund_subquery['from_clause'];
		if ( $refund_subquery['where_clause'] ) {
			$where_filters[] = $refund_subquery['where_clause'];
		}

		$where_filters   = array_filter( $where_filters );
		$where_subclause = implode( " $operator ", $where_filters );

		// Append status filter after to avoid matching ANY on default statuses.
		$order_status_filter = $this->get_status_subquery( $query_args, $operator );
		if ( $order_status_filter ) {
			if ( empty( $query_args['status_is'] ) && empty( $query_args['status_is_not'] ) ) {
				$operator = 'AND';
			}
			$where_subclause = implode( " $operator ", array_filter( array( $where_subclause, $order_status_filter ) ) );
		}

		// To avoid requesting the subqueries twice, the result is applied to all queries passed to the method.
		if ( $where_subclause ) {
			$this->total_query->add_sql_clause( 'where', "AND ( $where_subclause )" );
			$this->total_query->add_sql_clause( 'join', $from_clause );
			$this->interval_query->add_sql_clause( 'where', "AND ( $where_subclause )" );
			$this->interval_query->add_sql_clause( 'join', $from_clause );
		}
	}

	/**
	 * Get the default query arguments to be used by get_data().
	 * These defaults are only partially applied when used via REST API, as that has its own defaults.
	 *
	 * @override ReportsDataStore::get_default_query_vars()
	 *
	 * @return array Query parameters.
	 */
	public function get_default_query_vars() {
		$defaults = array_merge(
			parent::get_default_query_vars(),
			array(
				'interval'          => 'week',
				'segmentby'         => '',

				'match'             => 'all',
				'status_is'         => array(),
				'status_is_not'     => array(),
				'product_includes'  => array(),
				'product_excludes'  => array(),
				'coupon_includes'   => array(),
				'coupon_excludes'   => array(),
				'tax_rate_includes' => array(),
				'tax_rate_excludes' => array(),
				'customer_type'     => '',
				'category_includes' => array(),
			)
		);

		return $defaults;
	}

	/**
	 * Returns the report data based on normalized parameters.
	 * Will be called by `get_data` if there is no data in cache.
	 *
	 * @override ReportsDataStore::get_noncached_stats_data()
	 *
	 * @see get_data
	 * @see get_noncached_stats_data
	 * @param array    $query_args Query parameters.
	 * @param array    $params                  Query limit parameters.
	 * @param stdClass $data                    Reference to the data object to fill.
	 * @param int      $expected_interval_count Number of expected intervals.
	 * @return stdClass|WP_Error Data object `{ totals: *, intervals: array, total: int, pages: int, page_no: int }`, or error.
	 */
	public function get_noncached_stats_data( $query_args, $params, &$data, $expected_interval_count ) {
		global $wpdb;

		$table_name = self::get_db_table_name();

		if ( isset( $query_args['date_type'] ) ) {
			$this->date_column_name = $query_args['date_type'];
		}

		$this->initialize_queries();

		$selections = $this->selected_columns( $query_args );
		$this->add_time_period_sql_params( $query_args, $table_name );
		$this->add_intervals_sql_params( $query_args, $table_name );
		$this->add_order_by_sql_params( $query_args );
		$where_time  = $this->get_sql_clause( 'where_time' );
		$params      = $this->get_limit_sql_params( $query_args );
		$coupon_join = "LEFT JOIN (
					SELECT
						order_id,
						SUM(discount_amount) AS discount_amount,
						COUNT(DISTINCT coupon_id) AS coupons_count
					FROM
						{$wpdb->prefix}wc_order_coupon_lookup
					GROUP BY
						order_id
					) order_coupon_lookup
					ON order_coupon_lookup.order_id = {$wpdb->prefix}wc_order_stats.order_id";

		// Additional filtering for Orders report.
		$this->orders_stats_sql_filter( $query_args );
		$this->total_query->add_sql_clause( 'select', $selections );
		$this->total_query->add_sql_clause( 'left_join', $coupon_join );
		$this->total_query->add_sql_clause( 'where_time', $where_time );
		$totals = $wpdb->get_results(
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- cache ok, DB call ok, unprepared SQL ok.
			$this->total_query->get_query_statement(),
			ARRAY_A
		);
		if ( null === $totals ) {
			return new \WP_Error( 'woocommerce_analytics_revenue_result_failed', __( 'Sorry, fetching revenue data failed.', 'woocommerce' ) );
		}

		// phpcs:ignore Generic.Commenting.Todo.TaskFound
		// @todo Remove these assignements when refactoring segmenter classes to use query objects.
		$totals_query    = array(
			'from_clause'       => $this->total_query->get_sql_clause( 'join' ),
			'where_time_clause' => $where_time,
			'where_clause'      => $this->total_query->get_sql_clause( 'where' ),
		);
		$intervals_query = array(
			'select_clause'     => $this->get_sql_clause( 'select' ),
			'from_clause'       => $this->interval_query->get_sql_clause( 'join' ),
			'where_time_clause' => $where_time,
			'where_clause'      => $this->interval_query->get_sql_clause( 'where' ),
			'limit'             => $this->get_sql_clause( 'limit' ),
		);

		$unique_products            = $this->get_unique_product_count( $totals_query['from_clause'], $totals_query['where_time_clause'], $totals_query['where_clause'] );
		$totals[0]['products']      = $unique_products;
		$segmenter                  = new Segmenter( $query_args, $this->report_columns );
		$unique_coupons             = $this->get_unique_coupon_count( $totals_query['from_clause'], $totals_query['where_time_clause'], $totals_query['where_clause'] );
		$totals[0]['coupons_count'] = $unique_coupons;
		$totals[0]['segments']      = $segmenter->get_totals_segments( $totals_query, $table_name );
		$totals                     = (object) $this->cast_numbers( $totals[0] );

		$this->interval_query->add_sql_clause( 'select', $this->get_sql_clause( 'select' ) . ' AS time_interval' );
		$this->interval_query->add_sql_clause( 'left_join', $coupon_join );
		$this->interval_query->add_sql_clause( 'where_time', $where_time );
		$db_intervals = $wpdb->get_col(
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- cache ok, DB call ok, , unprepared SQL ok.
			$this->interval_query->get_query_statement()
		);

		$db_interval_count = count( $db_intervals );

		$this->update_intervals_sql_params( $query_args, $db_interval_count, $expected_interval_count, $table_name );
		$this->interval_query->add_sql_clause( 'order_by', $this->get_sql_clause( 'order_by' ) );
		$this->interval_query->add_sql_clause( 'limit', $this->get_sql_clause( 'limit' ) );
		$this->interval_query->add_sql_clause( 'select', ", MAX({$table_name}.{$this->date_column_name}) AS datetime_anchor" );
		if ( '' !== $selections ) {
			$this->interval_query->add_sql_clause( 'select', ', ' . $selections );
		}
		$intervals = $wpdb->get_results(
			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- cache ok, DB call ok, , unprepared SQL ok.
			$this->interval_query->get_query_statement(),
			ARRAY_A
		);

		if ( null === $intervals ) {
			return new \WP_Error( 'woocommerce_analytics_revenue_result_failed', __( 'Sorry, fetching revenue data failed.', 'woocommerce' ) );
		}

		if ( isset( $intervals[0] ) ) {
			$unique_coupons                = $this->get_unique_coupon_count( $intervals_query['from_clause'], $intervals_query['where_time_clause'], $intervals_query['where_clause'], true );
			$intervals[0]['coupons_count'] = $unique_coupons;
		}

		$data->totals    = $totals;
		$data->intervals = $intervals;

		if ( TimeInterval::intervals_missing( $expected_interval_count, $db_interval_count, $params['per_page'], $query_args['page'], $query_args['order'], $query_args['orderby'], count( $intervals ) ) ) {
			$this->fill_in_missing_intervals( $db_intervals, $query_args['adj_after'], $query_args['adj_before'], $query_args['interval'], $data );
			$this->sort_intervals( $data, $query_args['orderby'], $query_args['order'] );
			$this->remove_extra_records( $data, $query_args['page'], $params['per_page'], $db_interval_count, $expected_interval_count, $query_args['orderby'], $query_args['order'] );
		} else {
			$this->update_interval_boundary_dates( $query_args['after'], $query_args['before'], $query_args['interval'], $data->intervals );
		}
		$segmenter->add_intervals_segments( $data, $intervals_query, $table_name );

		return $data;
	}

	/**
	 * Get unique products based on user time query
	 *
	 * @param string $from_clause       From clause with date query.
	 * @param string $where_time_clause Where clause with date query.
	 * @param string $where_clause      Where clause with date query.
	 * @return integer Unique product count.
	 */
	public function get_unique_product_count( $from_clause, $where_time_clause, $where_clause ) {
		global $wpdb;

		$table_name = self::get_db_table_name();
		return $wpdb->get_var(
			"SELECT
					COUNT( DISTINCT {$wpdb->prefix}wc_order_product_lookup.product_id )
				FROM
					{$wpdb->prefix}wc_order_product_lookup JOIN {$table_name} ON {$wpdb->prefix}wc_order_product_lookup.order_id = {$table_name}.order_id
					{$from_clause}
				WHERE
					1=1
					{$where_time_clause}
					{$where_clause}"
		); // phpcs:ignore cache ok, DB call ok, unprepared SQL ok.
	}

	/**
	 * Get unique coupons based on user time query
	 *
	 * @param string $from_clause       From clause with date query.
	 * @param string $where_time_clause Where clause with date query.
	 * @param string $where_clause      Where clause with date query.
	 * @return integer Unique product count.
	 */
	public function get_unique_coupon_count( $from_clause, $where_time_clause, $where_clause ) {
		global $wpdb;

		$table_name = self::get_db_table_name();
		return $wpdb->get_var(
			"SELECT
					COUNT(DISTINCT coupon_id)
				FROM
					{$wpdb->prefix}wc_order_coupon_lookup JOIN {$table_name} ON {$wpdb->prefix}wc_order_coupon_lookup.order_id = {$table_name}.order_id
					{$from_clause}
				WHERE
					1=1
					{$where_time_clause}
					{$where_clause}"
		); // phpcs:ignore cache ok, DB call ok, unprepared SQL ok.
	}

	/**
	 * Add order information to the lookup table when orders are created or modified.
	 *
	 * @param int $post_id Post ID.
	 * @return int|bool Returns -1 if order won't be processed, or a boolean indicating processing success.
	 */
	public static function sync_order( $post_id ) {
		if ( ! OrderUtil::is_order( $post_id, array( 'shop_order', 'shop_order_refund' ) ) ) {
			return -1;
		}

		$order = wc_get_order( $post_id );
		if ( ! $order ) {
			return -1;
		}

		return self::update( $order );
	}

	/**
	 * Update the database with stats data.
	 *
	 * @param WC_Order|WC_Order_Refund $order Order or refund to update row for.
	 * @return int|bool Returns -1 if order won't be processed, or a boolean indicating processing success.
	 */
	public static function update( $order ) {
		global $wpdb;
		$table_name = self::get_db_table_name();

		if ( ! $order->get_id() || ! $order->get_date_created() ) {
			return -1;
		}

		$format = array(
			'%d',
			'%d',
			'%s',
			'%s',
			'%s',
			'%s',
			'%d',
			'%f',
			'%f',
			'%f',
			'%f',
			'%s',
			'%d',
			'%d',
		);

		$data = array(
			'order_id'           => $order->get_id(),
			'parent_id'          => $order->get_parent_id(),
			'date_created'       => $order->get_date_created()->date( 'Y-m-d H:i:s' ),
			'date_paid'          => $order->get_date_paid() ? $order->get_date_paid()->date( 'Y-m-d H:i:s' ) : null,
			'date_completed'     => $order->get_date_completed() ? $order->get_date_completed()->date( 'Y-m-d H:i:s' ) : null,
			'date_created_gmt'   => gmdate( 'Y-m-d H:i:s', $order->get_date_created()->getTimestamp() ),
			'num_items_sold'     => self::get_num_items_sold( $order ),
			'total_sales'        => $order->get_total(),
			'tax_total'          => $order->get_total_tax(),
			'shipping_total'     => $order->get_shipping_total(),
			'net_total'          => self::get_net_total( $order ),
			'status'             => self::normalize_order_status( $order->get_status() ),
			'customer_id'        => $order->get_report_customer_id(),
			'returning_customer' => $order->is_returning_customer(),
		);

		$order_fulfillment_status = '';
		if ( FeaturesUtil::feature_is_enabled( 'fulfillments' ) && true === self::has_fulfillment_status_column() && $order instanceof WC_Order ) {
			$order_fulfillment_status   = FulfillmentUtils::get_order_fulfillment_status( $order );
			$data['fulfillment_status'] = ( 'no_fulfillments' !== $order_fulfillment_status ) ? $order_fulfillment_status : null;
			$format[]                   = '%s';
		}

		/**
		 * Filters order stats data.
		 *
		 * @param array $data Data written to order stats lookup table.
		 * @param WC_Order $order  Order object.
		 *
		 * @since 4.0.0
		 */
		$data = apply_filters( 'woocommerce_analytics_update_order_stats_data', $data, $order );

		if ( 'shop_order_refund' === $order->get_type() ) {
			$parent_order = wc_get_order( $order->get_parent_id() );
			if ( $parent_order ) {
				$data['parent_id'] = $parent_order->get_id();
				$data['status']    = self::normalize_order_status( $parent_order->get_status() );

				$refund_type               = $order->get_meta( '_refund_type' );
				$uses_new_full_refund_data = OrderUtil::uses_new_full_refund_data();
				if ( 'full' === $refund_type && $uses_new_full_refund_data ) {
					$data['num_items_sold'] = -1 * self::get_num_items_sold( $parent_order );
					$data['tax_total']      = -1 * $parent_order->get_total_tax();
					$data['net_total']      = -1 * self::get_net_total( $parent_order );
					$data['shipping_total'] = -1 * $parent_order->get_shipping_total();
				}
			}
			/**
			 * Set date_completed and date_paid the same as date_created to avoid problems
			 * when they are being used to sort the data, as refunds don't have them filled
			*/
			$data['date_completed'] = $data['date_created'];
			$data['date_paid']      = $data['date_created'];
		}

		// Update or add the information to the DB.
		$result = $wpdb->replace( $table_name, $data, $format );

		/**
		 * Fires when order's stats reports are updated.
		 *
		 * @param int $order_id Order ID.
		 *
		 * @since 4.0.0.
		 */
		do_action( 'woocommerce_analytics_update_order_stats', $order->get_id() );

		// Check the rows affected for success. Using REPLACE can affect 2 rows if the row already exists.
		return ( 1 === $result || 2 === $result );
	}

	/**
	 * Deletes the order stats when an order is deleted.
	 *
	 * @param int $post_id Post ID.
	 */
	public static function delete_order( $post_id ) {
		global $wpdb;
		$order_id = (int) $post_id;

		if ( ! OrderUtil::is_order( $post_id, array( 'shop_order', 'shop_order_refund' ) ) ) {
			return;
		}

		// Retrieve customer details before the order is deleted.
		$order       = wc_get_order( $order_id );
		$customer_id = absint( CustomersDataStore::get_existing_customer_id_from_order( $order ) );

		// Delete the order.
		$wpdb->delete( self::get_db_table_name(), array( 'order_id' => $order_id ) );
		/**
		 * Fires when orders stats are deleted.
		 *
		 * @param int $order_id Order ID.
		 * @param int $customer_id Customer ID.
		 *
		 * @since 4.0.0
		 */
		do_action( 'woocommerce_analytics_delete_order_stats', $order_id, $customer_id );

		ReportsCache::invalidate();
	}


	/**
	 * Calculation methods.
	 */

	/**
	 * Get number of items sold among all orders.
	 *
	 * @param WC_Order $order WC_Order object.
	 * @return int
	 */
	protected static function get_num_items_sold( $order ) {
		$num_items = 0;

		$line_items = $order->get_items( 'line_item' );
		foreach ( $line_items as $line_item ) {
			$num_items += $line_item->get_quantity();
		}

		return $num_items;
	}

	/**
	 * Get the net amount from an order without shipping, tax, or refunds.
	 *
	 * @param WC_Order $order WC_Order object.
	 * @return float
	 */
	protected static function get_net_total( $order ) {
		$net_total = floatval( $order->get_total() ) - floatval( $order->get_total_tax() ) - floatval( $order->get_shipping_total() );
		return (float) $net_total;
	}

	/**
	 * Check if the wc_order_stats table has the fulfillment_status column.
	 *
	 * @return boolean
	 */
	public static function has_fulfillment_status_column() {
		$column_status = get_option( self::OPTION_ORDER_STATS_TABLE_HAS_COLUMN_ORDER_FULFILLMENT_STATUS );

		if ( ! empty( $column_status ) ) {
			return 'yes' === $column_status;
		}

		global $wpdb;

		$table_name = self::get_db_table_name();

		// Check if the table exists.
		$table_exists = $wpdb->get_var(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name cannot be prepared.
				'SHOW TABLES LIKE %s',
				$table_name
			)
		);

		// If table still does not exist, return false without setting the option to allow for table to be created with the column.
		if ( ! $table_exists ) {
			return false;
		}

		$column_exists = $wpdb->get_var(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name cannot be prepared.
				"SHOW COLUMNS FROM `{$table_name}` LIKE %s",
				'fulfillment_status'
			)
		);

		if ( ! empty( $column_exists ) ) {
			update_option( self::OPTION_ORDER_STATS_TABLE_HAS_COLUMN_ORDER_FULFILLMENT_STATUS, 'yes', false );
			return true;
		}

		// Update the option to indicate that the column does not exist.
		update_option( self::OPTION_ORDER_STATS_TABLE_HAS_COLUMN_ORDER_FULFILLMENT_STATUS, 'no', false );
		return false;
	}

	/**
	 * Check to see if an order's customer has made previous orders or not
	 *
	 * @param WC_Order  $order WC_Order object.
	 * @param int|false $customer_id Customer ID. Optional.
	 * @return bool
	 */
	public static function is_returning_customer( $order, $customer_id = null ) {
		if ( is_null( $customer_id ) ) {
			$customer_id = \Automattic\WooCommerce\Admin\API\Reports\Customers\DataStore::get_existing_customer_id_from_order( $order );
		}

		if ( ! $customer_id ) {
			return false;
		}

		$oldest_orders = \Automattic\WooCommerce\Admin\API\Reports\Customers\DataStore::get_oldest_orders( $customer_id );

		if ( empty( $oldest_orders ) ) {
			return false;
		}

		$first_order       = $oldest_orders[0];
		$second_order      = isset( $oldest_orders[1] ) ? $oldest_orders[1] : false;
		$excluded_statuses = self::get_excluded_report_order_statuses();

		// Order is older than previous first order.
		if ( $order->get_date_created() < wc_string_to_datetime( $first_order->date_created ) &&
			! in_array( $order->get_status(), $excluded_statuses, true )
		) {
			self::set_customer_first_order( $customer_id, $order->get_id() );
			return false;
		}

		// The current order is the oldest known order.
		$is_first_order = (int) $order->get_id() === (int) $first_order->order_id;
		// Order date has changed and next oldest is now the first order.
		$date_change = $second_order &&
			$order->get_date_created() > wc_string_to_datetime( $first_order->date_created ) &&
			wc_string_to_datetime( $second_order->date_created ) < $order->get_date_created();
		// Status has changed to an excluded status and next oldest order is now the first order.
		$status_change = $second_order &&
			in_array( $order->get_status(), $excluded_statuses, true );
		if ( $is_first_order && ( $date_change || $status_change ) ) {
			self::set_customer_first_order( $customer_id, $second_order->order_id );
			return true;
		}

		return (int) $order->get_id() !== (int) $first_order->order_id;
	}

	/**
	 * Set a customer's first order and all others to returning.
	 *
	 * @param int $customer_id Customer ID.
	 * @param int $order_id Order ID.
	 */
	protected static function set_customer_first_order( $customer_id, $order_id ) {
		global $wpdb;
		$orders_stats_table = self::get_db_table_name();

		$wpdb->query(
			$wpdb->prepare(
				// phpcs:ignore Generic.Commenting.Todo.TaskFound
				// TODO: use the %i placeholder to prepare the table name when available in the minimum required WordPress version.
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
				"UPDATE {$orders_stats_table} SET returning_customer = CASE WHEN order_id = %d THEN false ELSE true END WHERE customer_id = %d",
				$order_id,
				$customer_id
			)
		);
	}

	/**
	 * Add fulfillment_status column to wc_order_stats table.
	 *
	 * @return bool|string True on success, error message string on failure.
	 */
	public static function add_fulfillment_status_column() {
		if ( self::has_fulfillment_status_column() ) {
			return true;
		}

		global $wpdb;

		$result = $wpdb->query(
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
			"ALTER TABLE {$wpdb->prefix}wc_order_stats
			ADD COLUMN fulfillment_status VARCHAR(50) DEFAULT NULL,
			ADD INDEX fulfillment_status (fulfillment_status)"
		);

		if ( false === $result ) {
			return $wpdb->last_error ? $wpdb->last_error : __( 'Unknown database error occurred while adding fulfillment_status column.', 'woocommerce' );
		}

		// Update the option to indicate that the column has been added.
		update_option( self::OPTION_ORDER_STATS_TABLE_HAS_COLUMN_ORDER_FULFILLMENT_STATUS, 'yes', false );

		return true;
	}
}
