feat(order): add all-orders APIs and query workflow

src/Application/TakeoutSaaS.Application/App/Orders/Handlers/GetOrderAllStatsQueryHandler.cs

@@ -0,0 +1,81 @@
+using MediatR;
+using TakeoutSaaS.Application.App.Orders.Dto;
+using TakeoutSaaS.Application.App.Orders.Queries;
+using TakeoutSaaS.Domain.Orders.Entities;
+using TakeoutSaaS.Domain.Orders.Repositories;
+using TakeoutSaaS.Shared.Abstractions.Tenancy;
+
+namespace TakeoutSaaS.Application.App.Orders.Handlers;
+
+/// <summary>
+/// 全部订单统计查询处理器。
+/// </summary>
+public sealed class GetOrderAllStatsQueryHandler(
+    IOrderRepository orderRepository,
+    ITenantProvider tenantProvider)
+    : IRequestHandler<GetOrderAllStatsQuery, OrderAllStatsDto>
+{
+    /// <inheritdoc />
+    public async Task<OrderAllStatsDto> Handle(GetOrderAllStatsQuery request, CancellationToken cancellationToken)
+    {
+        var tenantId = tenantProvider.GetCurrentTenantId();
+
+        var orders = (await orderRepository.SearchAllOrdersAsync(
+                tenantId,
+                request.StoreId,
+                request.StartAt,
+                request.EndAt,
+                request.Status,
+                request.DeliveryType,
+                request.PaymentMethod,
+                request.Keyword,
+                cancellationToken))
+            .ToList();
+
+        var refundedIds = await LoadRefundedOrderIdsAsync(orders, tenantId, cancellationToken);
+        if (request.RefundedOnly)
+        {
+            orders = orders.Where(order => refundedIds.Contains(order.Id)).ToList();
+        }
+
+        var totalOrders = orders.Count;
+        if (totalOrders == 0)
+        {
+            return new OrderAllStatsDto();
+        }
+
+        var totalAmount = orders.Sum(ResolveDisplayAmount);
+        var averageAmount = decimal.Round(totalAmount / totalOrders, 2, MidpointRounding.AwayFromZero);
+        var refundCount = request.RefundedOnly
+            ? totalOrders
+            : orders.Count(order => refundedIds.Contains(order.Id));
+
+        return new OrderAllStatsDto
+        {
+            TotalOrders = totalOrders,
+            TotalAmount = totalAmount,
+            AverageAmount = averageAmount,
+            RefundCount = refundCount
+        };
+    }
+
+    private async Task<HashSet<long>> LoadRefundedOrderIdsAsync(
+        IReadOnlyCollection<Order> orders,
+        long tenantId,
+        CancellationToken cancellationToken)
+    {
+        var orderIds = orders.Select(order => order.Id).ToList();
+        if (orderIds.Count == 0)
+        {
+            return [];
+        }
+
+        var refunded = await orderRepository.GetRefundedOrderIdsAsync(orderIds, tenantId, cancellationToken);
+        return refunded.ToHashSet();
+    }
+
+    private static decimal ResolveDisplayAmount(Order order)
+    {
+        return order.PaidAmount > 0 ? order.PaidAmount : order.PayableAmount;
+    }
+}