add shared pricing resolution with fixed yem price,GRN weighted and FIFO valuation cost fallback

Backend/ERPCore/Dtos/Sales/SalesInvoiceDtos.cs

@@ -32,6 +32,7 @@ public sealed class CreateSalesInvoiceLineRequest
     [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
     [Range(0, double.MaxValue)] public decimal FreeQty { get; set; }
     [Range(0, double.MaxValue)] public decimal? UnitPrice { get; set; }
+    public bool AllowManualPriceOverride { get; set; }
     [Range(0, 100)] public decimal DiscountPct { get; set; }
     [Range(0, double.MaxValue)] public decimal DiscountAmount { get; set; }
     [Range(0, 100)] public decimal TaxPct { get; set; }

Backend/ERPCore/Dtos/Sales/SalesSlipDtos.cs

@@ -31,6 +31,7 @@ public sealed class CreateSalesSlipLineRequest
     [Range(0.0001, double.MaxValue)] public decimal Qty { get; set; }
     [Range(0, double.MaxValue)] public decimal FreeQty { get; set; }
     [Range(0, double.MaxValue)] public decimal? UnitPrice { get; set; }
+    public bool AllowManualPriceOverride { get; set; }
     [Range(0, 100)] public decimal DiscountPct { get; set; }
     [Range(0, double.MaxValue)] public decimal DiscountAmount { get; set; }
     [Range(0, 100)] public decimal TaxPct { get; set; }

Backend/ERPCore/Program.cs

@@ -90,6 +90,7 @@ builder.Services.AddScoped<IStockService, StockService>();
 builder.Services.AddScoped<IGrnService, GrnService>();
 
 // Sales (Phase 1)
+builder.Services.AddScoped<ISalesPricingService, SalesPricingService>();
 builder.Services.AddScoped<ISalesInvoiceService, SalesInvoiceService>();
 builder.Services.AddScoped<ISalesSlipService, SalesSlipService>();
 

Backend/ERPCore/Services/Interfaces/ISalesPricingService.cs

@@ -0,0 +1,16 @@
+namespace ERPCore.Services.Interfaces;
+
+public interface ISalesPricingService
+{
+    Task<SalesPriceResolution> ResolveAsync(
+        int itemId,
+        int warehouseId,
+        decimal? requestedUnitPrice,
+        bool allowManualOverride,
+        CancellationToken ct = default);
+}
+
+public sealed record SalesPriceResolution(
+    decimal UnitPrice,
+    string PriceSource,
+    decimal BaseCost);

Backend/ERPCore/Services/SalesInvoiceService.cs

@@ -21,6 +21,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
     private readonly IRepository<Item> _items;
     private readonly IRepository<Uom> _uoms;
     private readonly IRepository<Warehouse> _warehouses;
+    private readonly ISalesPricingService _pricing;
     private readonly IFifoCostingService _fifo;
     private readonly ICurrentUser _currentUser;
     private readonly INumberSequenceService _numbers;
@@ -28,7 +29,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
 
     public SalesInvoiceService(
         IRepository<SalesInvoice> invoices, IRepository<Customer> customers, IRepository<Item> items,
-        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, IFifoCostingService fifo,
+        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, ISalesPricingService pricing, IFifoCostingService fifo,
         ICurrentUser currentUser, INumberSequenceService numbers, IUnitOfWork uow)
     {
         _invoices = invoices;
@@ -36,6 +37,7 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         _items = items;
         _uoms = uoms;
         _warehouses = warehouses;
+        _pricing = pricing;
         _fifo = fifo;
         _currentUser = currentUser;
         _numbers = numbers;
@@ -175,23 +177,9 @@ public sealed class SalesInvoiceService : ISalesInvoiceService
         foreach (var r in requests)
         {
             var item = await _items.Query().AsNoTracking().FirstAsync(x => x.ItemId == r.ItemId, ct);
-            var priceSource = "SALE_PRICE";
+            var resolved = await _pricing.ResolveAsync(r.ItemId, r.WarehouseId, r.UnitPrice, r.AllowManualPriceOverride, ct);
-            decimal unitPrice;
+            var unitPrice = resolved.UnitPrice;
-            if (r.UnitPrice is not null)
+            var priceSource = resolved.PriceSource;
-            {
-                unitPrice = r.UnitPrice.Value;
-                priceSource = "MANUAL";
-            }
-            else if (item.SalePrice.HasValue)
-            {
-                unitPrice = item.SalePrice.Value;
-            }
-            else
-            {
-                var valuation = await _fifo.GetValuationAsync(r.ItemId, r.WarehouseId, ct);
-                unitPrice = valuation.TotalQty > 0 ? valuation.TotalValue / valuation.TotalQty : 0m;
-                priceSource = "FIFO_AVG";
-            }
 
             var gross = r.Qty * unitPrice;
             var discountAfterPct = gross * (r.DiscountPct / 100m);

Backend/ERPCore/Services/SalesPricingService.cs

@@ -0,0 +1,79 @@
+using ERPCore.Domain;
+using ERPCore.Domain.Entities;
+using ERPCore.Domain.Enums;
+using ERPCore.Repositories.Interfaces;
+using ERPCore.Services.Interfaces;
+using ERPCore.Services.Stock;
+using Microsoft.EntityFrameworkCore;
+
+namespace ERPCore.Services;
+
+public sealed class SalesPricingService : ISalesPricingService
+{
+    private readonly IRepository<Item> _items;
+    private readonly IRepository<GrnLine> _grnLines;
+    private readonly IFifoCostingService _fifo;
+
+    public SalesPricingService(IRepository<Item> items, IRepository<GrnLine> grnLines, IFifoCostingService fifo)
+    {
+        _items = items;
+        _grnLines = grnLines;
+        _fifo = fifo;
+    }
+
+    public async Task<SalesPriceResolution> ResolveAsync(
+        int itemId, int warehouseId, decimal? requestedUnitPrice, bool allowManualOverride, CancellationToken ct = default)
+    {
+        var item = await _items.Query().AsNoTracking().FirstOrDefaultAsync(x => x.ItemId == itemId, ct)
+            ?? throw new InvalidOperationException($"Item {itemId} was not found.");
+
+        if (requestedUnitPrice is not null)
+        {
+            if (!allowManualOverride)
+            {
+                if (item.SalePrice.HasValue)
+                    return new SalesPriceResolution(item.SalePrice.Value, "SALE_PRICE", item.SalePrice.Value);
+
+                var grnPrice = await GetWeightedGrnPriceAsync(itemId, warehouseId, ct);
+                if (grnPrice is not null)
+                    return new SalesPriceResolution(grnPrice.Value, "GRN_WEIGHTED_AVG", grnPrice.Value);
+
+                return new SalesPriceResolution(await GetFifoFallbackPriceAsync(itemId, warehouseId, ct), "FIFO_AVG", 0m);
+            }
+
+            return new SalesPriceResolution(requestedUnitPrice.Value, "MANUAL", requestedUnitPrice.Value);
+        }
+
+        if (item.SalePrice.HasValue)
+            return new SalesPriceResolution(item.SalePrice.Value, "SALE_PRICE", item.SalePrice.Value);
+
+        var weighted = await GetWeightedGrnPriceAsync(itemId, warehouseId, ct);
+        if (weighted is not null)
+            return new SalesPriceResolution(weighted.Value, "GRN_WEIGHTED_AVG", weighted.Value);
+
+        return new SalesPriceResolution(await GetFifoFallbackPriceAsync(itemId, warehouseId, ct), "FIFO_AVG", 0m);
+    }
+
+    private async Task<decimal?> GetWeightedGrnPriceAsync(int itemId, int warehouseId, CancellationToken ct)
+    {
+        var rows = await _grnLines.Query().AsNoTracking()
+            .Where(l => l.ItemId == itemId
+                        && l.Grn != null
+                        && l.Grn.WarehouseId == warehouseId
+                        && l.Grn.Status == GrnStatus.Confirmed)
+            .Select(l => new { l.Qty, l.ReceivedValue })
+            .ToListAsync(ct);
+
+        var totalQty = rows.Sum(x => x.Qty);
+        if (totalQty <= 0) return null;
+
+        var totalValue = rows.Sum(x => x.ReceivedValue);
+        return totalValue / totalQty;
+    }
+
+    private async Task<decimal> GetFifoFallbackPriceAsync(int itemId, int warehouseId, CancellationToken ct)
+    {
+        var valuation = await _fifo.GetValuationAsync(itemId, warehouseId, ct);
+        return valuation.TotalQty > 0 ? valuation.TotalValue / valuation.TotalQty : 0m;
+    }
+}

Backend/ERPCore/Services/SalesSlipService.cs

@@ -22,6 +22,7 @@ public sealed class SalesSlipService : ISalesSlipService
     private readonly IRepository<Uom> _uoms;
     private readonly IRepository<Warehouse> _warehouses;
     private readonly IRepository<User> _users;
+    private readonly ISalesPricingService _pricing;
     private readonly IFifoCostingService _fifo;
     private readonly ICurrentUser _currentUser;
     private readonly INumberSequenceService _numbers;
@@ -29,7 +30,7 @@ public sealed class SalesSlipService : ISalesSlipService
 
     public SalesSlipService(
         IRepository<SalesSlip> slips, IRepository<Customer> customers, IRepository<Item> items,
-        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, IRepository<User> users, IFifoCostingService fifo,
+        IRepository<Uom> uoms, IRepository<Warehouse> warehouses, IRepository<User> users, ISalesPricingService pricing, IFifoCostingService fifo,
         ICurrentUser currentUser, INumberSequenceService numbers, IUnitOfWork uow)
     {
         _slips = slips;
@@ -38,6 +39,7 @@ public sealed class SalesSlipService : ISalesSlipService
         _uoms = uoms;
         _warehouses = warehouses;
         _users = users;
+        _pricing = pricing;
         _fifo = fifo;
         _currentUser = currentUser;
         _numbers = numbers;
@@ -157,8 +159,6 @@ public sealed class SalesSlipService : ISalesSlipService
             throw new NotFoundException($"Customer {customerId} was not found.");
         if (!await _warehouses.Query().AnyAsync(x => x.WarehouseId == warehouseId, ct))
             throw new NotFoundException($"Warehouse {warehouseId} was not found.");
-        if (!await _customers.Query().AnyAsync(x => x.CustomerId == customerId, ct))
-            throw new NotFoundException($"Customer {customerId} was not found.");
         if (!await _users.Query().AnyAsync(x => x.UserId == cashierUserId, ct))
             throw new NotFoundException($"User {cashierUserId} was not found.");
         foreach (var line in lines)
@@ -178,23 +178,9 @@ public sealed class SalesSlipService : ISalesSlipService
         foreach (var r in requests)
         {
             var item = await _items.Query().AsNoTracking().FirstAsync(x => x.ItemId == r.ItemId, ct);
-            var priceSource = "SALE_PRICE";
+            var resolved = await _pricing.ResolveAsync(r.ItemId, r.WarehouseId, r.UnitPrice, r.AllowManualPriceOverride, ct);
-            decimal unitPrice;
+            var unitPrice = resolved.UnitPrice;
-            if (r.UnitPrice is not null)
+            var priceSource = resolved.PriceSource;
-            {
-                unitPrice = r.UnitPrice.Value;
-                priceSource = "MANUAL";
-            }
-            else if (item.SalePrice.HasValue)
-            {
-                unitPrice = item.SalePrice.Value;
-            }
-            else
-            {
-                var valuation = await _fifo.GetValuationAsync(r.ItemId, r.WarehouseId, ct);
-                unitPrice = valuation.TotalQty > 0 ? valuation.TotalValue / valuation.TotalQty : 0m;
-                priceSource = "FIFO_AVG";
-            }
 
             var gross = r.Qty * unitPrice;
             var discountAfterPct = gross * (r.DiscountPct / 100m);