Retail_manager/RMDataManagerLibrary/DataAcccess/SaleData.cs

using RMDataManagerLibrary.Internal.DataAccess;
using RMDataManagerLibrary.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace RMDataManagerLibrary.DataAcccess
{
    public class SaleData
    {
        //TODO: Make this SOLID/DRY/BETTER
        public void SaveSale(SaleModel saleInfo, string cashierId)
        {
            List<SaleDetailDBModel> details = new List<SaleDetailDBModel>();
            ProductData products = new ProductData();
            decimal taxRate = ConfigHelper.GetTaxRate()/100;

            foreach (var item in saleInfo.SaleDetails)
            {
                var detail = new SaleDetailDBModel
                {
                    ProductId = item.ProductId,
                    Quantity = item.Quantity
                };

                // get the information about this product
                var productInfo = products.GetProductById(item.ProductId);

                if (productInfo == null)
                {
                    throw new Exception($"Product with Id {item.ProductId} could not be found in DB");
                }

                detail.PurchasePrice = productInfo.RetailPrice * detail.Quantity;

                if (productInfo.IsTaxable)
                {
                    detail.Tax = detail.PurchasePrice * taxRate;
                }

                details.Add(detail);
            }

            SaleDBModel sale = new SaleDBModel
            {
                SubTotal = details.Sum(x => x.PurchasePrice),
                Tax = details.Sum(x => x.Tax),
                CashierId = cashierId
            };

            sale.Total = sale.SubTotal + sale.Tax;

            //save
            using (SqlDataAccess sql = new SqlDataAccess())
            {
                try
                {
                    sql.StartTransaction("RMData");

                    sql.SaveDataInTransaction("spSaleInsert", sale);

                    sale.Id = sql.LoadDataInTransaction<int, dynamic>("spSaleLookUp", new { sale.CashierId, sale.SaleDate }).FirstOrDefault();

                    // finish filling up sale details
                    foreach (var item in details)
                    {
                        item.SaleId = sale.Id;

                        sql.SaveDataInTransaction("dbo.spSaleDetailInsert", item);
                    }

                    sql.CommitTransaction();
                }
                catch
                {
                    sql.RollBackTransaction();
                    throw;
                }
            }
        }
    }
}