using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using TinyPosEntity.Entity;

namespace TinyPosEntity.Service
{
    public class ProductService
    {
        static ProductService instance;
        public static ProductService Instance { get { Init(); return instance; } }

        private static void Init()
        {
            if (instance == null)
                instance = new ProductService();
        }

        public void Create(Product targetObject)
        {
            using (EntityContext context = new EntityContext())
            {
                context.Products.Add(targetObject);
                context.SaveChanges();
            }
        }

        public void Create(List<Product> targetObject)
        {
            using (EntityContext context = new EntityContext())
            {
                foreach (Product type in targetObject)
                {
                    context.Products.Add(type);
                }

                context.SaveChanges();
            }
        }

        public Product Find(Product targetObject)
        {
            using (EntityContext context = new EntityContext())
            {
                var qry = from p in context.Products
                          where p.Name.Equals(targetObject.Barcode)
                          select p;

                if (qry.Count() < 1)
                    return null;

                return qry.ToArray()[0];
            }
        }

        public Product Find(string barcode)
        {
            using (EntityContext context = new EntityContext())
            {
                var qry = from p in context.Products
                          where p.Name.Equals(barcode)
                          select p;

                if (qry.Count() < 1)
                    return null;

                return qry.ToArray()[0];
            }
        }

        public List<Product> Find(List<TransactionItem> transactionItemList)
        {
            var subQry = from ti in transactionItemList
                         select ti.Product.ProductId;

            List<int> productIdList = subQry.ToList();
            if (productIdList == null || productIdList.Count < 1)
                return null;
            
            using (EntityContext context = new EntityContext())
            {
                var qry = from p in context.Products
                          where productIdList.Contains(p.ProductId)
                          orderby p.ProductId ascending
                          select p;

                if (qry.Count() < 1)
                    return null;

                return qry.ToList();
            }
        }

        public List<Product> Find(DateTime fromDateTime, DateTime toDateTime)
        {
            using (EntityContext context = new EntityContext())
            {
                var qry = from p in context.Products
                          join ti in context.TransactionItems
                            on p equals ti.Product
                          join t in context.Transactions
                            on ti.Transaction equals t
                          where (t.Timestamp >= fromDateTime && t.Timestamp <= toDateTime)
                          orderby p.ProductId ascending
                          select p;

                if (qry.Count() < 1)
                    return null;

                return qry.ToList();
            }
        }

        public void Remove(Product targetObject)
        {
            using (EntityContext context = new EntityContext())
            {
                context.Database.ExecuteSqlCommand(
                    "DELETE FROM dbo.Products WHERE ProductId = {0}",
                    targetObject.ProductId);
            }
        }

        public void Remove(string barcode)
        {
            using (EntityContext context = new EntityContext())
            {
                context.Database.ExecuteSqlCommand(
                    "DELETE FROM dbo.Products WHERE Barcode = {0}",
                    barcode);
            }
        }
    }
}