narsil/Tanshu.Accounts.Contracts/Data Contracts Display/BillItemKey.cs

using System;

namespace Tanshu.Accounts.Contracts
{
    public enum BillItemType
    {
        Product,
        Kot
    }
    public class BillItemKey
    {
        private BillItemKey(Guid productID, Guid kotID, BillItemType billItemType)
        {
            BillItemType = billItemType;
            ProductID = productID;
            KotID = kotID;
        }
        public BillItemKey(Guid kotID)
            : this(Guid.Empty, kotID, BillItemType.Kot)
        { }
        public BillItemKey(Guid productID, Guid kotID)
            : this(productID, kotID, BillItemType.Product)
        { }

        private Guid _productID;
        public Guid ProductID
        {
            get { return BillItemType == BillItemType.Product ? _productID : Guid.Empty; }
            private set { _productID = BillItemType == BillItemType.Product ? value : Guid.Empty; }
        }

        public Guid KotID { get; private set; }

        public BillItemType BillItemType { get; private set; }

        public override int GetHashCode()
        {
            return BillItemType.GetHashCode() ^ KotID.GetHashCode() ^ ProductID.GetHashCode();
        }
        public static bool operator ==(BillItemKey a, BillItemKey b)
        {
            if (object.ReferenceEquals(null, a))
                return object.ReferenceEquals(null, b);

            if (!(a is BillItemKey))
                return false;
            if (!(b is BillItemKey))
                return false;

            if (a.BillItemType != b.BillItemType)
                return false;

            return a.KotID == b.KotID && a.BillItemType == b.BillItemType && a.ProductID == b.ProductID;
        }
        public static bool operator !=(BillItemKey a, BillItemKey b)
        {
            return !(a == b);
        }
        public override bool Equals(object obj)
        {
            if (obj is BillItemKey)
                return (this == (BillItemKey)obj);
            else
                return false;
        }
    }
}