Visual Application Launcher

using System;
using System.Data.Entity;
using System.Diagnostics;
using System.Linq;
using System.Data.Entity.Infrastructure;
using VAL.Model;

namespace VAL.Data
{
    /// <summary>
    /// Entity Framework repository
    /// </summary>
    public partial class EntityRepository<T> : IRepository<T> where T : PocoEntityBase
    {
        private readonly IDbContext _context;
        private IDbSet<T> _entities;

        /// <summary>
        /// Ctor
        /// </summary>
        /// <param name="context">Object context</param>
        public EntityRepository(IDbContext context)
        {
            this._context = context;
        }

        private IDbSet<T> Entities
        {
            get
            {
                if (_entities == null)
                {
                    _entities = _context.Set<T>();
                }
                return _entities;
            }
        }

        public T GetById(int id)
        {
            return Entities.Find(id);
        }

        public void Add(T entity)
        {
            if (entity.Id == 0)
            {
                this.Insert(entity);
            }
            else
            {
                this.Update(entity);
            }
        }

        private void Insert(T entity)
        {
            if (entity == null)
                throw new ArgumentNullException("entity");

            Entities.Add(entity);
        }

        private void Update(T entity)
        {
            if (entity == null)
                throw new ArgumentNullException("entity");

            if (entity.Id == 0)
                throw new ArgumentException("Cannot update entity, invalid object Id");

            var original = _context.Set<T>().Find(entity.Id);
            _context.SetModifed(original, entity);
        }

        public void Delete(T entity)
        {
            if (entity == null)
                throw new ArgumentNullException("entity");
            Entities.Remove(entity);
        }

        public virtual IQueryable<T> Table
        {
            get
            {
                if (_context.ChangeTrackingDisabled)
                {
                    return this.Entities.AsNoTracking();
                }
                else
                {
                    return this.Entities;
                }                
            }
        }
        //TODO implement IDisposable interface
    }
}