using System.Linq;
using Organization.Project.Common.Dal;
using System.Data.Linq;

namespace Organization.Project.Dal
{
	/// <summary>
	/// Base L2S repository for different types of entities
	/// </summary>
	/// <typeparam name="IEntity">entity interface</typeparam>
	/// <typeparam name="TEntity">entity type</typeparam>
    public class BaseLinqRepository<IEntity, TEntity> : IRepository<IEntity> where TEntity : class, IEntity, new()
	{
		#region User Defined Variables

		private readonly DataContext context;

		#endregion

		#region Constructor
		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="context">L2S context</param>
		public BaseLinqRepository(DataContext context)
        {
            this.context = context;
		}

		#endregion

		#region Public Methods

		/// <summary>
		/// Gets IQueryable of all the entities of some type from the database (with possibility 
		/// to add some additional filters, sortings, etc. before the query really executes)
		/// </summary>
		/// <returns>IQueryable of all the entities of some type</returns>
		public IQueryable<IEntity> GetAll()
        {
            return context.GetTable<TEntity>().Select(e => (IEntity)e);
        }

		/// <summary>
		/// Adds a new entity to the context so it will be added to the database on submit
		/// </summary>
		/// <param name="entity">entity object</param>
		/// <returns>if result of the operation is successful</returns>
        public bool Add(IEntity entity)
        {
            var cEnt = entity as TEntity;
            if (cEnt != null)
            {
                context.GetTable<TEntity>().InsertOnSubmit(cEnt);
                return true;
            }
            return false;
        }

		/// <summary>
		/// Deletes a new entity from the context so it will be removed from the database on submit
		/// </summary>
		/// <param name="entity">entity object</param>
		/// <returns>if result of the operation is successful</returns>
        public bool Delete(IEntity entity)
        {
            var cEnt = entity as TEntity;
            if (cEnt != null)
            {
                context.GetTable<TEntity>().DeleteOnSubmit(cEnt);
                return true;
            }
            return false;
        }

		/// <summary>
		/// Creates an empty entity
		/// </summary>
		/// <returns>an entity through its common interface</returns>
        public IEntity CreateEmpty()
        {
            return new TEntity();
		}

		/// <summary>
		/// Refresh an entity by values from database
		/// </summary>
		/// <param name="entity">an entity to refresh</param>
		public void Refresh(IEntity entity)
		{
			context.Refresh(RefreshMode.OverwriteCurrentValues, entity);	
		}

		#endregion
	}
}