#region Copyright ©  2003-2008 Richard Beauchamp <rbeauchamp@gmail.com>

/*
* DomainObjects for .NET
* Copyright ©  2003-2008 Richard Beauchamp
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/

#endregion

using DomainObjects.Facade.Command;
using DomainObjects.Facade.Transaction;

namespace DomainObjects.Tutorial
{
  /// <summary>
  /// This class provides a transaction facade to the tutorial functionality. 
  /// Because the 'Transaction' attribute has been applied to this class,
  /// all methods are executed in the context of a transaction.
  ///
  /// This class defines the units of work supported by your application; it can
  /// be thought of as the 'service layer' of your application.
  /// 
  /// Any persistable objects created or modified during the execution of these
  /// methods will be automatically inserted or updated to the database by DomainObjects.
  /// </summary>
  [Transaction(TransactionOption.Required)]
  public sealed class TransactionFacade : Service<TransactionFacade>
  {
    /// <summary>
    /// Queries the database for an instance of Planet with the name of 'Earth'.
    /// </summary>
    /// <returns>
    /// The instance of planet if found, else null.
    /// </returns>
    public Planet HelloWorld()
    {
      // Create a new instance of Criteria which will hold the query criteria
      Criteria criteria = new Criteria();

      // The line below tell DomainObjects: "Query for an instance of type Planet
      // where the field '_name' has a value of 'Earth'"
      criteria.AddEqualTo(Types.Planet.Field._name, "Earth");

      // the name of the planet is unique so at most one planet will be selected
      // from the database. DomainObjects returns a 'managed instance' of Planet, if found.
      // A 'managed instance' of an object is one where DomainObjects can track modifications
      // to the object.
      return QueryFacade.FindObject<Planet>(criteria);
    }

    /// <summary>
    /// Creates a new instance of sun with the given sunName and an associated
    /// new planet with the given planetName and rotationalPeriod.
    /// Both new objects are persisted it to the database in the context of a 
    /// single transaction.
    /// 
    /// As an experiment, try entering a planetName that is over 20 characters;
    /// this will cause a database constraint to be thrown upon the insert. 
    /// You'll find that, because this method is transactional, neither the star
    /// nor the planet is persisted to the database.
    /// </summary>
    public Planet CreateNewStarAndPlanet(string starName, string planetName, decimal rotationalPeriod)
    {
      // A call to the method 'Manage()' must be called immediately after
      // constructing a persistable object so that DomainObjects can track 
      // modifications to the instance; your code must not hold a direct reference
      // to an unmanaged persistable object.
      Star newStar = new Star(starName).Manage<Star>();
      return new Planet(newStar, planetName, rotationalPeriod).Manage<Planet>();
    }
  }
}