/* This file is part of the db4o object database http://www.db4o.com

Copyright (C) 2004 - 2010  Versant Corporation http://www.versant.com

db4o is free software; you can redistribute it and/or modify it under
the terms of version 3 of the GNU General Public License as published
by the Free Software Foundation.

db4o 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 General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program.  If not, see http://www.gnu.org/licenses/. */
using System;
using Db4objects.Db4o;
using Db4objects.Db4o.Activation;
using Db4objects.Db4o.TA;

namespace Db4odoc.Tutorial.F1.Chapter9
{
    public class SensorReadout : IActivatable
    {
        private readonly DateTime _time;
        private readonly Car _car;
        private String _description;
        private SensorReadout _next;

        [Transient] 
        private IActivator _activator;

        protected SensorReadout(DateTime time, Car car, String description)
        {
            this._time = time;
            this._car = car;
            this._description = description;
            this._next = null;
        }

        public Car Car
        {
            get
            {
                Activate(ActivationPurpose.Read);
                return _car;
            }
        }

        public DateTime Time
        {
            get
            {
                Activate(ActivationPurpose.Read);
                return _time;
            }
        }

        public String Description
        {
            get
            {
                Activate(ActivationPurpose.Read);
                return _description;
            }
            set
            {
                Activate(ActivationPurpose.Write);
                _description = value;
            }
        }

        public SensorReadout Next
        {
            get
            {
                Activate(ActivationPurpose.Read);
                return _next;
            }
        }

        public void Append(SensorReadout readout)
        {
            Activate(ActivationPurpose.Write);
            if (_next == null)
            {
                _next = readout;
            }
            else
            {
                _next.Append(readout);
            }
        }

        public int CountElements()
        {
            Activate(ActivationPurpose.Read);
            return (_next == null ? 1 : _next.CountElements() + 1);
        }

        public override String ToString()
        {
            Activate(ActivationPurpose.Read);
            return String.Format("{0} : {1} : {2}", _car, _time, _description);
        }

        public void Activate(ActivationPurpose purpose)
        {
            if (_activator != null)
            {
                _activator.Activate(purpose);
            }
        }

        public void Bind(IActivator activator)
        {
            if (_activator == activator)
            {
                return;
            }
            if (activator != null && null != _activator)
            {
                throw new System.InvalidOperationException();
            }
            _activator = activator;
        }
    }
}