using System;

using System.ComponentModel;

using System.Reactive.Disposables;

using System.Reactive.Linq;

using System.Threading;

using System.Reactive.Subjects;

namespace ReactiveUI

{

/// <summary>

/// This class helps you take existing objects and make them compatible with

/// ReactiveUI and Rx.Net. To use this, declare an instance field of this

/// class in your class, initialize it in your Constructor, make your class

/// derive from IReactiveNotifyPropertyChanged, then implement all of the

/// properties/methods using MakeObjectReactiveHelper.

/// </summary>

public class MakeObjectReactiveHelper : IReactiveNotifyPropertyChanged

{

public MakeObjectReactiveHelper(INotifyPropertyChanged hostObject)

{

var hostChanging = hostObject as INotifyPropertyChanging;

if (hostChanging != null) {

hostChanging.PropertyChanging += (o, e) => _Changing.OnNext(

new ObservedChange<object, object>() { Sender = o, PropertyName = e.PropertyName });

} else {

this.Log().ErrorFormat("'{0}' does not implement INotifyPropertyChanging - RxUI may return duplicate change notifications",

hostObject.GetType().FullName);

}

hostObject.PropertyChanged += (o, e) => _Changed.OnNext(

new ObservedChange<object, object>() { Sender = o, PropertyName = e.PropertyName });

}

int _changeCountSuppressed = 0;

public IDisposable SuppressChangeNotifications()

{

Interlocked.Increment(ref _changeCountSuppressed);

return Disposable.Create(() => Interlocked.Decrement(ref _changeCountSuppressed));

}

public event PropertyChangedEventHandler PropertyChanged;

public event PropertyChangingEventHandler PropertyChanging;

readonly ISubject<IObservedChange<object, object>> _Changing =

new ScheduledSubject<IObservedChange<object, object>>(RxApp.DeferredScheduler);

public IObservable<IObservedChange<object, object>> Changing {

#if SILVERLIGHT || PORTABLE_LIB

get { return _Changing.Where(_ => _changeCountSuppressed == 0); }

#else

get { return _Changing.Where(_ => Interlocked.Read(ref _changeCountSuppressed) == 0); }

#endif

}

ISubject<IObservedChange<object, object>> _Changed =

new ScheduledSubject<IObservedChange<object, object>>(RxApp.DeferredScheduler);

public IObservable<IObservedChange<object, object>> Changed {

#if SILVERLIGHT || PORTABLE_LIB

get { return _Changed.Where(_ => _changeCountSuppressed == 0); }

#else

get { return _Changed.Where(_ => Interlocked.Read(ref _changeCountSuppressed) == 0); }

#endif

}

}

}