using System;

using System.Reactive.Linq;

using Splat;

namespace ReactiveUI

{

public static class ObservableLoggingMixin

{

/// <summary>

/// Logs an Observable to Splat's Logger

/// </summary>

/// <param name="klass">The hosting class, usually 'this'</param>

/// <param name="message">An optional method</param>

/// <param name="stringifier">An optional Func to convert Ts to strings.</param>

/// <returns>The same Observable</returns>

public static IObservable<T> Log<T, TObj>(this IObservable<T> This,

TObj klass,

string message = null,

Func<T, string> stringifier = null)

where TObj : IEnableLogger

{

message = message ?? "";

if (stringifier != null) {

return This.Do(

x => klass.Log().Info("{0} OnNext: {1}", message, stringifier(x)),

ex => klass.Log().WarnException(message + " " + "OnError", ex),

() => klass.Log().Info("{0} OnCompleted", message));

} else {

return This.Do(

x => klass.Log().Info("{0} OnNext: {1}", message, x),

ex => klass.Log().WarnException(message + " " + "OnError", ex),

() => klass.Log().Info("{0} OnCompleted", message));

}

}

/// <summary>

/// Like Catch, but also prints a message and the error to the log.

/// </summary>

/// <param name="klass">The hosting class, usually 'this'</param>

/// <param name="next">The Observable to replace the current one OnError.</param>

/// <param name="message">An error message to print.</param>

/// <returns>The same Observable</returns>

public static IObservable<T> LoggedCatch<T, TObj>(this IObservable<T> This, TObj klass, IObservable<T> next = null, string message = null)

where TObj : IEnableLogger

{

next = next ?? Observable<T>.Default;

return This.Catch<T, Exception>(ex => {

klass.Log().WarnException(message ?? "", ex);

return next;

});

}

/// <summary>

/// Like Catch, but also prints a message and the error to the log.

/// </summary>

/// <param name="klass">The hosting class, usually 'this'</param>

/// <param name="next">A Func to create an Observable to replace the

/// current one OnError.</param>

/// <param name="message">An error message to print.</param>

/// <returns>The same Observable</returns>

public static IObservable<T> LoggedCatch<T, TObj, TException>(this IObservable<T> This, TObj klass, Func<TException, IObservable<T>> next, string message = null)

where TObj : IEnableLogger

where TException : Exception

{

return This.Catch<T, TException>(ex => {

klass.Log().WarnException(message ?? "", ex);

return next(ex);

});

}

}

}