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package com.cookingfox.lapasse.impl.logging;
import com.cookingfox.lapasse.api.command.Command;
import com.cookingfox.lapasse.api.command.logging.CommandHandlerError;
import com.cookingfox.lapasse.api.command.logging.CommandHandlerResult;
import com.cookingfox.lapasse.api.command.logging.CommandLogger;
import com.cookingfox.lapasse.api.command.logging.CommandLoggerAware;
import com.cookingfox.lapasse.api.event.Event;
import com.cookingfox.lapasse.api.event.logging.EventHandlerError;
import com.cookingfox.lapasse.api.event.logging.EventHandlerResult;
import com.cookingfox.lapasse.api.event.logging.EventLogger;
import com.cookingfox.lapasse.api.event.logging.EventLoggerAware;
import com.cookingfox.lapasse.api.state.State;
import rx.Observable;
import rx.Subscriber;
import rx.functions.Action0;
import rx.subscriptions.Subscriptions;
import java.util.Collection;
import static java.util.Objects.requireNonNull;
/**
* Rx helper methods for logging features.
*/
public final class RxLoggerHelper {
//----------------------------------------------------------------------------------------------
// CONSTRUCTOR (disabled)
//----------------------------------------------------------------------------------------------
private RxLoggerHelper() {
throw new UnsupportedOperationException();
}
//----------------------------------------------------------------------------------------------
// PUBLIC METHODS
//----------------------------------------------------------------------------------------------
/**
* Creates an observable for command handler errors.
*
* @param loggerAware The subject for which to observe command handler errors.
* @return An observable for command handler errors.
*/
public static Observable observeCommandHandlerErrors(
CommandLoggerAware loggerAware) {
return logCommand(requireNonNull(loggerAware), new RxCommandLogger() {
@Override
public void onCommandHandlerError(final Throwable e, final Command command) {
subscriber.onNext(new CommandHandlerError() {
@Override
public Command getCommand() {
return command;
}
@Override
public Throwable getError() {
return e;
}
});
}
});
}
/**
* Creates an observable for command handler results.
*
* @param loggerAware The subject for which to observe command handler results.
* @return An observable for command handler results.
*/
public static Observable observeCommandHandlerResults(
CommandLoggerAware loggerAware) {
return logCommand(requireNonNull(loggerAware), new RxCommandLogger() {
@Override
public void onCommandHandlerResult(final Command command, final Collection events) {
subscriber.onNext(new CommandHandlerResult() {
@Override
public Command getCommand() {
return command;
}
@Override
public Collection getEvents() {
return events;
}
});
}
});
}
/**
* Creates an observable for event handler errors.
*
* @param loggerAware The subject for which to observe event handler errors.
* @param The concrete type of the state object.
* @return An observable for event handler errors.
*/
public static Observable observeEventHandlerErrors(
EventLoggerAware loggerAware) {
return logEvent(requireNonNull(loggerAware), new RxEventLogger() {
@Override
public void onEventHandlerError(final Throwable e, final Event event) {
subscriber.onNext(new EventHandlerError() {
@Override
public Throwable getError() {
return e;
}
@Override
public Event getEvent() {
return event;
}
});
}
});
}
/**
* Creates an observable for event handler results.
*
* @param loggerAware The subject for which to observe event handler results.
* @param The concrete type of the state object.
* @return An observable for event handler results.
*/
public static Observable observeEventHandlerResults(
EventLoggerAware loggerAware) {
return logEvent(requireNonNull(loggerAware), new RxEventLogger() {
@Override
public void onEventHandlerResult(final Event event, final S newState) {
subscriber.onNext(new EventHandlerResult() {
@Override
public Event getEvent() {
return event;
}
@Override
public S getNewState() {
return newState;
}
});
}
});
}
//----------------------------------------------------------------------------------------------
// PRIVATE METHODS
//----------------------------------------------------------------------------------------------
/**
* Creates an observable for the provided logger implementation. Adds the logger when subscribed
* to the observable and removes it when unsubscribed.
*
* @param loggerAware The subject for which to observe handler log calls.
* @param logger The logger implementation.
* @param The concrete log call VO that will be emitted by the observable.
* @return Observable for the provided log call VO.
*/
static Observable logCommand(final CommandLoggerAware loggerAware,
final RxCommandLogger logger) {
return Observable.create(new Observable.OnSubscribe() {
@Override
public void call(Subscriber subscriber) {
// set subscriber reference for logger
logger.subscriber = subscriber;
// add logger
loggerAware.addCommandLogger(logger);
// remove logger on subscriber unsubscribe
subscriber.add(Subscriptions.create(new Action0() {
@Override
public void call() {
loggerAware.removeCommandLogger(logger);
}
}));
}
});
}
/**
* * Creates an observable for the provided logger implementation. Adds the logger when subscribed
* to the observable and removes it when unsubscribed.
*
* @param loggerAware The subject for which to observe handler log calls.
* @param logger The logger implementation.
* @param The concrete type of the state object.
* @param The concrete log call VO that will be emitted by the observable.
* @return Observable for the provided log call VO.
*/
static Observable logEvent(final EventLoggerAware loggerAware,
final RxEventLogger logger) {
return Observable.create(new Observable.OnSubscribe() {
@Override
public void call(Subscriber subscriber) {
// set subscriber reference for logger
logger.subscriber = subscriber;
// add logger
loggerAware.addEventLogger(logger);
// remove logger on subscriber unsubscribe
subscriber.add(Subscriptions.create(new Action0() {
@Override
public void call() {
loggerAware.removeEventLogger(logger);
}
}));
}
});
}
//----------------------------------------------------------------------------------------------
// MEMBER CLASSES
//----------------------------------------------------------------------------------------------
/**
* Helper class for usage with Rx subscriber.
*
* @param The concrete type of the value this subscriber will receive.
*/
static abstract class SubscriberAware {
/**
* The subscriber reference.
*/
Subscriber subscriber;
}
/**
* No-operation implementation of {@link CommandLogger} that is {@link SubscriberAware}.
*
* @param The concrete type of the value which will be received by the subscriber.
*/
static class RxCommandLogger extends SubscriberAware implements CommandLogger {
@Override
public void onCommandHandlerError(Throwable e, Command command) {
// override in subclass
}
@Override
public void onCommandHandlerResult(Command command, Collection events) {
// override in subclass
}
}
/**
* No-operation implementation of {@link EventLogger} that is {@link SubscriberAware}.
*
* @param The concrete type of the state object.
* @param The concrete type of the value which will be received by the subscriber.
*/
static class RxEventLogger
extends SubscriberAware implements EventLogger {
@Override
public void onEventHandlerError(Throwable e, Event event) {
// override in subclass
}
@Override
public void onEventHandlerResult(Event event, S newState) {
// override in subclass
}
}
}
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