/*
 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
 *               2018, 2019, 2020
 *   Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This file is part of ObjFW. It may be distributed under the terms of the
 * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
 * the packaging of this file.
 *
 * Alternatively, it may be distributed under the terms of the GNU General
 * Public License, either version 2 or 3, which can be found in the file
 * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
 * file.
 */

#import "OFObject.h"

#ifdef OF_HAVE_SOCKETS
# import "socket.h"
#endif

#ifdef OF_AMIGAOS
# include <exec/types.h>
# include <exec/tasks.h>
#endif

OF_ASSUME_NONNULL_BEGIN

@class OFMutableArray OF_GENERIC(ObjectType);
@class OFDate;
#ifdef OF_HAVE_THREADS
@class OFMutex;
#endif
@class OFMutableData;

/*!
 * @protocol OFKernelEventObserverDelegate
 *	     OFKernelEventObserver.h ObjFW/OFKernelEventObserver.h
 *
 * @brief A protocol that needs to be implemented by delegates for
 *	  OFKernelEventObserver.
 */
@protocol OFKernelEventObserverDelegate <OFObject>
@optional
/*!
 * @brief This callback is called when an object did get ready for reading.
 *
 * @note If the object is a subclass of @ref OFStream and
 *	 @ref OFStream::tryReadLine or @ref OFStream::tryReadTillDelimiter: has
 *	 been called on the stream, this callback will not be called again
 *	 until new data has been received, even though there is still data in
 *	 the cache. The reason for this is to prevent spinning in a loop when
 *	 there is an incomplete string in the cache. Once the string has been
 *	 completed, the callback will be called again as long there is data in
 *	 the cache.
 *
 * @param object The object which did become ready for reading
 */
- (void)objectIsReadyForReading: (id)object;

/*!
 * @brief This callback is called when an object did get ready for writing.
 *
 * @param object The object which did become ready for writing
 */
- (void)objectIsReadyForWriting: (id)object;

#ifdef OF_AMIGAOS
/*!
 * @brief This callback is called when an Exec Signal was received.
 *
 * @note This is only available on AmigaOS!
 */
- (void)execSignalWasReceived: (ULONG)signalMask;
#endif
@end

/*!
 * @protocol OFReadyForReadingObserving
 *	     OFKernelEventObserver.h ObjFW/OFKernelEventObserver.h
 *
 * @brief This protocol is implemented by classes which can be observed for
 *	  readiness for reading by OFKernelEventObserver.
 */
@protocol OFReadyForReadingObserving <OFObject>
/*!
 * @brief The file descriptor for reading that should be checked by the
 *	  OFKernelEventObserver.
 */
@property (readonly, nonatomic) int fileDescriptorForReading;
@end

/*!
 * @protocol OFReadyForWritingObserving
 *	     OFKernelEventObserver.h ObjFW/OFKernelEventObserver.h
 *
 * @brief This protocol is implemented by classes which can be observed for
 *	  readiness for writing by OFKernelEventObserver.
 */
@protocol OFReadyForWritingObserving <OFObject>
/*!
 * @brief The file descriptor for writing that should be checked by the
 *	  OFKernelEventObserver.
 */
@property (readonly, nonatomic) int fileDescriptorForWriting;
@end

#ifdef OF_HAVE_SOCKETS
/*!
 * @class OFKernelEventObserver
 *	  OFKernelEventObserver.h ObjFW/OFKernelEventObserver.h
 *
 * @brief A class that can observe multiple kernel events (e.g. streams being
 *	  ready to read) at once.
 *
 * @note Currently, Win32 can only observe TCP and UDP sockets!
 */
@interface OFKernelEventObserver: OFObject
{
	OFMutableArray OF_GENERIC(id <OFReadyForReadingObserving>)
	    *_readObjects;
	OFMutableArray OF_GENERIC(id <OFReadyForWritingObserving>)
	    *_writeObjects;
	id <OFKernelEventObserverDelegate> _Nullable _delegate;
#if defined(OF_HAVE_PIPE)
	int _cancelFD[2];
#elif defined(OF_AMIGAOS)
	struct Task *_waitingTask;
	ULONG _cancelSignal;
#else
	of_socket_t _cancelFD[2];
	struct sockaddr_in _cancelAddr;
#endif
#ifdef OF_AMIGAOS
	ULONG _execSignalMask;
#endif
	OF_RESERVE_IVARS(4)
}

/*!
 * @brief The delegate for the OFKernelEventObserver.
 */
@property OF_NULLABLE_PROPERTY (assign, nonatomic)
    id <OFKernelEventObserverDelegate> delegate;

#ifdef OF_AMIGAOS
/*!
 * @brief A mask of Exec Signals to wait for.
 *
 * @note This is only available on AmigaOS!
 */
@property (nonatomic) ULONG execSignalMask;
#endif

/*!
 * @brief Creates a new OFKernelEventObserver.
 *
 * @return A new, autoreleased OFKernelEventObserver
 */
+ (instancetype)observer;

/*!
 * @brief Adds an object to observe for reading.
 *
 * This is also used to observe a listening socket for incoming connections,
 * which then triggers a read event for the observed object.
 *
 * If there is an @ref observe call blocking, it will be canceled. The reason
 * for this is to prevent blocking even though the newly added object is ready.
 *
 * @param object The object to observe for reading
 */
- (void)addObjectForReading: (id <OFReadyForReadingObserving>)object;

/*!
 * @brief Adds an object to observe for writing.
 *
 * If there is an @ref observe call blocking, it will be canceled. The reason
 * for this is to prevent blocking even though the newly added object is ready.
 *
 * @param object The object to observe for writing
 */
- (void)addObjectForWriting: (id <OFReadyForWritingObserving>)object;

/*!
 * @brief Removes an object to observe for reading.
 *
 * If there is an @ref observe call blocking, it will be canceled. The reason
 * for this is to prevent the removed object from still being observed.
 *
 * @param object The object to remove from observing for reading
 */
- (void)removeObjectForReading: (id <OFReadyForReadingObserving>)object;

/*!
 * @brief Removes an object to observe for writing.
 *
 * If there is an @ref observe call blocking, it will be canceled. The reason
 * for this is to prevent the removed object from still being observed.
 *
 * @param object The object to remove from observing for writing
 */
- (void)removeObjectForWriting: (id <OFReadyForWritingObserving>)object;

/*!
 * @brief Observes all objects and blocks until an event happens on an object.
 */
- (void)observe;

/*!
 * @brief Observes all objects until an event happens on an object or the
 *	  timeout is reached.
 *
 * @param timeInterval The time to wait for an event, in seconds
 */
- (void)observeForTimeInterval: (of_time_interval_t)timeInterval;

/*!
 * @brief Observes all objects until an event happens on an object or the
 *	  specified date is reached.
 *
 * @param date The until which to observe
 */
- (void)observeUntilDate: (OFDate *)date;

/*!
 * @brief Cancels the currently blocking observe call.
 *
 * This is the only method that can and should be called from another thread
 * than the one using the observer.
 */
- (void)cancel;

/*!
 * @brief This method should be called by subclasses in @ref observeUntilDate:
 *	  as the first thing to handle all sockets that currently have data in
 *	  the read buffer.
 */
- (bool)of_processReadBuffers;
@end
#endif

OF_ASSUME_NONNULL_END
