/*
 * Copyright (c) 2008-2024 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3.0 only,
 * as published by the Free Software Foundation.
 *
 * This program 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 Lesser General Public License
 * version 3.0 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3.0 along with this program. If not, see
 * <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "platform.h"

#ifdef OF_WINDOWS
/* Win32 has a ridiculous default of 64, even though it supports much more. */
# define FD_SETSIZE 1024
#endif

#include <errno.h>
#include <string.h>

#include <sys/time.h>

#import "OFSelectKernelEventObserver.h"
#import "OFArray.h"
#import "OFSocket+Private.h"

#import "OFInitializationFailedException.h"
#import "OFObserveKernelEventsFailedException.h"
#import "OFOutOfRangeException.h"

#ifdef OF_AMIGAOS
# define Class IntuitionClass
# include <proto/exec.h>
# undef Class
#endif

#ifdef OF_HPUX
/* FD_SET causes warnings on HP-UX/IA64. */
# pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif

@implementation OFSelectKernelEventObserver
- (instancetype)init
{
	self = [super init];

	@try {
		FD_ZERO(&_readFDs);
		FD_ZERO(&_writeFDs);

#ifdef OF_AMIGAOS
		_maxFD = -1;
#else
# ifndef OF_WINDOWS
		if (_cancelFD[0] >= (int)FD_SETSIZE)
			@throw [OFInitializationFailedException
			    exceptionWithClass: self.class];
# endif

		FD_SET(_cancelFD[0], &_readFDs);

		if (_cancelFD[0] > INT_MAX)
			@throw [OFOutOfRangeException exception];

		_maxFD = (int)_cancelFD[0];
#endif
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (void)addObjectForReading: (id <OFReadyForReadingObserving>)object
{
	int fd = object.fileDescriptorForReading;

	if (fd < 0)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: EBADF];

	if (fd > INT_MAX - 1)
		@throw [OFOutOfRangeException exception];

#ifndef OF_WINDOWS
	if (fd >= (int)FD_SETSIZE)
		@throw [OFOutOfRangeException exception];
#endif

	if (fd > _maxFD)
		_maxFD = fd;

	FD_SET((OFSocketHandle)fd, &_readFDs);

	[super addObjectForReading: object];
}

- (void)addObjectForWriting: (id <OFReadyForWritingObserving>)object
{
	int fd = object.fileDescriptorForWriting;

	if (fd < 0)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: EBADF];

	if (fd > INT_MAX - 1)
		@throw [OFOutOfRangeException exception];

#ifndef OF_WINDOWS
	if (fd >= (int)FD_SETSIZE)
		@throw [OFOutOfRangeException exception];
#endif

	if (fd > _maxFD)
		_maxFD = fd;

	FD_SET((OFSocketHandle)fd, &_writeFDs);

	[super addObjectForWriting: object];
}

- (void)removeObjectForReading: (id <OFReadyForReadingObserving>)object
{
	/* TODO: Adjust _maxFD */

	int fd = object.fileDescriptorForReading;

	if (fd < 0)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: EBADF];

#ifndef OF_WINDOWS
	if (fd >= (int)FD_SETSIZE)
		@throw [OFOutOfRangeException exception];
#endif

	FD_CLR((OFSocketHandle)fd, &_readFDs);

	[super removeObjectForReading: object];
}

- (void)removeObjectForWriting: (id <OFReadyForWritingObserving>)object
{
	/* TODO: Adjust _maxFD */

	int fd = object.fileDescriptorForWriting;

	if (fd < 0)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: EBADF];


#ifndef OF_WINDOWS
	if (fd >= (int)FD_SETSIZE)
		@throw [OFOutOfRangeException exception];
#endif

	FD_CLR((OFSocketHandle)fd, &_writeFDs);

	[super removeObjectForWriting: object];
}

- (void)observeForTimeInterval: (OFTimeInterval)timeInterval
{
	fd_set readFDs;
	fd_set writeFDs;
	struct timeval timeout;
	int events;
#ifdef OF_AMIGAOS
	BYTE cancelSignal;
	ULONG execSignalMask;
#endif
	void *pool;

	if ([self of_processReadBuffers])
		return;

#ifdef FD_COPY
	FD_COPY(&_readFDs, &readFDs);
	FD_COPY(&_writeFDs, &writeFDs);
#else
	readFDs = _readFDs;
	writeFDs = _writeFDs;
#endif

	/*
	 * We cast to int before assigning to tv_usec in order to avoid a
	 * warning with Apple GCC on PowerPC. POSIX defines this as suseconds_t,
	 * however, this is not available on Win32. As an int should always
	 * satisfy the required range, we just cast to int.
	 */
#ifndef OF_WINDOWS
	timeout.tv_sec = (time_t)timeInterval;
#else
	timeout.tv_sec = (long)timeInterval;
#endif
	timeout.tv_usec = (int)((timeInterval - timeout.tv_sec) * 1000000);

#ifdef OF_AMIGAOS
	if ((cancelSignal = AllocSignal(-1)) == (BYTE)-1)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: EAGAIN];

	execSignalMask = _execSignalMask | (1ul << cancelSignal);

	Forbid();

	_waitingTask = FindTask(NULL);
	_cancelSignal = cancelSignal;

	events = WaitSelect(_maxFD + 1, &readFDs, &writeFDs, NULL,
	    (void *)(timeInterval != -1 ? &timeout : NULL), &execSignalMask);

	execSignalMask &= ~(1ul << cancelSignal);

	_waitingTask = NULL;
	FreeSignal(_cancelSignal);

	Permit();
#else
	events = select(_maxFD + 1, &readFDs, &writeFDs, NULL,
	    (timeInterval != -1 ? &timeout : NULL));
#endif

	if (events < 0)
		@throw [OFObserveKernelEventsFailedException
		    exceptionWithObserver: self
				    errNo: _OFSocketErrNo()];

#ifdef OF_AMIGAOS
	if (execSignalMask != 0 &&
	    [_delegate respondsToSelector: @selector(execSignalWasReceived:)])
		[_delegate execSignalWasReceived: execSignalMask];
#else
	if (FD_ISSET(_cancelFD[0], &readFDs)) {
		char buffer;

# ifdef OF_HAVE_PIPE
		OFEnsure(read(_cancelFD[0], &buffer, 1) == 1);
# else
		OFEnsure(recvfrom(_cancelFD[0], (void *)&buffer, 1, 0, NULL,
		    NULL) == 1);
# endif
	}
#endif

	pool = objc_autoreleasePoolPush();

	for (id <OFReadyForReadingObserving> object in
	    [[_readObjects copy] autorelease]) {
		void *pool2 = objc_autoreleasePoolPush();
		int fd = object.fileDescriptorForReading;

		if (FD_ISSET((OFSocketHandle)fd, &readFDs) &&
		    [_delegate respondsToSelector:
		    @selector(objectIsReadyForReading:)])
			[_delegate objectIsReadyForReading: object];

		objc_autoreleasePoolPop(pool2);
	}

	for (id <OFReadyForWritingObserving> object in
	    [[_writeObjects copy] autorelease]) {
		void *pool2 = objc_autoreleasePoolPush();
		int fd = object.fileDescriptorForWriting;

		if (FD_ISSET((OFSocketHandle)fd, &writeFDs) &&
		    [_delegate respondsToSelector:
		    @selector(objectIsReadyForWriting:)])
			[_delegate objectIsReadyForWriting: object];

		objc_autoreleasePoolPop(pool2);
	}

	objc_autoreleasePoolPop(pool);
}
@end
