///////////////////////////////////////////////////////////////////////////////
// MediaInfoXP
// Copyright (C) 2004-2014 LoRd_MuldeR <MuldeR2@GMX.de>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// http://www.gnu.org/licenses/gpl-2.0.txt
///////////////////////////////////////////////////////////////////////////////

#include "IPC.h"

#include "Utils.h"

#include <QSharedMemory>
#include <QSystemSemaphore>
#include <QThread>

static const size_t MAX_STR_LEN = 1024;
static const size_t MAX_ENTRIES = 16;

static const char *s_key_smemory = "{35DE4BDD-F88C-41E1-8080-2EDC503757F2}";
static const char *s_key_sema_wr = "{C638D990-7553-4D4D-95E8-9B040BA6AE87}";
static const char *s_key_sema_rd = "{0C30B0B2-0B03-49D7-8DB3-A7D0DDDEA2B0}";

typedef struct
{
	wchar_t data[MAX_ENTRIES][MAX_STR_LEN];
	size_t posRd;
	size_t posWr;
}
mixp_ipc_t;

IPC::IPC(void)
{
	m_initialized  = -1;
	m_sharedMemory = NULL;
	m_semaphoreWr  = NULL;
	m_semaphoreRd  = NULL;
}

IPC::~IPC(void)
{
	MIXP_DELETE_OBJ(m_sharedMemory);
	MIXP_DELETE_OBJ(m_semaphoreWr);
	MIXP_DELETE_OBJ(m_semaphoreRd);
}

///////////////////////////////////////////////////////////////////////////////

class SendThread : public QThread
{
public:
	SendThread(IPC *ipc, const QString &str) : m_ipc(ipc), m_str(str)
	{
		m_result = false;
	}
	
	virtual void run(void)
	{
		try
		{
			m_result = m_ipc->pushStr(m_str);
		}
		catch(...)
		{
			m_result = false;
		}
	}

	inline bool result(void) { return m_result; }

protected:
	volatile bool m_result;
	IPC *const m_ipc;
	const QString m_str;
};

///////////////////////////////////////////////////////////////////////////////

int IPC::init(void)
{
	if(m_initialized >= 0)
	{
		return m_initialized;
	}

	m_semaphoreWr = new QSystemSemaphore(s_key_sema_wr, MAX_ENTRIES);
	m_semaphoreRd = new QSystemSemaphore(s_key_sema_rd, 0);

	if((m_semaphoreWr->error() != QSystemSemaphore::NoError) || (m_semaphoreRd->error() != QSystemSemaphore::NoError))
	{
		qWarning("IPC: Failed to created system semaphores!");
		return -1;
	}

	m_sharedMemory = new QSharedMemory(s_key_smemory, this);

	if(m_sharedMemory->create(sizeof(mixp_ipc_t)))
	{
		memset(m_sharedMemory->data(), 0, sizeof(mixp_ipc_t));
		m_initialized = 1;
		return 1;
	}

	if(m_sharedMemory->error() == QSharedMemory::AlreadyExists)
	{
		qDebug("Not the first instance -> attaching to existing shared memory");
		if(m_sharedMemory->attach())
		{
			m_initialized = 0;
			return 0;
		}
	}

	qWarning("IPC: Failed to attach to the shared memory!");
	return -1;
}

bool IPC::pushStr(const QString &str)
{
	if(m_initialized < 0)
	{
		qWarning("Error: IPC not initialized yet!");
		return false;
	}

	if(!m_semaphoreWr->acquire())
	{
		qWarning("IPC: Failed to acquire semaphore!");
		return false;
	}

	if(!m_sharedMemory->lock())
	{
		qWarning("IPC: Failed to lock shared memory!");
		return false;
	}

	try
	{
		mixp_ipc_t *memory = (mixp_ipc_t*) m_sharedMemory->data();
		wcsncpy_s(memory->data[memory->posWr], MAX_STR_LEN, (wchar_t*)str.utf16(), _TRUNCATE);
		memory->posWr = (memory->posWr + 1) % MAX_ENTRIES;
	}
	catch(...)
	{
		/*ignore any exception*/
	}

	m_sharedMemory->unlock();
	m_semaphoreRd->release();

	return true;
}

bool IPC::popStr(QString &str)
{
	if(m_initialized < 0)
	{
		qWarning("Error: IPC not initialized yet!");
		return false;
	}

	if(!m_semaphoreRd->acquire())
	{
		qWarning("IPC: Failed to acquire semaphore!");
		return false;
	}

	if(!m_sharedMemory->lock())
	{
		qWarning("IPC: Failed to lock shared memory!");
		return false;
	}

	try
	{
		mixp_ipc_t *memory = (mixp_ipc_t*) m_sharedMemory->data();
		str = QString::fromUtf16((const ushort*)memory->data[memory->posRd]);
		memory->posRd = (memory->posRd + 1) % MAX_ENTRIES;
	}
	catch(...)
	{
		/*ignore any exception*/
	}

	m_sharedMemory->unlock();
	m_semaphoreWr->release();

	return true;
}

bool IPC::sendAsync(const QString &str, const int timeout)
{
	SendThread sendThread(this, str);
	sendThread.start();

	if(!sendThread.wait(timeout))
	{
		qWarning("IPC send operation encountered timeout!");
		sendThread.terminate();
		sendThread.wait();
		return false;
	}

	return sendThread.result();
}