/*

Miranda NG: the free IM client for Microsoft* Windows*

Copyright 2012 Miranda NG project,
all portions of this codebase are copyrighted to the people
listed in contributors.txt.

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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

#include "commonheaders.h"

void CDb3Mmap::Map()
{
	m_hMap = CreateFileMapping(m_hDbFile, NULL, PAGE_READWRITE, 0, m_dwFileSize, NULL);

	if (m_hMap)
	{
		m_pDbCache = (PBYTE)MapViewOfFile(m_hMap, FILE_MAP_ALL_ACCESS/*FILE_MAP_WRITE*/, 0, 0 ,0);
		if (!m_pDbCache)
			DatabaseCorruption( _T("%s (MapViewOfFile failed. Code: %d)"));
	}
	else
		DatabaseCorruption( _T("%s (CreateFileMapping failed. Code: %d)"));
}

void CDb3Mmap::ReMap(DWORD needed)
{
	KillTimer(NULL,m_flushBuffersTimerId);

	log3("remapping %d + %d (file end: %d)",m_dwFileSize,needed,m_dbHeader.ofsFileEnd);

	if (needed > m_ChunkSize)
	{
		if (needed + m_dwFileSize > m_dbHeader.ofsFileEnd + m_ChunkSize)
			DatabaseCorruption( _T("%s (Too large increment)"));
		else
		{
			DWORD x = m_dbHeader.ofsFileEnd/m_ChunkSize;
			m_dwFileSize = (x+1)*m_ChunkSize;
		}
	}
	else
		m_dwFileSize += m_ChunkSize;

//	FlushViewOfFile(m_pDbCache, 0);
	UnmapViewOfFile(m_pDbCache);
	m_pDbCache = NULL;
	CloseHandle(m_hMap);

	Map();
}

void CDb3Mmap::DBMoveChunk(DWORD ofsDest,DWORD ofsSource,int bytes)
{
	int x = 0;
	log3("move %d %08x->%08x",bytes,ofsSource,ofsDest);
	if (ofsDest+bytes > m_dwFileSize) ReMap(ofsDest+bytes-m_dwFileSize);
	if (ofsSource+bytes > m_dwFileSize) {
		x = ofsSource+bytes-m_dwFileSize;
		log0("buggy move!");
	}
	if (x > 0)
		ZeroMemory(m_pDbCache+ofsDest+bytes-x, x);
	if (ofsSource < m_dwFileSize)
		MoveMemory(m_pDbCache+ofsDest,m_pDbCache+ofsSource, bytes-x);

	logg();
}

//we are assumed to be in a mutex here
PBYTE CDb3Mmap::DBRead(DWORD ofs,int bytesRequired,int *bytesAvail)
{
	// buggy read
	if (ofs>= m_dwFileSize) {
		log2("read from outside %d@%08x",bytesRequired,ofs);
		if (bytesAvail != NULL) *bytesAvail = m_ChunkSize;
		return m_pNull;
	}
	log3((ofs+bytesRequired > m_dwFileSize)?"read %d@%08x, only %d avaliable":"read %d@%08x",bytesRequired,ofs,m_dwFileSize-ofs);
	if (bytesAvail != NULL) *bytesAvail = m_dwFileSize - ofs;
	return m_pDbCache+ofs;
}

//we are assumed to be in a mutex here
void CDb3Mmap::DBWrite(DWORD ofs,PVOID pData,int bytes)
{
	log2("write %d@%08x",bytes,ofs);
	if (ofs+bytes > m_dwFileSize) ReMap(ofs+bytes-m_dwFileSize);
	MoveMemory(m_pDbCache+ofs,pData,bytes);
	logg();
}

//we are assumed to be in a mutex here
void CDb3Mmap::DBFill(DWORD ofs,int bytes)
{
	log2("zerofill %d@%08x",bytes,ofs);
	if (ofs+bytes <= m_dwFileSize)
		ZeroMemory(m_pDbCache+ofs,bytes);
	logg();
}

static VOID CALLBACK DoBufferFlushTimerProc(HWND hwnd, UINT message, UINT_PTR idEvent, DWORD dwTime)
{
	for (int i=0; i < g_Dbs.getCount(); i++) {
		CDb3Mmap* db = g_Dbs[i];
		if (db->m_flushBuffersTimerId != idEvent)
			continue;

		if (!db->m_pDbCache)
			return;

		KillTimer(NULL, db->m_flushBuffersTimerId);
		log0("tflush1");
		if (FlushViewOfFile(db->m_pDbCache, 0) == 0) {
			if (db->m_flushFailTick == 0)
				db->m_flushFailTick = GetTickCount();
			else if (GetTickCount() - db->m_flushFailTick > 5000)
				db->DatabaseCorruption(NULL);
		}
		else db->m_flushFailTick = 0;
		log0("tflush2");
	}
}

void CDb3Mmap::DBFlush(int setting)
{
	if (!setting) {
		log0("nflush1");
		if (m_safetyMode && m_pDbCache) {
			if (FlushViewOfFile(m_pDbCache, 0) == 0) {
				if (m_flushFailTick == 0)
					m_flushFailTick = GetTickCount();
				else if (GetTickCount() - m_flushFailTick > 5000)
					DatabaseCorruption(NULL);
			}
			else
				m_flushFailTick = 0;
		}
		log0("nflush2");
		return;
	}
	KillTimer(NULL, m_flushBuffersTimerId);
	m_flushBuffersTimerId = SetTimer(NULL, m_flushBuffersTimerId, 50, DoBufferFlushTimerProc);
}

int CDb3Mmap::InitCache(void)
{
	m_dwFileSize = GetFileSize(m_hDbFile,  NULL);

	// Align to chunk
	DWORD x = m_dwFileSize % m_ChunkSize;
	if (x)
		m_dwFileSize += m_ChunkSize - x;

	Map();

	// zero region for reads outside the file
	m_pNull = (PBYTE)calloc(m_ChunkSize, 1);
	return 0;
}