//
// The developer of the original code and/or files is Tripwire, Inc.
// Portions created by Tripwire, Inc. are copyright (C) 2000 Tripwire,
// Inc. Tripwire is a registered trademark of Tripwire, Inc.  All rights
// reserved.
// 
// This program is free software.  The contents of this file are subject
// to 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.  You may redistribute it and/or modify it
// only in compliance with the GNU General Public License.
// 
// This program is distributed in the hope that it will be useful.
// However, this program is distributed AS-IS WITHOUT ANY
// WARRANTY; INCLUDING THE IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS
// FOR A PARTICULAR PURPOSE.  Please 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.
// 
// Nothing in the GNU General Public License or any other license to use
// the code or files shall permit you to use Tripwire's trademarks,
// service marks, or other intellectual property without Tripwire's
// prior written consent.
// 
// If you have any questions, please contact Tripwire, Inc. at either
// info@tripwire.org or www.tripwire.org.
//
///////////////////////////////////////////////////////////////////////////////
// blockfile.cpp

#include "stddb.h"

#ifndef __TCHAR_H
#error
#endif

#include "blockfile.h"
#include "core/archive.h"
#include "core/debug.h"
#include "core/archive.h"

#include <vector>

//-----------------------------------------------------------------------------
// cBlockFile
//-----------------------------------------------------------------------------

///////////////////////////////////////////////////////////////////////////////
// ctor
///////////////////////////////////////////////////////////////////////////////
cBlockFile::cBlockFile()
:	mNumPages	(-1),
	mNumBlocks	(-1),
	mTimer		(0),
	mpArchive	(0)
{
#ifdef _BLOCKFILE_DEBUG

	mNumBlockWrite		= 0;
	mNumBlockRead		= 0;
	mNumPageFault		= 0;
	mNumPageRequests	= 0;

#endif //_BLOCKFILE_DEBUG
}

///////////////////////////////////////////////////////////////////////////////
// dtor
///////////////////////////////////////////////////////////////////////////////
cBlockFile::~cBlockFile()
{
	Close();
}

///////////////////////////////////////////////////////////////////////////////
// Open
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::Open( const TSTRING& fileName, int numPages, bool bTruncate) //throw (eArchive)
{
	ASSERT( numPages > 0 );
	ASSERT( ! mpArchive );
	
	cFileArchive* pArch = new cFileArchive;
    pArch->OpenReadWrite( fileName.c_str(), ( bTruncate ? cFileArchive::FA_OPEN_TRUNCATE : 0 ) );
	
	Open( pArch, numPages );
}

void cBlockFile::Open( cBidirArchive* pArch, int numPages ) //throw (eArchive)
{
	ASSERT( numPages > 0 );
	ASSERT( ! mpArchive );
	//
	// keep my sanity...
	//
	pArch->Seek( 0, cBidirArchive::BEGINNING );
	//
	// initialize the paged blocks list...
	//
	mpArchive	= pArch;
	mNumPages	= numPages;
	mvPagedBlocks.resize( mNumPages );
	ASSERT( mvPagedBlocks.capacity() == mNumPages );	// make sure that we didn't alloc too many!
	//
	// if the file is newly created, set its size to that of a single block
	//
	if( mpArchive->Length() == 0 )
	{
		mpArchive->WriteBlob( mvPagedBlocks[0].GetData(), GetBlockSize() );
	}
	//
	// make sure that the file is an appropriate length
	// TODO -- what is the correct thing to do if this fails? right now, I assert, but
	//		perhaps I should throw an exception or increase the file size to the next block interval
	ASSERT( mpArchive->Length() % GetBlockSize() == 0 );
	mNumBlocks = mpArchive->Length() / GetBlockSize();
}


///////////////////////////////////////////////////////////////////////////////
// Close
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::Close()
{
	if( mpArchive )
	{
		Flush();
		delete mpArchive;
		mpArchive = 0;
	}
}

///////////////////////////////////////////////////////////////////////////////
// Flush
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::Flush()
{
	ASSERT( mpArchive );
	for( BlockVector::iterator i = mvPagedBlocks.begin(); i != mvPagedBlocks.end(); i++ )
	{
		FlushBlock( &(*i) );
	}
}

///////////////////////////////////////////////////////////////////////////////
// GetBlock
///////////////////////////////////////////////////////////////////////////////
cBlockFile::Block*	cBlockFile::GetBlock( int blockNum ) //throw (eArchive)
{
#ifdef _BLOCKFILE_DEBUG
	mNumPageRequests++;
	AssertValid();
#endif
	//
	// debug stuff
	//
	cDebug d( "cBlockFile::GetBlock" );
	d.TraceNever( "Request for block %d\n", blockNum );
	
	//TODO -- I should really throw an exception here...
	ASSERT( (blockNum >= 0) && (blockNum < GetNumBlocks()) );
	ASSERT( mpArchive );

	//
	// first, increment the timer; if it flips, reset everybody's access times to 0.
	//
	mTimer++;
	if( mTimer == 0 )
	{
		for( BlockVector::iterator i = mvPagedBlocks.begin(); i != mvPagedBlocks.end(); i++ )
		{
			i->SetTimestamp( 0 );
		}
	}
	//
	// now, see if the desired block is in memory...
	//
	for( BlockVector::iterator i = mvPagedBlocks.begin(); i != mvPagedBlocks.end(); i++ )
	{
		if( i->GetBlockNum() == blockNum )
		{
			// this is easy; just return the block.
			i->SetTimestamp( mTimer );
			d.TraceNever( "\tBlock %d was in memory.\n", blockNum );
			return &(*i);
		}
	}
	//
	// ok, we are going to have to page it into memory; look for the page with the earliest timestamp to 
	// remove...
	//
#ifdef _BLOCKFILE_DEBUG
	mNumPageFault++;
#endif
	d.TraceNever( "\tBlock %d was not in memory; paging it in\n", blockNum );
	
	uint32 earliestTime					= mvPagedBlocks[0].GetTimestamp();
	BlockVector::iterator it			= mvPagedBlocks.begin();
	BlockVector::iterator earliestIter	= it;
	it++;	// since we don't want to check the first one
	ASSERT(it != mvPagedBlocks.end());
	for( ; it != mvPagedBlocks.end(); it++ )
	{
		if( it->GetTimestamp() < earliestTime )
		{
			earliestIter = it;
			earliestTime = it->GetTimestamp();
		}
	}
	ASSERT( (earliestIter >= mvPagedBlocks.begin()) && (earliestIter < mvPagedBlocks.end()) );
	//
	// flush the page data to disk if it is dirty...
	//
	FlushBlock( &(*earliestIter) );
	d.TraceNever( "\tPaging out block %d\n", earliestIter->GetBlockNum() );
	//
	// ok, now we can read in the new page...
	//
	earliestIter->SetBlockNum	( blockNum   );
	earliestIter->Read			( *mpArchive );
	earliestIter->SetTimestamp	( mTimer     );
	//
	// this variable keeps track of how many block reads we do.
#ifdef _BLOCKFILE_DEBUG
	mNumBlockRead++;
	AssertValid();
#endif
	return &(*earliestIter);

}

///////////////////////////////////////////////////////////////////////////////
// CreateBlock
///////////////////////////////////////////////////////////////////////////////
cBlockFile::Block* cBlockFile::CreateBlock()
{
	// debug stuff
	//
	ASSERT( mpArchive );
	cDebug d( "cBlockFile::CreateBlock()" );
	d.TraceDetail( "Creating new block (number %d)\n", GetNumBlocks() );
	
	char emptyBlock[BLOCK_SIZE];
	memset( emptyBlock, 0, BLOCK_SIZE );
	//
	// write empty data in the new block's location
	//
    //ASSERT(GetNumBlocks() * GetBlockSize() <= mpArchive->Length());
    d.TraceDetail("Seeking to %d * %d = %d\n", GetNumBlocks(), GetBlockSize(), GetNumBlocks() * GetBlockSize());
	mpArchive->Seek		( GetNumBlocks() * GetBlockSize(), cBidirArchive::BEGINNING );
	mpArchive->WriteBlob	( emptyBlock, BLOCK_SIZE );
	//
	// now, page it in...
	//
	mNumBlocks++;
	return GetBlock( GetNumBlocks() - 1 );
}

///////////////////////////////////////////////////////////////////////////////
// DestroyLastBlock
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::DestroyLastBlock(  )
{
	//TODO -- implement this!!!
	ASSERT( false );
/*
	mNumBlocks--;
	mpArchive->Seek( mNumBlocks * BLOCK_SIZE, cBidirArchive::BEGINNING );
	mpArchive->Truncate();

	AssertValid();
*/
}


//-----------------------------------------------------------------------------
// Debug methods...
//-----------------------------------------------------------------------------
#ifdef _BLOCKFILE_DEBUG

///////////////////////////////////////////////////////////////////////////////
// TraceContents
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::TraceContents(int dl) const
{
	cDebug d( "cBlockFile::TraceContents" );
	if( dl == -1 ) 
		dl = cDebug::D_DEBUG;

	d.Trace( dl, "Block size:             %d\n", GetBlockSize()		);
	d.Trace( dl, "Number of blocks:       %d\n", mNumBlocks			);
	d.Trace( dl, "Current timer:          %d\n", mTimer				);
	//
	// trace out the profiling info...
	//
	d.Trace( dl, "Number of page writes:  %d\n", mNumBlockWrite		);
	d.Trace( dl, "Number of page reads:   %d\n", mNumBlockRead		);
	d.Trace( dl, "Number of page faults:  %d\n", mNumPageFault		);
	d.Trace( dl, "Number of page requests:%d\n", mNumPageRequests	);
	
	d.Trace( dl, "Number of pages:        %d\n", mNumPages			);
	d.Trace( dl, "-------------------------\n");
	//
	// trace out all the block information...
	//
	int cnt = 0;
	for( BlockVector::const_iterator i = mvPagedBlocks.begin(); i != mvPagedBlocks.end(); i++, cnt++ )
	{
		d.Trace( dl, "Page[%d] Block Num=%d Timestamp=%d Dirty=%s\n", cnt, i->GetBlockNum(), i->GetTimestamp(), i->IsDirty() ? "true" : "false");
	}
	d.Trace( dl, "-------------------------\n");

}

///////////////////////////////////////////////////////////////////////////////
// CreateBlock
///////////////////////////////////////////////////////////////////////////////
void cBlockFile::AssertValid() const
{
	if( ! mpArchive )
		return;
	//
	// make sure the archive length and block count match up
	//
    #ifdef _DEBUG
    if (mpArchive->Length() != (GetBlockSize() * GetNumBlocks()))
	{
      	cDebug d("cBlockFile::AssertValid");
		d.Trace(cDebug::D_DEBUG, "FATAL ERROR!!!\n");
		d.Trace(cDebug::D_DEBUG, "mpArchive->Length() = %d \n\t!= blocksize * numblocks = %d * %d\n", int(mpArchive->Length()), int(GetBlockSize()), int(GetNumBlocks()));
		d.Trace(cDebug::D_DEBUG, "now tracing the contents...\n");
		TraceContents(cDebug::D_DEBUG);
	}
	#endif
    ASSERT( mpArchive->Length() == (GetBlockSize() * GetNumBlocks()) );

	//
	// iterate through the pages...
	//
	for( BlockVector::const_iterator i = mvPagedBlocks.begin(); i != mvPagedBlocks.end(); i++)
	{
		// make sure the block number is valid
		//
		int blockNum = i->GetBlockNum();
		ASSERT( (blockNum == cBlock<BLOCK_SIZE>::INVALID_NUM) || 
				( (blockNum >= 0) && (blockNum < GetNumBlocks()) ) );
		//
		// make sure the time stamp is less than or equal to the timer time...
		// 
		ASSERT( i->GetTimestamp() <= mTimer );
		//
		// assert that the guard bytes haven't been modified
		i->AssertValid();
	}
}

#endif //_BLOCKFILE_DEBUG