/*

* Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

#include "t_rndutils.h"

const TInt KMaxWordLength =  64 ;

const TInt KMaxNgramSize = 8;

void CWordNgrams::ConstructL(const TDesC& aFilename, const TInt  aN, TBool aUseNarrowChar)

	{

	ASSERT(aN<KMaxNgramSize && aN>0);

	RFs fsSession;

	RFileReadStream fileStream;

	User::LeaveIfError(fsSession.Connect());

	CleanupClosePushL(fsSession);

	User::LeaveIfError(fileStream.Open(fsSession, aFilename, EFileRead));

	CleanupClosePushL(fileStream);

	TUint number = 0;

	TBuf8<KMaxNgramSize> ngram8;

#ifdef _UNICODE

	TBuf<KMaxNgramSize> ngram;

#else

#define  ngram ngram8;

#endif

	TInt err=KErrNone; 

	while(err==KErrNone)

		{

		TRAP(err, number = fileStream.ReadUint8L()); 

		if(err==KErrNone)

			{

			if(aUseNarrowChar)

				{

				fileStream.ReadL(ngram8,aN);

				SetNgram(ngram8, number);

				}

			else

				{

				fileStream.ReadL(ngram,aN);

				SetNgram(ngram, number);

				}

			}

		}

	CleanupStack::PopAndDestroy(2);

	}

HBufC*  CWordNgrams::WordLC()

	{

	HBufC* buffer = HBufC::NewLC(KMaxWordLength);

	TPtr word = buffer->Des();

	while(AddLetter(word))

		{}

	return buffer;

	}

/** Return false if done*/

TBool CWordNgrams::AddLetter(TDes& aWord)

	{

	if(aWord.Length()==aWord.MaxLength())

		{

		return EFalse;

		}

	TChar c = NextLetter(aWord);

	if(c==0)

		{

		return EFalse;

		}

	aWord.Append(c);

	return ETrue;

	}

//

// CWordDigrams.

//

CWordDigrams::CWordDigrams(TInt64& aRandSeed) : iRandSeed(aRandSeed)

	{}

CWordDigrams* CWordDigrams::NewLC(const TDesC& aFilename, TInt64& aRandSeed)

	{

	CWordDigrams* self = new(ELeave) CWordDigrams(aRandSeed);

	CleanupStack::PushL(self);

	self->ConstructL(aFilename);

	return self;

	}

void CWordDigrams::SetNgram(const TDesC8& aNgram, TUint aNumber)

	{

	iDigrams[Index(aNgram[0])][Index(aNgram[1])] = (TUint8) aNumber;

	}

void CWordDigrams::SetNgram(const TDesC16& /*aNgram*/, TUint /*aNumber*/)

	{}

void CWordDigrams::ConstructL(const TDesC& aFilename)

	{

	CWordNgrams::ConstructL(aFilename);

	for(TInt i=0;i<KDigramNumberOfChars;i++)

		{

		TUint max =0;

		for(TInt j=0;j<KDigramNumberOfChars;j++)

			{

			max += iDigrams[i][j];

			}

		iSizes[i] = (TUint16)max;

		}

	}

TChar CWordDigrams::NextLetter(const TDesC& aWord)

	{

	TInt len = aWord.Length();

	TInt index = 0;

	if(len!=0)

		{

		index = Index(aWord[len-1]);

		}

	if(iSizes[index]==0)

		{

		return 0;

		}

	TInt x = Math::Rand(iRandSeed) % iSizes[index];

	for(TInt i=0;i<KDigramNumberOfChars;i++)

		{

		if(x<iDigrams[index][i])

			{

			return Char(i);

			}

		x-=iDigrams[index][i];

		if(x<=0) 

			{

			x=1;

			}

		}

	return 0;

	}

TInt CWordDigrams::Index(TChar c)

	{

	if(c.IsSpace())

		return 1;

	if(c=='-')

		return 2;

	if(c.IsUpper())

		return ((TUint)c)-'A'+KDigramNumberOfNonLetters;

	if(c.IsLower())

		return ((TUint) c)-'a'+KDigramNumberOfLetters+KDigramNumberOfNonLetters;

	return 0;

	}

TChar CWordDigrams::Char(TInt i)

	{

	if(i==0)

		return 0;

	if(i==1)

		return ' ';

	if(i==2)

		return '-';

	if(i<KDigramNumberOfNonLetters+KDigramNumberOfLetters)

		return TChar('A'+i-KDigramNumberOfNonLetters);

	return TChar('a'+i-KDigramNumberOfNonLetters-KDigramNumberOfLetters);

	}

CWordDigrams::~CWordDigrams()

	{}