/****************************************************************************

**

** Copyright (C) 2008-2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (developer.feedback@nokia.com)

**

** This file is part of the HbCore module of the UI Extensions for Mobile.

**

** GNU Lesser General Public License Usage

** This file may be used under the terms of the GNU Lesser General Public

** License version 2.1 as published by the Free Software Foundation and

** appearing in the file LICENSE.LGPL included in the packaging of this file.

** Please review the following information to ensure the GNU Lesser General

** Public License version 2.1 requirements will be met:

** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at developer.feedback@nokia.com.

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****************************************************************************/

#include "hbinputextrauserdictionary.h"

#include "hbinputextrauserdictionary_p.h"

#include <qbytearray.h> // For memmove()

#include <QFile>

#include <QDir>

#include <QSharedMemory>

#include <QVector>

#include "hbinputsettingproxy.h"

const int HbExtraDictMaxFrequency = 255;

/*!

@proto

@hbcore

\class HbExtraUserDictionary

\brief A generic implementation of HbUserDictionary class.

This class provides generic all-purpose implementation of HbUserDictionary class.

It uses shared memory and words are stored in plain text format. Entries are sorted and

a binary search algorithm is provided for finding matches. There is a random access

operator for read operations. It also knows how to save its contents to disk and load it again.

There is a separate factory class for creating and accessing HbExtraUserDictionary

instances.

The dictionary data is organized so that there is a directory area and data area. Directory area

contains an array of HbExtraUDDirectoryEntry items. They specify where each word begins in the

data area and how long it is. Data area contains characters in a single long string. There are

methods for accessing directory and data area in case direct access is needed.

Typically this is not needed and default search and access operators are enough.

Example uses cases for extra dictonaries are additional prediction engine databases and

acting as a backend for auto-completing fields.

\sa HbUserDictionary

\sa HbExtraDictionaryFactory

*/

/// @cond

bool HbExtraUserDictionaryPrivate::createSharedBlock(int aSize)

{

    if (sharedMemory.isAttached()) {

        return true;

    }

    if (id == 0) {

        return false;

    }

    sharedMemory.setKey(name());

    if (!sharedMemory.attach()) {

        if (sharedMemory.error() != QSharedMemory::NotFound) {

            qDebug("HbExtraUserDictionaryPrivate: QSharedMemory::attached returned error %d", sharedMemory.error());

            return false;

        }

        if (!sharedMemory.create(aSize)) {

            qDebug("HbExtraUserDictionaryPrivate: Unable to create shared memory block!");

            return false;

        }

        dataHeader()->numWords = 0;

        dataHeader()->numUsers = 0;

        dataHeader()->modified = false;

        dataHeader()->dataSize = 0;

    }

    dataHeader()->numUsers++;

    return true;

}

QString HbExtraUserDictionaryPrivate::name() const

{

    QString num;

    num.setNum(id);

    return QString(KExtraUserDictKeyBase) + num;

}

QString HbExtraUserDictionaryPrivate::fileName() const

{

    return HbInputSettingProxy::extraDictionaryPath() + QDir::separator() + name() + QString(KExtraFileExt);

}

bool HbExtraUserDictionaryPrivate::save(QString fileName)

{

    QFile file(fileName);

    if (file.open(QIODevice::WriteOnly)) {

        file.write((char *)&id, sizeof(int));

        if (sharedMemory.isAttached()) {

            file.write((char *)sharedMemory.data(), KExtraUDBlockSize);

        }

        file.close();

        dataHeader()->modified = false;

        return true;

    }

    return false;

}

int HbExtraUserDictionaryPrivate::findFirstMatch(int start, int end, const QString &searchString, int knownMatch, Qt::CaseSensitivity caseSensitivity) const

{

    HbExtraUDDirectoryEntry *dir = directory();

    QChar *data = dataArea();

    if (start >= end) {

        if (QString(&data[dir[start].start], dir[start].length).startsWith(searchString, Qt::CaseInsensitive)) {

            return start;

        }

        return knownMatch;

    }

    int half = (start + end) / 2;

    if (QString(&data[dir[half].start], dir[half].length).startsWith(searchString, Qt::CaseInsensitive)) {

        knownMatch = half;

        return findFirstMatch(start, half, searchString, knownMatch, caseSensitivity);

    }

    if (compareWords(half, searchString, caseSensitivity) > 0) {

        return findFirstMatch(half + 1, end, searchString, knownMatch, caseSensitivity);

    }

    return findFirstMatch(start, half, searchString, knownMatch, caseSensitivity);

}

void HbExtraUserDictionaryPrivate::removeEntry(int index)

{

    HbExtraUDDirectoryEntry *dir = directory();

    QChar *data = dataArea();

    int start = dir[index].start;

    int length = dir[index].length;

    // First move trailing directory entries and the beginning of the data area

    // by size of one dictionary entry item.

    memmove((char *)&dir[index], (char *)&dir[index + 1], (dataHeader()->numWords - index) * sizeof(HbExtraUDDirectoryEntry) + start * sizeof(QChar));

    // Then move trailing part of the data area.

    memmove(((char *)&data[start]) - sizeof(HbExtraUDDirectoryEntry), (char *)&data[start + length], (dataHeader()->dataSize - (start + length)) * 2);

    // Update word count.

    dataHeader()->numWords--;

    dataHeader()->dataSize -= length;

    dataHeader()->modified = true;

    // Then update remaining dictionary entries.

    const int rounds = dataHeader()->numWords;

    for (int i = index; i < rounds; i++) {

        dir[i].start -= length;

    }

}

void HbExtraUserDictionaryPrivate::addEntry(int index, const QString &newWord)

{

    HbExtraUDDirectoryEntry *dir = directory();

    QChar *data = dataArea();

    const int origNumWords = dataHeader()->numWords;

    if (origNumWords > 0) {

        if (index < origNumWords) {

            // First move the trailing part of the data area to make space for the new word.

            memmove((char *)&data[dir[index].start + newWord.size()] + sizeof(HbExtraUDDirectoryEntry),

                    (char *)(&data[dir[index].start]),

                    (dataHeader()->dataSize - dir[index].start) * 2);

            // Then move the trailing part of the dictionary and the leading part of the data area.

            memmove((char *)(&dir[index + 1]),

                    (char *)(&dir[index]),

                    ((dataHeader()->numWords - index) * sizeof(HbExtraUDDirectoryEntry)) + (dir[index].start * 2));

        } else {

            // This will be the last one. Just make room for new directory entry.

            memmove((char *)data + sizeof(HbExtraUDDirectoryEntry),

                    (char *)data,

                    dataHeader()->dataSize * 2);

        }

    }

    // Update word count.

    dataHeader()->numWords++;

    dataHeader()->dataSize += newWord.size();

    dataHeader()->modified = true;

    data = dataArea();  // data area starting point has changed, refresh.

    if (index == 0) {

        dir[index].start = 0;

    } else {

        dir[index].start = dir[index - 1].start + dir[index - 1].length;

    }

    dir[index].length = newWord.size();

    dir[index].frequency = 0;

    const int startPoint = dir[index].start;

    for (int i = 0; i < newWord.size(); i++) {

        data[startPoint + i] = newWord[i];

    }

    // Then update remaining dictionary entries.

    const int rounds = dataHeader()->numWords;

    for (int i = index + 1; i < rounds; i++) {

        dir[i].start += newWord.size();

    }

}

int HbExtraUserDictionaryPrivate::findWord(int startIndex, int endIndex, const QString &newWord, Qt::CaseSensitivity caseSensitivity) const

{

    if (startIndex >= endIndex) {

        if (startIndex < dataHeader()->numWords && compareWords(startIndex, newWord, caseSensitivity) == 0) {

            return startIndex;

        }

        return -1;   // No matches

    }

    int half = (startIndex + endIndex) / 2;

    int compare = compareWords(half, newWord, caseSensitivity);

    if (compare == 0) {

        return half;

    } else if (compare > 0) {

        return findWord(half + 1, endIndex, newWord, caseSensitivity);

    } else {

        return findWord(startIndex, half, newWord, caseSensitivity);

    }

}

int HbExtraUserDictionaryPrivate::findIndexForNewWord(int start, int end, const QString &newWord) const

{

    if (start >= end) {

        if (dataHeader()->numWords == 0) {

            return 0;

        }

        if (compareWords(start, newWord) > 0) {

            return start + 1;

        } else {

            return start;

        }

    }

    int half = (start + end) / 2;

    int compare = compareWords(half, newWord);

    if (compare == 0) {

        return half;

    } else if (compare > 0) {

        return findIndexForNewWord(half + 1, end, newWord);

    } else {

        return findIndexForNewWord(start, half, newWord);

    }

}

int HbExtraUserDictionaryPrivate::compareWords(int index, const QString &otherWord, Qt::CaseSensitivity caseSensitivity) const

{

    HbExtraUDDirectoryEntry *dir = directory();

    QChar *data = dataArea();

    const int start = dir[index].start;

    const int rounds = (dir[index].length > otherWord.size() ? otherWord.size() : dir[index].length);

    if (caseSensitivity == Qt::CaseSensitive) {

        for (int i = 0; i < rounds; i++) {

            if (data[start + i] == otherWord[i]) {

                continue;

            }

            if (otherWord[i] > data[start + i]) {

                return 1;

            }

            return -1;

        }

    } else {

        for (int i = 0; i < rounds; i++) {

            if (data[start + i].toCaseFolded() == otherWord[i].toCaseFolded()) {

                continue;

            }

            if (otherWord[i].toCaseFolded() > data[start + i].toCaseFolded()) {

                return 1;

            }

            return -1;

        }

    }

    if (dir[index].length == otherWord.size()) {

        return 0;  // Match!

    }

    if (otherWord.size() > dir[index].length) {

        return 1;

    }

    return -1;

}

bool HbExtraUserDictionaryPrivate::hasEnoughSpaceForNewWord(const QString &newWord) const

{

    if ((unsigned int)dataAreaSize() - (dataHeader()->dataSize * 2) >= (newWord.size() * 2) + sizeof(HbExtraUDDirectoryEntry)) {

        return true;

    }

    return false;

}

/// @endcond

/*!

Constructs the object.

*/

HbExtraUserDictionary::HbExtraUserDictionary() : d_ptr(new HbExtraUserDictionaryPrivate)

{

}

/*!

Constructs the object. This version tries to attachs to given user dictionary and

if not found, initializes it.

*/

HbExtraUserDictionary::HbExtraUserDictionary(int dbId) : d_ptr(new HbExtraUserDictionaryPrivate)

{

    setId(dbId);

    attach();

}

/*!

Destructs the object.

*/

HbExtraUserDictionary::~HbExtraUserDictionary()

{

    Q_D(HbExtraUserDictionary);

    d->lock();

    if (d->sharedMemory.isAttached()) {

        if (d->dataHeader()->numUsers <= 1 && d->dataHeader()->modified) {

            d->save(fileName());

        }

        d->dataHeader()->numUsers--;

    }

    d->unlock();

    delete d;

}

/*!

Returns user dictionary id value.

*/

int HbExtraUserDictionary::id() const

{

    Q_D(const HbExtraUserDictionary);

    return d->id;

}

/*!

Adds single word to the database. Returns true if there was enough space for new

word and the word was successfully added. Returns false if word already

exists.

\sa addWords

\sa removeWord

*/

bool HbExtraUserDictionary::addWord(const QString &newWord, HbPredictionCallback *callback)

{

    Q_UNUSED(callback);

    Q_D(HbExtraUserDictionary);

    d->lock();

    if (d->findWord(0, d->dataHeader()->numWords - 1, newWord) >= 0) {

        // Already there.

        d->unlock();

        return false;

    }

    if (newWord.size() < KExtraUserDictionaryMaxWordLength &&

        d->hasEnoughSpaceForNewWord(newWord) &&

        d->dataHeader()->numWords < KExtraUserDictionaryMaxWords) {

        int newIndex = d->findIndexForNewWord(0, d->dataHeader()->numWords - 1, newWord);

        d->addEntry(newIndex, newWord);

        d->unlock();

        return true;

    }

    d->unlock();

    return false;

}

/*!

Adds a list of words to the database. Returns true if all the words were

successfully added to the database.

\sa addWord

\sa removeWord

*/

bool HbExtraUserDictionary::addWords(const QStringList &wordList)

{

    bool ret = true;

    for (int i = 0; i < wordList.count(); i++) {

        ret &= addWord(wordList[i]);

    }

    return ret;

}

/*!

Removes a word from the database. Returns true if the word was found and removed.

\sa addWord

\sa addWords

*/

bool HbExtraUserDictionary::removeWord(const QString &toBeRemoved)

{

    Q_D(HbExtraUserDictionary);

    d->lock();

    int index = d->findWord(0, d->dataHeader()->numWords - 1, toBeRemoved, Qt::CaseInsensitive);

    if (index >= 0) {

        d->removeEntry(index);

        d->unlock();

        return true;

    }

    d->unlock();

    return false;

}

/*!

Returns the number of words in the dictionary.

*/

int HbExtraUserDictionary::numberOfWords() const

{

    Q_D(const HbExtraUserDictionary);

    int ret = 0;

    if (d->dataHeader()) {

        ret = d->dataHeader()->numWords;

    }

    return ret;

}

/*!

Returns a list of strings containing all the words currently stored in the database.

*/

QStringList HbExtraUserDictionary::listWords()

{

    Q_D(HbExtraUserDictionary);

    d->lock();

    QStringList result;

    if (d->sharedMemory.isAttached()) {

        HbExtraUDDirectoryEntry *dir = d->directory();

        QChar *data = d->dataArea();

        for (int i = 0; i < d->dataHeader()->numWords; i++) {

            result << QString(&data[dir[i].start], dir[i].length);

        }

    }

    d->unlock();

    return QStringList(result);

}

/*!

Removes all the words from the dictionary. Memory block will remain active in the memory.

*/

void HbExtraUserDictionary::clear()

{

    Q_D(HbExtraUserDictionary);

    d->lock();

    HbExtraUDHeader *header = d->dataHeader();

    if (d->sharedMemory.isAttached()) {

        if (header->numWords) {

            header->modified = true;

        }

        header->dataSize = 0;

        header->numWords = 0;

    }

    d->unlock();

}