/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Virtual Keyboard module of the Qt Toolkit.
**
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** the Free Software Foundation and appearing in the file LICENSE.GPL3
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#include "pinyindecoderservice.h"
#include "pinyinime.h"
#include "dictdef.h"
#include <QStandardPaths>
#include <QFileInfo>
#include <QDir>
#include <QtCore/QLibraryInfo>
#include "virtualkeyboarddebug.h"

namespace QtVirtualKeyboard {

using namespace ime_pinyin;

QScopedPointer<PinyinDecoderService> PinyinDecoderService::_instance;

/*!
    \class QtVirtualKeyboard::PinyinDecoderService
    \internal
*/

PinyinDecoderService::PinyinDecoderService(QObject *parent) :
    QObject(parent),
    initDone(false)
{
}

PinyinDecoderService::~PinyinDecoderService()
{
    if (initDone) {
        im_close_decoder();
        initDone = false;
    }
}

PinyinDecoderService *PinyinDecoderService::getInstance()
{
    if (!_instance)
        _instance.reset(new PinyinDecoderService());
    if (!_instance->init())
        return 0;
    return _instance.data();
}

bool PinyinDecoderService::init()
{
    if (initDone)
        return true;

    QString sysDict(qEnvironmentVariable("QT_VIRTUALKEYBOARD_PINYIN_DICTIONARY"));
    if (sysDict.isEmpty())
        sysDict = QLibraryInfo::location(QLibraryInfo::DataPath) + "/qtvirtualkeyboard/pinyin/dict_pinyin.dat";

    QString usrDictPath = QStandardPaths::writableLocation(QStandardPaths::ConfigLocation);
    QFileInfo usrDictInfo(usrDictPath + "/qtvirtualkeyboard/pinyin/usr_dict.dat");
    if (!usrDictInfo.exists()) {
        VIRTUALKEYBOARD_DEBUG() << "PinyinDecoderService::init(): creating directory for user dictionary" << usrDictInfo.absolutePath();
        QDir().mkpath(usrDictInfo.absolutePath());
    }

    initDone = im_open_decoder(sysDict.toUtf8().constData(), usrDictInfo.absoluteFilePath().toUtf8().constData());
    if (!initDone)
        VIRTUALKEYBOARD_DEBUG() << "Could not initialize pinyin engine. sys_dict:" << sysDict << "usr_dict:" << usrDictInfo.absoluteFilePath();

    return initDone;
}

void PinyinDecoderService::setUserDictionary(bool enabled)
{
    if (enabled == im_is_user_dictionary_enabled())
        return;
    if (enabled) {
        QString usrDictPath = QStandardPaths::writableLocation(QStandardPaths::ConfigLocation);
        QFileInfo usrDictInfo(usrDictPath + "/qtvirtualkeyboard/pinyin/usr_dict.dat");
        im_init_user_dictionary(usrDictInfo.absoluteFilePath().toUtf8().constData());
    } else {
        im_init_user_dictionary(NULL);
    }
}

bool PinyinDecoderService::isUserDictionaryEnabled() const
{
    return im_is_user_dictionary_enabled();
}

void PinyinDecoderService::setLimits(int maxSpsLen, int maxHzsLen)
{
    if (maxSpsLen <= 0)
        maxSpsLen = kMaxSearchSteps - 1;
    if (maxHzsLen <= 0)
        maxHzsLen = kMaxSearchSteps;
    im_set_max_lens(size_t(maxSpsLen), size_t(maxHzsLen));
}

int PinyinDecoderService::search(const QString &spelling)
{
    QByteArray spellingBuf = spelling.toLatin1();
    return int(im_search(spellingBuf.constData(), spellingBuf.length()));
}

int PinyinDecoderService::deleteSearch(int pos, bool isPosInSpellingId, bool clearFixedInThisStep)
{
    if (pos <= 0)
        pos = 0;
    return int(im_delsearch(size_t(pos), isPosInSpellingId, clearFixedInThisStep));
}

void PinyinDecoderService::resetSearch()
{
    im_reset_search();
}

QString PinyinDecoderService::pinyinString(bool decoded)
{
    size_t py_len;
    const char *py = im_get_sps_str(&py_len);
    if (!decoded)
        py_len = strlen(py);

    return QString(QLatin1String(py, (int)py_len));
}

int PinyinDecoderService::pinyinStringLength(bool decoded)
{
    size_t py_len;
    const char *py = im_get_sps_str(&py_len);
    if (!decoded)
        py_len = strlen(py);
    return (int)py_len;
}

QVector<int> PinyinDecoderService::spellingStartPositions()
{
    const unsigned short *spl_start;
    int len;
    // There will be len + 1 elements in the buffer when len > 0.
    len = (int)im_get_spl_start_pos(spl_start);

    QVector<int> arr;
    arr.resize(len + 2);
    arr[0] = len; // element 0 is used to store the length of buffer.
    for (int i = 0; i <= len; i++)
        arr[i + 1] = spl_start[i];
    return arr;
}

QString PinyinDecoderService::candidateAt(int index)
{
    Q_ASSERT(index >= 0);
    QVector<QChar> candidateBuf;
    candidateBuf.resize(kMaxSearchSteps + 1);
    if (!im_get_candidate(size_t(index), (char16 *)candidateBuf.data(), candidateBuf.length() - 1))
        return QString();
    candidateBuf.last() = 0;
    return QString(candidateBuf.data());
}

QList<QString> PinyinDecoderService::fetchCandidates(int index, int count, int sentFixedLen)
{
    QList<QString> candidatesList;
    for (int i = index; i < index + count; i++) {
        QString retStr = candidateAt(i);
        if (0 == i)
            retStr.remove(0, sentFixedLen);
        candidatesList.append(retStr);
    }
    return candidatesList;
}

int PinyinDecoderService::chooceCandidate(int index)
{
    return int(im_choose(index));
}

int PinyinDecoderService::cancelLastChoice()
{
    return int(im_cancel_last_choice());
}

int PinyinDecoderService::fixedLength()
{
    return (int)im_get_fixed_len();
}

void PinyinDecoderService::flushCache()
{
    im_flush_cache();
}

QList<QString> PinyinDecoderService::predictionList(const QString &history)
{
    QList<QString> predictList;
    char16 (*predictItems)[kMaxPredictSize + 1] = 0;
    int predictNum = int(im_get_predicts(history.utf16(), predictItems));
    predictList.reserve(predictNum);
    for (int i = 0; i < predictNum; i++)
        predictList.append(QString((QChar *)predictItems[i]));
    return predictList;
}

} // namespace QtVirtualKeyboard