/**
 * backgroundchecker.h
 *
 * Copyright (C)  2004  Zack Rusin <zack@kde.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301  USA
 */
#ifndef SONNET_BACKGROUNDCHECKER_H
#define SONNET_BACKGROUNDCHECKER_H

#include "speller.h"

#include <kdecore_export.h>

#include <QtCore/QObject>

namespace Sonnet
{
    class Speller;

    /**
     *
     * BackgroundChecker is used to perform spell checking without
     * blocking the application. You can use it as is by calling
     * the checkText function or subclass it and reimplement
     * getMoreText function.
     *
     * The misspelling signal is emitted whenever a misspelled word
     * is found. The background checker stops right before emitting
     * the signal. So the parent has to call continueChecking function
     * to resume the checking.
     *
     * done signal is emitted when whole text is spell checked.
     *
     * @author Zack Rusin <zack@kde.org>
     * @short class used for spell checking in the background
     */
    class KDECORE_EXPORT BackgroundChecker : public QObject
    {
        Q_OBJECT
    public:
        explicit BackgroundChecker(QObject *parent =0);
        explicit BackgroundChecker(const Speller &speller, QObject *parent =0);
        ~BackgroundChecker();

        /**
         * This method is used to spell check static text.
         * It automatically invokes start().
         *
         * Use fetchMoreText() with start() to spell check a stream.
         */
        void setText(const QString &text);
        QString text() const;

        QString currentContext() const;

        Speller speller() const;
        void setSpeller(const Speller &speller);

        bool checkWord(const QString &word);
        QStringList suggest(const QString &word) const;
        bool addWordToPersonal(const QString &word);
    public Q_SLOTS:
        virtual void start();
        virtual void stop();
        void replace(int start, const QString &oldText,
                     const QString &newText);
        void changeLanguage(const QString &lang);

        /**
         * After emitting misspelling signal the background
         * checker stops. The catcher is responsible for calling
         * continueChecking function to resume checking.
         */
        virtual void continueChecking();

    Q_SIGNALS:
        /**
         * Emitted whenever a misspelled word is found
         */
        void misspelling(const QString &word, int start);

        /**
         * Emitted after the whole text has been spell checked.
         */
        void done();

    protected:
        /**
         * This function is called to get the text to spell check.
         * It will be called continuesly until it returns QString()
         * in which case the done() signal is emitted.
         * Note: the start parameter in mispelling() is not a combined
         * position but a position in the last string returned
         * by fetchMoreText. You need to store the state in the derivatives.
         */
        virtual QString fetchMoreText();

        /**
         * This function will be called whenever the background checker
         * will be finished text which it got from fetchMoreText.
         */
        virtual void finishedCurrentFeed();

    protected Q_SLOTS:
        void slotEngineDone();
    private:
        class Private;
        Private *const d;
    };

}

#endif
