/***************************************************************************
       SignalManager.cpp -  manager class for multi channel signals
                             -------------------
    begin                : Sun Oct 15 2000
    copyright            : (C) 2000 by Thomas Eschenbacher
    email                : Thomas.Eschenbacher@gmx.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under 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.                                   *
 *                                                                         *
 ***************************************************************************/

#include "config.h"

#include <errno.h>
#include <math.h>

#include <new>

#include <QApplication>
#include <QByteArray>
#include <QCursor>
#include <QDate>
#include <QFile>
#include <QFileInfo>
#include <QMutableListIterator>
#include <QMutexLocker>
#include <QUrl>
#include <QVector>

#include <KAboutData>
#include <KLocalizedString>
#include <kxmlgui_version.h>

#include "libkwave/ClipBoard.h"
#include "libkwave/CodecManager.h"
#include "libkwave/Decoder.h"
#include "libkwave/Encoder.h"
#include "libkwave/FileProgress.h"
#include "libkwave/InsertMode.h"
#include "libkwave/LabelList.h"
#include "libkwave/MessageBox.h"
#include "libkwave/MultiTrackReader.h"
#include "libkwave/MultiTrackWriter.h"
#include "libkwave/Parser.h"
#include "libkwave/Sample.h"
#include "libkwave/Signal.h"
#include "libkwave/SignalManager.h"
#include "libkwave/String.h"
#include "libkwave/Track.h"
#include "libkwave/Utils.h"
#include "libkwave/Writer.h"
#include "libkwave/undo/UndoAction.h"
#include "libkwave/undo/UndoAddMetaDataAction.h"
#include "libkwave/undo/UndoDeleteAction.h"
#include "libkwave/undo/UndoDeleteMetaDataAction.h"
#include "libkwave/undo/UndoDeleteTrack.h"
#include "libkwave/undo/UndoInsertAction.h"
#include "libkwave/undo/UndoInsertTrack.h"
#include "libkwave/undo/UndoModifyAction.h"
#include "libkwave/undo/UndoModifyMetaDataAction.h"
#include "libkwave/undo/UndoSelection.h"
#include "libkwave/undo/UndoTransaction.h"
#include "libkwave/undo/UndoTransactionGuard.h"

#define CASE_COMMAND(x) } else if (parser.command() == _(x)) {

//***************************************************************************
Kwave::SignalManager::SignalManager(QWidget *parent)
    :QObject(),
    m_parent_widget(parent),
    m_closed(true),
    m_empty(true),
    m_modified(false),
    m_modified_enabled(true),
    m_signal(),
    m_selection(0,0),
    m_last_selection(0,0),
    m_last_track_selection(),
    m_last_length(0),
    m_playback_controller(*this),
    m_undo_enabled(false),
    m_undo_buffer(),
    m_redo_buffer(),
    m_undo_transaction(nullptr),
    m_undo_transaction_level(0),
    m_undo_transaction_lock(),
    m_meta_data()
{
    // connect to the track's signals
    Kwave::Signal *sig = &m_signal;
    connect(sig, SIGNAL(sigTrackInserted(uint,Kwave::Track*)),
            this, SLOT(slotTrackInserted(uint,Kwave::Track*)));
    connect(sig, SIGNAL(sigTrackDeleted(uint,Kwave::Track*)),
            this, SLOT(slotTrackDeleted(uint,Kwave::Track*)));
    connect(sig, SIGNAL(sigTrackSelectionChanged(bool)),
            this,SIGNAL(sigTrackSelectionChanged(bool)));
    connect(sig, SIGNAL(sigSamplesDeleted(unsigned int, sample_index_t,
            sample_index_t)),
            this, SLOT(slotSamplesDeleted(unsigned int, sample_index_t,
            sample_index_t)));
    connect(sig, SIGNAL(sigSamplesInserted(unsigned int, sample_index_t,
            sample_index_t)),
            this, SLOT(slotSamplesInserted(unsigned int, sample_index_t,
            sample_index_t)));
    connect(sig, SIGNAL(sigSamplesModified(unsigned int, sample_index_t,
            sample_index_t)),
            this, SLOT(slotSamplesModified(unsigned int, sample_index_t,
            sample_index_t)));
}

//***************************************************************************
Kwave::SignalManager::~SignalManager()
{
    close();
}

//***************************************************************************
int Kwave::SignalManager::loadFile(const QUrl &url)
{
    int res = 0;
    Kwave::FileProgress *dialog = nullptr;

    // take over the new file name, so that we have a valid signal
    // name during loading
    QString filename = url.path();
    QFile src(filename);
    QFileInfo fi(src);
    {
        Kwave::FileInfo info(m_meta_data);
        info.set(Kwave::INF_FILENAME, fi.absoluteFilePath());
        m_meta_data.replace(Kwave::MetaDataList(info));
    }

    // work with a copy of meta data, to avoid flicker effects
    Kwave::MetaDataList meta_data(m_meta_data);

    // enter and stay in not modified state
    enableModifiedChange(true);
    setModified(false);
    enableModifiedChange(false);

    // disable undo (discards all undo/redo data)
    disableUndo();

    QString mimetype = Kwave::CodecManager::mimeTypeOf(url);
    qDebug("SignalManager::loadFile(%s) - [%s]",
           DBG(url.toDisplayString()), DBG(mimetype));
    Kwave::Decoder *decoder = Kwave::CodecManager::decoder(mimetype);
    while (decoder) {
        // be sure that the current signal is really closed
        m_signal.close();

        // open the source file
        if (!(res = decoder->open(m_parent_widget, src))) {
            qWarning("unable to open source: '%s'", DBG(url.toDisplayString()));
            res = -EIO;
            break;
        }

        // get the initial meta data from the decoder
        meta_data = decoder->metaData();
        Kwave::FileInfo info(meta_data);

        // take the preliminary meta data, needed for estimated length
        m_meta_data = meta_data;

        // detect stream mode. if so, use one sample as display
        bool streaming = (!info.length());

        // we must change to open state to see the file while
        // it is loaded
        m_closed = false;
        m_empty = false;

        // create all tracks (empty)
        unsigned int track;
        const unsigned int tracks   = info.tracks();
        const sample_index_t length = info.length();
        Q_ASSERT(tracks);
        if (!tracks) break;

        for (track = 0; track < tracks; ++track) {
            Kwave::Track *t = m_signal.insertTrack(0, length, nullptr);
            Q_ASSERT(t);
            if (!t || (t->length() != length)) {
                qWarning("SignalManager::loadFile: out of memory");
                res = -ENOMEM;
                break;
            }
        }
        if (track < tracks) break;

        // create the multitrack writer as destination
        // if length was zero -> append mode / decode a stream ?
        Kwave::InsertMode mode = (streaming) ? Kwave::Append : Kwave::Overwrite;
        Kwave::MultiTrackWriter writers(*this, allTracks(), mode, 0,
            (length) ? length-1 : 0);

        // try to calculate the resulting length, but if this is
        // not possible, we try to use the source length instead
        quint64 resulting_size = info.tracks() * info.length() *
                                      (info.bits() >> 3);
        bool use_src_size = (!resulting_size);
        if (use_src_size) resulting_size = src.size();

        // prepare and show the progress dialog
        dialog = new(std::nothrow) Kwave::FileProgress(m_parent_widget,
            QUrl(filename), resulting_size,
            info.length(), info.rate(), info.bits(), info.tracks());
        Q_ASSERT(dialog);

        if (dialog)
        {
            if (use_src_size) {
                // use source size for progress / stream mode
                QObject::connect(decoder, SIGNAL(sourceProcessed(quint64)),
                                 dialog,  SLOT(setBytePosition(quint64)));
                QObject::connect(&writers, SIGNAL(written(quint64)),
                                 dialog,   SLOT(setLength(quint64)));
            } else {
                // use resulting size percentage for progress
                QObject::connect(&writers, SIGNAL(progress(qreal)),
                                 dialog,   SLOT(setValue(qreal)));
            }
            QObject::connect(dialog,   SIGNAL(canceled()),
                             &writers, SLOT(cancel()));
        }

        // now decode
        res = 0;
        if (!decoder->decode(m_parent_widget, writers)) {
            qWarning("decoding failed.");
            res = -EIO;
        } else {
            // read information back from the decoder, some settings
            // might have become available during the decoding process
            meta_data = decoder->metaData();
            info = Kwave::FileInfo(meta_data);
        }

        decoder->close();

        // check for length info in stream mode
        if (!res && streaming) {
            // source was opened in stream mode -> now we have the length
            writers.flush();
            sample_index_t new_length = writers.last();
            if (new_length) new_length++;
            info.setLength(new_length);
        } else {
            info.setLength(this->length());
            info.setTracks(tracks);
        }

        // enter the filename/mimetype and size into the file info
        info.set(Kwave::INF_FILENAME, fi.absoluteFilePath());
        info.set(Kwave::INF_FILESIZE, src.size());
        if (!info.contains(Kwave::INF_MIMETYPE))
            info.set(Kwave::INF_MIMETYPE, mimetype);

        // remove the estimated length again, it is no longer needed
        info.set(Kwave::INF_ESTIMATED_LENGTH, QVariant());

        // take over the decoded and updated file info
        meta_data.replace(Kwave::MetaDataList(info));
        m_meta_data = meta_data;

        // update the length info in the progress dialog if needed
        if (dialog && use_src_size) {
            dialog->setLength(
                quint64(info.length()) *
                quint64(info.tracks()));
            dialog->setBytePosition(src.size());
        }

        break;
    }

    if (!decoder) {
        qWarning("unknown file type");
        res = -EINVAL;
    } else {
        delete decoder;
    }

    // process any queued events of the writers, like "sigSamplesInserted"
    qApp->processEvents(QEventLoop::ExcludeUserInputEvents);

    // remember the last length and selection
    m_last_length = length();
    rememberCurrentSelection();

    // from now on, undo is enabled
    enableUndo();

    // modified can change from now on
    enableModifiedChange(true);

    delete dialog;
    if (res) close();

    m_meta_data.dump();

    // we now have new meta data
    emit sigMetaDataChanged(m_meta_data);

    return res;
}

//***************************************************************************
int Kwave::SignalManager::save(const QUrl &url, bool selection)
{
    int res = 0;
    sample_index_t ofs  = 0;
    sample_index_t len  = length();
    unsigned int tracks = this->tracks();
    unsigned int bits   = this->bits();

    if (selection) {
        // zero-length -> nothing to do
        ofs = m_selection.offset();
        len = m_selection.length();
        tracks = static_cast<unsigned int>(selectedTracks().count());
    }

    if (!tracks || !len) {
        Kwave::MessageBox::error(m_parent_widget,
            i18n("Signal is empty, nothing to save."));
        return 0;
    }

    QString mimetype_name;
    mimetype_name = Kwave::CodecManager::mimeTypeOf(url);
    qDebug("SignalManager::save(%s) - [%s] (%u bit, selection=%d)",
        DBG(url.toDisplayString()), DBG(mimetype_name), bits, selection);

    Kwave::Encoder *encoder = Kwave::CodecManager::encoder(mimetype_name);
    Kwave::FileInfo file_info(m_meta_data);
    if (encoder) {

        // maybe we now have a new mime type
        file_info.set(Kwave::INF_MIMETYPE, mimetype_name);

        // check if we lose information and ask the user if this would
        // be acceptable
        QList<Kwave::FileProperty> unsupported = encoder->unsupportedProperties(
            file_info.properties().keys());
        if (!unsupported.isEmpty()) {
            QString list_of_lost_properties = _("\n");
            foreach (const Kwave::FileProperty &p, unsupported) {
                list_of_lost_properties +=
                    i18n(UTF8(file_info.name(p))) + _("\n");
            }

            // show a warning to the user and ask him if he wants to continue
            if (Kwave::MessageBox::warningContinueCancel(m_parent_widget,
                i18n("Saving in this format will lose the following "
                     "additional file attribute(s):\n"
                     "%1\n"
                     "Do you still want to continue?",
                     list_of_lost_properties),
                QString(),
                QString(),
                QString(),
                _("accept_lose_attributes_on_export")
                ) != KMessageBox::Continue)
            {
                delete encoder;
                return -1;
            }
        }

        // open the destination file
        QString filename = url.path();
        QFile dst(filename);

        Kwave::MultiTrackReader src(Kwave::SinglePassForward, *this,
            (selection) ? selectedTracks() : allTracks(),
            ofs, ofs + len - 1);

        // update the file information
        file_info.setLength(len);
        file_info.setRate(rate());
        file_info.setBits(bits);
        file_info.setTracks(tracks);

        if (!file_info.contains(Kwave::INF_SOFTWARE) &&
            encoder->supportedProperties().contains(Kwave::INF_SOFTWARE))
        {
            // add our Kwave Software tag
            const KAboutData about_data = KAboutData::applicationData();
            QString software = about_data.displayName() + _("-") +
                               about_data.version() + _(" ") +
                               i18n("(built with KDE Frameworks %1)",
                                    _(KXMLGUI_VERSION_STRING));
            file_info.set(Kwave::INF_SOFTWARE, software);
        }

        if (!file_info.contains(Kwave::INF_CREATION_DATE) &&
            encoder->supportedProperties().contains(Kwave::INF_CREATION_DATE))
        {
            // add a date tag
            QString date(QDate::currentDate().toString(_("yyyy-MM-dd")));
            qDebug("adding date tag: '%s'", DBG(date));
            file_info.set(Kwave::INF_CREATION_DATE, date);
        }

        // prepare and show the progress dialog
        Kwave::FileProgress *dialog = new(std::nothrow)
            Kwave::FileProgress(m_parent_widget, QUrl(filename),
                file_info.length() * file_info.tracks() *
                (file_info.bits() >> 3),
                file_info.length(), file_info.rate(), file_info.bits(),
                file_info.tracks()
            );
        Q_ASSERT(dialog);
        if (dialog) {
            QObject::connect(&src,   SIGNAL(progress(qreal)),
                             dialog, SLOT(setValue(qreal)),
                             Qt::QueuedConnection);
            QObject::connect(dialog, SIGNAL(canceled()),
                             &src,   SLOT(cancel()));
        }

        // invoke the encoder...
        bool encoded = false;
        m_meta_data.replace(Kwave::MetaDataList(file_info));

        if (selection) {
            // use a copy, don't touch the original !
            Kwave::MetaDataList meta = m_meta_data;

            // we have to adjust all position aware meta data
            meta.cropByRange(ofs, ofs + len - 1);

            // set the filename in the copy of the fileinfo, the original
            // file which is currently open keeps it's name
            Kwave::FileInfo info(meta);
            info.set(Kwave::INF_FILENAME, filename);
            meta.replace(Kwave::MetaDataList(info));

            encoded = encoder->encode(m_parent_widget, src, dst, meta);
        } else {
            // in case of a "save as" -> modify the current filename
            file_info.set(Kwave::INF_FILENAME, filename);
            m_meta_data.replace(Kwave::MetaDataList(file_info));
            encoded = encoder->encode(m_parent_widget, src, dst, m_meta_data);
        }
        if (!encoded) {
            Kwave::MessageBox::error(m_parent_widget,
                i18n("An error occurred while saving the file."));
            res = -1;
        }

        delete encoder;
        encoder = nullptr;

        if (dialog) {
            qApp->processEvents();
            if (dialog->isCanceled()) {
                // user really pressed cancel !
                Kwave::MessageBox::error(m_parent_widget,
                    i18n("The file has been truncated and "
                          "might be corrupted."));
                res = -EINTR;
            }
            delete dialog;
            dialog = nullptr;
        }
    } else {
        Kwave::MessageBox::error(m_parent_widget,
            i18n("Sorry, the file type is not supported."));
        res = -EINVAL;
    }

    if (!res && !selection) {
        // saved without error -> no longer modified
        flushUndoBuffers();
        enableModifiedChange(true);
        setModified(false);
    }

    emit sigMetaDataChanged(m_meta_data);
    qDebug("SignalManager::save(): res=%d",res);
    return res;
}

//***************************************************************************
void Kwave::SignalManager::newSignal(sample_index_t samples, double rate,
                                     unsigned int bits, unsigned int tracks)
{
    // enter and stay in modified state
    enableModifiedChange(true);
    setModified(true);
    enableModifiedChange(false);

    // disable undo (discards all undo/redo data)
    disableUndo();

    m_meta_data.clear();
    Kwave::FileInfo file_info(m_meta_data);
    file_info.setRate(rate);
    file_info.setBits(bits);
    file_info.setTracks(tracks);
    m_meta_data.replace(Kwave::MetaDataList(file_info));

    // now the signal is considered not to be empty
    m_closed = false;
    m_empty = false;

    // add all empty tracks
    while (tracks) {
        m_signal.insertTrack(0, samples, nullptr);
        tracks--;
    }

    // remember the last length
    m_last_length = samples;
    file_info.setLength(length());
    m_meta_data.replace(Kwave::MetaDataList(file_info));
    rememberCurrentSelection();

    // from now on, undo is enabled
    enableUndo();

    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::close()
{
    // stop the playback
    m_playback_controller.playbackStop();
    m_playback_controller.reset();

    // fix the modified flag to false
    enableModifiedChange(true);
    setModified(false);
    enableModifiedChange(false);

    // reset the last length of the signal
    m_last_length = 0;

    // disable undo and discard all undo buffers
    // undo will be re-enabled when a signal is loaded or created
    disableUndo();

    // for safety: flush all undo/redo buffers
    flushUndoBuffers();
    flushRedoBuffer();

    // reset the selection
    m_selection.clear();

    m_empty = true;
    while (tracks()) deleteTrack(tracks() - 1);
    m_signal.close();

    // clear all meta data
    m_meta_data.clear();

    m_closed = true;
    rememberCurrentSelection();

    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
QString Kwave::SignalManager::signalName()
{
    // if a file is loaded -> path of the URL if it has one
    QUrl url;
    url = QUrl(Kwave::FileInfo(m_meta_data).get(
               Kwave::INF_FILENAME).toString());
    if (url.isValid()) return url.path();

    // we have something, but no name yet
    if (!isClosed()) return QString(NEW_FILENAME);

    // otherwise: closed, nothing loaded
    return _("");
}

//***************************************************************************
const QVector<unsigned int> Kwave::SignalManager::selectedTracks()
{
    QVector<unsigned int> list;
    const unsigned int tracks = this->tracks();

    for (unsigned int track = 0; track < tracks; track++) {
        if (!m_signal.trackSelected(track)) continue;
        list.append(track);
    }

    return list;
}

//***************************************************************************
const QVector<unsigned int> Kwave::SignalManager::allTracks()
{
    return m_signal.allTracks();
}

//***************************************************************************
int Kwave::SignalManager::executeCommand(const QString &command)
{
    sample_index_t offset = m_selection.offset();
    sample_index_t length = m_selection.length();

    if (!command.length()) return -EINVAL;
    Kwave::Parser parser(command);

    if (false) {
    // --- undo / redo ---
    CASE_COMMAND("undo")
        undo();
    CASE_COMMAND("redo")
        redo();
    CASE_COMMAND("undo_all")
        while (m_undo_enabled && !m_undo_buffer.isEmpty())
            undo();
    CASE_COMMAND("redo_all")
        while (!m_redo_buffer.isEmpty())
            redo();

    // --- copy & paste + clipboard ---
    CASE_COMMAND("copy")
        if (length) {
            Kwave::ClipBoard &clip = Kwave::ClipBoard::instance();
            clip.copy(
                m_parent_widget,
                *this,
                selectedTracks(),
                offset, length
            );
            // remember the last selection
            rememberCurrentSelection();
        }
    CASE_COMMAND("insert_at")
        Kwave::ClipBoard &clip = Kwave::ClipBoard::instance();
        if (clip.isEmpty()) return 0;
        if (!selectedTracks().size()) return 0;
        sample_index_t ofs = parser.toSampleIndex();

        Kwave::UndoTransactionGuard undo(*this,
                                         i18n("Insert Clipboard at position"));

        selectRange(ofs, 0);
        clip.paste(m_parent_widget, *this, ofs, 0);

    CASE_COMMAND("paste")
        Kwave::ClipBoard &clip = Kwave::ClipBoard::instance();
        if (clip.isEmpty()) return 0;
        if (!selectedTracks().size()) return 0;

        Kwave::UndoTransactionGuard undo(*this, i18n("Paste"));
        clip.paste(m_parent_widget, *this, offset, length);
    CASE_COMMAND("cut")
        if (length) {
            // remember the last selection
            rememberCurrentSelection();

            Kwave::ClipBoard &clip = Kwave::ClipBoard::instance();
            clip.copy(
                m_parent_widget,
                *this,
                selectedTracks(),
                offset, length
            );
            Kwave::UndoTransactionGuard undo(*this, i18n("Cut"));
            deleteRange(offset, length);
            selectRange(m_selection.offset(), 0);
        }
    CASE_COMMAND("clipboard_flush")
        Kwave::ClipBoard::instance().clear();
    CASE_COMMAND("crop")
        if (length) {
            Kwave::UndoTransactionGuard undo(*this, i18n("Crop"));
            sample_index_t rest = this->length() - offset;
            rest = (rest > length) ? (rest-length) : 0;
            QVector<unsigned int> tracks = selectedTracks();
            if (saveUndoDelete(tracks, offset+length, rest) &&
                saveUndoDelete(tracks, 0, offset))
            {
                // remember the last selection
                rememberCurrentSelection();

                unsigned int count = static_cast<unsigned int>(tracks.count());
                while (count--) {
                    m_signal.deleteRange(count, offset+length, rest);
                    m_signal.deleteRange(count, 0, offset);
                }
                selectRange(0, length);
            }
        }
    CASE_COMMAND("delete")
        Kwave::UndoTransactionGuard undo(*this, i18n("Delete"));
        deleteRange(offset, length);
        selectRange(m_selection.offset(), 0);

//    CASE_COMMAND("mixpaste")
//      if (globals.clipboard) {
//          SignalManager *toinsert = globals.clipboard->getSignal();
//          if (toinsert) {
//              unsigned int clipchan = toinsert->channels();
//              unsigned int sourcechan = 0;
//
//              /* ### check if the signal has to be re-sampled ### */
//
//              for (unsigned int i = 0; i < m_channels; i++) {
//                  Q_ASSERT(signal.at(i));
//                  if (signal.at(i)) {
//                      signal.at(i)->mixPaste(
//                          toinsert->getSignal(sourcechan)
//                      );
//                  }
//                  sourcechan++;
//                  sourcechan %= clipchan;
//              }
//          }
//      }

    CASE_COMMAND("label:delete")
        int index = parser.toInt();
        deleteLabel(index, true);

    CASE_COMMAND("expandtolabel")
        Kwave::UndoTransactionGuard undo(*this,
                                         i18n("Expand Selection to Label"));
        sample_index_t selection_left  = m_selection.first();
        sample_index_t selection_right = m_selection.last();
        Kwave::LabelList labels(m_meta_data);
        if (labels.isEmpty()) return false; // we need labels for this
        Kwave::Label label_left  = Kwave::Label();
        Kwave::Label label_right = Kwave::Label();

        // the last label <= selection start -> label_left
        // the first label >= selection end  -> label_right
        foreach (const Kwave::Label &label, labels) {
            sample_index_t lp = label.pos();
            if (lp <= selection_left)
                label_left = label;
            if ((lp >= selection_right) && (label_right.isNull())) {
                label_right = label;
                break; // done
            }
        }
        // default left label = start of file
        selection_left = (label_left.isNull()) ? 0 :
            label_left.pos();
        // default right label = end of file
        selection_right = (label_right.isNull()) ?
            (this->length() - 1) : label_right.pos();
        sample_index_t len = selection_right - selection_left + 1;
        selectRange(selection_left, len);

    CASE_COMMAND("selectnextlabels")
        Kwave::UndoTransactionGuard undo(*this, i18n("Select Next Labels"));
        sample_index_t selection_left;
        sample_index_t selection_right = m_selection.last();
        Kwave::Label label_left  = Kwave::Label();
        Kwave::Label label_right = Kwave::Label();
        Kwave::LabelList labels(m_meta_data);
        if (labels.isEmpty()) return false; // we need labels for this

        // special case: nothing selected -> select up to the first label
        if (selection_right == 0) {
            label_right = labels.first();
            selection_left = 0;
        } else {
            // find the first label starting after the current selection
            LabelListIterator it(labels);
            while (it.hasNext()) {
                Kwave::Label label = it.next();
                if (label.pos() >= selection_right) {
                    // take it as selection start
                    label_left  = label;
                    // and it's next one as selection end (might be null)
                    label_right = it.hasNext() ? it.next() : Kwave::Label();
                    break;
                }
            }
            // default selection start = last label
            if (label_left.isNull()) label_left = labels.last();
            if (label_left.isNull()) return false; // no labels at all !?
            selection_left = label_left.pos();
        }
        // default selection end = end of the file
        selection_right = (label_right.isNull()) ?
            (this->length() - 1) : label_right.pos();
        sample_index_t len = (selection_right > selection_left) ?
            (selection_right - selection_left + 1) : 1;
        selectRange(selection_left, len);

    CASE_COMMAND("selectprevlabels")
        Kwave::UndoTransactionGuard undo(*this, i18n("Select Previous Labels"));
        sample_index_t selection_left  = selection().first();
        Kwave::Label label_left  = Kwave::Label();
        Kwave::Label label_right = Kwave::Label();
        Kwave::LabelList labels(m_meta_data);
        if (labels.isEmpty()) return false; // we need labels for this

        // find the last label before the start of the selection
        foreach (const Kwave::Label &label, labels) {
            if (label.pos() > selection_left)
                break; // done
            label_left  = label_right;
            label_right = label;
        }
        // default selection start = start of file
        selection_left = (label_left.isNull()) ? 0 :
            label_left.pos();
        // default selection end = first label
        if (label_right.isNull()) label_right = labels.first();
        if (label_right.isNull()) return false; // no labels at all !?
        sample_index_t selection_right = label_right.pos();
        sample_index_t len = selection_right - selection_left + 1;
        selectRange(selection_left, len);

    // --- track related functions ---
    CASE_COMMAND("add_track")
        appendTrack();
    CASE_COMMAND("delete_track")
        Kwave::Parser p(command);
        unsigned int track = p.toUInt();
        if (track >= tracks()) return -EINVAL;
        deleteTrack(track);
    CASE_COMMAND("insert_track")
        Kwave::Parser p(command);
        unsigned int track = p.toUInt();
        insertTrack(track);

    // track selection
    CASE_COMMAND("select_track:all")
        Kwave::UndoTransactionGuard undo(*this, i18n("Select All Tracks"));
        foreach (unsigned int track, allTracks())
            selectTrack(track, true);
    CASE_COMMAND("select_track:none")
        Kwave::UndoTransactionGuard undo(*this, i18n("Deselect all tracks"));
        foreach (unsigned int track, allTracks())
            selectTrack(track, false);
    CASE_COMMAND("select_track:invert")
        Kwave::UndoTransactionGuard undo(*this, i18n("Invert Track Selection"));
        foreach (unsigned int track, allTracks())
            selectTrack(track, !trackSelected(track));
    CASE_COMMAND("select_track:on")
        unsigned int track = parser.toUInt();
        if (track >= tracks()) return -EINVAL;
        Kwave::UndoTransactionGuard undo(*this, i18n("Select Track"));
        selectTrack(track, true);
    CASE_COMMAND("select_track:off")
        unsigned int track = parser.toUInt();
        if (track >= tracks()) return -EINVAL;
        Kwave::UndoTransactionGuard undo(*this, i18n("Deselect Track"));
        selectTrack(track, false);
    CASE_COMMAND("select_track:toggle")
        unsigned int track = parser.toUInt();
        if (track >= tracks()) return -EINVAL;
        Kwave::UndoTransactionGuard undo(*this, i18n("Toggle Track Selection"));
        selectTrack(track, !(trackSelected(track)));

    // playback control
    CASE_COMMAND("playback_start")
        m_playback_controller.playbackStart();

    CASE_COMMAND("fileinfo")
        QString property = parser.firstParam();
        QString value    = parser.nextParam();
        Kwave::FileInfo info(m_meta_data);
        bool found = false;
        foreach (Kwave::FileProperty p, info.allKnownProperties()) {
            if (info.name(p) == property) {
                if (value.length())
                    info.set(p, QVariant(value)); // add/modify
                else
                    info.set(p, QVariant());      // delete
                found = true;
                break;
            }
        }

        if (found) {
            m_meta_data.replace(Kwave::MetaDataList(info));
            // we now have new meta data
            emit sigMetaDataChanged(m_meta_data);
        } else
            return -EINVAL;
    CASE_COMMAND("dump_metadata")
        qDebug("DUMP OF META DATA => %s", DBG(parser.firstParam()));
        m_meta_data.dump();
    } else {
        return -ENOSYS;
    }

    return 0;
}

//***************************************************************************
void Kwave::SignalManager::appendTrack()
{
    Kwave::UndoTransactionGuard undo(*this, i18n("Append Track"));
    insertTrack(tracks());
}

//***************************************************************************
void Kwave::SignalManager::insertTrack(unsigned int index)
{
    Kwave::UndoTransactionGuard undo(*this, i18n("Insert Track"));

    const unsigned int count = tracks();
    if (index > count) index = count;

    // undo action for the track insert
    if (m_undo_enabled && !registerUndoAction(
        new(std::nothrow) Kwave::UndoInsertTrack(m_signal, index))) return;

    // if the signal is currently empty, use the last
    // known length instead of the current one
    sample_index_t len = (count) ? length() : m_last_length;

    // insert/append to the list
    m_signal.insertTrack(index, len, nullptr);

    // remember the last length
    m_last_length = length();
}

//***************************************************************************
void Kwave::SignalManager::deleteTrack(unsigned int index)
{
    Kwave::UndoTransactionGuard undo(*this, i18n("Delete Track"));

    const unsigned int count = tracks();
    Q_ASSERT(index <= count);
    if (index > count) return;

    if (m_undo_enabled) {
        // undo action for the track deletion
        if (!registerUndoAction(new(std::nothrow)
            UndoDeleteTrack(m_signal, index)))
                return;
    }

    setModified(true);
    m_signal.deleteTrack(index);
}

//***************************************************************************
void Kwave::SignalManager::slotTrackInserted(unsigned int index,
                                             Kwave::Track *track)
{
    setModified(true);

    Kwave::FileInfo file_info(m_meta_data);
    file_info.setTracks(tracks());
    m_meta_data.replace(Kwave::MetaDataList(file_info));

    emit sigTrackInserted(index, track);
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::slotTrackDeleted(unsigned int index,
                                             Kwave::Track *track)
{
    setModified(true);

    Kwave::FileInfo file_info(m_meta_data);
    file_info.setTracks(tracks());
    m_meta_data.replace(Kwave::MetaDataList(file_info));

    emit sigTrackDeleted(index, track);
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::slotSamplesInserted(unsigned int track,
        sample_index_t offset, sample_index_t length)
{
    // remember the last known length
    m_last_length = m_signal.length();

    setModified(true);

    // only adjust the meta data once per operation
    QVector<unsigned int> tracks = selectedTracks();
    if (track == tracks.first()) {
        m_meta_data.shiftRight(offset, length);
    }

    emit sigSamplesInserted(track, offset, length);

    Kwave::FileInfo info(m_meta_data);
    info.setLength(m_last_length);
    m_meta_data.replace(Kwave::MetaDataList(info));
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::slotSamplesDeleted(unsigned int track,
        sample_index_t offset, sample_index_t length)
{
    // remember the last known length
    m_last_length = m_signal.length();

    setModified(true);

    // only adjust the meta data once per operation
    QVector<unsigned int> tracks = selectedTracks();
    if (track == tracks.first()) {
        m_meta_data.shiftLeft(offset, length);
    }

    emit sigSamplesDeleted(track, offset, length);

    Kwave::FileInfo info(m_meta_data);
    info.setLength(m_last_length);
    m_meta_data.replace(Kwave::MetaDataList(info));
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::slotSamplesModified(unsigned int track,
        sample_index_t offset, sample_index_t length)
{
    setModified(true);
    emit sigSamplesModified(track, offset, length);
}

//***************************************************************************
bool Kwave::SignalManager::deleteRange(sample_index_t offset,
                                       sample_index_t length,
                                       const QVector<unsigned int> &track_list)
{
    if (!length || track_list.isEmpty()) return true; // nothing to do

    // put the selected meta data into a undo action
    if (m_undo_enabled) {
        if (!registerUndoAction(new(std::nothrow) UndoDeleteMetaDataAction(
            m_meta_data.copy(offset, length))))
        {
            abortUndoTransaction();
            return false;
        }
        m_meta_data.deleteRange(offset, length);

        // store undo data for all audio data (without meta data)
        if (!registerUndoAction(new(std::nothrow) UndoDeleteAction(
            m_parent_widget, track_list, offset, length)))
        {
            abortUndoTransaction();
            return false;
        }
    } else {
        // delete without undo
        m_meta_data.deleteRange(offset, length);
    }

    // delete the ranges in all tracks
    // (this makes all metadata positions after the selected range invalid)
    foreach (unsigned int track, track_list) {
        m_signal.deleteRange(track, offset, length);
    }

    emit sigMetaDataChanged(m_meta_data);

    return true;
}

//***************************************************************************
bool Kwave::SignalManager::deleteRange(sample_index_t offset,
                                       sample_index_t length)
{
    return deleteRange(offset, length, selectedTracks());
}

//***************************************************************************
bool Kwave::SignalManager::insertSpace(sample_index_t offset,
                                       sample_index_t length,
                                       const QVector<unsigned int> &track_list)
{
    if (!length || track_list.isEmpty()) return true; // nothing to do

    Kwave::UndoTransactionGuard undo(*this, i18n("Insert Space"));

    // first store undo data for all tracks
    if (m_undo_enabled) {
        if (!registerUndoAction(new(std::nothrow) Kwave::UndoInsertAction(
            m_parent_widget, track_list, offset, length))) return false;
    }

    // then insert space into all tracks
    foreach (unsigned int track, track_list) {
        m_signal.insertSpace(track, offset, length);
    }

    return true;
}

//***************************************************************************
void Kwave::SignalManager::selectRange(sample_index_t offset,
                                       sample_index_t length)
{
    // first do some range checking
    sample_index_t len = this->length();

    if (length > len)  length = len;
    if (offset >= len) offset = (len) ? (len - 1) : 0;
    if ((offset + length) > len) length = len - offset;

    m_selection.select(offset, length);
}

//***************************************************************************
void Kwave::SignalManager::selectTracks(QVector<unsigned int> &track_list)
{
    unsigned int track;
    unsigned int n_tracks = tracks();
    for (track = 0; track < n_tracks; track++) {
        bool old_select = m_signal.trackSelected(track);
        bool new_select = track_list.contains(track);
        if (new_select != old_select) {
            m_signal.selectTrack(track, new_select);
        }
    }
}

//***************************************************************************
void Kwave::SignalManager::selectTrack(unsigned int track, bool select)
{
    bool old_select = m_signal.trackSelected(track);
    if (select != old_select) {
        m_signal.selectTrack(track, select);
    }
}

//***************************************************************************
QList<Kwave::Stripe::List> Kwave::SignalManager::stripes(
    const QVector<unsigned int> &track_list,
    sample_index_t left, sample_index_t right)
{
    QList<Kwave::Stripe::List> stripes;

    foreach (unsigned int track, track_list) {
        Kwave::Stripe::List s = m_signal.stripes(track, left, right);
        if (s.isEmpty()) {
            stripes.clear(); // something went wrong -> abort
            break;
        }
        stripes.append(s);
    }

    return stripes;
}

//***************************************************************************
bool Kwave::SignalManager::mergeStripes(
    const QList<Kwave::Stripe::List> &stripes,
    const QVector<unsigned int> &track_list)
{
    Q_ASSERT(stripes.count() == track_list.count());
    if (stripes.count() != track_list.count())
        return false;

    QListIterator<Kwave::Stripe::List> it_s(stripes);
    QVector<unsigned int>::const_iterator it_t = track_list.constBegin();
    while (it_s.hasNext() && (it_t != track_list.constEnd())) {
        Kwave::Stripe::List s = it_s.next();
        unsigned int        t = *(it_t++);
        if (!m_signal.mergeStripes(s, t))
            return false; // operation failed
    }

    return true;
}

//***************************************************************************
Kwave::PlaybackController &Kwave::SignalManager::playbackController()
{
    return m_playback_controller;
}

//***************************************************************************
void Kwave::SignalManager::startUndoTransaction(const QString &name)
{
    if (!m_undo_enabled) return; // undo is currently not enabled

    QMutexLocker lock(&m_undo_transaction_lock);

    // check for modified selection
    checkSelectionChange();

    // increase recursion level
    m_undo_transaction_level++;

    // start/create a new transaction if none existing
    if (!m_undo_transaction) {

        // if a new action starts, discard all redo actions !
        flushRedoBuffer();

        m_undo_transaction = new(std::nothrow) Kwave::UndoTransaction(name);
        Q_ASSERT(m_undo_transaction);
        if (!m_undo_transaction) return;

        // give all registered undo handlers a chance to register their own
        // undo actions
        if (!m_undo_manager.startUndoTransaction(m_undo_transaction)) {
            delete m_undo_transaction;
            m_undo_transaction = nullptr;
        }

        // if it is the start of the transaction, also create one
        // for the selection
        UndoAction *selection = new(std::nothrow) Kwave::UndoSelection(*this);
        Q_ASSERT(selection);
        if (selection && selection->store(*this)) {
            m_undo_transaction->append(selection);
        } else {
            // out of memory
            delete selection;
            delete m_undo_transaction;
            m_undo_transaction = nullptr;
        }
    }
}

//***************************************************************************
void Kwave::SignalManager::closeUndoTransaction()
{
    QMutexLocker lock(&m_undo_transaction_lock);

    // decrease recursion level
    if (!m_undo_transaction_level) return; // undo was not enabled ?
    m_undo_transaction_level--;

    if (!m_undo_transaction_level) {
        // append the current transaction to the undo buffer if
        // not empty
        if (m_undo_transaction) {
            if (!m_undo_transaction->isEmpty()) {
                // if the transaction has been aborted, undo all actions
                // that have currently been queued but do not
                // use the transaction any more, instead delete it.
                if (m_undo_transaction->isAborted()) {
                    qDebug("SignalManager::closeUndoTransaction(): aborted");
                    while (!m_undo_transaction->isEmpty()) {
                        UndoAction *undo_action;
                        UndoAction *redo_action;

                        // unqueue the undo action
                        undo_action = m_undo_transaction->takeLast();
                        Q_ASSERT(undo_action);
                        if (!undo_action) continue;

                        // execute the undo operation
                        redo_action = undo_action->undo(*this, false);

                        // remove the old undo action if no longer used
                        if (redo_action && (redo_action != undo_action))
                            delete redo_action;
                        delete undo_action;
                    }
                    delete m_undo_transaction;
                    m_undo_transaction = nullptr;
                } else {
                    m_undo_buffer.append(m_undo_transaction);
                }
            } else {
                qDebug("SignalManager::closeUndoTransaction(): empty");
                delete m_undo_transaction;
                m_undo_transaction = nullptr;
            }
        }

        // dump, for debugging
//      if (m_undo_transaction)
//          m_undo_transaction->dump("closed undo transaction: ");

        // declare the current transaction as "closed"
        rememberCurrentSelection();
        m_undo_transaction = nullptr;
        emitUndoRedoInfo();
    }
}

//***************************************************************************
void Kwave::SignalManager::enableUndo()
{
    m_undo_enabled = true;
    emitUndoRedoInfo();
}

//***************************************************************************
void Kwave::SignalManager::disableUndo()
{
    if (m_undo_transaction_level)
        qWarning("SignalManager::disableUndo(): undo transaction level=%u",
            m_undo_transaction_level);

    flushUndoBuffers();
    m_undo_enabled = false;
}

//***************************************************************************
void Kwave::SignalManager::flushUndoBuffers()
{
    QMutexLocker lock(&m_undo_transaction_lock);

    // if the signal was modified, it will stay in this state, it is
    // not possible to change to "non-modified" state through undo
    if ((!m_undo_buffer.isEmpty()) && (m_modified)) {
        enableModifiedChange(false);
    }

    // clear all buffers
    qDeleteAll(m_undo_buffer);
    qDeleteAll(m_redo_buffer);
    m_undo_buffer.clear();
    m_redo_buffer.clear();

    emitUndoRedoInfo();
}

//***************************************************************************
void Kwave::SignalManager::abortUndoTransaction()
{
    // abort the current transaction
    if (m_undo_transaction) m_undo_transaction->abort();
}

//***************************************************************************
void Kwave::SignalManager::flushRedoBuffer()
{
    qDeleteAll(m_redo_buffer);
    m_redo_buffer.clear();
    emitUndoRedoInfo();
}

//***************************************************************************
bool Kwave::SignalManager::continueWithoutUndo()
{
    // undo has not been enabled before?
    if (!m_undo_transaction) return true;

    // transaction has been aborted before
    if (m_undo_transaction->isAborted()) return false;

    // transaction is empty -> must have been flushed before, otherwise
    // it would contain at least a undo action for the selection
    // => user already has pressed "continue"
    if (m_undo_transaction->isEmpty()) return true;

    if (Kwave::MessageBox::warningContinueCancel(m_parent_widget,
        _("<html>") +
        i18n("Not enough memory for saving undo information.") +
        _("<br><br><b>") +
        i18n("Do you want to continue without the possibility to undo?") +
        _("</b><br><br><i>") +
        i18n("<b>Hint</b>: you can configure the amount of memory<br>"
             "available for undo under '%1'/'%2'.",
             i18n("Settings"),
             i18n("Memory") +
        _("</i></html>"))) == KMessageBox::Continue)
    {
        // the signal was modified, it will stay in this state, it is
        // not possible to change to "non-modified" state through undo
        // from now on...
        setModified(true);
        enableModifiedChange(false);

        // flush the current undo transaction
        while (!m_undo_transaction->isEmpty())
            delete m_undo_transaction->takeLast();

        // flush all undo/redo buffers
        flushUndoBuffers();
        return true;
    }

    // Set the undo transaction into "aborted" state. The final
    // closeUndoTransaction() will take care of the rest when
    // detecting that state and clean up...
    abortUndoTransaction();
    return false;
}

//***************************************************************************
bool Kwave::SignalManager::registerUndoAction(Kwave::UndoAction *action)
{
    QMutexLocker lock(&m_undo_transaction_lock);

    if (!action) return continueWithoutUndo();

    // if undo is not enabled, this will fail -> discard the action
    if (!m_undo_enabled) {
        delete action;
        return true;
    }

    // check if the undo action is too large
    qint64 limit_mb     = Kwave::undoLimit();
    qint64 needed_size  = action->undoSize();
    qint64 needed_mb    = needed_size  >> 20;
    if (needed_mb > limit_mb) {
        delete action;
        return continueWithoutUndo();
    }

    // undo has been aborted before ?
    if (!m_undo_transaction) return true;

    // transaction has been aborted before
    if (m_undo_transaction->isAborted()) {
        delete action;
        return true;
    }

    // make room...
    freeUndoMemory(needed_size);

    // now we might have enough place to append the undo action
    // and store all undo info
    if (!action->store(*this)) {
        delete action;
        return continueWithoutUndo();
    }

    // everything went ok, register internally
    m_undo_transaction->append(action);

    return true;
}

//***************************************************************************
bool Kwave::SignalManager::saveUndoDelete(QVector<unsigned int> &track_list,
                                          sample_index_t offset,
                                          sample_index_t length)
{
    if (!m_undo_enabled) return true;
    if (track_list.isEmpty()) return true;

    // create a undo action for deletion
    UndoDeleteAction *action = new(std::nothrow)
        UndoDeleteAction(m_parent_widget, track_list, offset, length);
    if (!registerUndoAction(action)) return false;

    return true;
}

//***************************************************************************
qint64 Kwave::SignalManager::usedUndoRedoMemory()
{
    qint64 size = 0;

    foreach (Kwave::UndoTransaction *undo, m_undo_buffer)
        if (undo) size += undo->undoSize();

    foreach (Kwave::UndoTransaction *redo, m_redo_buffer)
        if (redo) size += redo->undoSize();

    return size;
}

//***************************************************************************
void Kwave::SignalManager::freeUndoMemory(qint64 needed)
{
    qint64 size = usedUndoRedoMemory() + needed;
    qint64 undo_limit = Kwave::undoLimit() << 20;

    // remove old undo actions if not enough free memory
    while (!m_undo_buffer.isEmpty() && (size > undo_limit)) {
        Kwave::UndoTransaction *undo = m_undo_buffer.takeFirst();
        if (!undo) continue;
        qint64 s = undo->undoSize();
        size = (size >= s) ? (size - s) : 0;
        delete undo;

        // if the signal was modified, it will stay in this state, it is
        // not possible to change to "non-modified" state through undo
        if (m_modified) enableModifiedChange(false);
    }

    // remove old redo actions if still not enough memory
    while (!m_redo_buffer.isEmpty() && (size > undo_limit)) {
        Kwave::UndoTransaction *redo = m_redo_buffer.takeLast();
        if (!redo) continue;
        qint64 s = redo->undoSize();
        size = (size >= s) ? (size - s) : 0;
        delete redo;
    }
}

//***************************************************************************
void Kwave::SignalManager::emitUndoRedoInfo()
{
    QString undo_name = QString();
    QString redo_name = QString();

    if (m_undo_enabled) {
        Kwave::UndoTransaction *transaction;

        // get the description of the last undo action
        if (!m_undo_buffer.isEmpty()) {
            transaction = m_undo_buffer.last();
            if (transaction) undo_name = transaction->description();
            if (!undo_name.length()) undo_name = i18n("Last Action");
        }

        // get the description of the last redo action
        if (!m_redo_buffer.isEmpty()) {
            transaction = m_redo_buffer.first();
            if (transaction) redo_name = transaction->description();
            if (!redo_name.length()) redo_name = i18n("Last Action");
        }
    }

    // now emit the undo/redo transaction names
    emit sigUndoRedoInfo(undo_name, redo_name);
}

//***************************************************************************
void Kwave::SignalManager::undo()
{
    QMutexLocker lock(&m_undo_transaction_lock);

    // check for modified selection
    checkSelectionChange();

    // remember the last selection
    rememberCurrentSelection();

    // get the last undo transaction and abort if none present
    if (m_undo_buffer.isEmpty()) return;
    Kwave::UndoTransaction *undo_transaction = m_undo_buffer.takeLast();
    if (!undo_transaction) return;

    // dump, for debugging
//     undo_transaction->dump("before undo: ");

    // temporarily disable undo while undo itself is running
    bool old_undo_enabled = m_undo_enabled;
    m_undo_enabled = false;

    // get free memory for redo
    qint64 undo_limit = Kwave::undoLimit() << 20;
    qint64 redo_size = undo_transaction->redoSize();
    qint64 undo_size = undo_transaction->undoSize();
    Kwave::UndoTransaction *redo_transaction = nullptr;
    if ((redo_size > undo_size) && (redo_size - undo_size > undo_limit)) {
        // not enough memory for redo
        qWarning("SignalManager::undo(): not enough memory for redo !");
    } else {
        // only free the memory if it will be used
        freeUndoMemory(redo_size);

        // create a new redo transaction
        QString name = undo_transaction->description();
        redo_transaction = new(std::nothrow) Kwave::UndoTransaction(name);
        Q_ASSERT(redo_transaction);
    }

    // if *one* redo fails, all following redoes will also fail or
    // produce inconsistent data -> remove all of them !
    if (!redo_transaction) {
        flushRedoBuffer();
        qDebug("SignalManager::undo(): redo buffer flushed!");
    }

    // set hourglass cursor
    QApplication::setOverrideCursor(QCursor(Qt::WaitCursor));

    // execute all undo actions and store the resulting redo
    // actions into the redo transaction
    while (!undo_transaction->isEmpty()) {
        UndoAction *undo_action;
        UndoAction *redo_action;

        // unqueue the undo action
        undo_action = undo_transaction->takeLast();
        Q_ASSERT(undo_action);
        if (!undo_action) continue;

        // execute the undo operation
        redo_action = undo_action->undo(*this, (redo_transaction != nullptr));

        // remove the old undo action if no longer used
        if (redo_action != undo_action) {
            delete undo_action;
        }

        // queue the action into the redo transaction
        if (redo_action) {
            if (redo_transaction) {
                redo_transaction->prepend(redo_action);
            } else {
                // redo is not usable :-(
                delete redo_action;
            }
        }
    }

    // now the undo_transaction should be empty -> get rid of it
    Q_ASSERT(undo_transaction->isEmpty());
    delete undo_transaction;

    if (redo_transaction && (redo_transaction->count() < 1)) {
        // if there is no redo action -> no redo possible
        qWarning("SignalManager::undo(): no redo possible");
        delete redo_transaction;
        redo_transaction = nullptr;
    }

    // check whether the selection has changed, if yes: put a undo action
    // for this selection change at the end of the redo transaction
    if (redo_transaction) {
        bool range_modified = !(m_selection == m_last_selection);
        QVector<unsigned int> tracks = selectedTracks();
        bool tracks_modified = !(tracks == m_last_track_selection);
        if (range_modified || tracks_modified) {
            UndoAction *redo_action = new(std::nothrow) Kwave::UndoSelection(
                *this,
                m_last_track_selection,
                m_last_selection.offset(),
                m_last_selection.length());
            Q_ASSERT(redo_action);
            if (redo_action) redo_transaction->append(redo_action);
        }
    }

    // find out if there is still an action in the undo buffer
    // that has to do with modification of the signal
    if (m_modified) {
        bool stay_modified = false;
        foreach (Kwave::UndoTransaction *transaction, m_undo_buffer) {
            if (!transaction) continue;
            if (transaction->containsModification()) {
                stay_modified = true;
                break;
            }
        }
        if (!stay_modified) {
            // try to return to non-modified mode (might be a nop if
            // not enabled)
            setModified(false);
        }
    }

    // save "redo" information if possible
    if (redo_transaction)
        m_redo_buffer.prepend(redo_transaction);

    // remember the last selection
    rememberCurrentSelection();

    // re-enable undo
    m_undo_enabled = old_undo_enabled;

    // finished / buffers have changed, emit new undo/redo info
    emitUndoRedoInfo();

    // maybe the meta data has changed
    emit sigMetaDataChanged(m_meta_data);

    // remove hourglass
    QApplication::restoreOverrideCursor();
}

//***************************************************************************
void Kwave::SignalManager::redo()
{
    QMutexLocker lock(&m_undo_transaction_lock);

    // get the last redo transaction and abort if none present
    if (m_redo_buffer.isEmpty()) return;
    Kwave::UndoTransaction *redo_transaction = m_redo_buffer.takeFirst();
    if (!redo_transaction) return;

    // check for modified selection
    checkSelectionChange();

    // temporarily disable undo while redo is running
    bool old_undo_enabled = m_undo_enabled;
    m_undo_enabled = false;

    // get free memory for undo
    qint64 undo_limit = Kwave::undoLimit() << 20;
    qint64 undo_size = redo_transaction->undoSize();
    qint64 redo_size = redo_transaction->redoSize();
    Kwave::UndoTransaction *undo_transaction = nullptr;
    if ((undo_size > redo_size) && (undo_size - redo_size > undo_limit)) {
        // not enough memory for undo
        qWarning("SignalManager::redo(): not enough memory for undo !");
    } else {
        // only free the memory if it will be used
        freeUndoMemory(undo_size);

        // create a new undo transaction
        QString name = redo_transaction->description();
        undo_transaction = new(std::nothrow) Kwave::UndoTransaction(name);
        Q_ASSERT(undo_transaction);
    }

    // if *one* undo fails, all following undoes will also fail or
    // produce inconsistent data -> remove all of them !
    if (!undo_transaction) {
        qDeleteAll(m_undo_buffer);
        m_undo_buffer.clear();
    } else {
        m_undo_buffer.append(undo_transaction);
    }

    // set hourglass cursor
    QApplication::setOverrideCursor(QCursor(Qt::WaitCursor));

    // execute all redo actions and store the resulting undo
    // actions into the undo transaction
    bool modified = false;
    while (!redo_transaction->isEmpty()) {
        UndoAction *undo_action;
        UndoAction *redo_action;

        // unqueue the undo action
        redo_action = redo_transaction->takeFirst();

        // execute the redo operation
        Q_ASSERT(redo_action);
        if (!redo_action) continue;
        modified |= redo_transaction->containsModification();
        undo_action = redo_action->undo(*this, (undo_transaction != nullptr));

        // remove the old redo action if no longer used
        if (redo_action != undo_action) {
            delete redo_action;
        }

        // queue the action into the undo transaction
        if (undo_action) {
            if (undo_transaction) {
                undo_transaction->append(undo_action);
            } else {
                // undo is not usable :-(
                delete undo_action;
            }
        }
    }

    // now the redo_transaction should be empty -> get rid of it
    Q_ASSERT(redo_transaction->isEmpty());
    delete redo_transaction;

    if (undo_transaction && (undo_transaction->count() < 1)) {
        // if there is no undo action -> no undo possible
        qWarning("SignalManager::redo(): no undo possible");
        m_undo_buffer.removeAll(undo_transaction);
        delete undo_transaction;
    }

    // if the redo operation modified something,
    // we have to update the "modified" flag of the current signal
    if (modified) setModified(true);

    // remember the last selection
    rememberCurrentSelection();

    // re-enable undo
    m_undo_enabled = old_undo_enabled;

    // finished / buffers have changed, emit new undo/redo info
    emitUndoRedoInfo();

    // maybe the meta data has changed
    emit sigMetaDataChanged(m_meta_data);

    // remove hourglass
    QApplication::restoreOverrideCursor();
}

//***************************************************************************
void Kwave::SignalManager::setModified(bool mod)
{
    if (!m_modified_enabled) return;

    if (m_modified != mod) {
        m_modified = mod;
//      qDebug("SignalManager::setModified(%d)",mod);
        emit sigModified();
    }
}

//***************************************************************************
void Kwave::SignalManager::enableModifiedChange(bool en)
{
    m_modified_enabled = en;
}

//***************************************************************************
void Kwave::SignalManager::setFileInfo(const Kwave::FileInfo &new_info,
                                       bool with_undo)
{
    if (m_undo_enabled && with_undo) {
        /* save data for undo */
        Kwave::UndoTransactionGuard undo_transaction(*this,
                                                     i18n("Modify File Info"));
        Kwave::FileInfo old_inf(m_meta_data);
        if (!registerUndoAction(
            new(std::nothrow) Kwave::UndoModifyMetaDataAction(
                Kwave::MetaDataList(old_inf))))
            return;
    }

    m_meta_data.replace(Kwave::MetaDataList(new_info));
    setModified(true);
    emitUndoRedoInfo();
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
Kwave::Label Kwave::SignalManager::findLabel(sample_index_t pos)
{
    Kwave::LabelList labels(m_meta_data);
    foreach (const Kwave::Label &label, labels) {
        if (label.pos() == pos) return label; // found it
    }
    return Kwave::Label(); // nothing found
}

//***************************************************************************
int Kwave::SignalManager::labelIndex(const Kwave::Label &label) const
{
    int index = 0;
    Kwave::LabelList labels(m_meta_data);
    foreach (const Kwave::Label &l, labels) {
        if (l == label) return index; // found it
        index++;
    }
    return -1; // nothing found*/
}

//***************************************************************************
Kwave::Label Kwave::SignalManager::addLabel(sample_index_t pos,
                                            const QString &name)
{
    // if there already is a label at the given position, do nothing
    if (!findLabel(pos).isNull()) return Kwave::Label();

    // create a new label
    Kwave::Label label(pos, name);

    // register the undo action
    if (m_undo_enabled) {
        Kwave::UndoTransactionGuard undo(*this, i18n("Add Label"));
        if (!registerUndoAction(new(std::nothrow) UndoAddMetaDataAction(
                Kwave::MetaDataList(label))))
            return Kwave::Label();
    }

    // put the label into the list
    m_meta_data.add(label);

    // register this as a modification
    setModified(true);

    emit sigMetaDataChanged(m_meta_data);

    return label;
}

//***************************************************************************
void Kwave::SignalManager::deleteLabel(int index, bool with_undo)
{
    Kwave::LabelList labels(m_meta_data);
    int count = Kwave::toInt(labels.count());
    if (!count) return;

    if (index == -1) {
        // special handling for index == -1 -> delete all labels

        if (with_undo) startUndoTransaction(i18n("Delete All Labels"));

        for (index = count - 1; index >= 0; --index) {
            Kwave::MetaData label(labels.at(index));
            if (with_undo) {
                if (!registerUndoAction(new(std::nothrow)
                    UndoDeleteMetaDataAction(Kwave::MetaDataList(label))))
                    break;
            }
            m_meta_data.remove(label);
        }
    } else {
        // delete a single label
        if ((index < 0) || (index >= count)) return;

        Kwave::MetaData label(labels.at(index));

        // register the undo action
        if (with_undo) {
            startUndoTransaction(i18n("Delete Label"));
            if (!registerUndoAction(new(std::nothrow)
                UndoDeleteMetaDataAction(Kwave::MetaDataList(label)))) {
                abortUndoTransaction();
                return;
            }
        }

        m_meta_data.remove(label);
    }

    if (with_undo) closeUndoTransaction();

    // register this as a modification
    setModified(true);

    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
bool Kwave::SignalManager::modifyLabel(int index, sample_index_t pos,
                                       const QString &name,
                                       bool with_undo)
{
    Kwave::LabelList labels(m_meta_data);
    if ((index < 0) || (index >= Kwave::toInt(labels.count())))
        return false;

    Kwave::Label label = labels.at(index);

    // check: if the label should be moved and there already is a label
    // at the new position -> fail
    if ((pos != label.pos()) && !findLabel(pos).isNull())
        return false;

    // add a undo action
    if (with_undo && m_undo_enabled) {
        Kwave::UndoModifyMetaDataAction *undo_modify =
            new(std::nothrow) Kwave::UndoModifyMetaDataAction(
                    Kwave::MetaDataList(label));
        if (!registerUndoAction(undo_modify))
            return false;
    }

    // now modify the label
    label.moveTo(pos);
    label.rename(name);
    m_meta_data.add(label);

    // register this as a modification
    setModified(true);

    emit sigMetaDataChanged(m_meta_data);
    return true;
}

//***************************************************************************
void Kwave::SignalManager::mergeMetaData(const Kwave::MetaDataList &meta_data)
{
    m_meta_data.add(meta_data);
    emit sigMetaDataChanged(m_meta_data);
}

//***************************************************************************
void Kwave::SignalManager::rememberCurrentSelection()
{
    m_last_selection       = m_selection;
    m_last_track_selection = selectedTracks();
}

//***************************************************************************
void Kwave::SignalManager::checkSelectionChange()
{
    if (m_undo_transaction_level) return;

    // detect sample selection change
    bool range_modified = !(m_selection == m_last_selection);

    // detect track selection change
    QVector<unsigned int> tracks = selectedTracks();
    bool tracks_modified = !(tracks == m_last_track_selection);

    if (range_modified || tracks_modified) {
        // selection has changed since last undo/redo operation
        // qDebug("SignalManager::checkSelectionChange() => manually modified");
        // qDebug("    before: [%8u...%8u]", m_last_selection.first(),
        //                                   m_last_selection.last());
        // qDebug("    after : [%8u...%8u]", m_selection.first(),
        //                                   m_selection.last());

        // temporarily activate the previous selection (last stored)
        Kwave::Selection new_selection(m_selection);
        m_selection = m_last_selection;
        selectTracks(m_last_track_selection);

        // save the last selection into a undo action
        if (tracks_modified && !range_modified)
            Kwave::UndoTransactionGuard undo(*this,
                                             i18n("Manual Track Selection"));
        else
            Kwave::UndoTransactionGuard undo(*this,
                                             i18n("Manual Selection"));

        // restore the current selection again
        m_selection = new_selection;
        selectTracks(tracks);
    }

}

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

#include "moc_SignalManager.cpp"