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#include "downloadmanager.h"

#include <QFileInfo>

#include <QNetworkRequest>

#include <QNetworkReply>

#include <QString>

#include <QStringList>

#include <QTimer>

#include <stdio.h>

DownloadManager::DownloadManager(QObject *parent)

    : QObject(parent), downloadedCount(0), totalCount(0)

{

}

void DownloadManager::append(const QStringList &urlList)

{

    foreach (QString url, urlList)

        append(QUrl::fromEncoded(url.toLocal8Bit()));

    if (downloadQueue.isEmpty())

        QTimer::singleShot(0, this, SIGNAL(finished()));

}

void DownloadManager::append(const QUrl &url)

{

    if (downloadQueue.isEmpty())

        QTimer::singleShot(0, this, SLOT(startNextDownload()));

    downloadQueue.enqueue(url);

    ++totalCount;

}

QString DownloadManager::saveFileName(const QUrl &url)

{

    QString path = url.path();

    QString basename = QFileInfo(path).fileName();

    if (basename.isEmpty())

        basename = "download";

    if (QFile::exists(basename)) {

        // already exists, don't overwrite

        int i = 0;

        basename += '.';

        while (QFile::exists(basename + QString::number(i)))

            ++i;

        basename += QString::number(i);

    }

    return basename;

}

void DownloadManager::startNextDownload()

{

    if (downloadQueue.isEmpty()) {

        printf("%d/%d files downloaded successfully\n", downloadedCount, totalCount);

        emit finished();

        return;

    }

    QUrl url = downloadQueue.dequeue();

    QString filename = saveFileName(url);

    output.setFileName(filename);

    if (!output.open(QIODevice::WriteOnly)) {

        fprintf(stderr, "Problem opening save file '%s' for download '%s': %s\n",

                qPrintable(filename), url.toEncoded().constData(),

                qPrintable(output.errorString()));

        startNextDownload();

        return;                 // skip this download

    }

    QNetworkRequest request(url);

    currentDownload = manager.get(request);

    connect(currentDownload, SIGNAL(downloadProgress(qint64,qint64)),

            SLOT(downloadProgress(qint64,qint64)));

    connect(currentDownload, SIGNAL(finished()),

            SLOT(downloadFinished()));

    connect(currentDownload, SIGNAL(readyRead()),

            SLOT(downloadReadyRead()));

    // prepare the output

    printf("Downloading %s...\n", url.toEncoded().constData());

    downloadTime.start();

}

void DownloadManager::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)

{

    progressBar.setStatus(bytesReceived, bytesTotal);

    // calculate the download speed

    double speed = bytesReceived * 1000.0 / downloadTime.elapsed();

    QString unit;

    if (speed < 1024) {

        unit = "bytes/sec";

    } else if (speed < 1024*1024) {

        speed /= 1024;

        unit = "kB/s";

    } else {

        speed /= 1024*1024;

        unit = "MB/s";

    }

    progressBar.setMessage(QString::fromLatin1("%1 %2")

                           .arg(speed, 3, 'f', 1).arg(unit));

    progressBar.update();

}

void DownloadManager::downloadFinished()

{

    progressBar.clear();

    output.close();

    if (currentDownload->error()) {

        // download failed

        fprintf(stderr, "Failed: %s\n", qPrintable(currentDownload->errorString()));

    } else {

        printf("Succeeded.\n");

        ++downloadedCount;

    }

    currentDownload->deleteLater();

    startNextDownload();

}

void DownloadManager::downloadReadyRead()

{

    output.write(currentDownload->readAll());

}