Improve Search handling

Legacy SearchEngine class really has three roles:
  1. Manage search plugins,
  2. Handle the search job, and
  3. Handle the download of the torrent file using the search plugin.
Now it is splitted into 3 classes: SearchManager, SearchHandler and
SearchDownloadHandler.
Search GUI is also improved.

src/base/search/searchhandler.cpp

@@ -0,0 +1,199 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2015, 2018  Vladimir Golovnev <glassez@yandex.ru>
+ * Copyright (C) 2006  Christophe Dumez <chris@qbittorrent.org>
+ *
+ * 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.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#include "searchhandler.h"
+
+#include <QProcess>
+#include <QTimer>
+
+#include "../utils/fs.h"
+#include "../utils/misc.h"
+#include "searchpluginmanager.h"
+
+namespace
+{
+    enum SearchResultColumn
+    {
+        PL_DL_LINK,
+        PL_NAME,
+        PL_SIZE,
+        PL_SEEDS,
+        PL_LEECHS,
+        PL_ENGINE_URL,
+        PL_DESC_LINK,
+        NB_PLUGIN_COLUMNS
+    };
+}
+
+SearchHandler::SearchHandler(const QString &pattern, const QString &category, const QStringList &usedPlugins, SearchPluginManager *manager)
+    : QObject {manager}
+    , m_pattern {pattern}
+    , m_category {category}
+    , m_usedPlugins {usedPlugins}
+    , m_manager {manager}
+    , m_searchProcess {new QProcess {this}}
+    , m_searchTimeout {new QTimer {this}}
+{
+    // Load environment variables (proxy)
+    m_searchProcess->setEnvironment(QProcess::systemEnvironment());
+
+    const QStringList params {
+        Utils::Fs::toNativePath(m_manager->engineLocation() + "/nova2.py"),
+        m_usedPlugins.join(","),
+        m_category
+    };
+
+    // Launch search
+    m_searchProcess->setProgram(Utils::Misc::pythonExecutable());
+    m_searchProcess->setArguments(params + m_pattern.split(" "));
+
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
+    connect(m_searchProcess, &QProcess::errorOccurred, this, &SearchHandler::processFailed);
+#else
+    connect(m_searchProcess, static_cast<void(QProcess::*)(QProcess::ProcessError)>(&QProcess::error)
+            , this, &SearchHandler::processFailed);
+#endif
+    connect(m_searchProcess, &QProcess::readyReadStandardOutput, this, &SearchHandler::readSearchOutput);
+    connect(m_searchProcess, static_cast<void (QProcess::*)(int)>(&QProcess::finished)
+            , this, &SearchHandler::processFinished);
+
+    m_searchTimeout->setSingleShot(true);
+    connect(m_searchTimeout, &QTimer::timeout, this, &SearchHandler::cancelSearch);
+    m_searchTimeout->start(180000); // 3 min
+
+    // deferred start allows clients to handle starting-related signals
+    QTimer::singleShot(0, this, [this]() { m_searchProcess->start(QIODevice::ReadOnly); });
+}
+
+bool SearchHandler::isActive() const
+{
+    return (m_searchProcess->state() != QProcess::NotRunning);
+}
+
+void SearchHandler::cancelSearch()
+{
+    if ((m_searchProcess->state() == QProcess::NotRunning) || m_searchCancelled)
+        return;
+
+#ifdef Q_OS_WIN
+    m_searchProcess->kill();
+#else
+    m_searchProcess->terminate();
+#endif
+    m_searchCancelled = true;
+    m_searchTimeout->stop();
+}
+
+// Slot called when QProcess is Finished
+// QProcess can be finished for 3 reasons:
+// Error | Stopped by user | Finished normally
+void SearchHandler::processFinished(int exitcode)
+{
+    m_searchTimeout->stop();
+
+    if (m_searchCancelled)
+        emit searchFinished(true);
+    else if ((m_searchProcess->exitStatus() == QProcess::NormalExit) && (exitcode == 0))
+        emit searchFinished(false);
+    else
+        emit searchFailed();
+}
+
+// search QProcess return output as soon as it gets new
+// stuff to read. We split it into lines and parse each
+// line to SearchResult calling parseSearchResult().
+void SearchHandler::readSearchOutput()
+{
+    QByteArray output = m_searchProcess->readAllStandardOutput();
+    output.replace("\r", "");
+    QList<QByteArray> lines = output.split('\n');
+    if (!m_searchResultLineTruncated.isEmpty())
+        lines.prepend(m_searchResultLineTruncated + lines.takeFirst());
+    m_searchResultLineTruncated = lines.takeLast().trimmed();
+
+    QList<SearchResult> searchResultList;
+    foreach (const QByteArray &line, lines) {
+        SearchResult searchResult;
+        if (parseSearchResult(QString::fromUtf8(line), searchResult))
+            searchResultList << searchResult;
+    }
+
+    if (!searchResultList.isEmpty()) {
+        m_results.append(searchResultList);
+        emit newSearchResults(searchResultList);
+    }
+}
+
+void SearchHandler::processFailed()
+{
+    if (!m_searchCancelled)
+        emit searchFailed();
+}
+
+// Parse one line of search results list
+// Line is in the following form:
+// file url | file name | file size | nb seeds | nb leechers | Search engine url
+bool SearchHandler::parseSearchResult(const QString &line, SearchResult &searchResult)
+{
+    const QStringList parts = line.split("|");
+    const int nbFields = parts.size();
+    if (nbFields < (NB_PLUGIN_COLUMNS - 1)) return false; // -1 because desc_link is optional
+
+    searchResult = SearchResult();
+    searchResult.fileUrl = parts.at(PL_DL_LINK).trimmed(); // download URL
+    searchResult.fileName = parts.at(PL_NAME).trimmed(); // Name
+    searchResult.fileSize = parts.at(PL_SIZE).trimmed().toLongLong(); // Size
+    bool ok = false;
+    searchResult.nbSeeders = parts.at(PL_SEEDS).trimmed().toLongLong(&ok); // Seeders
+    if (!ok || (searchResult.nbSeeders < 0))
+        searchResult.nbSeeders = -1;
+    searchResult.nbLeechers = parts.at(PL_LEECHS).trimmed().toLongLong(&ok); // Leechers
+    if (!ok || (searchResult.nbLeechers < 0))
+        searchResult.nbLeechers = -1;
+    searchResult.siteUrl = parts.at(PL_ENGINE_URL).trimmed(); // Search site URL
+    if (nbFields == NB_PLUGIN_COLUMNS)
+        searchResult.descrLink = parts.at(PL_DESC_LINK).trimmed(); // Description Link
+
+    return true;
+}
+
+SearchPluginManager *SearchHandler::manager() const
+{
+    return m_manager;
+}
+
+QList<SearchResult> SearchHandler::results() const
+{
+    return m_results;
+}
+
+QString SearchHandler::pattern() const
+{
+    return m_pattern;
+}