Revert "DragAndDropHelper::updateDropAction: use StatJob for remote URLs"

This reverts commit dc149ec5e52f52c514cf362603d05ba8eea506b8.

This prevents a crash. One issue identified is that the commit that
I am reverting here accesses a QDropEvent at a moment in time in
which it might have already been deleted. We cannot check if it
exists by that time because we do not control its lifetime and it
is not a QObject.

6 files changed, 22 insertions, 129 deletions

diff --git a/src/dolphintabwidget.cpp b/src/dolphintabwidget.cpp
index 9bfd6076a..f80b94ea7 100644
--- a/src/dolphintabwidget.cpp
+++ b/src/dolphintabwidget.cpp
@@ -9,6 +9,7 @@
 #include "dolphin_generalsettings.h"
 #include "dolphintabbar.h"
 #include "dolphinviewcontainer.h"
+#include "views/draganddrophelper.h"
 
 #include <KAcceleratorManager>
 #include <KConfigGroup>
@@ -23,7 +24,6 @@
 
 DolphinTabWidget::DolphinTabWidget(DolphinNavigatorsWidgetAction *navigatorsWidget, QWidget *parent)
     : QTabWidget(parent)
-    , m_dragAndDropHelper{this}
     , m_lastViewedTab(nullptr)
     , m_navigatorsWidget{navigatorsWidget}
 {
@@ -394,7 +394,7 @@ void DolphinTabWidget::tabDragMoveEvent(int index, QDragMoveEvent *event)
 {
     if (index >= 0) {
         DolphinView *view = tabPageAt(index)->activeViewContainer()->view();
-        m_dragAndDropHelper.updateDropAction(event, view->url());
+        DragAndDropHelper::updateDropAction(event, view->url());
     }
 }
 
diff --git a/src/dolphintabwidget.h b/src/dolphintabwidget.h
index a02c8fb84..a28a6bea1 100644
--- a/src/dolphintabwidget.h
+++ b/src/dolphintabwidget.h
@@ -9,7 +9,6 @@
 
 #include "dolphinnavigatorswidgetaction.h"
 #include "dolphintabpage.h"
-#include "views/draganddrophelper.h"
 
 #include <QTabWidget>
 #include <QUrl>
@@ -277,8 +276,6 @@ private:
      */
     const std::optional<const ViewIndex> viewShowingItem(const QUrl &item) const;
 
-    DragAndDropHelper m_dragAndDropHelper;
-
 private:
     QPointer<DolphinTabPage> m_lastViewedTab;
     QPointer<DolphinNavigatorsWidgetAction> m_navigatorsWidget;
diff --git a/src/panels/places/placespanel.cpp b/src/panels/places/placespanel.cpp
index eaf2642eb..ba3451bd5 100644
--- a/src/panels/places/placespanel.cpp
+++ b/src/panels/places/placespanel.cpp
@@ -15,6 +15,7 @@
 #include "dolphin_placespanelsettings.h"
 #include "dolphinplacesmodelsingleton.h"
 #include "settings/dolphinsettingsdialog.h"
+#include "views/draganddrophelper.h"
 
 #include <KFilePlacesModel>
 #include <KIO/DropJob>
@@ -31,7 +32,6 @@
 
 PlacesPanel::PlacesPanel(QWidget *parent)
     : KFilePlacesView(parent)
-    , m_dragAndDropHelper(this)
 {
     setDropOnPlaceEnabled(true);
     connect(this, &PlacesPanel::urlsDropped, this, &PlacesPanel::slotUrlsDropped);
@@ -161,7 +161,7 @@ void PlacesPanel::dragMoveEvent(QDragMoveEvent *event)
             if (!url.isValid() || !KProtocolManager::supportsWriting(url)) {
                 event->setDropAction(Qt::IgnoreAction);
             } else {
-                m_dragAndDropHelper.updateDropAction(event, url);
+                DragAndDropHelper::updateDropAction(event, url);
             }
         }
     }
diff --git a/src/panels/places/placespanel.h b/src/panels/places/placespanel.h
index d21e7d64e..cbd5fc224 100644
--- a/src/panels/places/placespanel.h
+++ b/src/panels/places/placespanel.h
@@ -10,7 +10,6 @@
 #define PLACESPANEL_H
 
 #include "panels/panel.h"
-#include "views/draganddrophelper.h"
 
 #include <KFilePlacesView>
 #include <QUrl>
@@ -79,8 +78,6 @@ private:
     QAction *m_configureTrashAction;
     QAction *m_openInSplitView;
     QAction *m_lockPanelsAction;
-
-    DragAndDropHelper m_dragAndDropHelper;
 };
 
 #endif // PLACESPANEL_H
diff --git a/src/views/draganddrophelper.cpp b/src/views/draganddrophelper.cpp
index 7163507a6..7b9949df4 100644
--- a/src/views/draganddrophelper.cpp
+++ b/src/views/draganddrophelper.cpp
@@ -73,85 +73,20 @@ bool DragAndDropHelper::supportsDropping(const KFileItem &destItem)
     return (destItem.isDir() && destItem.isWritable()) || destItem.isDesktopFile();
 }
 
-DragAndDropHelper::DragAndDropHelper(QObject *parent)
-    : QObject(parent)
-{
-    m_destItemCacheInvalidationTimer.setSingleShot(true);
-    m_destItemCacheInvalidationTimer.setInterval(30000);
-    connect(&m_destItemCacheInvalidationTimer, &QTimer::timeout, this, [this]() {
-        m_destItemCache = KFileItem();
-    });
-}
-
 void DragAndDropHelper::updateDropAction(QDropEvent *event, const QUrl &destUrl)
 {
-    auto processEvent = [this](QDropEvent *event) {
-        if (supportsDropping(m_destItemCache)) {
-            event->setDropAction(event->proposedAction());
-            event->accept();
-        } else {
-            event->setDropAction(Qt::IgnoreAction);
-            event->ignore();
-        }
-    };
-
-    m_lastUndecidedEvent = nullptr;
-
     if (urlListMatchesUrl(event->mimeData()->urls(), destUrl)) {
         event->setDropAction(Qt::IgnoreAction);
         event->ignore();
-        return;
     }
-
-    if (destUrl == m_destItemCache.url()) {
-        // We already received events for this URL, and already have the
-        // stat result cached because:
-        // 1. it's a local file, and we already called KFileItem(destUrl)
-        // 2. it's a remote file, and StatJob finished
-        processEvent(event);
-        return;
-    }
-
-    if (m_statJob) {
-        if (destUrl == m_statJobUrl) {
-            // We already received events for this URL. Still waiting for
-            // the stat result. StatJob will process the event when it finishes.
-            m_lastUndecidedEvent = event;
-            return;
-        }
-
-        // We are waiting for the stat result of a different URL. Cancel.
-        m_statJob->kill();
-        m_statJob = nullptr;
-        m_statJobUrl.clear();
-    }
-
-    if (destUrl.isLocalFile()) {
-        // New local URL. KFileItem will stat on demand.
-        m_destItemCache = KFileItem(destUrl);
-        m_destItemCacheInvalidationTimer.start();
-        processEvent(event);
-        return;
+    KFileItem item(destUrl);
+    if (!item.isLocalFile() || supportsDropping(item)) {
+        event->setDropAction(event->proposedAction());
+        event->accept();
+    } else {
+        event->setDropAction(Qt::IgnoreAction);
+        event->ignore();
     }
-
-    // New remote URL. Start a StatJob and process the event when it finishes.
-    m_lastUndecidedEvent = event;
-    m_statJob = KIO::stat(destUrl, KIO::StatJob::SourceSide, KIO::StatDetail::StatBasic, KIO::JobFlag::HideProgressInfo);
-    m_statJobUrl = destUrl;
-    connect(m_statJob, &KIO::StatJob::result, this, [this, processEvent](KJob *job) {
-        KIO::StatJob *statJob = static_cast<KIO::StatJob *>(job);
-
-        m_destItemCache = KFileItem(statJob->statResult(), m_statJobUrl);
-        m_destItemCacheInvalidationTimer.start();
-
-        if (m_lastUndecidedEvent) {
-            processEvent(m_lastUndecidedEvent);
-            m_lastUndecidedEvent = nullptr;
-        }
-
-        m_statJob = nullptr;
-        m_statJobUrl.clear();
-    });
 }
 
 void DragAndDropHelper::clearUrlListMatchesUrlCache()
diff --git a/src/views/draganddrophelper.h b/src/views/draganddrophelper.h
index df3b49966..73043febc 100644
--- a/src/views/draganddrophelper.h
+++ b/src/views/draganddrophelper.h
@@ -11,11 +11,9 @@
 #include "dolphin_export.h"
 
 #include <KFileItem>
-#include <KIO/StatJob>
 
 #include <QList>
 #include <QString>
-#include <QTimer>
 #include <QUrl>
 
 class QDropEvent;
@@ -26,7 +24,7 @@ namespace KIO
 class DropJob;
 }
 
-class DOLPHIN_EXPORT DragAndDropHelper : public QObject
+class DOLPHIN_EXPORT DragAndDropHelper
 {
 public:
     /**
@@ -54,6 +52,16 @@ public:
     static bool supportsDropping(const KFileItem &destItem);
 
     /**
+     * Updates the drop action according to whether the destination supports dropping.
+     * If supportsDropping(destUrl), set dropAction = proposedAction. Otherwise, set
+     * dropAction = Qt::IgnoreAction.
+     *
+     * @param event     Drop event.
+     * @param destUrl   Destination URL.
+     */
+    static void updateDropAction(QDropEvent *event, const QUrl &destUrl);
+
+    /**
      * @return True if destUrl is contained in the urls parameter.
      */
     static bool urlListMatchesUrl(const QList<QUrl> &urls, const QUrl &destUrl);
@@ -76,55 +84,11 @@ public:
      */
     static void clearUrlListMatchesUrlCache();
 
-    DragAndDropHelper(QObject *parent);
-
-    /**
-     * Updates the drop action according to whether the destination supports dropping.
-     * If supportsDropping(destUrl), set dropAction = proposedAction. Otherwise, set
-     * dropAction = Qt::IgnoreAction.
-     *
-     * @param event     Drop event.
-     * @param destUrl   Destination URL.
-     */
-    void updateDropAction(QDropEvent *event, const QUrl &destUrl);
-
 private:
     /**
      * Stores the results of the expensive checks made in urlListMatchesUrl.
      */
     static QHash<QUrl, bool> m_urlListMatchesUrlCache;
-
-    /**
-     * When updateDropAction() is called with a remote URL, we create a StatJob to
-     * check if the destination is a directory or a desktop file. We cache the result
-     * here to avoid doing the stat again on subsequent calls to updateDropAction().
-     */
-    KFileItem m_destItemCache;
-
-    /**
-     * Only keep the cache for 30 seconds, because the stat of the destUrl might change.
-     */
-    QTimer m_destItemCacheInvalidationTimer;
-
-    /**
-     * A StatJob on-fly to fill the cache for a remote URL. We shouldn't create more
-     * than one StatJob at a time, so we keep a pointer to the current one.
-     */
-    KIO::StatJob *m_statJob = nullptr;
-
-    /**
-     * The URL for which the StatJob is running.
-     * Note: We can't use m_statJob->url() because StatJob might resolve the URL to be
-     *       different from what we passed into stat(). E.g. "mtp:<bus-name>" is resolved
-     *       to "mtp:<phone name>"
-     */
-    QUrl m_statJobUrl;
-
-    /**
-     * The last event we received in updateDropAction(), but can't react to yet,
-     * because a StatJob is on-fly.
-     */
-    QDropEvent *m_lastUndecidedEvent = nullptr;
 };
 
 #endif