Accept file drops across the channel footer

tools/chatgui/src/channellist.cpp

@@ -13,6 +13,9 @@
 #include <QMouseEvent>
 #include <QMenu>
 #include <QStyle>
+#include <QDropEvent>
+#include <QMimeData>
+#include <QUrl>
 
 extern "C" {
 #include "../../lib/debug_config.h"
@@ -175,6 +178,7 @@ ChannelList::ChannelList(DbManager* db, QWidget *parent)
     layout->addWidget(m_listView);
 
     auto *footer = new QWidget(this);
+    m_footer = footer; m_footer->setObjectName("channelFooter");
     auto *fl = new QHBoxLayout(footer);
     fl->setContentsMargins(6, 4, 6, 4);
     fl->setSpacing(6);
@@ -240,6 +244,12 @@ ChannelList::ChannelList(DbManager* db, QWidget *parent)
     fl->addWidget(plusBtn);
 
     layout->addWidget(footer);
+    auto targets = footer->findChildren<QWidget*>(); targets.append(footer);
+    for (auto* target : targets) { target->setAcceptDrops(true); target->installEventFilter(this); }
+    m_dropHint = new QLabel(footer); m_dropHint->setObjectName("ownFilesDropHint");
+    m_dropHint->setAttribute(Qt::WA_TransparentForMouseEvents); m_dropHint->setAlignment(Qt::AlignCenter);
+    m_dropHint->setStyleSheet("QLabel { border: 2px dashed palette(highlight); background: palette(window); color: palette(text); }");
+    m_dropHint->hide();
 
     connect(m_listView->selectionModel(), &QItemSelectionModel::currentChanged,
             this, [this](const QModelIndex &current, const QModelIndex &) {
@@ -266,6 +276,46 @@ ChannelList::ChannelList(DbManager* db, QWidget *parent)
     });
 }
 
+bool ChannelList::eventFilter(QObject* target, QEvent* event) {
+    if (event->type() == QEvent::DragLeave) { m_dropHint->hide(); return true; }
+    if (event->type() != QEvent::DragEnter && event->type() != QEvent::DragMove && event->type() != QEvent::Drop)
+        return QWidget::eventFilter(target, event);
+    auto* drop = static_cast<QDropEvent*>(event);
+    QString channel = m_listView->currentIndex().data(ChannelChannelIdRole).toString();
+    QString reason;
+    if (!channel.toULongLong()) reason = QCoreApplication::translate("ChatGui", "Select a group to upload files");
+    else if (!m_db || !m_db->myNodeId() || !gui_bridge_is_uasync_ready())
+        reason = QCoreApplication::translate("ChatGui", "Upload unavailable");
+    else if (!drop->mimeData()->hasUrls() || drop->mimeData()->urls().isEmpty() || !(drop->possibleActions() & Qt::CopyAction))
+        reason = QCoreApplication::translate("ChatGui", "Drop local files to copy");
+    QStringList paths;
+    if (reason.isEmpty()) for (const auto& url : drop->mimeData()->urls()) {
+        if (!url.isLocalFile() || url.toLocalFile().isEmpty()) {
+            reason = QCoreApplication::translate("ChatGui", "Only local files can be uploaded"); break;
+        }
+        paths.append(url.toLocalFile());
+    }
+    if (event->type() == QEvent::Drop) m_dropHint->hide();
+    else {
+        m_dropHint->setGeometry(m_footer->rect());
+        m_dropHint->setText(reason.isEmpty() ? QCoreApplication::translate("ChatGui", "Copy to my files") : reason);
+        m_dropHint->show(); m_dropHint->raise();
+    }
+    if (!reason.isEmpty()) {
+        if (event->type() != QEvent::DragMove)
+            DEBUG_WARN(DEBUG_CATEGORY_MEDIA, "file drop: rejected channel=%s reason=%s", qPrintable(channel), qPrintable(reason));
+        drop->ignore();
+        // После отклонённого DragEnter Qt не гарантирует DragLeave.
+        m_dropHint->hide(); return true;
+    }
+    drop->setDropAction(Qt::CopyAction); drop->accept();
+    if (event->type() == QEvent::Drop) {
+        DEBUG_INFO(DEBUG_CATEGORY_MEDIA, "file drop: accepted channel=%s files=%d", qPrintable(channel), int(paths.size()));
+        QTimer::singleShot(0, this, [this, channel, paths] { emit ownFilesDropped(channel, paths); });
+    }
+    return true;
+}
+
 void ChannelList::refreshDmPresence() {
     if (!m_dmPresenceTimer->isActive()) m_dmPresenceTimer->start();
 }