From de954f644abf1576e7a8dc66b133830fa395b3d8 Mon Sep 17 00:00:00 2001
From: Bart De Vries <bart@mogwai.be>
Date: Wed, 6 Oct 2021 16:07:05 +0200
Subject: [PATCH] Fix issues with cached images being accessed while the
 download is still running

---
 src/fetcher.cpp | 29 +++++++++++++++++++++++------
 src/fetcher.h   |  4 +++-
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/src/fetcher.cpp b/src/fetcher.cpp
index 32904f03..7d2f99d5 100644
--- a/src/fetcher.cpp
+++ b/src/fetcher.cpp
@@ -109,7 +109,7 @@ void Fetcher::fetch(const QStringList &urls)
     qCDebug(kastsFetcher) << "end of Fetcher::fetch";
 }
 
-QString Fetcher::image(const QString &url) const
+QString Fetcher::image(const QString &url)
 {
     if (url.isEmpty()) {
         return QLatin1String("no-image");
@@ -123,18 +123,35 @@ QString Fetcher::image(const QString &url) const
         }
     }
 
+    // avoid restarting an image download if it's already running
+    if (m_ongoingImageDownloads.contains(url)) {
+        return QLatin1String("fetching");
+    }
+
     // if image has not yet been cached, then check for network connectivity if
     // possible; and download the image
     if (canCheckNetworkStatus()) {
-        if (networkConnected() && (!isMeteredConnection() || SettingsManager::self()->allowMeteredImageDownloads())) {
-            download(url, path);
-        } else {
+        if (!networkConnected() || (isMeteredConnection() && !SettingsManager::self()->allowMeteredImageDownloads())) {
             return QLatin1String("no-image");
         }
-    } else {
-        download(url, path);
     }
 
+    m_ongoingImageDownloads.insert(url);
+    QNetworkRequest request((QUrl(url)));
+    request.setTransferTimeout();
+    QNetworkReply *reply = get(request);
+    connect(reply, &QNetworkReply::finished, this, [=]() {
+        if (reply->isOpen() && !reply->error()) {
+            QByteArray data = reply->readAll();
+            QFile file(path);
+            file.open(QIODevice::WriteOnly);
+            file.write(data);
+            file.close();
+            Q_EMIT downloadFinished(url);
+        }
+        m_ongoingImageDownloads.remove(url);
+        reply->deleteLater();
+    });
     return QLatin1String("fetching");
 }
 
diff --git a/src/fetcher.h b/src/fetcher.h
index 6aa54d09..b716b660 100644
--- a/src/fetcher.h
+++ b/src/fetcher.h
@@ -39,7 +39,7 @@ public:
     Q_INVOKABLE void fetch(const QString &url);
     Q_INVOKABLE void fetch(const QStringList &urls);
     Q_INVOKABLE void fetchAll();
-    Q_INVOKABLE QString image(const QString &url) const;
+    Q_INVOKABLE QString image(const QString &url);
     Q_INVOKABLE QNetworkReply *download(const QString &url, const QString &fileName) const;
 
     QNetworkReply *get(QNetworkRequest &request) const;
@@ -74,6 +74,8 @@ private:
     QNetworkReply *head(QNetworkRequest &request) const;
     void setHeader(QNetworkRequest &request) const;
 
+    QSet<QString> m_ongoingImageDownloads;
+
     QNetworkAccessManager *manager;
     int m_updateProgress;
     int m_updateTotal;