Improve Filelight installation UX

Before this commit pressing the free space button when Filelight
is not installed would show a singular action called "Install
Filelight to View Disk Usage Statistics…". Pressing this button
would open the store page for Filelight. This is an okay user
experience, but we can do better.

This commit makes it so pressing the free space button when
Filelight is not installed shows an attractive UI that makes clear
that freeing up disk space can be accomplished nicely by installing
Filelight. The "Install Filelight…" button on this UI is connected
to PackageKit directly, so we do not need to show a separate store
like Discover and instead trigger an installation right then and
there. For this, the recently introduced DolphinPackageInstaller
KJob is used.

Installation progress is reported through the status bar similar to
the progress reporting of slowly loading directories or searches.
Installation failure or success is ultimately shown within Dolphin
as a passive notification above the view.

On Microsoft Windows or when PackageKit is not available, the
install button will only open a store page for Filelight.

CCBUG: 477739

4 files changed, 144 insertions, 11 deletions

diff --git a/src/statusbar/dolphinstatusbar.cpp b/src/statusbar/dolphinstatusbar.cpp
index 5a3aa5857..c8369febc 100644
--- a/src/statusbar/dolphinstatusbar.cpp
+++ b/src/statusbar/dolphinstatusbar.cpp
@@ -70,6 +70,13 @@ DolphinStatusBar::DolphinStatusBar(QWidget *parent)
 
     // Initialize space information
     m_spaceInfo = new StatusBarSpaceInfo(contentsContainer);
+    connect(m_spaceInfo, &StatusBarSpaceInfo::showMessage, this, &DolphinStatusBar::showMessage);
+    connect(m_spaceInfo,
+            &StatusBarSpaceInfo::showInstallationProgress,
+            this,
+            [this](const QString &currentlyRunningTaskTitle, int installationProgressPercent) {
+                showProgress(currentlyRunningTaskTitle, installationProgressPercent, CancelLoading::Disallowed);
+            });
 
     // Initialize progress information
     m_stopButton = new QToolButton(contentsContainer);
diff --git a/src/statusbar/dolphinstatusbar.h b/src/statusbar/dolphinstatusbar.h
index 8abbed66b..a620a0117 100644
--- a/src/statusbar/dolphinstatusbar.h
+++ b/src/statusbar/dolphinstatusbar.h
@@ -9,6 +9,8 @@
 
 #include "animatedheightwidget.h"
 
+#include <KMessageWidget>
+
 #include <QTime>
 
 class QUrl;
@@ -96,6 +98,11 @@ Q_SIGNALS:
 
     void zoomLevelChanged(int zoomLevel);
 
+    /**
+     * Requests for @p message with the given @p messageType to be shown to the user in a non-modal way.
+     */
+    void showMessage(const QString &message, KMessageWidget::MessageType messageType);
+
 protected:
     void contextMenuEvent(QContextMenuEvent *event) override;
     void paintEvent(QPaintEvent *paintEvent) override;
diff --git a/src/statusbar/statusbarspaceinfo.cpp b/src/statusbar/statusbarspaceinfo.cpp
index 9df416467..a482bde9c 100644
--- a/src/statusbar/statusbarspaceinfo.cpp
+++ b/src/statusbar/statusbarspaceinfo.cpp
@@ -6,6 +6,9 @@
 
 #include "statusbarspaceinfo.h"
 
+#include "config-dolphin.h"
+#include "dolphinpackageinstaller.h"
+#include "global.h"
 #include "spaceinfoobserver.h"
 
 #include <KCapacityBar>
@@ -16,14 +19,19 @@
 
 #include <QDesktopServices>
 #include <QHBoxLayout>
+#include <QLabel>
 #include <QMenu>
 #include <QMouseEvent>
+#include <QPushButton>
 #include <QStorageInfo>
 #include <QToolButton>
+#include <QVBoxLayout>
+#include <QWidgetAction>
 
 StatusBarSpaceInfo::StatusBarSpaceInfo(QWidget *parent)
     : QWidget(parent)
     , m_observer(nullptr)
+    , m_installFilelightWidgetAction{nullptr}
 {
     m_capacityBar = new KCapacityBar(KCapacityBar::DrawTextInline, this);
     m_textInfoButton = new QToolButton(this);
@@ -116,17 +124,11 @@ void StatusBarSpaceInfo::updateMenu()
     const KService::Ptr kdiskfree = KService::serviceByDesktopName(QStringLiteral("org.kde.kdf"));
 
     if (!filelight && !kdiskfree) {
-        QAction *installFilelight =
-            m_buttonMenu->addAction(QIcon::fromTheme(QStringLiteral("filelight")), i18n("Install Filelight to View Disk Usage Statistics…"));
-
-        connect(installFilelight, &QAction::triggered, this, [] {
-#ifdef Q_OS_WIN
-            QDesktopServices::openUrl(QUrl("https://apps.kde.org/filelight"));
-#else
-            QDesktopServices::openUrl(QUrl("appstream://org.kde.filelight.desktop"));
-#endif
-        });
-
+        // Show an UI to install a tool to free up disk space because this is what a user pressing on a "free space" button would want.
+        if (!m_installFilelightWidgetAction) {
+            initialiseInstallFilelightWidgetAction();
+        }
+        m_buttonMenu->addAction(m_installFilelightWidgetAction);
         return;
     }
 
@@ -177,6 +179,42 @@ void StatusBarSpaceInfo::updateMenu()
     }
 }
 
+void StatusBarSpaceInfo::slotInstallFilelightButtonClicked()
+{
+#ifdef Q_OS_WIN
+    QDesktopServices::openUrl(QUrl("https://apps.kde.org/filelight"));
+#else
+    auto packageInstaller = new DolphinPackageInstaller(
+        FILELIGHT_PACKAGE_NAME,
+        QUrl("appstream://org.kde.filelight.desktop"),
+        []() {
+            return KService::serviceByDesktopName(QStringLiteral("org.kde.filelight"));
+        },
+        this);
+    connect(packageInstaller, &KJob::result, this, [this](KJob *job) {
+        Q_EMIT showInstallationProgress(QString(), 100); // Hides the progress information in the status bar.
+        if (job->error()) {
+            Q_EMIT showMessage(job->errorString(), KMessageWidget::Error);
+        } else {
+            Q_EMIT showMessage(xi18nc("@info", "<application>Filelight</application> installed successfully."), KMessageWidget::Positive);
+            if (m_textInfoButton->menu()->isVisible()) {
+                m_textInfoButton->menu()->hide();
+                updateMenu();
+                m_textInfoButton->menu()->show();
+            }
+        }
+    });
+    const auto installationTaskText{i18nc("@info:status", "Installing Filelight…")};
+    Q_EMIT showInstallationProgress(installationTaskText, -1);
+    connect(packageInstaller, &KJob::percentChanged, this, [this, installationTaskText](KJob * /* job */, long unsigned int percent) {
+        if (percent < 100) { // Ignore some weird reported values.
+            Q_EMIT showInstallationProgress(installationTaskText, percent);
+        }
+    });
+    packageInstaller->start();
+#endif
+}
+
 void StatusBarSpaceInfo::slotValuesChanged()
 {
     Q_ASSERT(m_observer);
@@ -211,4 +249,53 @@ void StatusBarSpaceInfo::slotValuesChanged()
     }
 }
 
+void StatusBarSpaceInfo::initialiseInstallFilelightWidgetAction()
+{
+    Q_ASSERT(!m_installFilelightWidgetAction);
+
+    auto containerWidget = new QWidget{this};
+    containerWidget->setContentsMargins(Dolphin::VERTICAL_SPACER_HEIGHT,
+                                        Dolphin::VERTICAL_SPACER_HEIGHT,
+                                        Dolphin::VERTICAL_SPACER_HEIGHT, // Using the same value for every spacing in this containerWidget looks nice.
+                                        Dolphin::VERTICAL_SPACER_HEIGHT);
+    auto vLayout = new QVBoxLayout(containerWidget);
+
+    auto installFilelightTitle = new QLabel(i18nc("@title", "Free Up Disk Space"), containerWidget);
+    installFilelightTitle->setAlignment(Qt::AlignCenter);
+    installFilelightTitle->setTextInteractionFlags(Qt::TextSelectableByMouse | Qt::TextSelectableByKeyboard | Qt::LinksAccessibleByKeyboard);
+    QFont titleFont{installFilelightTitle->font()};
+    titleFont.setPointSize(titleFont.pointSize() + 2);
+    installFilelightTitle->setFont(titleFont);
+    vLayout->addWidget(installFilelightTitle);
+
+    vLayout->addSpacing(Dolphin::VERTICAL_SPACER_HEIGHT);
+
+    auto installFilelightBody =
+        // i18n: The new line ("<nl/>") tag is only there to format this text visually pleasing, i.e. to avoid having one very long line.
+        new QLabel(xi18nc("@title", "<para>Install additional software to view disk usage statistics<nl/>and identify big files and folders.</para>"),
+                   containerWidget);
+    installFilelightBody->setAlignment(Qt::AlignCenter);
+    installFilelightBody->setTextInteractionFlags(Qt::TextSelectableByMouse | Qt::TextSelectableByKeyboard | Qt::LinksAccessibleByKeyboard);
+    vLayout->addWidget(installFilelightBody);
+
+    vLayout->addSpacing(Dolphin::VERTICAL_SPACER_HEIGHT);
+
+    auto installFilelightButton =
+        new QPushButton(QIcon::fromTheme(QStringLiteral("filelight")), i18nc("@action:button", "Install Filelight…"), containerWidget);
+    installFilelightButton->setMinimumWidth(std::max(installFilelightButton->sizeHint().width(), installFilelightTitle->sizeHint().width()));
+    auto buttonLayout = new QHBoxLayout; // The parent is automatically set on addLayout() below.
+    buttonLayout->addWidget(installFilelightButton, 0, Qt::AlignHCenter);
+    vLayout->addLayout(buttonLayout);
+
+    // Make sure one Tab press focuses the button after the UI opened.
+    m_buttonMenu->setFocusProxy(installFilelightButton);
+    containerWidget->setFocusPolicy(Qt::TabFocus);
+    containerWidget->setFocusProxy(installFilelightButton);
+    installFilelightButton->setAccessibleDescription(installFilelightBody->text());
+    connect(installFilelightButton, &QAbstractButton::clicked, this, &StatusBarSpaceInfo::slotInstallFilelightButtonClicked);
+
+    m_installFilelightWidgetAction = new QWidgetAction{this};
+    m_installFilelightWidgetAction->setDefaultWidget(containerWidget); // transfers ownership of containerWidget
+}
+
 #include "moc_statusbarspaceinfo.cpp"
diff --git a/src/statusbar/statusbarspaceinfo.h b/src/statusbar/statusbarspaceinfo.h
index 23a77d045..237192c9c 100644
--- a/src/statusbar/statusbarspaceinfo.h
+++ b/src/statusbar/statusbarspaceinfo.h
@@ -6,6 +6,8 @@
 #ifndef STATUSBARSPACEINFO_H
 #define STATUSBARSPACEINFO_H
 
+#include <KMessageWidget>
+
 #include <QUrl>
 #include <QWidget>
 
@@ -14,6 +16,7 @@ class QShowEvent;
 class QMenu;
 class QMouseEvent;
 class QToolButton;
+class QWidgetAction;
 
 class KCapacityBar;
 
@@ -40,6 +43,19 @@ public:
 
     void update();
 
+Q_SIGNALS:
+    /**
+     * Requests for @p message with the given @p messageType to be shown to the user in a non-modal way.
+     */
+    void showMessage(const QString &message, KMessageWidget::MessageType messageType);
+
+    /**
+     * Requests for a progress update to be shown to the user in a non-modal way.
+     * @param currentlyRunningTaskTitle     The task that is currently progressing.
+     * @param installationProgressPercent   The current percentage of completion.
+     */
+    void showInstallationProgress(const QString &currentlyRunningTaskTitle, int installationProgressPercent);
+
 protected:
     void showEvent(QShowEvent *event) override;
     void hideEvent(QHideEvent *event) override;
@@ -48,13 +64,29 @@ protected:
     void updateMenu();
 
 private Q_SLOTS:
+    /**
+     * Asynchronously starts a Filelight installation using DolphinPackageInstaller. @see DolphinPackageInstaller.
+     * Installation success or failure is reported through showMessage(). @see StatusBarSpaceInfo::showMessage().
+     * Installation progress is reported through showInstallationProgress(). @see StatusBarSpaceInfo::showInstallationProgress().
+     */
+    void slotInstallFilelightButtonClicked();
+
     void slotValuesChanged();
 
 private:
+    /**
+     * Creates a new QWidgetAction that contains a UI to install Filelight.
+     * m_installFilelightWidgetAction is initialised after calling this method once.
+     */
+    void initialiseInstallFilelightWidgetAction();
+
+private:
     QScopedPointer<SpaceInfoObserver> m_observer;
     KCapacityBar *m_capacityBar;
     QToolButton *m_textInfoButton;
     QMenu *m_buttonMenu;
+    /** An action containing a UI to install Filelight. */
+    QWidgetAction *m_installFilelightWidgetAction;
     QUrl m_url;
     bool m_ready;
     bool m_shown;