Ask whether to enable Unified Mailboxes when more than 1 account is detected

We ask on start and when a new account is added. We only ever ask once as
not to bother users too much.

src/kmkernel.cpp

@@ -208,6 +208,8 @@ KMKernel::KMKernel(QObject *parent)
 
     connect(Akonadi::AgentManager::self(), &Akonadi::AgentManager::instanceRemoved, this, &KMKernel::slotInstanceRemoved);
 
+    connect(Akonadi::AgentManager::self(), &Akonadi::AgentManager::instanceAdded, this, &KMKernel::slotInstanceAdded);
+
     connect(PimCommon::NetworkManager::self()->networkConfigureManager(), &QNetworkConfigurationManager::onlineStateChanged,
             this, &KMKernel::slotSystemNetworkStatusChanged);
 
@@ -1809,6 +1811,17 @@ void KMKernel::slotInstanceRemoved(const Akonadi::AgentInstance &instance)
         mResourceCryptoSettingCache.remove(identifier);
     }
     mFolderArchiveManager->slotInstanceRemoved(instance);
+
+    if (MailCommon::Util::isMailAgent(instance)) {
+        Q_EMIT incomingAccountsChanged();
+    }
+}
+
+void KMKernel::slotInstanceAdded(const Akonadi::AgentInstance &instance)
+{
+    if (MailCommon::Util::isMailAgent(instance)) {
+        Q_EMIT incomingAccountsChanged();
+    }
 }
 
 void KMKernel::savePaneSelection()

src/kmkernel.h

@@ -443,7 +443,6 @@ public Q_SLOTS:
     void slotRunBackgroundTasks();
 
     void slotConfigChanged();
-
 Q_SIGNALS:
     void configChanged();
     void onlineStatusChanged(KMailSettings::EnumNetworkState::type);
@@ -452,6 +451,7 @@ Q_SIGNALS:
     void startCheckMail();
     void endCheckMail();
 
+    void incomingAccountsChanged();
 private Q_SLOTS:
     /** Updates identities when a transport has been deleted. */
     void transportRemoved(int id, const QString &name);
@@ -467,6 +467,7 @@ private Q_SLOTS:
     void slotCollectionRemoved(const Akonadi::Collection &col);
     void slotDeleteIdentity(uint identity);
     void slotInstanceRemoved(const Akonadi::AgentInstance &);
+    void slotInstanceAdded(const Akonadi::AgentInstance &);
     void slotSystemNetworkStatusChanged(bool isOnline);
     void slotCollectionChanged(const Akonadi::Collection &, const QSet<QByteArray> &set);
 

src/kmmainwidget.cpp

@@ -185,6 +185,9 @@
 // System includes
 #include <AkonadiWidgets/standardactionmanager.h>
 #include <QStandardPaths>
+#include <QDBusInterface>
+#include <QDBusConnection>
+#include <QDBusReply>
 
 #include "PimCommonAkonadi/ManageServerSideSubscriptionJob"
 #include <job/removeduplicatemailjob.h>
@@ -323,6 +326,8 @@ KMMainWidget::KMMainWidget(QWidget *parent, KXMLGUIClient *aGUIClient, KActionCo
     mCheckMailTimer.setInterval(3 * 1000);
     mCheckMailTimer.setSingleShot(true);
     connect(&mCheckMailTimer, &QTimer::timeout, this, &KMMainWidget::slotUpdateActionsAfterMailChecking);
+
+    setupUnifiedMailboxChecker();
 }
 
 void KMMainWidget::restoreCollectionFolderViewConfig()
@@ -4700,3 +4705,51 @@ void KMMainWidget::slotSetFocusToViewer()
         messageView()->viewer()->setFocus();
     }
 }
+
+void KMMainWidget::setupUnifiedMailboxChecker()
+{
+    if (!KMailSettings::self()->askEnableUnifiedMailboxes()) {
+        return;
+    }
+
+    const auto ask = [this]() {
+        if (!KMailSettings::self()->askEnableUnifiedMailboxes()) {
+            return;
+        }
+
+        if (kmkernel->accounts().count() <= 1) {
+            return;
+        }
+
+        const auto service = Akonadi::ServerManager::self()->agentServiceName(Akonadi::ServerManager::Agent, QStringLiteral("akonadi_unifiedmailbox_agent"));
+        QDBusInterface iface(service, QStringLiteral("/"), QStringLiteral("org.freedesktop.Akonadi.UnifiedMailboxAgent"),
+                             QDBusConnection::sessionBus(), this);
+        if (!iface.isValid()) {
+            return;
+        }
+
+        QDBusReply<bool> reply = iface.call(QStringLiteral("enabledAgent"));
+        if (!reply.isValid() || bool(reply)) {
+            return;
+        }
+
+        const auto answer = KMessageBox::questionYesNo(
+            this, i18n("You have more than one email account set up. Do you want to enable the Unified Mailbox feature to "
+                        "show unified content of your inbox, sent and drafts folders?\n"
+                        "You can configure unified mailboxes, create custom ones or disable the feature completely in KMail's Plugin settings."),
+            i18n("Enable Unified Mailboxes?"),
+            KGuiItem(i18n("Enable Unified Mailboxes"), QStringLiteral("dialog-ok")),
+            KGuiItem(i18n("Cancel"), QStringLiteral("dialog-cancel")));
+        if (answer == KMessageBox::Yes) {
+            iface.call(QStringLiteral("setEnableAgent"), true);
+        }
+
+        KMailSettings::self()->setAskEnableUnifiedMailboxes(false);
+    };
+
+    connect(kmkernel, &KMKernel::incomingAccountsChanged, this, ask);
+
+    // Wait for a bit before asking so we at least have the window on screen
+    QTimer::singleShot(500, this, ask);
+}
+

src/kmmainwidget.h

@@ -513,6 +513,7 @@ private:
     void slotPageIsScrolledToBottom(bool isAtBottom);
     void printCurrentMessage(bool preview);
     void replyCurrentMessageCommand(MessageComposer::ReplyStrategy strategy);
+    void setupUnifiedMailboxChecker();
     QAction *filterToAction(MailCommon::MailFilter *filter);
     Akonadi::Collection::List applyFilterOnCollection(bool recursive);
 

src/settings/kmail.kcfg.cmake

@@ -134,7 +134,10 @@
         <label></label>
         <whatsthis></whatsthis>
       </entry>
-
+      <entry key="AskEnableUnifiedMailboxes" type="Bool">
+        <default>true</default>
+        <label>Whether to ask if users wants to enable Unified Mailboxes if more than one email accounts are detected. We only ever ask once.</label>
+      </entry>
     </group>
 <!-- General -->