From dcdd5996223a4e1043cd4e492f976fd432de0691 Mon Sep 17 00:00:00 2001
From: "Michael Ziminsky (Z)" <mgziminsky@users.noreply.github.com>
Date: Sat, 7 Jun 2025 17:26:49 -0700
Subject: [PATCH] Factor out common socket messaging code to simplify adding
 new single instance commands

---
 src/gui/Application.cpp | 71 ++++++++++++++++-------------------------
 src/gui/Application.h   |  5 +++
 2 files changed, 33 insertions(+), 43 deletions(-)

diff --git a/src/gui/Application.cpp b/src/gui/Application.cpp
index 01553ad91..402b50c3d 100644
--- a/src/gui/Application.cpp
+++ b/src/gui/Application.cpp
@@ -47,6 +47,12 @@ namespace
     int g_OriginalFontSize = 0;
 } // namespace
 
+enum Application::SocketCmd : quint32
+{
+    OpenFiles = 1,
+    LockAll,
+};
+
 Application::Application(int& argc, char** argv)
     : QApplication(argc, argv)
 #ifdef Q_OS_UNIX
@@ -54,11 +60,7 @@ Application::Application(int& argc, char** argv)
 #endif
     , m_alreadyRunning(false)
     , m_lockFile(nullptr)
-#if defined(Q_OS_WIN) || (defined(Q_OS_UNIX) && !defined(Q_OS_MACOS))
 {
-#else
-{
-#endif
 #if defined(Q_OS_UNIX)
     registerUnixSignals();
 #endif
@@ -324,13 +326,13 @@ void Application::socketReadyRead()
         return;
     }
 
-    QStringList fileNames;
-    quint32 id;
-    in >> id;
+    SocketCmd id;
+    // manual reinterpret_cast not needed for Qt 5.14+
+    in >> reinterpret_cast<typename std::underlying_type<SocketCmd>::type&>(id);
 
-    // TODO: move constants to enum
     switch (id) {
-    case 1:
+    case SocketCmd::OpenFiles: {
+        QStringList fileNames;
         in >> fileNames;
         for (const QString& fileName : asConst(fileNames)) {
             const QFileInfo fInfo(fileName);
@@ -338,9 +340,9 @@ void Application::socketReadyRead()
                 emit openFile(fileName);
             }
         }
-
         break;
-    case 2:
+    }
+    case SocketCmd::LockAll:
         getMainWindow()->lockAllDatabases();
         break;
     }
@@ -357,13 +359,7 @@ bool Application::isAlreadyRunning() const
     return config()->get(Config::SingleInstance).toBool() && m_alreadyRunning;
 }
 
-/**
- * Send to-open file names to the running UI instance
- *
- * @param fileNames - list of file names to open
- * @return true if all operations succeeded (connection made, data sent, connection closed)
- */
-bool Application::sendFileNamesToRunningInstance(const QStringList& fileNames)
+bool Application::sendSocketCommand(SocketCmd id, const std::function<void(QDataStream&)>& caller)
 {
     QLocalSocket client;
     client.connectToServer(m_socketName);
@@ -376,8 +372,8 @@ bool Application::sendFileNamesToRunningInstance(const QStringList& fileNames)
     QDataStream out(&data, QIODevice::WriteOnly);
     out.setVersion(QDataStream::Qt_5_0);
     out << quint32(0); // reserve space for block size
-    out << quint32(1); // ID for file name send. TODO: move to enum
-    out << fileNames; // send file names to be opened
+    out << id; // ID of command being sent.
+    caller(out); // Pass to caller to add any additional data
     out.device()->seek(0);
     out << quint32(data.size() - sizeof(quint32)); // replace the previous constant 0 with block size
 
@@ -388,6 +384,17 @@ bool Application::sendFileNamesToRunningInstance(const QStringList& fileNames)
     return writeOk && disconnected;
 }
 
+/**
+ * Send to-open file names to the running UI instance
+ *
+ * @param fileNames - list of file names to open
+ * @return true if all operations succeeded (connection made, data sent, connection closed)
+ */
+bool Application::sendFileNamesToRunningInstance(const QStringList& fileNames)
+{
+    return this->sendSocketCommand(SocketCmd::OpenFiles, [fileNames](QDataStream& out) { out << fileNames; });
+}
+
 /**
  * Locks all open databases in the running instance
  *
@@ -395,29 +402,7 @@ bool Application::sendFileNamesToRunningInstance(const QStringList& fileNames)
  */
 bool Application::sendLockToInstance()
 {
-    // Make a connection to avoid SIGSEGV
-    QLocalSocket client;
-    client.connectToServer(m_socketName);
-    const bool connected = client.waitForConnected(WaitTimeoutMSec);
-    if (!connected) {
-        return false;
-    }
-
-    // Send lock signal
-    QByteArray data;
-    QDataStream out(&data, QIODevice::WriteOnly);
-    out.setVersion(QDataStream::Qt_5_0);
-    out << quint32(0); // reserve space for block size
-    out << quint32(2); // ID for database lock. TODO: move to enum
-    out.device()->seek(0);
-    out << quint32(data.size() - sizeof(quint32)); // replace the previous constant 0 with block size
-
-    // Finish gracefully
-    const bool writeOk = client.write(data) != -1 && client.waitForBytesWritten(WaitTimeoutMSec);
-    client.disconnectFromServer();
-    const bool disconnected =
-        client.state() == QLocalSocket::UnconnectedState || client.waitForConnected(WaitTimeoutMSec);
-    return writeOk && disconnected;
+    return this->sendSocketCommand(SocketCmd::LockAll, [](QDataStream&) { /* No Data */ });
 }
 
 bool Application::isDarkTheme() const
diff --git a/src/gui/Application.h b/src/gui/Application.h
index 349c93923..4d7a87fca 100644
--- a/src/gui/Application.h
+++ b/src/gui/Application.h
@@ -23,6 +23,7 @@
 #include <QApplication>
 #include <QString>
 #include <QtNetwork/qlocalserver.h>
+#include <functional>
 
 #if defined(Q_OS_WIN) || (defined(Q_OS_UNIX) && !defined(Q_OS_MACOS))
 
@@ -78,6 +79,10 @@ private:
     static void handleUnixSignal(int sig);
     static int unixSignalSocket[2];
 #endif
+
+    enum SocketCmd : quint32;
+    bool sendSocketCommand(SocketCmd id, const std::function<void(QDataStream&)>&);
+
     bool m_alreadyRunning;
     bool m_darkTheme = false;
     QLockFile* m_lockFile;