From 02fa295085ae2297062d10f476a0b40b7fcb2559 Mon Sep 17 00:00:00 2001
From: Kitsune Ral <Kitsune-Ral@users.sf.net>
Date: Fri, 3 Nov 2017 17:53:23 +0300
Subject: Provide facilities to migrate from legacy settings location

This is for a case of renaming an organisation or an application
---
 settings.cpp | 33 ++++++++++++++++++++++++++++-----
 settings.h   | 22 +++++++++++++++++++++-
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/settings.cpp b/settings.cpp
index 3a5f4d26..98921869 100644
--- a/settings.cpp
+++ b/settings.cpp
@@ -5,6 +5,16 @@
 
 using namespace QMatrixClient;
 
+QString Settings::legacyOrganizationName {};
+QString Settings::legacyApplicationName {};
+
+void Settings::setLegacyNames(const QString& organizationName,
+                              const QString& applicationName)
+{
+    legacyOrganizationName = organizationName;
+    legacyApplicationName = applicationName;
+}
+
 void Settings::setValue(const QString& key, const QVariant& value)
 {
 //    qCDebug() << "Setting" << key << "to" << value;
@@ -13,22 +23,33 @@ void Settings::setValue(const QString& key, const QVariant& value)
 
 QVariant Settings::value(const QString& key, const QVariant& defaultValue) const
 {
-    return QSettings::value(key, defaultValue);
+    return QSettings::value(key, legacySettings.value(key, defaultValue));
+}
+
+bool Settings::contains(const QString& key) const
+{
+    return QSettings::contains(key) || legacySettings.contains(key);
+}
+
+QStringList Settings::childGroups() const
+{
+    auto l = QSettings::childGroups();
+    return !l.isEmpty() ? l : legacySettings.childGroups();
 }
 
 void SettingsGroup::setValue(const QString& key, const QVariant& value)
 {
-    Settings::setValue(groupPath + "/" + key, value);
+    Settings::setValue(groupPath + '/' + key, value);
 }
 
 bool SettingsGroup::contains(const QString& key) const
 {
-    return Settings::contains(groupPath + "/" + key);
+    return Settings::contains(groupPath + '/' + key);
 }
 
 QVariant SettingsGroup::value(const QString& key, const QVariant& defaultValue) const
 {
-    return Settings::value(groupPath + "/" + key, defaultValue);
+    return Settings::value(groupPath + '/' + key, defaultValue);
 }
 
 QString SettingsGroup::group() const
@@ -39,8 +60,10 @@ QString SettingsGroup::group() const
 QStringList SettingsGroup::childGroups() const
 {
     const_cast<SettingsGroup*>(this)->beginGroup(groupPath);
-    QStringList l { Settings::childGroups() };
+    const_cast<QSettings&>(legacySettings).beginGroup(groupPath);
+    QStringList l = Settings::childGroups();
     const_cast<SettingsGroup*>(this)->endGroup();
+    const_cast<QSettings&>(legacySettings).endGroup();
     return l;
 }
 
diff --git a/settings.h b/settings.h
index a6c0420e..ab3aae8b 100644
--- a/settings.h
+++ b/settings.h
@@ -28,7 +28,17 @@ namespace QMatrixClient
 {
     class Settings: public QSettings
     {
+            Q_OBJECT
         public:
+            /**
+             * Use this function before creating any Settings objects in order
+             * to setup a read-only location where configuration has previously
+             * been stored. This will provide an additional fallback in case of
+             * renaming the organisation/application.
+             */
+            static void setLegacyNames(const QString& organizationName,
+                                       const QString& applicationName = {});
+
 #if defined(_MSC_VER) && _MSC_VER < 1900
             // VS 2013 (and probably older) aren't friends with 'using' statements
             // that involve private constructors
@@ -41,6 +51,16 @@ namespace QMatrixClient
                                       const QVariant &value);
             Q_INVOKABLE QVariant value(const QString &key,
                                        const QVariant &defaultValue = {}) const;
+            Q_INVOKABLE bool contains(const QString& key) const;
+            Q_INVOKABLE QStringList childGroups() const;
+
+        private:
+            static QString legacyOrganizationName;
+            static QString legacyApplicationName;
+
+        protected:
+            const QSettings legacySettings { legacyOrganizationName,
+                                             legacyApplicationName };
     };
 
     class SettingsGroup: public Settings
@@ -69,7 +89,7 @@ namespace QMatrixClient
     class AccountSettings: public SettingsGroup
     {
             Q_OBJECT
-            Q_PROPERTY(QString userId READ userId)
+            Q_PROPERTY(QString userId READ userId CONSTANT)
             Q_PROPERTY(QString deviceId READ deviceId WRITE setDeviceId)
             Q_PROPERTY(QString deviceName READ deviceName WRITE setDeviceName)
             Q_PROPERTY(QUrl homeserver READ homeserver WRITE setHomeserver)
-- 
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