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diff --git a/src/backend/config/btconfigcore.h b/src/backend/config/btconfigcore.h
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+/*********
+*
+* In the name of the Father, and of the Son, and of the Holy Spirit.
+*
+* This file is part of BibleTime's source code, http://www.bibletime.info/.
+*
+* Copyright 1999-2014 by the BibleTime developers.
+* The BibleTime source code is licensed under the GNU General Public License version 2.0.
+*
+**********/
+
+#ifndef BTCONFIGCORE_H
+#define BTCONFIGCORE_H
+
+#include <QSettings>
+
+#include <QCoreApplication>
+#include <QHash>
+#include <QMutex>
+#include <QStringList>
+
+
+/**
+  \note Session keys are QStrings because we even want to handle cases where the
+        configuration file is manually changed. When creating new sessions, they
+        are still generated from unsigned integers.
+*/
+class BtConfigCore {
+
+    Q_DISABLE_COPY(BtConfigCore)
+    Q_DECLARE_TR_FUNCTIONS(BtConfigCore)
+
+public: /* Types: */
+
+    typedef QHash<QString, QString> SessionNamesHashMap;
+
+public: /* Methods: */
+
+    /**
+      \param[in] settingsFile The filename of the settings file.
+    */
+    explicit BtConfigCore(const QString & settingsFile);
+
+    inline ~BtConfigCore() { sync(); }
+
+
+    /**
+      \returns the key of the current session.
+    */
+    inline const QString & currentSessionKey() const {
+        QMutexLocker lock(&m_mutex);
+        return m_currentSessionKey;
+    }
+
+    /**
+      \returns the name of the current session.
+    */
+    inline const QString & currentSessionName() const {
+        QMutexLocker lock(&m_mutex);
+        typedef QHash<QString, QString>::const_iterator SSHCI;
+        SSHCI it = m_sessionNames.constFind(m_currentSessionKey);
+        Q_ASSERT(it != m_sessionNames.constEnd());
+        return it.value();
+    }
+
+    /**
+      \returns a hashmap with the keys and printable names of the sessions.
+    */
+    inline const SessionNamesHashMap & sessionNames() const {
+        QMutexLocker lock(&m_mutex);
+        return m_sessionNames;
+    }
+
+    /**
+      \brief Notifies the configuration system that the session settings
+             should be read from and saved to the given session.
+
+      \pre The session with the given key must exist.
+      \param[in] key the key of the session to switch to.
+      \post the sessionValue() and value() methods will work with the settings
+            of the given session.
+    */
+    void setCurrentSession(const QString & key);
+
+    /**
+      \brief Creates a new session with the given name.
+
+      \pre The given name must not be an empty string.
+      \param[in] name the name of the session
+      \returns the key of the created session.
+    */
+    QString addSession(const QString & name);
+
+    /**
+      \brief Deletes the session with the given key.
+
+      \pre The session with the given key must exist.
+      \pre The session with the given key must not be the current session.
+      \param[in] key the key of the session to delete.
+      \post The session with the given key and its settings are deleted.
+      \returns whether deleting the session was successful.
+    */
+    void deleteSession(const QString & key);
+
+    /**
+      \brief Returns the settings value for the given global key.
+
+      \param[in] key Key to get the value for.
+      \param[in] defaultValue The value to return if no saved value is found.
+      \returns the value of type specified by the template parameter.
+    */
+    template<typename T>
+    inline T value(const QString & key, const T & defaultValue = T()) {
+        QMutexLocker lock(&m_mutex);
+        return m_settings.value(group() + key,
+                                QVariant::fromValue(defaultValue)).template value<T>();
+    }
+
+    /**
+      \brief Returns the settings value for the given global key as a QVariant.
+
+      \param[in] key Key to get the value for.
+      \param[in] defaultValue The value to return if no saved value is found.
+      \returns the value.
+    */
+    inline QVariant qVariantValue(const QString & key,
+                                  const QVariant & defaultValue = QVariant())
+    {
+        QMutexLocker lock(&m_mutex);
+        return m_settings.value(group() + key,
+                                QVariant::fromValue(defaultValue));
+    }
+
+    /**
+      \brief Returns the settings value for the given session key.
+
+      \param[in] key Session key to get the value for.
+      \param[in] defaultValue The value to return if no saved value is found.
+      \returns the value of type specified by the template parameter.
+    */
+    template<typename T>
+    inline T sessionValue(const QString & key, const T & defaultValue = T()) {
+        QMutexLocker lock(&m_mutex);
+        return m_settings.value(m_cachedCurrentSessionGroup + group() + key,
+                                QVariant::fromValue(defaultValue)).template value<T>();
+    }
+
+    /**
+      \brief Sets a value for a global settings key.
+
+      \param[in] key Ket to set.
+      \param[in] value Value to set.
+    */
+    template<typename T>
+    inline void setValue(const QString & key, const T & value) {
+        QMutexLocker lock(&m_mutex);
+        m_settings.setValue(group() + key, QVariant::fromValue<T>(value));
+    }
+
+    /**
+      \brief Sets a value for a session settings key.
+
+      \param[in] key Ket to set.
+      \param[in] value Value to set.
+    */
+    template<typename T>
+    inline void setSessionValue(const QString & key, const T & value) {
+        QMutexLocker lock(&m_mutex);
+        m_settings.setValue(m_cachedCurrentSessionGroup + group() + key,
+                            QVariant::fromValue<T>(value));
+    }
+
+    /**
+      \returns a list of first-level keys in the current group in global settings.
+    */
+    QStringList childKeys();
+
+    /**
+      \pre subkey is not empty
+      \param[in] subkey the subkey
+      \returns a list of keys under the current group and subkey in global settings.
+    */
+    QStringList childKeys(const QString & subkey);
+
+    /**
+      \returns a list of first-level groups in the current group in global settings.
+    */
+    QStringList childGroups();
+
+    /**
+      \pre subkey is not empty
+      \param[in] subkey the subkey
+      \returns a list of groups under the current group and subkey in global settings.
+    */
+    QStringList childGroups(const QString & subkey);
+
+    /**
+      \returns a list of first-level groups in the current group in session settings.
+    */
+    QStringList sessionChildGroups();
+
+    /**
+      \pre subkey is not empty
+      \param[in] subkey the subkey
+      \returns a list of groups under the current group and subkey in session settings.
+    */
+    QStringList sessionChildGroups(const QString & subkey);
+
+    /**
+      \brief removes a key all its children from global settings.
+
+      \param[in] key the key to remove
+    */
+    void remove(const QString & key);
+
+    /**
+      \brief removes a key all its children from session settings.
+
+      \param[in] key the key to remove
+    */
+    void sessionRemove(const QString & key);
+
+    /**
+      \brief Synchronize the underlying QSettings.
+    */
+    inline void sync() {
+        QMutexLocker lock(&m_mutex);
+        m_settings.sync();
+    }
+
+    /**
+      \brief Appends the given prefix to the current group.
+
+      The current group is automatically prepended to all keys when reading or
+      writing settings values. The behaviour is similar to QSettings::beginGroup().
+
+      \warning Locks the object (recursively) until endGroup().
+
+      \param[in] prefix the prefix to append
+    */
+    inline void beginGroup(QString prefix) {
+        Q_ASSERT(!prefix.isEmpty());
+        while (prefix.startsWith('/'))
+            prefix.remove(0, 1);
+        Q_ASSERT(!prefix.isEmpty());
+        while (prefix.endsWith('/'))
+            prefix.chop(1);
+        Q_ASSERT(!prefix.isEmpty());
+
+        m_mutex.lock();
+        m_groups.append(prefix);
+        m_cachedGroup = QString();
+    }
+
+    /**
+      \brief Resets the current group to its previous value.
+
+      Call this function after you are done with a started group. Every call to
+      beginGroup() must be matched with a call to this function in the same
+      thread.
+
+      \warning Locks the object (recursively) until endGroup().
+    */
+    inline void endGroup() {
+        Q_ASSERT_X(!m_groups.isEmpty(), "BtConfig", "endGroup() called, but no beginGroup() active.");
+        m_groups.removeLast();
+        m_cachedGroup = QString();
+        m_mutex.unlock();
+    }
+
+    /**
+      \brief Returns the current group.
+
+      Returns the group the BtConfig is currently set to. It will contain a
+      trailing / so is suitable to be preprended to a key directly.
+
+      \returns the group string or an empty string if no group is set.
+    */
+    inline QString group() const {
+        QMutexLocker lock(&m_mutex);
+        if (m_cachedGroup.isNull()) {
+            m_cachedGroup = m_groups.isEmpty()
+                            ? ""
+                            : m_groups.join("/") + '/';
+        }
+        return m_cachedGroup;
+    }
+
+private: /* Methods: */
+
+    /**
+      \Brief Same childKeys(), but not thread-safe.
+      \returns a list of first-level keys in the current group in global settings.
+    */
+    QStringList childKeys__();
+
+    /**
+      \Brief Same childGroups(), but not thread-safe.
+      \returns a list of first-level groups in the current group in global settings.
+    */
+    QStringList childGroups__();
+
+    /**
+      \Brief Same sessionChildGroups(), but not thread-safe.
+      \returns a list of first-level groups in the current group in session settings.
+    */
+    QStringList sessionChildGroups__();
+
+protected: /* Fields: */
+
+    /** Required for asynchronous access */
+    mutable QMutex m_mutex;
+
+private: /* Fields: */
+
+    /** Underlying backend */
+    QSettings m_settings;
+
+    /** List of active group prefixes */
+    QStringList m_groups;
+
+    /** Cached group() string or QString::null if not cached */
+    mutable QString m_cachedGroup;
+
+    /** Index of currently active session */
+    QString m_currentSessionKey;
+
+    /** Cached group name of the currently active session */
+    mutable QString m_cachedCurrentSessionGroup;
+
+    /** Keys and names all sessions */
+    SessionNamesHashMap m_sessionNames;
+
+    // Helper key strings:
+    static const QString GROUP_SESSIONS;
+    static const QString KEY_CURRENT_SESSION;
+    static const QString GROUP_SESSION;
+    static const QString KEY_SESSION_NAME;
+    static const QString UI_FONT_SIZE;
+};
+
+#endif // BTCONFIGCORE_H