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#include "gconfitem_p.h"

#include <QtCore/qdebug.h>
#include <QtCore/qstringlist.h>

#include <glib.h>
#include <gconf/gconf-value.h>
#include <gconf/gconf-client.h>

struct GConfItemPrivate {
    QString key;
    QVariant value;
    guint notify_id;

    static void notify_trampoline(GConfClient *, guint, GConfEntry *, gpointer);
};

void GConfItemPrivate::notify_trampoline(GConfClient *, guint, GConfEntry *, gpointer data)
{
    GConfItem *item = (GConfItem *)data;
    item->update_value(true);
}

#define withClient(c) for(GConfClient *c = (g_type_init(), gconf_client_get_default()); c; g_object_unref(c), c=NULL)

static QByteArray convertKey(QString key)
{
    if (key.startsWith('/')) {
        return key.toUtf8();
    } else {
        qWarning() << "Using dot-separated key names with GConfItem is deprecated.";
        qWarning() << "Please use" << '/' + key.replace('.', '/') << "instead of" << key;
        return '/' + key.replace('.', '/').toUtf8();
    }
}

static QString convertKey(const char *key)
{
    return QString::fromUtf8(key);
}

static QVariant convertValue(GConfValue *src)
{
    if (!src) {
        return QVariant();
    } else {
        switch (src->type) {
        case GCONF_VALUE_INVALID:
            return QVariant(QVariant::Invalid);
        case GCONF_VALUE_BOOL:
            return QVariant((bool)gconf_value_get_bool(src));
        case GCONF_VALUE_INT:
            return QVariant(gconf_value_get_int(src));
        case GCONF_VALUE_FLOAT:
            return QVariant(gconf_value_get_float(src));
        case GCONF_VALUE_STRING:
            return QVariant(QString::fromUtf8(gconf_value_get_string(src)));
        case GCONF_VALUE_LIST:
            switch (gconf_value_get_list_type(src)) {
            case GCONF_VALUE_STRING: {
                QStringList result;
                for (GSList *elts = gconf_value_get_list(src); elts; elts = elts->next)
                    result.append(QString::fromUtf8(gconf_value_get_string((GConfValue *)elts->data)));
                return QVariant(result);
            }
            default: {
                QList<QVariant> result;
                for (GSList *elts = gconf_value_get_list(src); elts; elts = elts->next)
                    result.append(convertValue((GConfValue *)elts->data));
                return QVariant(result);
            }
            }
        case GCONF_VALUE_SCHEMA:
        default:
            return QVariant();
        }
    }
}

static GConfValue *convertString(const QString &str)
{
    GConfValue *v = gconf_value_new (GCONF_VALUE_STRING);
    gconf_value_set_string (v, str.toUtf8().data());
    return v;
}

static GConfValueType primitiveType(const QVariant &elt)
{
    switch(elt.type()) {
    case QVariant::String:
        return GCONF_VALUE_STRING;
    case QVariant::Int:
        return GCONF_VALUE_INT;
    case QVariant::Double:
        return GCONF_VALUE_FLOAT;
    case QVariant::Bool:
        return GCONF_VALUE_BOOL;
    default:
        return GCONF_VALUE_INVALID;
    }
}

static GConfValueType uniformType(const QList<QVariant> &list)
{
    GConfValueType result = GCONF_VALUE_INVALID;

    foreach (const QVariant &elt, list) {
        GConfValueType elt_type = primitiveType (elt);

        if (elt_type == GCONF_VALUE_INVALID)
            return GCONF_VALUE_INVALID;

        if (result == GCONF_VALUE_INVALID)
            result = elt_type;
        else if (result != elt_type)
            return GCONF_VALUE_INVALID;
    }

    if (result == GCONF_VALUE_INVALID)
        return GCONF_VALUE_STRING;  // empty list.
    else
        return result;
}

static int convertValue(const QVariant &src, GConfValue **valp)
{
    GConfValue *v;

    switch(src.type()) {
    case QVariant::Invalid:
        v = NULL;
        break;
    case QVariant::Bool:
        v = gconf_value_new (GCONF_VALUE_BOOL);
        gconf_value_set_bool (v, src.toBool());
        break;
    case QVariant::Int:
        v = gconf_value_new (GCONF_VALUE_INT);
        gconf_value_set_int (v, src.toInt());
        break;
    case QVariant::Double:
        v = gconf_value_new (GCONF_VALUE_FLOAT);
        gconf_value_set_float (v, src.toDouble());
        break;
    case QVariant::String:
        v = convertString(src.toString());
        break;
    case QVariant::StringList: {
        GSList *elts = NULL;
        v = gconf_value_new(GCONF_VALUE_LIST);
        gconf_value_set_list_type(v, GCONF_VALUE_STRING);
        foreach (const QString &str, src.toStringList())
            elts = g_slist_prepend(elts, convertString(str));
        gconf_value_set_list_nocopy(v, g_slist_reverse(elts));
        break;
    }
    case QVariant::List: {
        GConfValueType elt_type = uniformType(src.toList());
        if (elt_type == GCONF_VALUE_INVALID) {
            v = NULL;
        } else {
            GSList *elts = NULL;
            v = gconf_value_new(GCONF_VALUE_LIST);
            gconf_value_set_list_type(v, elt_type);
            foreach (const QVariant &elt, src.toList()) {
                GConfValue *val = NULL;
                convertValue(elt, &val);  // guaranteed to succeed.
                elts = g_slist_prepend(elts, val);
            }
            gconf_value_set_list_nocopy(v, g_slist_reverse(elts));
        }
        break;
    }
    default:
        return 0;
    }

    *valp = v;
    return 1;
}

/*!
    \brief GConfItem is a simple C++ wrapper for GConf.

    Creating a GConfItem instance gives you access to a single GConf
    key.  You can get and set its value, and connect to its
    valueChanged() signal to be notified about changes.

    The value of a GConf key is returned to you as a QVariant, and you
    pass in a QVariant when setting the value.  GConfItem converts
    between a QVariant and GConf values as needed, and according to the
    following rules:

    - A QVariant of type QVariant::Invalid denotes an unset GConf key.

    - QVariant::Int, QVariant::Double, QVariant::Bool are converted to
      and from the obvious equivalents.

    - QVariant::String is converted to/from a GConf string and always
      uses the UTF-8 encoding.  No other encoding is supported.

    - QVariant::StringList is converted to a list of UTF-8 strings.

    - QVariant::List (which denotes a QList<QVariant>) is converted
      to/from a GConf list.  All elements of such a list must have the
      same type, and that type must be one of QVariant::Int,
      QVariant::Double, QVariant::Bool, or QVariant::String.  (A list of
      strings is returned as a QVariant::StringList, however, when you
      get it back.)

    - Any other QVariant or GConf value is essentially ignored.

    \warning GConfItem is as thread-safe as GConf.
*/

/*!
    \fn void GConfItem::valueChanged()

    Emitted when the value of this item has changed.
*/

/*!
    \internal
*/
void GConfItem::update_value(bool emit_signal)
{
    QVariant new_value;

    withClient(client) {
        GError *error = NULL;
        QByteArray k = convertKey(priv->key);
        GConfValue *v = gconf_client_get(client, k.data(), &error);

        if (error) {
            qWarning() << error->message;
            g_error_free (error);
            new_value = priv->value;
        } else {
            new_value = convertValue(v);
            if (v)
                gconf_value_free(v);
        }
    }

    if (new_value != priv->value) {
        priv->value = new_value;
        if (emit_signal)
            emit valueChanged();
    }
}

/*!
    Returns the current value of this item, as a QVariant.
*/
QVariant GConfItem::value() const
{
    return priv->value;
}

/*!
    Returns the current value of this item, as a QVariant.  If
    there is no value for this item, return \a def instead.
*/
QVariant GConfItem::value(const QVariant &def) const
{
    if (priv->value.isNull())
        return def;
    else
        return priv->value;
}

/*!
    Return a list of entries below this item.  The returned
    strings are absolute key names like "/myapp/settings/first".

    A entry is a key that has a value.  The same key might also
    have children, but that is confusing and is best avoided.
*/
QList<QString> GConfItem::listEntries() const
{
    QList<QString> children;

    withClient(client) {
        QByteArray k = convertKey(priv->key);
        GSList *entries = gconf_client_all_entries(client, k.data(), NULL);
        for (GSList *e = entries; e; e = e->next) {
            children.append(convertKey(((GConfEntry *)e->data)->key));
            gconf_entry_free ((GConfEntry *)e->data);
        }
        g_slist_free (entries);
    }

    return children;
}

/*!
    Initializes a GConfItem to access the GConf key denoted by
    \a key.  Key names should follow the normal GConf conventions
    like "/myapp/settings/first".

    \param key    The name of the key.
    \param parent Parent object
*/
GConfItem::GConfItem(const QString &key, QObject *parent)
    : QObject(parent)
{
    priv = new GConfItemPrivate;
    priv->key = key;
    withClient(client) {
        update_value(false);
        QByteArray k = convertKey(priv->key);
        gconf_client_add_dir(client, k.data(), GCONF_CLIENT_PRELOAD_ONELEVEL, NULL);
        priv->notify_id = gconf_client_notify_add(client, k.data(),
                                                  GConfItemPrivate::notify_trampoline, this,
                                                  NULL, NULL);
    }
}

/*!
    Finalizes a GConfItem.
*/
GConfItem::~GConfItem()
{
    withClient(client) {
        QByteArray k = convertKey(priv->key);
        gconf_client_notify_remove (client, priv->notify_id);
        gconf_client_remove_dir (client, k.data(), NULL);
    }
    delete priv;
}
