Introduce OptionsModel backend, Wire up Storage Amount settings to backend

src/Makefile.qt.include

@@ -37,6 +37,7 @@ QT_FORMS_UI = \
 QT_MOC_CPP = \
   qml/moc_appmode.cpp \
   qml/moc_nodemodel.cpp \
+  qml/moc_options_model.cpp \
   qt/moc_addressbookpage.cpp \
   qt/moc_addresstablemodel.cpp \
   qt/moc_askpassphrasedialog.cpp \
@@ -112,6 +113,7 @@ BITCOIN_QT_H = \
   qml/bitcoin.h \
   qml/imageprovider.h \
   qml/nodemodel.h \
+  qml/options_model.h \
   qml/util.h \
   qt/addressbookpage.h \
   qt/addresstablemodel.h \
@@ -291,6 +293,7 @@ BITCOIN_QML_BASE_CPP = \
   qml/bitcoin.cpp \
   qml/imageprovider.cpp \
   qml/nodemodel.cpp \
+  qml/options_model.cpp \
   qml/util.cpp
 
 QML_RES_FONTS = \

src/qml/bitcoin.cpp

@@ -14,6 +14,7 @@
 #include <qml/appmode.h>
 #include <qml/imageprovider.h>
 #include <qml/nodemodel.h>
+#include <qml/options_model.h>
 #include <qml/util.h>
 #include <qt/guiconstants.h>
 #include <qt/guiutil.h>
@@ -185,6 +186,9 @@ int QmlGuiMain(int argc, char* argv[])
 
     engine.rootContext()->setContextProperty("nodeModel", &node_model);
 
+    OptionsQmlModel options_model{*node};
+    engine.rootContext()->setContextProperty("optionsModel", &options_model);
+
 #ifdef __ANDROID__
     AppMode app_mode(AppMode::MOBILE);
 #else

src/qml/components/StorageOptions.qml

@@ -19,11 +19,18 @@ ColumnLayout {
         description: qsTr("Uses about 2GB. For simple wallet use.")
         recommended: true
         checked: true
+        onClicked: {
+            optionsModel.prune = true
+            optionsModel.pruneSizeGB = 2
+        }
     }
     OptionButton {
         Layout.fillWidth: true
         ButtonGroup.group: group
         text: qsTr("Store all data")
         description: qsTr("Uses about 550GB. Support the network.")
+        onClicked: {
+            optionsModel.prune = false
+        }
     }
 }

src/qml/components/StorageSettings.qml

@@ -11,21 +11,18 @@ ColumnLayout {
     spacing: 20
     Setting {
         Layout.fillWidth: true
-        header: qsTr("Store Recent blocks only")
-        actionItem: OptionSwitch {}
-    }
-    Setting {
-        Layout.fillWidth: true
-        header: qsTr("Storage limit")
-        actionItem: ValueInput {
-            description: qsTr("2 GB")
+        header: qsTr("Store recent blocks only")
+        actionItem: OptionSwitch {
+            checked: optionsModel.prune
+            onToggled: optionsModel.prune = checked
         }
     }
     Setting {
         Layout.fillWidth: true
-        header: qsTr("Data location")
+        header: qsTr("Storage limit (GB)")
         actionItem: ValueInput {
-            description: "c://.../data"
+            description: optionsModel.pruneSizeGB
+            onEditingFinished: optionsModel.pruneSizeGB = parseInt(text)
         }
     }
 }

src/qml/options_model.cpp

@@ -0,0 +1,46 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <qml/options_model.h>
+
+#include <interfaces/node.h>
+#include <qt/guiconstants.h>
+#include <qt/optionsmodel.h>
+#include <univalue.h>
+#include <util/settings.h>
+#include <util/system.h>
+
+#include <cassert>
+
+OptionsQmlModel::OptionsQmlModel(interfaces::Node& node)
+    : m_node{node}
+{
+    int64_t prune_value{SettingToInt(m_node.getPersistentSetting("prune"), 0)};
+    m_prune = (prune_value > 1);
+    m_prune_size_gb = m_prune ? PruneMiBtoGB(prune_value) : DEFAULT_PRUNE_TARGET_GB;
+}
+
+void OptionsQmlModel::setPrune(bool new_prune)
+{
+    if (new_prune != m_prune) {
+        m_prune = new_prune;
+        m_node.updateRwSetting("prune", pruneSetting());
+        Q_EMIT pruneChanged(new_prune);
+    }
+}
+
+void OptionsQmlModel::setPruneSizeGB(int new_prune_size_gb)
+{
+    if (new_prune_size_gb != m_prune_size_gb) {
+        m_prune_size_gb = new_prune_size_gb;
+        m_node.updateRwSetting("prune", pruneSetting());
+        Q_EMIT pruneSizeGBChanged(new_prune_size_gb);
+    }
+}
+
+util::SettingsValue OptionsQmlModel::pruneSetting() const
+{
+    assert(!m_prune || m_prune_size_gb >= 1);
+    return m_prune ? PruneGBtoMiB(m_prune_size_gb) : 0;
+}

src/qml/options_model.h

@@ -0,0 +1,45 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_QML_OPTIONS_MODEL_H
+#define BITCOIN_QML_OPTIONS_MODEL_H
+
+#include <util/settings.h>
+
+#include <QObject>
+
+namespace interfaces {
+class Node;
+}
+
+/** Model for Bitcoin client options. */
+class OptionsQmlModel : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(bool prune READ prune WRITE setPrune NOTIFY pruneChanged)
+    Q_PROPERTY(int pruneSizeGB READ pruneSizeGB WRITE setPruneSizeGB NOTIFY pruneSizeGBChanged)
+
+public:
+    explicit OptionsQmlModel(interfaces::Node& node);
+
+    bool prune() const { return m_prune; }
+    void setPrune(bool new_prune);
+    int pruneSizeGB() const { return m_prune_size_gb; }
+    void setPruneSizeGB(int new_prune_size);
+
+Q_SIGNALS:
+    void pruneChanged(bool new_prune);
+    void pruneSizeGBChanged(int new_prune_size_gb);
+
+private:
+    interfaces::Node& m_node;
+
+    // Properties that are exposed to QML.
+    bool m_prune;
+    int m_prune_size_gb;
+
+    util::SettingsValue pruneSetting() const;
+};
+
+#endif // BITCOIN_QML_OPTIONS_MODEL_H

src/qml/pages/settings/SettingsStorage.qml

@@ -14,5 +14,11 @@ InformationPage {
     headerText: qsTr("Storage settings")
     headerMargin: 0
     detailActive: true
-    detailItem: StorageSettings {}
+    detailItem: StorageSettings {
+        // Set default prune values
+        Component.onCompleted: {
+            optionsModel.prune = true
+            optionsModel.pruneSizeGB = 2
+        }
+    }
 }