3 files changed, 70 insertions, 1 deletions
diff --git a/plugin/src/Caelestia/CMakeLists.txt b/plugin/src/Caelestia/CMakeLists.txt
index d00247e..6461027 100644
--- a/plugin/src/Caelestia/CMakeLists.txt
+++ b/plugin/src/Caelestia/CMakeLists.txt
@@ -1,3 +1,6 @@
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(QALCULATE REQUIRED libqalculate)
+
 qt_add_qml_module(caelestia
     URI Caelestia
     VERSION 0.1
@@ -5,6 +8,7 @@ qt_add_qml_module(caelestia
         cutils.hpp cutils.cpp
         cachingimagemanager.hpp cachingimagemanager.cpp
         filesystemmodel.hpp filesystemmodel.cpp
+        qalculator.hpp qalculator.cpp
 )
 
 qt_query_qml_module(caelestia
@@ -24,4 +28,5 @@ install(TARGETS "${module_plugin_target}" LIBRARY DESTINATION "${module_dir}" RU
 install(FILES "${module_qmldir}" DESTINATION "${module_dir}")
 install(FILES "${module_typeinfo}" DESTINATION "${module_dir}")
 
-target_link_libraries(caelestia PRIVATE Qt::Core Qt::Qml Qt::Gui Qt::Concurrent)
+target_include_directories(caelestia SYSTEM PRIVATE ${QALCULATE_INCLUDE_DIRS})
+target_link_libraries(caelestia PRIVATE Qt::Core Qt::Qml Qt::Gui Qt::Concurrent ${QALCULATE_LIBRARIES})
diff --git a/plugin/src/Caelestia/qalculator.cpp b/plugin/src/Caelestia/qalculator.cpp
new file mode 100644
index 0000000..2e18033
--- /dev/null
+++ b/plugin/src/Caelestia/qalculator.cpp
@@ -0,0 +1,49 @@
+#include "qalculator.hpp"
+
+#include <QObject>
+#include <libqalculate/qalculate.h>
+
+Qalculator::Qalculator(QObject* parent)
+    : QObject(parent) {
+    if (!CALCULATOR) {
+        new Calculator();
+        CALCULATOR->loadExchangeRates();
+        CALCULATOR->loadGlobalDefinitions();
+        CALCULATOR->loadLocalDefinitions();
+    }
+}
+
+QString Qalculator::eval(const QString& expr, bool printExpr) const {
+    if (expr.isEmpty()) {
+        return QString();
+    }
+
+    EvaluationOptions eo;
+    PrintOptions po;
+
+    std::string parsed;
+    std::string result = CALCULATOR->calculateAndPrint(
+        CALCULATOR->unlocalizeExpression(expr.toStdString(), eo.parse_options), 100, eo, po, &parsed);
+
+    std::string error;
+    while (CALCULATOR->message()) {
+        if (!CALCULATOR->message()->message().empty()) {
+            if (CALCULATOR->message()->type() == MESSAGE_ERROR) {
+                error += "error: ";
+            } else if (CALCULATOR->message()->type() == MESSAGE_WARNING) {
+                error += "warning: ";
+            }
+            error += CALCULATOR->message()->message();
+        }
+        CALCULATOR->nextMessage();
+    }
+    if (!error.empty()) {
+        return QString::fromStdString(error);
+    }
+
+    if (printExpr) {
+        return QString("%1 = %2").arg(parsed).arg(result);
+    }
+
+    return QString::fromStdString(result);
+}
diff --git a/plugin/src/Caelestia/qalculator.hpp b/plugin/src/Caelestia/qalculator.hpp
new file mode 100644
index 0000000..266699f
--- /dev/null
+++ b/plugin/src/Caelestia/qalculator.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <QObject>
+#include <qqmlintegration.h>
+
+class Qalculator : public QObject {
+    Q_OBJECT
+    QML_ELEMENT
+    QML_SINGLETON
+
+public:
+    explicit Qalculator(QObject* parent = nullptr);
+
+    Q_INVOKABLE QString eval(const QString& expr, bool printExpr = true) const;
+};