svx: chart look helpers a kit client can drive

ChartHelper gains IsChartLook, SetChartLook and WriteChartLook (type,
titles, legend, as JSON), moved here from Calc so Impress can use them.
The JSON keeps its types (boost.json): a field of the wrong type, such
as a legend that is not true or false or a title that is not text, is
refused before anything changes.
A scatter starts as points only when the chart becomes one; a scatter
kept as one keeps its lines.

diff --git a/include/svx/charthelper.hxx b/include/svx/charthelper.hxx
index 3ad1fba..9bdf0a6 100644
--- a/include/svx/charthelper.hxx
+++ b/include/svx/charthelper.hxx
@@ -31,6 +31,8 @@ namespace com::sun::star {
 }
 
 namespace basegfx { class B2DRange; }
+namespace tools { class JsonWriter; }
+namespace com::sun::star::uno { class XInterface; }
 
 class SAL_WARN_UNUSED SVXCORE_DLLPUBLIC ChartHelper
 {
@@ -54,6 +56,13 @@ public:
     // newly created charts using this method
     static void AdaptDefaultsForChart(
         const css::uno::Reference < css::embed::XEmbeddedObject > & xEmbObj);
+
+    /// A kit chart look: type, titles, legend, as JSON.
+    static bool IsChartLook(std::u16string_view rJson);
+    static bool SetChartLook(const css::uno::Reference<css::uno::XInterface>& xChart,
+                             std::u16string_view rJson);
+    static void WriteChartLook(::tools::JsonWriter& rJson,
+                               const css::uno::Reference<css::uno::XInterface>& xChart);
 };
 
 #endif // INCLUDED_SVX_CHARTHELPER_HXX
diff --git a/svx/Library_svxcore.mk b/svx/Library_svxcore.mk
index e2d178b..1dfa044 100644
--- a/svx/Library_svxcore.mk
+++ b/svx/Library_svxcore.mk
@@ -332,6 +332,7 @@ $(eval $(call gb_Library_add_exception_objects,svxcore,\
     svx/source/sdr/properties/e3dcompoundproperties \
     svx/source/sdr/properties/oleproperties \
     svx/source/svdraw/charthelper \
+    svx/source/svdraw/chartlook \
     svx/source/svdraw/constructhelper \
     svx/source/svdraw/clonelist \
     svx/source/svdraw/gradtrns \
diff --git a/svx/source/svdraw/chartjson.hxx b/svx/source/svdraw/chartjson.hxx
new file mode 100644
index 0000000..d105464
--- /dev/null
+++ b/svx/source/svdraw/chartjson.hxx
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include <rtl/ustring.hxx>
+#include <boost/json.hpp>
+
+#include <optional>
+#include <string_view>
+
+namespace svx::chartjson
+{
+/// The JSON object, or none if it is not one.
+std::optional<boost::json::object> Object(std::u16string_view rJson);
+/// Member `rKey` as text; absent is empty, another type fails.
+std::optional<OUString> Text(const boost::json::object& rObject, std::string_view rKey);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/svx/source/svdraw/chartlook.cxx b/svx/source/svdraw/chartlook.cxx
new file mode 100644
index 0000000..79d4e6c
--- /dev/null
+++ b/svx/source/svdraw/chartlook.cxx
@@ -0,0 +1,193 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <svx/charthelper.hxx>
+#include "chartjson.hxx"
+
+#include <com/sun/star/beans/XPropertySet.hpp>
+#include <com/sun/star/chart/XAxisXSupplier.hpp>
+#include <com/sun/star/chart/XAxisYSupplier.hpp>
+#include <com/sun/star/chart/XChartDocument.hpp>
+#include <com/sun/star/drawing/XShape.hpp>
+#include <com/sun/star/lang/XMultiServiceFactory.hpp>
+#include <tools/json_writer.hxx>
+// One translation unit builds boost.json.
+#include <boost/json/src.hpp>
+
+#include <algorithm>
+#include <functional>
+#include <optional>
+
+using namespace ::com::sun::star;
+
+namespace svx::chartjson
+{
+/// The JSON object, or none if it is not one.
+std::optional<boost::json::object> Object(std::u16string_view rJson)
+{
+    boost::system::error_code aError;
+    boost::json::value aValue = boost::json::parse(std::string(OUString(rJson).toUtf8()), aError);
+    if (aError || !aValue.is_object())
+        return std::nullopt;
+    return aValue.as_object();
+}
+
+/// Member `rKey` as text; absent is empty, another type fails.
+std::optional<OUString> Text(const boost::json::object& rObject, std::string_view rKey)
+{
+    const boost::json::value* pValue = rObject.if_contains(rKey);
+    if (!pValue)
+        return OUString();
+    if (!pValue->is_string())
+        return std::nullopt;
+    const boost::json::string& rText = pValue->as_string();
+    return OUString::fromUtf8(std::string_view(rText.data(), rText.size()));
+}
+}
+
+namespace
+{
+/// Kit names and the diagram services they map to.
+constexpr std::pair<std::string_view, std::u16string_view> aChartTypes[]
+    = { { "column", u"com.sun.star.chart.BarDiagram" },
+        { "bar", u"com.sun.star.chart.BarDiagram" },
+        { "line", u"com.sun.star.chart.LineDiagram" },
+        { "scatter", u"com.sun.star.chart.XYDiagram" },
+        { "pie", u"com.sun.star.chart.PieDiagram" } };
+
+/// A parsed look; "other" keeps the diagram.
+struct ChartLook
+{
+    std::string_view aType;
+    OUString aTitle, aXTitle, aYTitle;
+    bool bLegend = true;
+};
+
+std::optional<ChartLook> lcl_ParseLook(std::u16string_view rJson)
+{
+    const std::optional<boost::json::object> oObject = svx::chartjson::Object(rJson);
+    if (!oObject)
+        return std::nullopt;
+    const boost::json::value* pType = oObject->if_contains("type");
+    if (!pType || !pType->is_string())
+        return std::nullopt;
+    const std::string_view aType(pType->as_string().data(), pType->as_string().size());
+    ChartLook aLook;
+    if (aType == "other")
+        aLook.aType = "other";
+    for (const auto& [rName, rService] : aChartTypes)
+        if (rName == aType)
+            aLook.aType = rName;
+    const std::optional<OUString> oTitle = svx::chartjson::Text(*oObject, "title");
+    const std::optional<OUString> oXTitle = svx::chartjson::Text(*oObject, "xtitle");
+    const std::optional<OUString> oYTitle = svx::chartjson::Text(*oObject, "ytitle");
+    const boost::json::value* pLegend = oObject->if_contains("legend");
+    if (aLook.aType.empty() || !oTitle || !oXTitle || !oYTitle || (pLegend && !pLegend->is_bool()))
+        return std::nullopt;
+    aLook.aTitle = *oTitle;
+    aLook.aXTitle = *oXTitle;
+    aLook.aYTitle = *oYTitle;
+    aLook.bLegend = !pLegend || pLegend->as_bool();
+    return aLook;
+}
+
+/// Shows a title with this text; empty hides it.
+void lcl_SetTitle(const uno::Reference<beans::XPropertySet>& xOwner, const OUString& rHas,
+                  const std::function<uno::Reference<drawing::XShape>()>& rTitle,
+                  const OUString& rText)
+{
+    xOwner->setPropertyValue(rHas, uno::Any(!rText.isEmpty()));
+    if (rText.isEmpty())
+        return;
+    uno::Reference<beans::XPropertySet> xTitle(rTitle(), uno::UNO_QUERY_THROW);
+    xTitle->setPropertyValue(u"String"_ustr, uno::Any(rText));
+}
+
+OUString lcl_Title(const uno::Reference<beans::XPropertySet>& xOwner, const OUString& rHas,
+                   const std::function<uno::Reference<drawing::XShape>()>& rTitle)
+{
+    OUString aText;
+    if (!xOwner->getPropertyValue(rHas).get<bool>())
+        return aText;
+    uno::Reference<beans::XPropertySet> xTitle(rTitle(), uno::UNO_QUERY_THROW);
+    xTitle->getPropertyValue(u"String"_ustr) >>= aText;
+    return aText;
+}
+}
+
+bool ChartHelper::IsChartLook(std::u16string_view rJson) { return lcl_ParseLook(rJson).has_value(); }
+
+bool ChartHelper::SetChartLook(const uno::Reference<uno::XInterface>& xChart,
+                               std::u16string_view rJson)
+{
+    const std::optional<ChartLook> oLook = lcl_ParseLook(rJson);
+    uno::Reference<chart::XChartDocument> xDoc(xChart, uno::UNO_QUERY);
+    if (!oLook || !xDoc.is())
+        return false;
+    uno::Reference<chart::XDiagram> xDiagram = xDoc->getDiagram();
+    const auto pType = std::find_if(std::begin(aChartTypes), std::end(aChartTypes),
+                                    [&oLook](const auto& rPair) { return rPair.first == oLook->aType; });
+    if (pType != std::end(aChartTypes))
+    {
+        const bool bNewType = xDiagram->getDiagramType() != pType->second;
+        if (bNewType)
+        {
+            uno::Reference<lang::XMultiServiceFactory> xFactory(xDoc, uno::UNO_QUERY_THROW);
+            xDiagram.set(xFactory->createInstance(OUString(pType->second)), uno::UNO_QUERY_THROW);
+            xDoc->setDiagram(xDiagram);
+        }
+        uno::Reference<beans::XPropertySet> xProps(xDiagram, uno::UNO_QUERY_THROW);
+        if (pType->second == u"com.sun.star.chart.BarDiagram")
+            xProps->setPropertyValue(u"Vertical"_ustr, uno::Any(oLook->aType == "bar"));
+        // A new scatter starts as points; kept ones keep lines.
+        if (bNewType && oLook->aType == "scatter")
+            xProps->setPropertyValue(u"Lines"_ustr, uno::Any(false));
+    }
+    uno::Reference<beans::XPropertySet> xDocProps(xDoc, uno::UNO_QUERY_THROW);
+    lcl_SetTitle(xDocProps, u"HasMainTitle"_ustr, [&xDoc] { return xDoc->getTitle(); },
+                 oLook->aTitle);
+    xDocProps->setPropertyValue(u"HasLegend"_ustr, uno::Any(oLook->bLegend));
+    // A pie has no axes.
+    if (xDiagram->getDiagramType() == u"com.sun.star.chart.PieDiagram")
+        return true;
+    uno::Reference<chart::XAxisXSupplier> xX(xDiagram, uno::UNO_QUERY_THROW);
+    uno::Reference<chart::XAxisYSupplier> xY(xDiagram, uno::UNO_QUERY_THROW);
+    uno::Reference<beans::XPropertySet> xProps(xDiagram, uno::UNO_QUERY_THROW);
+    lcl_SetTitle(xProps, u"HasXAxisTitle"_ustr, [&xX] { return xX->getXAxisTitle(); },
+                 oLook->aXTitle);
+    lcl_SetTitle(xProps, u"HasYAxisTitle"_ustr, [&xY] { return xY->getYAxisTitle(); },
+                 oLook->aYTitle);
+    return true;
+}
+
+void ChartHelper::WriteChartLook(::tools::JsonWriter& rJson,
+                                 const uno::Reference<uno::XInterface>& xChart)
+{
+    uno::Reference<chart::XChartDocument> xDoc(xChart, uno::UNO_QUERY_THROW);
+    uno::Reference<chart::XDiagram> xDiagram = xDoc->getDiagram();
+    uno::Reference<beans::XPropertySet> xProps(xDiagram, uno::UNO_QUERY_THROW);
+    const OUString aService = xDiagram->getDiagramType();
+    std::string_view aType = "other";
+    for (const auto& [rName, rService] : aChartTypes)
+        if (rService == aService && aType == "other")
+            aType = rName;
+    if (aType == "column" && xProps->getPropertyValue(u"Vertical"_ustr).get<bool>())
+        aType = "bar";
+    rJson.put("type", aType);
+    uno::Reference<beans::XPropertySet> xDocProps(xDoc, uno::UNO_QUERY_THROW);
+    rJson.put("title", lcl_Title(xDocProps, u"HasMainTitle"_ustr, [&xDoc] { return xDoc->getTitle(); }));
+    rJson.put("legend", xDocProps->getPropertyValue(u"HasLegend"_ustr).get<bool>());
+    uno::Reference<chart::XAxisXSupplier> xX(xDiagram, uno::UNO_QUERY_THROW);
+    uno::Reference<chart::XAxisYSupplier> xY(xDiagram, uno::UNO_QUERY_THROW);
+    const bool bAxes = aType != "pie";
+    rJson.put("xtitle", bAxes ? lcl_Title(xProps, u"HasXAxisTitle"_ustr, [&xX] { return xX->getXAxisTitle(); }) : OUString());
+    rJson.put("ytitle", bAxes ? lcl_Title(xProps, u"HasYAxisTitle"_ustr, [&xY] { return xY->getYAxisTitle(); }) : OUString());
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */