From 87ac85223a25aaa72586ab77570834e12c1e0c02 Mon Sep 17 00:00:00 2001
From: elsid <elsid.mail@gmail.com>
Date: Tue, 4 Apr 2023 09:58:49 +0200
Subject: [PATCH] Support loading ESM4 GMST records

---
 apps/esmtool/tes4.cpp          | 28 +++++++++++++-
 components/CMakeLists.txt      |  1 +
 components/esm4/loadgmst.cpp   | 68 ++++++++++++++++++++++++++++++++++
 components/esm4/loadgmst.hpp   | 27 ++++++++++++++
 components/esm4/records.hpp    |  1 +
 components/esm4/typetraits.hpp | 13 +++++++
 6 files changed, 137 insertions(+), 1 deletion(-)
 create mode 100644 components/esm4/loadgmst.cpp
 create mode 100644 components/esm4/loadgmst.hpp

diff --git a/apps/esmtool/tes4.cpp b/apps/esmtool/tes4.cpp
index 25054b614a..ecc80eded6 100644
--- a/apps/esmtool/tes4.cpp
+++ b/apps/esmtool/tes4.cpp
@@ -72,6 +72,17 @@ namespace EsmTool
             }
         };
 
+        template <class T>
+        struct WriteData
+        {
+            const T& mValue;
+
+            explicit WriteData(const T& value)
+                : mValue(value)
+            {
+            }
+        };
+
         template <class T>
         std::ostream& operator<<(std::ostream& stream, const WriteArray<T>& write)
         {
@@ -80,6 +91,18 @@ namespace EsmTool
             return stream;
         }
 
+        template <class T>
+        std::ostream& operator<<(std::ostream& stream, const WriteData<T>& /*write*/)
+        {
+            return stream << " ?";
+        }
+
+        std::ostream& operator<<(std::ostream& stream, const WriteData<ESM4::GameSetting::Data>& write)
+        {
+            std::visit([&](const auto& v) { stream << v; }, write.mValue);
+            return stream;
+        }
+
         template <class T>
         void readTypedRecord(const Params& params, ESM4::Reader& reader)
         {
@@ -114,6 +137,8 @@ namespace EsmTool
                 std::cout << "\n  Type: " << value.mType;
             if constexpr (ESM4::hasValue<T>)
                 std::cout << "\n  Value: " << value.mValue;
+            if constexpr (ESM4::hasData<T>)
+                std::cout << "\n  Data: " << WriteData(value.mData);
             std::cout << '\n';
         }
 
@@ -253,7 +278,8 @@ namespace EsmTool
                     readTypedRecord<ESM4::GlobalVariable>(params, reader);
                     return true;
                 case ESM4::REC_GMST:
-                    break;
+                    readTypedRecord<ESM4::GameSetting>(params, reader);
+                    return true;
                 case ESM4::REC_GRAS:
                     readTypedRecord<ESM4::Grass>(params, reader);
                     return true;
diff --git a/components/CMakeLists.txt b/components/CMakeLists.txt
index b8463c8af0..34be828cb9 100644
--- a/components/CMakeLists.txt
+++ b/components/CMakeLists.txt
@@ -151,6 +151,7 @@ add_component_dir (esm4
     loadflst
     loadfurn
     loadglob
+    loadgmst
     loadgras
     loadgrup
     loadhair
diff --git a/components/esm4/loadgmst.cpp b/components/esm4/loadgmst.cpp
new file mode 100644
index 0000000000..7fb5d7af5c
--- /dev/null
+++ b/components/esm4/loadgmst.cpp
@@ -0,0 +1,68 @@
+#include "loadgmst.hpp"
+
+#include <stdexcept>
+
+#include "reader.hpp"
+
+namespace ESM4
+{
+    namespace
+    {
+        GameSetting::Data readData(FormId formId, std::string_view editorId, Reader& reader)
+        {
+            if (editorId.empty())
+                throw std::runtime_error(
+                    "Unknown ESM4 GMST (" + std::to_string(formId) + ") data type: editor id is empty");
+            const char type = editorId[0];
+            switch (type)
+            {
+                case 'i':
+                {
+                    std::int32_t value = 0;
+                    reader.get(value);
+                    return value;
+                }
+                case 'f':
+                {
+                    float value = 0;
+                    reader.get(value);
+                    return value;
+                }
+                case 's':
+                {
+                    std::string value;
+                    reader.getZString(value);
+                    return value;
+                }
+                default:
+                    throw std::runtime_error(
+                        "Unsupported ESM4 GMST (" + std::to_string(formId) + ") data type: " + std::string(editorId));
+            }
+        }
+    }
+
+    void GameSetting::load(Reader& reader)
+    {
+        mFormId = reader.hdr().record.id;
+        reader.adjustFormId(mFormId);
+        mFlags = reader.hdr().record.flags;
+
+        while (reader.getSubRecordHeader())
+        {
+            const ESM4::SubRecordHeader& subHdr = reader.subRecordHeader();
+            switch (subHdr.typeId)
+            {
+                case ESM4::SUB_EDID:
+                    reader.getZString(mEditorId);
+                    break;
+                case ESM4::SUB_DATA:
+                    mData = readData(mFormId, mEditorId, reader);
+                    break;
+                default:
+                    throw std::runtime_error("Unknown ESM4 GMST (" + std::to_string(mFormId) + ") subrecord "
+                        + ESM::printName(subHdr.typeId));
+            }
+        }
+    }
+
+}
diff --git a/components/esm4/loadgmst.hpp b/components/esm4/loadgmst.hpp
new file mode 100644
index 0000000000..62a5071eb3
--- /dev/null
+++ b/components/esm4/loadgmst.hpp
@@ -0,0 +1,27 @@
+#ifndef OPENMW_COMPONENTS_ESM4_LOADGMST_H
+#define OPENMW_COMPONENTS_ESM4_LOADGMST_H
+
+#include <cstdint>
+#include <string>
+#include <variant>
+
+#include "formid.hpp"
+
+namespace ESM4
+{
+    class Reader;
+
+    struct GameSetting
+    {
+        using Data = std::variant<float, std::int32_t, std::string>;
+
+        FormId mFormId; // from the header
+        std::uint32_t mFlags; // from the header, see enum type RecordFlag for details
+        std::string mEditorId;
+        Data mData;
+
+        void load(Reader& reader);
+    };
+}
+
+#endif // OPENMW_COMPONENTS_ESM4_LOADGMST_H
diff --git a/components/esm4/records.hpp b/components/esm4/records.hpp
index ae2a7a78f7..25bcba5cf2 100644
--- a/components/esm4/records.hpp
+++ b/components/esm4/records.hpp
@@ -28,6 +28,7 @@
 #include <components/esm4/loadflst.hpp>
 #include <components/esm4/loadfurn.hpp>
 #include <components/esm4/loadglob.hpp>
+#include <components/esm4/loadgmst.hpp>
 #include <components/esm4/loadgras.hpp>
 #include <components/esm4/loadgrup.hpp>
 #include <components/esm4/loadhair.hpp>
diff --git a/components/esm4/typetraits.hpp b/components/esm4/typetraits.hpp
index 1d39a23018..bbac3a6ac1 100644
--- a/components/esm4/typetraits.hpp
+++ b/components/esm4/typetraits.hpp
@@ -121,6 +121,19 @@ namespace ESM4
 
     template <class T>
     inline constexpr bool hasValue = HasValue<T>::value;
+
+    template <class T, class = std::void_t<>>
+    struct HasData : std::false_type
+    {
+    };
+
+    template <class T>
+    struct HasData<T, std::void_t<decltype(T::mData)>> : std::true_type
+    {
+    };
+
+    template <class T>
+    inline constexpr bool hasData = HasData<T>::value;
 }
 
 #endif // OPENMW_COMPONENTS_ESM4_TYPETRAITS