Adds support for including angelscript files using #include pragma, as long as they're within a set source directory.

src/ScriptResolving/AngelScript/AngelScriptResolver.cpp

@@ -1,5 +1,6 @@
 #include "AngelScriptResolver.hpp"
 #include <CreatureLib/Battling/Models/Creature.hpp>
+#include <filesystem>
 #include <regex>
 #include "../../../extern/angelscript_addons/scriptdictionary/scriptdictionary.h"
 #include "../../../extern/angelscript_addons/scripthandle/scripthandle.h"
@@ -85,6 +86,7 @@ void AngelScriptResolver::Initialize(CreatureLib::Battling::BattleLibrary* arg,
         r = _engine->RegisterGlobalFunction("void print(const constString &in)", asFUNCTION(PrintConst), asCALL_CDECL);
         if (r < 0)
             throw ArbUt::Exception("Registering print function failed.");
+        _builder.SetIncludeCallback(IncludeCallback, this);
     }
 
     _builder.StartNewModule(_engine, "pkmn");
@@ -401,4 +403,27 @@ void AngelScriptResolver::InitializeByteCode(
         }
     }
     _typeDatabase = typeDatabase;
-}
+}
+
+i32 AngelScriptResolver::IncludeCallback(const char* include, const char*, CScriptBuilder* builder, void* userParam) {
+    auto* r = reinterpret_cast<AngelScriptResolver*>(userParam);
+    // If source directory is not set, bail out.
+    if (r->_sourceDirectory.empty()) {
+        return -100;
+    }
+    auto root = std::filesystem::path(r->_sourceDirectory);
+    // Resolve any special operators, to get the actual path.
+    auto path = (root / std::filesystem::path(include)).lexically_normal();
+
+    // Validate the path is inside the root directory. If not, bail out.
+    auto [rootEnd, nothing] = std::mismatch(root.begin(), root.end(), path.begin());
+    if (rootEnd != root.end()) {
+        return -101;
+    }
+
+    // If the file doesn't exist, bail out.
+    if (!std::filesystem::exists(path)) {
+        return -102;
+    }
+    return builder->AddSectionFromFile(path.c_str());
+}