config/lua: init lua config manager, use lua if available (#13817)

Adds a new lua config manager, which will automatically be used if there is a lua config present.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/config/lua/LuaEventHandler.hpp b/src/config/lua/LuaEventHandler.hpp
new file mode 100644
index 00000000..a48d7800
--- /dev/null
+++ b/src/config/lua/LuaEventHandler.hpp
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <functional>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+#include <optional>
+#include <cstdint>
+
+#include "../../helpers/memory/Memory.hpp"
+#include "../../helpers/signal/Signal.hpp"
+#include "../../desktop/DesktopTypes.hpp"
+
+extern "C" {
+#include <lua.h>
+}
+
+namespace Config::Lua {
+
+    // Manages hl.on() event subscriptions for a single Lua state lifetime.
+    // Destroyed (and recreated) on every config reload so callbacks never double-up.
+    //
+    // Hyprland objects (window, workspace, monitor, layer surface) are exposed to Lua
+    // as typed userdata holding a weak pointer.  Field accesses read live C++ state via
+    // __index; accessing a field on a destroyed object raises a Lua error.
+    class CLuaEventHandler {
+      public:
+        explicit CLuaEventHandler(lua_State* L);
+        ~CLuaEventHandler();
+
+        // Store a Lua function (as a registry ref) to be called when `name` fires.
+        // Returns a subscription handle, or std::nullopt if the event name is unknown.
+        std::optional<uint64_t>                       registerEvent(const std::string& name, int luaRef);
+        bool                                          unregisterEvent(uint64_t handle);
+
+        void                                          clearEvents();
+
+        static const std::unordered_set<std::string>& knownEvents();
+
+      private:
+        struct SSubscription {
+            std::string eventName;
+            int         luaRef = -1;
+        };
+
+        lua_State*                                             m_lua = nullptr;
+        std::unordered_map<std::string, std::vector<uint64_t>> m_callbacks;
+        std::unordered_map<uint64_t, SSubscription>            m_subscriptions;
+        std::unordered_set<uint64_t>                           m_activeHandles;
+        std::unordered_set<uint64_t>                           m_reentrancyWarnedHandles;
+        uint64_t                                               m_nextHandle    = 1;
+        size_t                                                 m_dispatchDepth = 0;
+        std::vector<CHyprSignalListener>                       m_listeners;
+
+        static constexpr size_t                                MAX_DISPATCH_DEPTH = 32;
+
+        void                                                   dispatch(const std::string& name, int nargs, const std::function<void()>& pushArgs);
+    };
+
+}