work in progress

designer/src/hot_reload.cpp

@@ -0,0 +1,93 @@
+// Hot-reload file watcher implementation
+#include "hot_reload.h"
+#include <iostream>
+
+#ifdef _WIN32
+#include <Windows.h>
+#endif
+
+namespace mosis::desktop {
+
+HotReload::HotReload(const std::filesystem::path& watch_path, ReloadCallback callback)
+    : m_watch_path(watch_path)
+    , m_callback(std::move(callback))
+    , m_last_change(std::chrono::steady_clock::now())
+{}
+
+HotReload::~HotReload() {
+    Stop();
+}
+
+void HotReload::Start() {
+    if (m_running) return;
+
+#ifdef _WIN32
+    m_notification_handle = FindFirstChangeNotificationW(
+        m_watch_path.c_str(),
+        TRUE,  // Watch subtree
+        FILE_NOTIFY_CHANGE_LAST_WRITE
+    );
+
+    if (m_notification_handle == INVALID_HANDLE_VALUE) {
+        std::cerr << "Failed to create file change notification for: "
+                  << m_watch_path << std::endl;
+        return;
+    }
+#endif
+
+    m_running = true;
+    m_watch_thread = std::thread(&HotReload::WatchThread, this);
+}
+
+void HotReload::Stop() {
+    m_running = false;
+
+    if (m_watch_thread.joinable()) {
+        m_watch_thread.join();
+    }
+
+#ifdef _WIN32
+    if (m_notification_handle && m_notification_handle != INVALID_HANDLE_VALUE) {
+        FindCloseChangeNotification(m_notification_handle);
+        m_notification_handle = nullptr;
+    }
+#endif
+}
+
+bool HotReload::CheckForChanges() {
+    if (m_change_detected) {
+        auto now = std::chrono::steady_clock::now();
+        if (now - m_last_change >= m_debounce_delay) {
+            m_change_detected = false;
+            if (m_callback) {
+                m_callback();
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+void HotReload::WatchThread() {
+    while (m_running) {
+#ifdef _WIN32
+        DWORD result = WaitForSingleObject(m_notification_handle, 100);  // 100ms timeout
+        if (result == WAIT_OBJECT_0) {
+            m_last_change = std::chrono::steady_clock::now();
+            m_change_detected = true;
+
+            // Reset the notification
+            if (!FindNextChangeNotification(m_notification_handle)) {
+                std::cerr << "FindNextChangeNotification failed" << std::endl;
+                break;
+            }
+        }
+#else
+        // TODO: Linux inotify / macOS FSEvents implementation
+        // For now, just sleep to avoid busy loop
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+#endif
+    }
+}
+
+} // namespace mosis::desktop