feat(panel): add Insert as FX — ReaSampler 9000 onto the selected track, preloaded with the focused capture, over the existing instrument-drop body

src/core/ui/insert_fx_enable.cpp

@@ -0,0 +1,36 @@
+// insert_fx_enable — pure implementation. See insert_fx_enable.h.
+
+#include "core/ui/insert_fx_enable.h"
+
+namespace reasampler::ui {
+
+InsertFxRefusal insertFxRefusal(int focusedCaptureCount, bool trackSelected) {
+    if (focusedCaptureCount <= 0) return InsertFxRefusal::NoCapture;
+    if (focusedCaptureCount > 1) return InsertFxRefusal::MultiCapture;
+    if (!trackSelected) return InsertFxRefusal::NoTrack;
+    return InsertFxRefusal::None;
+}
+
+bool insertFxButtonEnabled(int focusedCaptureCount) {
+    return insertFxRefusal(focusedCaptureCount, /*trackSelected=*/true) ==
+           InsertFxRefusal::None;
+}
+
+std::string insertFxRefusalMessage(InsertFxRefusal refusal) {
+    switch (refusal) {
+        case InsertFxRefusal::None:
+            return {};
+        case InsertFxRefusal::NoCapture:
+            return "select a capture in the bank panel first, then insert it as an "
+                   "instrument on the selected track";
+        case InsertFxRefusal::MultiCapture:
+            return "select exactly ONE capture -- a ReaSampler 9000 instance holds one "
+                   "capture, so a multi-capture selection has no single sound to load";
+        case InsertFxRefusal::NoTrack:
+            return "select a track first -- the instrument is added to the selected "
+                   "track's FX chain";
+    }
+    return {};
+}
+
+} // namespace reasampler::ui