Plan cloud upload decisions in app core

src/app_core/document_cloud.h

@@ -0,0 +1,32 @@
+#pragma once
+
+namespace pp::app {
+
+enum class CloudUploadAction {
+    unavailable_no_canvas,
+    show_save_required_warning,
+    prompt_publish,
+};
+
+struct CloudUploadPlan {
+    CloudUploadAction action = CloudUploadAction::unavailable_no_canvas;
+    bool save_before_upload = false;
+};
+
+[[nodiscard]] constexpr CloudUploadPlan plan_cloud_upload(
+    bool has_canvas,
+    bool is_new_document,
+    bool has_unsaved_changes) noexcept
+{
+    if (!has_canvas) {
+        return { CloudUploadAction::unavailable_no_canvas, false };
+    }
+
+    if (is_new_document) {
+        return { CloudUploadAction::show_save_required_warning, false };
+    }
+
+    return { CloudUploadAction::prompt_publish, has_unsaved_changes };
+}
+
+}