Plan document file saves in app core

src/app_core/document_session.h

@@ -1,5 +1,11 @@
 #pragma once
 
+#include "foundation/result.h"
+
+#include <string>
+#include <string_view>
+#include <utility>
+
 namespace pp::app {
 
 enum class ProjectOpenDecision {
@@ -33,6 +39,17 @@ enum class DocumentWorkflowDecision {
     prompt_save_before_continue,
 };
 
+enum class DocumentFileWriteDecision {
+    save_now,
+    prompt_overwrite,
+};
+
+struct DocumentFileTarget {
+    std::string name;
+    std::string directory;
+    std::string path;
+};
+
 [[nodiscard]] constexpr ProjectOpenDecision plan_project_open(bool has_unsaved_changes) noexcept
 {
     return has_unsaved_changes
@@ -97,4 +114,32 @@ enum class DocumentWorkflowDecision {
         : DocumentWorkflowDecision::continue_now;
 }
 
+[[nodiscard]] inline pp::foundation::Result<DocumentFileTarget> make_document_file_target(
+    std::string_view work_directory,
+    std::string_view document_name)
+{
+    if (document_name.empty()) {
+        return pp::foundation::Result<DocumentFileTarget>::failure(
+            pp::foundation::Status::invalid_argument("document name must not be empty"));
+    }
+
+    DocumentFileTarget target;
+    target.name = std::string(document_name);
+    target.directory = std::string(work_directory);
+    target.path.reserve(target.directory.size() + target.name.size() + 5);
+    target.path += target.directory;
+    target.path += "/";
+    target.path += target.name;
+    target.path += ".ppi";
+    return pp::foundation::Result<DocumentFileTarget>::success(std::move(target));
+}
+
+[[nodiscard]] constexpr DocumentFileWriteDecision plan_document_file_write(
+    bool target_exists) noexcept
+{
+    return target_exists
+        ? DocumentFileWriteDecision::prompt_overwrite
+        : DocumentFileWriteDecision::save_now;
+}
+
 }