add fragment store draft doc

src/chat_gui4.cpp

@@ -737,7 +737,11 @@ void ChatGui4::renderMessageBodyFile(Message3Registry& reg, const Message3 e) {
 	) {
 		if (ImGui::Button("save to")) {
 			_fss.requestFile(
-				[](const auto& path) -> bool { return std::filesystem::is_directory(path); },
+				[](std::filesystem::path& path) -> bool {
+					// remove file path
+					path.remove_filename();
+					return std::filesystem::is_directory(path);
+				},
 				[this, &reg, e](const auto& path) {
 					if (reg.valid(e)) { // still valid
 						// TODO: trim file?

src/file_selector.cpp

@@ -18,7 +18,7 @@ FileSelector::FileSelector(void) {
 }
 
 void FileSelector::requestFile(
-	std::function<bool(const std::filesystem::path& path)>&& is_valid,
+	std::function<bool(std::filesystem::path& path)>&& is_valid,
 	std::function<void(const std::filesystem::path& path)>&& on_choose,
 	std::function<void(void)>&& on_cancel
 ) {
@@ -77,7 +77,9 @@ void FileSelector::render(void) {
 			if (current_path.has_parent_path()) {
 				if (ImGui::TableNextColumn()) {
 					if (ImGui::Selectable("D##..", false, ImGuiSelectableFlags_SpanAllColumns | ImGuiSelectableFlags_AllowItemOverlap)) {
-						_current_file_path = _current_file_path.parent_path();
+						// the first "parent_path()" only removes the filename and the ending "/"
+						_current_file_path = _current_file_path.parent_path().parent_path() / "";
+						//_current_file_path = _current_file_path.remove_filename().parent_path() / "";
 					}
 				}
 

src/file_selector.hpp

@@ -8,7 +8,7 @@ struct FileSelector {
 
 	bool _open_popup {false};
 
-	std::function<bool(const std::filesystem::path& path)> _is_valid = [](auto){ return true; };
+	std::function<bool(std::filesystem::path& path)> _is_valid = [](auto){ return true; };
 	std::function<void(const std::filesystem::path& path)> _on_choose = [](auto){};
 	std::function<void(void)> _on_cancel = [](){};
 
@@ -18,8 +18,9 @@ struct FileSelector {
 		FileSelector(void);
 
 		// TODO: supply hints
+		// HACK: until we supply hints, is_valid can modify
 		void requestFile(
-			std::function<bool(const std::filesystem::path& path)>&& is_valid,
+			std::function<bool(std::filesystem::path& path)>&& is_valid,
 			std::function<void(const std::filesystem::path& path)>&& on_choose,
 			std::function<void(void)>&& on_cancel
 		);

src/fragment_store/README.md

@@ -0,0 +1,72 @@
+# Fragment Store
+
+Fragments are are pieces of information split into Metadata and Data.
+They can be stored seperated or together.
+They can be used as a Transport protocol/logic too.
+
+# Store types
+
+### Object Store
+
+Fragment files are stored with the first 2 hex chars as sub folders:
+eg:
+objects/ (object store root)
+  - 5f/ (first 2hex subfolder)
+    - 4fffffff (the fragment file without the first 2 hexchars)
+
+### Split Object Store
+
+Same as Object Store, but medadata and data stored in seperate files.
+Metadata files have the `.meta` suffix. They also have a filetype specific suffix, like `.json`, `.msgpack` etc.
+
+### Memory Store
+
+Just keeps the Fragments in memory.
+
+
+# File formats
+
+Files can be compressed and encrypted. Since compression needs the data structure to funcion, it is applied before it is encrypted.
+
+### Text Json
+
+Text json only makes sense for metadata if it's neither compressed nor encrypted. (otherwise its binary on disk anyway, so why waste bytes).
+Since the content of data is not looked at, nothing stops you from using text json and ecrypt it, but atleast basic compression is advised.
+
+A Metadata json object has the following keys:
+- `enc` Encryption type of the data, if any
+- `comp` Compression type of the data, if any
+
+## Binary file headers
+
+### Split Metadata
+
+file magic bytes `SOLMET` (6 bytes)
+
+1 byte encryption type (0x00 is none)
+
+1 byte compression type (0x00 is none)
+
+...metadata here...
+
+note that the ecnryption and compression are for the metadata only.
+The metadata itself contains encryption and compression about the data.
+
+### Split Data
+
+(none) all the data is in the metadata file.
+This is mostly to allow direct storage for files in the Fragment store without excessive duplication.
+Keep in mind to not use the actual file name as the data/meta file name.
+
+### Single fragment
+
+file magic bytes `SOLFIL` (6 bytes)
+
+1 byte encryption type (0x00 is none)
+
+1 byte compression type (0x00 is none)
+
+...metadata here...
+
+...data here...
+