Add file upload and download (zip for directories)

Backend/Explorer.py

@@ -124,6 +124,28 @@ def MoveEntry(RootName: str, SourceRelativePath: str, DestinationRelativePath: s
         RenameDirectoryNote(DestinationPath, OldName)
 
 
+def SaveUploadedFile(
+    RootName: str, DirectoryRelativePath: str, FileName: str, FileBytes: bytes
+) -> str:
+    DirectoryPath = ResolvePath(RootName, DirectoryRelativePath)
+
+    if not DirectoryPath.is_dir():
+        raise NotADirectoryError(f"{DirectoryPath} is not a directory.")
+
+    SafeName = Path(FileName).name
+
+    if not SafeName or SafeName in (".", ".."):
+        raise ValueError("Invalid file name.")
+
+    TargetPath = DirectoryPath / SafeName
+
+    if TargetPath.exists():
+        raise FileExistsError(f"{SafeName} already exists.")
+
+    TargetPath.write_bytes(FileBytes)
+    return SafeName
+
+
 def DeleteEntry(RootName: str, RelativePath: str) -> None:
     EntryPath = ResolvePath(RootName, RelativePath)