Local itk-vtk-viewer

It is ready to install the itk-viewer in case it is not installed in qim https://www.notion.so/qim-dtu/Improve-CLI-viz-f4254522fa1e4159b8ce6d9206793b13

qim3d/viz/itk_vtk_viewer/helpers.py

 from pathlib import Path
 import os
 import platform
+from typing import Callable
 
 import qim3d
 
@@ -8,7 +9,11 @@ class NotInstalledError(Exception): pass
 
 SOURCE_FNM = "fnm env --use-on-cd | Out-String | Invoke-Expression;"
 
-def get_dir() -> Path:
+LINUX = 'Linux'
+WINDOWS = 'Windows'
+MAC = 'Darwin'
+
+def get_itk_dir() -> Path:
     qim_dir = Path(qim3d.__file__).parents[0] #points to .../qim3d/qim3d/
     dir = qim_dir.joinpath("viz/itk_vtk_viewer")
     return dir
@@ -18,7 +23,7 @@ def get_nvm_dir(dir:Path = None) -> Path:
         following_folder = ".nvm"
     elif platform.system() == 'Windows':
         following_folder = ''
-    return dir.joinpath(following_folder) if dir is not None else get_dir().joinpath(following_folder)
+    return dir.joinpath(following_folder) if dir is not None else get_qim_dir().joinpath(following_folder)
 
 def get_node_binaries_dir(nvm_dir:Path = None) -> Path:
     """
@@ -34,10 +39,12 @@ def get_node_binaries_dir(nvm_dir:Path = None) -> Path:
         binaries_folder = 'installation'
 
     node_folder =  nvm_dir.joinpath(following_folder) if nvm_dir is not None else get_nvm_dir().joinpath(following_folder)
-    try:
-        l = sorted(os.listdir(node_folder))
-    except FileNotFoundError:
-        raise NotInstalledError
+    
+    # We don't wanna throw an error
+    # Instead we return None and check the returned value in run.py
+    if not os.path.isdir(node_folder):
+        return None
+    l = sorted(os.listdir(node_folder))
 
     for name in l[::-1]:
         path = node_folder.joinpath(name)
@@ -46,11 +53,24 @@ def get_node_binaries_dir(nvm_dir:Path = None) -> Path:
     
 def get_viewer_dir(dir:Path = None) -> Path:
     following_folder = "viewer_app"
-    return dir.joinpath(following_folder) if dir is not None else get_dir().joinpath(following_folder)
+    return dir.joinpath(following_folder) if dir is not None else get_qim_dir().joinpath(following_folder)
 
 def get_viewer_binaries(viewer_dir:Path = None) -> Path:
     following_folder1 = 'node_modules'
     following_folder2 = '.bin'
     if viewer_dir is None:
         viewer_dir = get_viewer_dir()
-    return viewer_dir.joinpath(following_folder1).joinpath(following_folder2)
\ No newline at end of file
+    return viewer_dir.joinpath(following_folder1).joinpath(following_folder2)
+
+def run_for_platform(linux_func:Callable, windows_func:Callable, macos_func:Callable):
+    this_platform = platform.system()
+    if this_platform == LINUX:
+        return linux_func()
+    elif this_platform == WINDOWS:
+        return windows_func()
+    elif this_platform == MAC:
+        # return macos_func()
+        raise NotImplementedError
+    
+def lambda_raise(err):
+    raise err