Make following changes

 - Refactor file save function to handle with a single filename for parameter
 - Add 'preview' key to paths dict
 - Simplify 'path exists' function

felicette/utils/file_manager.py

@@ -16,10 +16,10 @@ def check_sat_path(id):
  os.mkdir(data_path)
 
 
-def save_to_file(url, filename, id):
+def save_to_file(url, filename, id, info_message):
  data_path = os.path.join(workdir, id)
- data_id = filename.split("-")[1].split(".")[0]
- rprint("✗ required data doesn't exist, downloading", band_tag_map[data_id], "band")
+ data_id = filename.split("/")[-1].split("-")[1].split(".")[0]
+ rprint(info_message)
  file_path = os.path.join(data_path, filename)
  response = requests.get(url, stream=True)
  with tqdm.wrapattr(
@@ -34,16 +34,15 @@ def save_to_file(url, filename, id):
  fout.close()
 
 
-def data_file_exists(filename, id):
- data_path = os.path.join(workdir, id)
- file_path = os.path.join(data_path, filename)
- return os.path.exists(file_path)
+def data_file_exists(filename):
+ return os.path.exists(filename)
 
 
 def file_paths_wrt_id(id):
  home_path_id = os.path.join(workdir, id)
  return {
  "base": home_path_id,
+ "preview": os.path.join(home_path_id, "%s-preview.jpg" % (id)),
  "b4": os.path.join(home_path_id, "%s-b4.tiff" % (id)),
  "b3": os.path.join(home_path_id, "%s-b3.tiff" % (id)),
  "b2": os.path.join(home_path_id, "%s-b2.tiff" % (id)),