def describe_file_systems(self,
marker=None,
max_items=10,
creation_token=None,
file_system_id=None):
"""Describe all the EFS File Systems, or specific File Systems.
https://docs.aws.amazon.com/efs/latest/ug/API_DescribeFileSystems.html
"""
# Restrict the possible corpus of resules based on inputs.
if creation_token and file_system_id:
raise BadRequest(
"Request cannot contain both a file system ID and a creation token."
)
elif creation_token:
# Handle the creation token case.
corpus = []
for fs in self.file_systems_by_id.values():
if fs.creation_token == creation_token:
corpus.append(fs)
elif file_system_id:
# Handle the case that a file_system_id is given.
if file_system_id not in self.file_systems_by_id:
raise FileSystemNotFound(file_system_id)
corpus = [self.file_systems_by_id[file_system_id]]
elif marker is not None:
# Handle the case that a marker is given.
if marker not in self.next_markers:
raise BadRequest("Invalid Marker")
corpus = self.next_markers[marker]
else:
# Handle the vanilla case.
corpus = [fs for fs in self.file_systems_by_id.values()]
# Handle the max_items parameter.
file_systems = corpus[:max_items]
next_marker = self._mark_description(corpus, max_items)
return next_marker, file_systems
