kiwi-scp/src/kiwi/config.py
2020-08-13 11:30:25 +02:00

136 lines
3.7 KiB
Python

# system
import copy
import logging
import os
import re
import yaml
# local
from ._constants import KIWI_ROOT, KIWI_CONF_NAME
###########
# CONSTANTS
# text files inside kiwi-config "src" directory
HEADER_KIWI_CONF_NAME = f"{KIWI_ROOT}/kiwi_header.yml"
DEFAULT_KIWI_CONF_NAME = f"{KIWI_ROOT}/kiwi_default.yml"
VERSION_TAG_NAME = f"{KIWI_ROOT}/version-tag"
class Config:
"""represents a kiwi.yml"""
__yml_content = {}
def __key_resolve(self, key):
"""
Resolve nested dictionaries
If __yml_content is {'a': {'b': {'c': "val"}}} and key is 'a:b:c',
this returns a single dict {'c': "val"} and the direct key 'c'
"""
# "a:b:c" => path = ['a', 'b'], key = 'c'
path = key.split(':')
path, key = path[:-1], path[-1]
# resolve path
container = self.__yml_content
for step in path:
container = container[step]
return container, key
def __getitem__(self, key):
"""array-like read access to __yml_content"""
container, key = self.__key_resolve(key)
return container[key]
def __setitem__(self, key, value):
"""array-like write access to __yml_content"""
container, key = self.__key_resolve(key)
container[key] = value
def __str__(self):
"""dump into textual representation"""
# dump yml content
yml_string = yaml.dump(self.__yml_content, default_flow_style=False, sort_keys=False)
# insert newline before every main key
yml_string = re.sub(r'^(\S)', r'\n\1', yml_string, flags=re.MULTILINE)
# load header comment from file
with open(HEADER_KIWI_CONF_NAME, 'r') as stream:
yml_string = stream.read() + yml_string
return yml_string
def _update_from_file(self, filename):
"""return a copy updated using a kiwi.yml file"""
with open(filename, 'r') as stream:
try:
# create copy
result = Config()
result.__yml_content = copy.deepcopy(self.__yml_content)
# read file
logging.debug(f"Reading '{filename}' into '{id(result.__yml_content)}'")
result.__yml_content.update(yaml.safe_load(stream))
return result
except yaml.YAMLError as exc:
logging.error(exc)
def save(self):
"""save current yml representation in current directory's kiwi.yml"""
with open(KIWI_CONF_NAME, 'w') as stream:
stream.write(str(self))
class DefaultConfig(Config):
"""Singleton: The default kiwi.yml file"""
__instance = None
@classmethod
def get(cls):
if cls.__instance is None:
# create singleton
cls.__instance = cls()._update_from_file(DEFAULT_KIWI_CONF_NAME)
# add version data from separate file (keeps default config cleaner)
with open(VERSION_TAG_NAME, 'r') as stream:
cls.__instance['version'] = stream.read().strip()
# return singleton
return cls.__instance
class LoadedConfig(Config):
"""Singleton collection: kiwi.yml files by path"""
__instances = {}
@classmethod
def get(cls):
cwd = os.getcwd()
if cwd not in LoadedConfig.__instances:
# create singleton for new path
result = DefaultConfig.get()
# update with current dir's kiwi.yml
try:
result = result._update_from_file(KIWI_CONF_NAME)
except FileNotFoundError:
logging.info(f"No '{KIWI_CONF_NAME}' found at '{cwd}'. Using defaults.")
LoadedConfig.__instances[cwd] = result
# return singleton
return LoadedConfig.__instances[cwd]