Implement reading from a settings file

setup.py

@@ -38,6 +38,7 @@ setup(
         "beautifulsoup4>=4.5.0,<5.0",
         "wcwidth>=0.1.7",
         "urwid>=2.0.0,<3.0",
+        "tomlkit>=0.10.0,<1.0"
     ],
     entry_points={
         'console_scripts': [

toot/settings.py

@@ -0,0 +1,52 @@
+from functools import lru_cache
+from os.path import exists, join
+from typing import Optional, Type, TypeVar
+from tomlkit import parse
+from toot.config import get_config_dir
+
+
+TOOT_SETTINGS_FILE_NAME = "settings.toml"
+
+
+def get_settings_path():
+    return join(get_config_dir(), TOOT_SETTINGS_FILE_NAME)
+
+
+SETTINGS_FILE = get_settings_path()
+
+
+def load_settings() -> dict:
+    if not exists(SETTINGS_FILE):
+        return {}
+
+    with open(SETTINGS_FILE) as f:
+        return parse(f.read())
+
+
+@lru_cache(maxsize=None)
+def get_settings():
+    return load_settings()
+
+
+def get_setting(key: str, type: Type, default=None):
+    """
+    Get a setting value. The key should be a dot-separated string,
+    e.g. "commands.post.editor" which will correspond to the "editor" setting
+    inside the `[commands.post]` section.
+    """
+    settings = get_settings()
+    return _get_setting(settings, key.split("."), type, default)
+
+
+def _get_setting(dct, keys, type: Type, default=None):
+    if len(keys) == 0:
+        if isinstance(dct, type):
+            return dct
+        else:
+            return default
+
+    key = keys[0]
+    if isinstance(dct, dict) and key in dct:
+        return _get_setting(dct[key], keys[1:], type, default)
+
+    return default