add json config and its manager class

+ rewrite logic to prevent removing last admin role
+ handle showing users on login and enabling guest

app/config.py

@@ -0,0 +1,97 @@
+from dataclasses import dataclass, asdict, field
+import json
+import os
+import time
+from typing import Any
+from .settings import Paths
+
+# TODO: Publish this on PyPi
+
+@dataclass
+class UserConfig:
+    _config_path: str = ""
+    # NOTE: only auth stuff are used (the others are still reading/writing to db)
+    # TODO: Move the rest of the settings to the config file
+
+    # auth stuff
+    usersOnLogin: bool = True
+    enableGuest: bool = False
+
+    # lists
+    rootDirs: list[str] = field(default_factory=list)
+    excludeDirs: list[str] = field(default_factory=list)
+    artistSeparators: set[str] = field(default_factory=list)
+
+    # tracks
+    extractFeaturedArtists: bool = True
+    removeProdBy: bool = True
+    removeRemasterInfo: bool = True
+
+    # albums
+    mergeAlbums: bool = False
+    cleanAlbumTitle: bool = True
+    showAlbumsAsSingles: bool = False
+
+    def __post_init__(self):
+        """
+        Loads the config file and sets the values to this instance
+        """
+        # set config path locally to avoid writing to file
+        config_path = Paths.get_config_file_path()
+
+        try:
+            config = self.load_config(config_path)
+        except FileNotFoundError:
+            self._config_path = config_path
+            return
+
+        # loop through the config file and set the values
+        for key, value in config.items():
+            setattr(self, key, value)
+
+        # finally set the config path
+        self._config_path = config_path
+
+    def setup_config_file(self) -> None:
+        """
+        Creates the config file with the default settings
+        if it doesn't exist
+        """
+        print("config path: ", self._config_path)
+
+        # if not exists, create the config file
+        if not os.path.exists(self._config_path):
+            self.write_to_file(asdict(self))
+
+    def load_config(self, path: str) -> dict[str, Any]:
+        """
+        Reads the settings from the config file.
+        Returns a dictget_root_dirs
+        """
+        with open(path, "r") as f:
+            settings = json.load(f)
+
+        return settings
+
+    def write_to_file(self, settings: dict[str, Any]):
+        """
+        Writes the settings to the config file
+        """
+        # remove internal attributes
+        settings = {k: v for k, v in settings.items() if not k.startswith("_")}
+
+        with open(self._config_path, "w") as f:
+            json.dump(settings, f, indent=4)
+
+    def __setattr__(self, key: str, value: Any) -> None:
+        """
+        Writes to the config file whenever a value is set
+        """
+        super().__setattr__(key, value)
+
+        # if is internal attribute, don't write to file
+        if key.startswith("_") or not self._config_path:
+            return
+
+        print(f"writing to file: {key}={value}")
+        self.write_to_file(asdict(self))