[settings] fuck it, rework the settings again

this time using pydantic-settings as a base
- removed all os.getenv calls
- removed the secret_key default option
- reworked database loading, creating tables
- prob. something else also but its 4:30 and i have to sleep

app/services/settings.py

@@ -1,52 +1,70 @@
 import logging
-import os
 from functools import lru_cache
 
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
 logger = logging.getLogger(__name__)
 
 
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env")
+
+    secret_key: str
+    sqlalchemy_database_url: str = "sqlite:///./gatekeeper.db"
+    lock_pin: int = 17
+    unlock_pin: int = 18
+    mock_gpio: bool = True
+    alembic_config: str = "./alembic.ini"
+
+    disable_cards: bool = False
+    mifare_app_master_key: str | None = None
+    mifare_acl_read_base_key: str | None = None
+    mifare_acl_write_base_key: str | None = None
+
+
 @lru_cache(1)
-def disable_cards_check():
-    if os.environ.get("DISABLE_CARDS", "").lower() in ("1", "true"):
-        return True
-
-    for env in (
-        "MIFARE_APP_MASTER_KEY",
-        "MIFARE_ACL_READ_BASE_KEY",
-        "MIFARE_ACL_WRITE_BASE_KEY",
-    ):
-        if not os.getenv(env):
+def _create_settings():
+    settings = Settings()
+    if not settings.disable_cards:
+        missing = [
+            name.upper()
+            for name in (
+                "mifare_app_master_key",
+                "mifare_acl_read_base_key",
+                "mifare_acl_write_base_key",
+            )
+            if not getattr(settings, name)
+        ]
+        if missing:
             logger.critical(
-                f"Missing environment variable for scanner start: {env} \n Card scanner and related funcionality is disabled!"  # noqa: E501
+                "Missing environment variable for scanner start: %s"
+                "Card scanner and related funcionality is disabled!",
+                ", ".join(missing),
             )
-            return True
-    return False
+            settings.disable_cards = True
+    return settings
 
 
-disable_cards = disable_cards_check()
+class _SettingsProxy:
+    _instance: Settings | None = None
 
-if not disable_cards:
-    mifare_app_master_key = os.getenv("MIFARE_APP_MASTER_KEY")
-    mifare_acl_read_base_key = os.getenv("MIFARE_ACL_READ_BASE_KEY")
-    mifare_acl_write_base_key = os.getenv("MIFARE_ACL_WRITE_BASE_KEY")
+    def _load(self) -> Settings:
+        if self._instance is None:
+            self._instance = _create_settings()
+        return self._instance
+
+    def __getattr__(self, name: str):
+        return getattr(self._load(), name)
+
+    def __setattr__(self, name: str, value):
+        if name == "_instance":
+            super().__setattr__(name, value)
+        else:
+            setattr(self._load(), name, value)
+
+    def reset(self) -> None:
+        self._instance = None
+        _create_settings.cache_clear()
 
 
-def verify_settings():
-    important_envs = ["SECRET_KEY"]
-    other_envs = ["SQLALCHEMY_DATABASE_PATH", "LOCK_PIN", "UNLOCK_PIN", "MOCK_GPIO"]
-    for setting in important_envs:
-        if not os.getenv(setting):
-            raise ValueError(
-                f"Missing critical environment variable {setting}. Stopping..."
-            )
-    for setting in other_envs:
-        if setting not in os.environ:
-            logger.warning(f"Env var {setting} not set. Continuing with defaults.")
-
-
-verify_settings()
-secret_key = os.getenv("SECRET_KEY")
-sqlalchemy_database_path = os.getenv("SQLALCHEMY_DATABASE_PATH")
-lock_pin = os.getenv("LOCK_PIN")
-unlock_pin = os.getenv("UNLOCK_PIN")
-mock_gpio = os.getenv("MOCK_GPIO")
+settings = _SettingsProxy()