[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/database.py

@@ -1,38 +1,48 @@
 import logging
-from os import getenv, path
+from functools import lru_cache
 
+from sqlalchemy import inspect
 from sqlmodel import Session, SQLModel, create_engine
 
+from app.services.settings import settings
+
 logger = logging.getLogger(__name__)
 
-SQLALCHEMY_DATABASE_PATH = getenv("SQLALCHEMY_DATABASE_PATH", "./gatekeeper.db")
-SQLALCHEMY_DATABASE_URL = "sqlite:///" + SQLALCHEMY_DATABASE_PATH
 
-engine = create_engine(SQLALCHEMY_DATABASE_URL)
+@lru_cache
+def get_engine():
+    return create_engine(
+        settings.sqlalchemy_database_url, connect_args={"check_same_thread": False}
+    )
 
 
 def create_db_and_tables():
-    if not path.exists(SQLALCHEMY_DATABASE_PATH):
-        SQLModel.metadata.create_all(engine)
+    inspector = inspect(get_engine())
+    existing_tables = inspector.get_table_names()
+    if not existing_tables:
+        SQLModel.metadata.create_all(get_engine())
         from alembic.config import Config
 
         from alembic import command
 
-        alembic_cfg = Config("./alembic.ini")
-        alembic_cfg.attributes["sqlalchemy.url"] = SQLALCHEMY_DATABASE_URL
+        alembic_cfg = Config(settings.alembic_config)
+        alembic_cfg.set_main_option("sqlalchemy.url", str(get_engine().url))
+        alembic_cfg.attributes["sqlalchemy.url"] = settings.sqlalchemy_database_url
         command.stamp(alembic_cfg, "head")
         logger.info("Database created and tables initialized.")
     else:
-        logger.info("Database already exists")
+        logger.info(
+            "Database already initialized (%d tables found).", len(existing_tables)
+        )
 
 
 def get_session():
-    with Session(engine) as db:
+    with Session(get_engine()) as db:
         yield db
 
 
 def get_db_session():
-    return Session(engine)
+    return Session(get_engine())
 
 
 def add_and_refresh(db: Session, obj):