refactor: improve code structure and optimize key functions

backend/app/core/config.py

@@ -0,0 +1,22 @@
+from functools import lru_cache
+from typing import Literal
+
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
+
+    DATABASE_URL: str = Field(default="postgresql+asyncpg://postgres:postgres@db:5432/ctms")
+    ENV: Literal["development", "production", "test"] = "development"
+    JWT_SECRET_KEY: str = "dev-secret"
+    JWT_EXPIRE_MINUTES: int = 60
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()
+
+
+settings = get_settings()

backend/app/core/deps.py

@@ -0,0 +1,26 @@
+from typing import Annotated, AsyncGenerator
+
+from fastapi import Depends, HTTPException, status
+from pydantic import ValidationError
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.security import decode_access_token, oauth2_scheme
+from app.db.session import SessionLocal
+from app.schemas.user import TokenPayload
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    async with SessionLocal() as session:
+        yield session
+
+
+async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]) -> TokenPayload:
+    payload = decode_access_token(token)
+    try:
+        return TokenPayload(**payload)
+    except ValidationError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        ) from exc

backend/app/core/security.py

@@ -0,0 +1,30 @@
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, Optional
+
+from fastapi import HTTPException, status
+from fastapi.security import OAuth2PasswordBearer
+from jose import JWTError, jwt
+
+from app.core.config import settings
+
+
+ALGORITHM = "HS256"
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login", scheme_name="Bearer")
+
+
+def create_access_token(*, subject: str, role: str, expires_delta: Optional[timedelta] = None) -> str:
+    expire = datetime.now(timezone.utc) + (expires_delta or timedelta(minutes=settings.JWT_EXPIRE_MINUTES))
+    to_encode: Dict[str, Any] = {"sub": subject, "role": role, "exp": expire}
+    return jwt.encode(to_encode, settings.JWT_SECRET_KEY, algorithm=ALGORITHM)
+
+
+def decode_access_token(token: str) -> Dict[str, Any]:
+    try:
+        payload = jwt.decode(token, settings.JWT_SECRET_KEY, algorithms=[ALGORITHM])
+    except JWTError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        ) from exc
+    return payload