feat: implement JWT authentication system

- Add register endpoint with bcrypt password hashing
- Add login endpoint returning JWT tokens
- Add logout endpoint with token blacklisting
- Add /me endpoint for current user info
- Add rate limiting (5/minute) for login attempts using slowapi
- Add user settings GET and PATCH endpoints
- Create auth middleware via get_current_user dependency
- Add UserSettings and UserSettingsUpdate schemas

src/backend/app/api/auth.py

@@ -1,7 +1,6 @@
-from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, status, Request
 from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
 from sqlalchemy.orm import Session
-from datetime import timedelta
 from typing import Annotated
 
 from ..core.database import get_db
@@ -12,41 +11,133 @@ from ..core.security import (
     verify_token,
 )
 from ..core.config import get_settings
-from ..db.schemas import UserCreate, UserResponse, Token
+from ..core.limiter import limiter
+from ..db.schemas import (
+    UserCreate,
+    UserResponse,
+    Token,
+    UserSettings,
+    UserSettingsUpdate,
+)
+from ..db.models import User
 
 router = APIRouter()
 settings = get_settings()
-oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/token")
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")
+
+TOKEN_BLACKLIST = set()
 
 
-@router.post("/register", response_model=UserResponse)
+def get_current_user(
+    token: Annotated[str, Depends(oauth2_scheme)], db: Session = Depends(get_db)
+) -> User:
+    if token in TOKEN_BLACKLIST:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Token has been revoked",
+        )
+    payload = verify_token(token)
+    if payload is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid or expired token",
+        )
+    user_id = payload.get("sub")
+    if user_id is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid token payload",
+        )
+    user = db.query(User).filter(User.id == user_id).first()
+    if user is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="User not found",
+        )
+    return user
+
+
+@router.post(
+    "/register", response_model=UserResponse, status_code=status.HTTP_201_CREATED
+)
 def register(user: UserCreate, db: Session = Depends(get_db)):
-    raise HTTPException(
-        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    existing_user = db.query(User).filter(User.email == user.email).first()
+    if existing_user:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Email already registered",
+        )
+    hashed_password = get_password_hash(user.password)
+    db_user = User(
+        email=user.email,
+        password_hash=hashed_password,
     )
+    db.add(db_user)
+    db.commit()
+    db.refresh(db_user)
+    return db_user
 
 
-@router.post("/login")
+@router.post("/login", response_model=Token)
+@limiter.limit("5/minute")
 def login(
+    request: Request,
     form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
     db: Session = Depends(get_db),
 ):
-    raise HTTPException(
-        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
-    )
+    user = db.query(User).filter(User.email == form_data.username).first()
+    if not user or not verify_password(form_data.password, user.password_hash):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+        )
+    access_token = create_access_token(data={"sub": user.id})
+    return Token(access_token=access_token, token_type="bearer")
 
 
 @router.post("/logout")
-def logout(token: Annotated[str, Depends(oauth2_scheme)]):
-    raise HTTPException(
-        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
-    )
+def logout(
+    current_user: Annotated[User, Depends(get_current_user)],
+    token: Annotated[str, Depends(oauth2_scheme)],
+):
+    TOKEN_BLACKLIST.add(token)
+    return {"message": "Successfully logged out"}
 
 
 @router.get("/me", response_model=UserResponse)
 def get_me(
-    token: Annotated[str, Depends(oauth2_scheme)], db: Session = Depends(get_db)
+    current_user: Annotated[User, Depends(get_current_user)],
 ):
-    raise HTTPException(
-        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
-    )
+    return current_user
+
+
+@router.get("/settings", response_model=UserSettings)
+def get_settings_endpoint(
+    current_user: Annotated[User, Depends(get_current_user)],
+):
+    return UserSettings(email=current_user.email)
+
+
+@router.patch("/settings", response_model=UserSettings)
+def update_settings(
+    current_user: Annotated[User, Depends(get_current_user)],
+    settings_update: UserSettingsUpdate,
+    db: Session = Depends(get_db),
+):
+    if settings_update.email:
+        existing = (
+            db.query(User)
+            .filter(User.email == settings_update.email, User.id != current_user.id)
+            .first()
+        )
+        if existing:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="Email already in use",
+            )
+        current_user.email = settings_update.email
+    if settings_update.password:
+        current_user.password_hash = get_password_hash(settings_update.password)
+    db.commit()
+    db.refresh(current_user)
+    return UserSettings(email=current_user.email)