feat: add login, session cookies, and get_current_user

backend/app/routes/auth.py

@@ -1,11 +1,15 @@
-from fastapi import APIRouter, Depends, HTTPException, status
+from datetime import datetime, timezone
+
+from fastapi import APIRouter, Depends, HTTPException, Response, status
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.db import get_db
+from app.deps import SESSION_COOKIE_NAME, get_current_user
+from app.models.auth_session import AuthSession, SESSION_TTL, generate_session_token
 from app.models.user import User
-from app.schemas import RegisterRequest, UserOut
-from app.security import hash_password
+from app.schemas import LoginRequest, RegisterRequest, UserOut
+from app.security import hash_password, verify_password
 
 router = APIRouter(prefix="/auth", tags=["auth"])
 
@@ -25,3 +29,38 @@ async def register(payload: RegisterRequest, db: AsyncSession = Depends(get_db))
     await db.commit()
     await db.refresh(user)
     return user
+
+
+@router.post("/login", response_model=UserOut)
+async def login(payload: LoginRequest, response: Response, db: AsyncSession = Depends(get_db)):
+    user = await db.scalar(select(User).where(User.username == payload.username))
+    if user is None or not verify_password(payload.password, user.password_hash):
+        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="invalid credentials")
+
+    raw_token, token_hash = generate_session_token()
+    session = AuthSession(
+        user_id=user.id,
+        token_hash=token_hash,
+        expires_at=datetime.now(timezone.utc) + SESSION_TTL,
+    )
+    db.add(session)
+    await db.commit()
+
+    response.set_cookie(
+        SESSION_COOKIE_NAME,
+        raw_token,
+        httponly=True,
+        samesite="lax",
+        max_age=int(SESSION_TTL.total_seconds()),
+    )
+    return user
+
+
+@router.post("/logout", status_code=status.HTTP_204_NO_CONTENT)
+async def logout(response: Response):
+    response.delete_cookie(SESSION_COOKIE_NAME)
+
+
+@router.get("/me", response_model=UserOut)
+async def me(user: User = Depends(get_current_user)):
+    return user