LMS/backend/app/routers/auth.py

from fastapi import APIRouter, Cookie, Depends, HTTPException, Response, status
from sqlalchemy.orm import Session
import os

from ..database import get_db
from ..dependencies import get_current_user
from ..models import User, UserRole, UserStatus
from ..schemas import UserLogin, UserOut, UserRegister, UserApprove, ChangePassword
from ..security import (
    ACCESS_TOKEN_EXPIRE_MINUTES,
    create_access_token,
    hash_password,
    verify_password,
)

router = APIRouter(prefix="/auth", tags=["auth"])

_COOKIE_NAME = "access_token"
_COOKIE_MAX_AGE = ACCESS_TOKEN_EXPIRE_MINUTES * 60   # seconds
_COOKIE_SECURE = os.getenv("COOKIE_SECURE", "false").lower() == "true"


def _set_auth_cookie(response: Response, user_id: int) -> None:
    token = create_access_token(user_id)
    response.set_cookie(
        key=_COOKIE_NAME,
        value=token,
        httponly=True,
        secure=_COOKIE_SECURE,
        samesite="lax",
        max_age=_COOKIE_MAX_AGE,
        path="/",
    )


# ── POST /auth/register ───────────────────────────────────────────────────────

@router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
def register(body: UserRegister, response: Response, db: Session = Depends(get_db)):
    if db.query(User).filter(User.username == body.username).first():
        raise HTTPException(status_code=400, detail="Username already taken.")
    if db.query(User).filter(User.email == body.email).first():
        raise HTTPException(status_code=400, detail="Email already registered.")

    # Admin registers as approved immediately; others start as pending
    initial_status = (
        UserStatus.approved if body.role == UserRole.admin else UserStatus.pending
    )

    user = User(
        username=body.username,
        email=body.email,
        password_hash=hash_password(body.password),
        role=body.role,
        status=initial_status,
    )
    db.add(user)
    db.commit()
    db.refresh(user)

    # Only set auth cookie if immediately approved (admin self-registration)
    if user.status == UserStatus.approved:
        _set_auth_cookie(response, user.id)
    return user


# ── POST /auth/login ──────────────────────────────────────────────────────────

@router.post("/login", response_model=UserOut)
def login(body: UserLogin, response: Response, db: Session = Depends(get_db)):
    user: User | None = db.query(User).filter(User.username == body.username).first()

    # Constant-time: always verify even when user is None to prevent timing attacks
    dummy_hash = "$2b$12$KIXyb/r7MBJ3z32Dc3y8YuNfj7DhpNcaYgU2q8uGiHjJ6YFe6RVxm"
    password_ok = verify_password(body.password, user.password_hash if user else dummy_hash)

    if not user or not password_ok:
        raise HTTPException(status_code=401, detail="Invalid username or password.")

    if user.status == UserStatus.pending:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Your account is pending admin approval.",
        )
    if user.status == UserStatus.rejected:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Your account has been rejected.",
        )

    _set_auth_cookie(response, user.id)
    return user


# ── POST /auth/logout ─────────────────────────────────────────────────────────

@router.post("/logout", status_code=status.HTTP_204_NO_CONTENT)
def logout(response: Response):
    response.delete_cookie(key=_COOKIE_NAME, path="/")


# ── GET /auth/me ──────────────────────────────────────────────────────────────

@router.get("/me", response_model=UserOut)
def me(current_user: User = Depends(get_current_user)):
    return current_user


# ── GET /auth/token  (return raw JWT for WebSocket auth) ─────────────────────

@router.get("/token")
def get_token(access_token: str | None = Cookie(default=None)):
    """
    Returns the current JWT so the frontend can pass it as a WebSocket
    query param (browsers can't send cookies on WS upgrade in all cases).
    """
    if not access_token:
        raise HTTPException(status_code=401, detail="Not authenticated.")
    return {"access_token": access_token}


# ── POST /auth/change-password ────────────────────────────────────────────────

@router.post("/change-password", status_code=status.HTTP_204_NO_CONTENT)
def change_password(
    body: ChangePassword,
    current_user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
):
    if not verify_password(body.current_password, current_user.password_hash):
        raise HTTPException(status_code=400, detail="Mật khẩu hiện tại không đúng.")
    current_user.password_hash = hash_password(body.new_password)
    db.commit()