from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordRequestForm
from pydantic import BaseModel, field_validator

from bd import Settings
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

from bd.tables.users import User
from route.auth_utils import hash_password, verify_password, create_access_token

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


def _get_session():
    settings = Settings()
    engine = create_engine(settings.DATABASE_URL_syncpg, future=True)
    return sessionmaker(bind=engine, future=True)


class RegisterIn(BaseModel):
    username: str
    password: str
    first_name: str
    last_name: str

    @field_validator("password")
    @classmethod
    def password_strength(cls, v: str) -> str:
        if len(v) < 8:
            raise ValueError("Password must be at least 8 characters")
        return v

    @field_validator("username")
    @classmethod
    def username_clean(cls, v: str) -> str:
        v = v.strip()
        if len(v) < 3:
            raise ValueError("Username must be at least 3 characters")
        return v


@router.post("/register", status_code=201)
def register(payload: RegisterIn):
    Session = _get_session()
    with Session() as session:
        existing = session.query(User).filter(User.username == payload.username).first()
        if existing:
            raise HTTPException(status_code=400, detail="Username already taken")
        user = User(
            first_name=payload.first_name.strip(),
            last_name=payload.last_name.strip(),
            username=payload.username,
            hashed_password=hash_password(payload.password),
        )
        session.add(user)
        session.commit()
        session.refresh(user)
        return {"id": str(user.id), "username": user.username}


@router.post("/login")
def login(form: OAuth2PasswordRequestForm = Depends()):
    Session = _get_session()
    with Session() as session:
        user = session.query(User).filter(User.username == form.username).first()
        if not user or not verify_password(form.password, user.hashed_password):
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Incorrect username or password",
                headers={"WWW-Authenticate": "Bearer"},
            )
        token = create_access_token({"sub": str(user.id)})
        return {"access_token": token, "token_type": "bearer"}