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 LoginRequest, RegisterRequest, UserOut
from app.security import hash_password, verify_password

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


@router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
async def register(payload: RegisterRequest, db: AsyncSession = Depends(get_db)):
    existing = await db.scalar(select(User).where(User.username == payload.username))
    if existing is not None:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="username taken")

    user = User(
        username=payload.username,
        password_hash=hash_password(payload.password),
        email=payload.email,
    )
    db.add(user)
    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