import secrets
from datetime import datetime, timedelta

import bcrypt
from fastapi import Depends, HTTPException, Request, status
from sqlalchemy.orm import Session as DbSession

from app.config import settings
from app.database import get_db
from app.models import Session, User

SESSION_COOKIE = "session_token"


def hash_password(password: str) -> str:
    return bcrypt.hashpw(password.encode(), bcrypt.gensalt()).decode()


def verify_password(plain: str, hashed: str) -> bool:
    return bcrypt.checkpw(plain.encode(), hashed.encode())


def create_session_token() -> str:
    return secrets.token_urlsafe(32)


def create_user_session(db: DbSession, user: User) -> Session:
    token = create_session_token()
    expires_at = datetime.utcnow() + timedelta(hours=settings.session_lifetime_hours)
    session = Session(user_id=user.id, token=token, expires_at=expires_at)
    db.add(session)
    db.commit()
    db.refresh(session)
    return session


def get_session_by_token(db: DbSession, token: str) -> Session | None:
    session = db.query(Session).filter(Session.token == token, Session.is_active.is_(True)).first()
    if not session:
        return None
    if session.expires_at < datetime.utcnow():
        session.is_active = False
        db.commit()
        return None
    return session


def get_current_user(request: Request, db: DbSession = Depends(get_db)) -> User:
    token = request.cookies.get(SESSION_COOKIE)
    if not token:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Not authenticated")
    session = get_session_by_token(db, token)
    if not session:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Session expired")
    user = db.query(User).filter(User.id == session.user_id).first()
    if not user:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
    return user


def get_current_user_optional(request: Request, db: DbSession = Depends(get_db)) -> User | None:
    token = request.cookies.get(SESSION_COOKIE)
    if not token:
        return None
    session = get_session_by_token(db, token)
    if not session:
        return None
    return db.query(User).filter(User.id == session.user_id).first()


def verify_api_key(request: Request) -> None:
    auth = request.headers.get("Authorization", "")
    if not auth.startswith("Bearer "):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid API key")
    key = auth.removeprefix("Bearer ").strip()
    if not secrets.compare_digest(key, settings.api_key):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Invalid API key")