from datetime import datetime, timedelta, timezone
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
from config import get_settings
from database import get_db
import models

settings = get_settings()
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login", auto_error=False)


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + (
        expires_delta or timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    )
    to_encode.update({"exp": expire, "type": "access"})
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def create_refresh_token(data: dict) -> str:
    to_encode = data.copy()
    expire = datetime.now(timezone.utc) + timedelta(days=settings.REFRESH_TOKEN_EXPIRE_DAYS)
    to_encode.update({"exp": expire, "type": "refresh"})
    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)


def verify_token(token: str, token_type: str) -> Optional[dict]:
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        if payload.get("type") != token_type:
            return None
        return payload
    except JWTError:
        return None


def get_current_user(
    token: Optional[str] = Depends(oauth2_scheme),
    db: Session = Depends(get_db),
) -> Optional[models.User]:
    if not token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )
    payload = verify_token(token, "access")
    if not payload or "sub" not in payload:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
    user = db.query(models.User).filter(models.User.username == payload["sub"]).first()
    if not user:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
    return user


def require_admin(user: models.User = Depends(get_current_user)):
    if user.role != "admin":
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin required")
    return user


def log_action(db: Session, user: Optional[models.User], action: str, details: Optional[str] = None):
    try:
        entry = models.AuditLog(
            user_id=user.id if user else None,
            username=user.username if user else None,
            action=action,
            details=details,
        )
        db.add(entry)
        db.commit()
    except Exception:
        db.rollback()


def create_default_admin(db: Session) -> Optional[models.User]:
    if not settings.CREATE_ADMIN_ON_STARTUP:
        return None
    existing = db.query(models.User).filter(models.User.username == settings.ADMIN_USERNAME).first()
    if existing:
        return existing
    admin = models.User(
        username=settings.ADMIN_USERNAME,
        password_hash=get_password_hash(settings.ADMIN_PASSWORD),
        role="admin",
    )
    db.add(admin)
    db.commit()
    db.refresh(admin)
    return admin