from datetime import datetime, timedelta
from typing import Optional

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from jose import JWTError, jwt
from passlib.context import CryptContext

from core.config import settings

# Password hashing
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# Security scheme
security = HTTPBearer()


def hash_password(password: str) -> str:
    """Hash a password using bcrypt."""
    return pwd_context.hash(password)


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a plain password against a hash."""
    return pwd_context.verify(plain_password, hashed_password)


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """Create a JWT access token."""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def decode_token(token: str) -> dict:
    """Decode and validate a JWT token."""
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        return payload
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
        )


def get_current_user(credentials: HTTPAuthorizationCredentials = Depends(security)) -> dict:
    """Dependency to get current authenticated user from token."""
    token = credentials.credentials
    payload = decode_token(token)
    user_id = payload.get("sub")
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
        )
    return {"user_id": user_id}