from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
import bcrypt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from .config import settings


# OAuth2 scheme
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")


def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a password against a hash"""
    try:
        password_bytes = plain_password.encode('utf-8')
        hashed_bytes = hashed_password.encode('utf-8')
        return bcrypt.checkpw(password_bytes, hashed_bytes)
    except Exception as e:
        print(f"Password verification error: {e}")
        return False


def get_password_hash(password: str) -> str:
    """Hash a password"""
    password_bytes = password.encode('utf-8')
    salt = bcrypt.gensalt()
    hashed = bcrypt.hashpw(password_bytes, salt)
    return hashed.decode('utf-8')


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """Create 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, "type": "access"})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


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


def decode_token(token: str) -> dict:
    """Decode and validate 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="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )


async def get_current_user_id(token: str = Depends(oauth2_scheme)) -> str:
    """Extract user ID from token"""
    payload = decode_token(token)
    user_id: str = payload.get("sub")
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )
    return user_id