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

oauth2_scheme = OAuth2PasswordBearer(tokenUrl=f"{settings.API_V1_STR}/auth/login")

# We call bcrypt directly rather than through passlib: passlib 1.7.x is
# incompatible with bcrypt >= 4.1 (its version shim raises on the modern
# library). bcrypt only uses the first 72 bytes of a password, so we truncate
# to that to avoid the ValueError bcrypt 5.x raises on longer inputs. Existing
# $2b$ hashes (created via passlib's bcrypt backend) verify unchanged.
_BCRYPT_MAX_BYTES = 72


def _to_bytes(password: str) -> bytes:
    return password.encode("utf-8")[:_BCRYPT_MAX_BYTES]


def verify_password(plain: str, hashed: str) -> bool:
    try:
        return bcrypt.checkpw(_to_bytes(plain), hashed.encode("utf-8"))
    except (ValueError, TypeError):
        return False


def hash_password(password: str) -> str:
    return bcrypt.hashpw(_to_bytes(password), bcrypt.gensalt()).decode("utf-8")


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


def decode_token(token: str) -> dict:
    try:
        return jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Could not validate credentials",
            headers={"WWW-Authenticate": "Bearer"},
        )


async def get_current_user_payload(token: str = Depends(oauth2_scheme)) -> dict:
    return decode_token(token)


def require_roles(*roles: str):
    """Dependency factory — require one of the specified roles."""
    async def role_checker(payload: dict = Depends(get_current_user_payload)):
        if payload.get("role") not in roles:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Insufficient permissions"
            )
        return payload
    return role_checker


require_executive_or_above = require_roles("executive", "it_admin", "trustos_admin")
require_it_or_above = require_roles("it_admin", "trustos_admin")
require_admin = require_roles("trustos_admin")