from datetime import datetime, timedelta

import bcrypt
import jwt
from fastapi import Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer

# 密钥，用于签名JWT
SECRET_KEY = "_CM__CMCMCM__CM_"
ALGORITHM = "HS256"
user_db = {
    "admin": {
        "user_id": "1",
        "username": "admin",
        "password": bcrypt.hashpw("admin123".encode("utf-8"), bcrypt.gensalt())
    }
}
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="login")


def verify_password(plain_password, hashed_password):
    return bcrypt.checkpw(plain_password.encode('utf-8'), hashed_password)


def create_access_token(data: dict, expires_delta: timedelta = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=120)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


def get_current_user(token: str = Depends(oauth2_scheme)):
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        if payload["exp"] < int(datetime.utcnow().timestamp()):
            raise HTTPException(status_code=401, detail="Token已过期")
        username = payload["sub"]
    except jwt.ExpiredSignatureError:
        raise HTTPException(status_code=401, detail="Token已过期")
    except jwt.InvalidSignatureError:
        raise HTTPException(status_code=401, detail="Token无效")
    return username