from datetime import datetime, timedelta

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

from internal.database import execute_query, create_connection

# 设置密码上下文
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# 随机秘钥
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7" 
# JWT签名算法变量
ALGORITHM = "HS256"
# 设置令牌过期时间
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# 校验密码方法
def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

# 将密码进行hash
def get_password_hash(password):
    return pwd_context.hash(password)

# 认证用户
def authenticate_user(username: str, password: str):
    query = "SELECT * FROM users WHERE username = %s"
    user_data = execute_query(query, (username,))
    if not user_data:
        return None
    stored_password = user_data["password"]
    if not verify_password(password, stored_password):
        return None
    return user_data

# 创建访问令牌
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=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# 获取当前用户
async def get_current_user(token: str = Depends(create_connection)):
    # 首先定义一个 HTTPException 用于处理认证失败的情况
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    
    try:
        # 解码 JWT 令牌，验证签名和有效期
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
    except JWTError:
        # 如果 JWT 解码失败，则返回认证异常
        raise credentials_exception
    
    # 根据用户名从数据库中获取用户数据
    user = authenticate_user(username)
    if user is None:
        raise credentials_exception
    
    # 返回获取到的用户数据
    return user