import json
from fastapi import Header
from typing import Optional

from app.core.security import ServerEnum
from app.utils.jwt_utils import verify_jwt_token
from app.models.user import User
from app.core.exceptions import (
    UnauthorizedException,
    ValidationException,
    StatusCode,
    ErrorMessage
)


def USER_KEY(user_id: str, server: str) -> str:
    """生成用户缓存key"""
    return f"user:{user_id}:{server}"


class AuthService:
    """认证服务"""

    @staticmethod
    async def verify_and_get_user(
            authorization: Optional[str] = Header(None),
            source: Optional[str] = Header(None)
    ) -> User:
        """验证用户token并返回用户信息"""

        # 检查请求来源
        if not source or not ServerEnum.exist(source):
            raise ValidationException(detail=ErrorMessage.INVALID_HEADER)

        # 检查token是否存在
        if not authorization:
            raise UnauthorizedException(detail=ErrorMessage.UNAUTHORIZED)
        
        token = authorization.replace("Bearer ", "")
        # 验证JWT token
        claims = verify_jwt_token(token)
        if not claims:
            raise UnauthorizedException(
                detail=ErrorMessage.INVALID_TOKEN,
                code=StatusCode.INVALID_TOKEN
            )
        user_id = claims.get("sub")
        if not user_id:
            raise UnauthorizedException(
                detail=ErrorMessage.INVALID_TOKEN,
                code=StatusCode.INVALID_TOKEN
            )
        return User(id=user_id, token=token)


# 创建全局实例
auth_service = AuthService()