import aiohttp
from app.core.config import settings
import requests
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization
import json
import base64
import time
import random
import string
from cryptography.x509 import load_pem_x509_certificate
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

def generate_random_string(length=32):
    """生成指定长度的随机字符串"""
    return ''.join(random.choices(string.ascii_letters + string.digits, k=length))


class WeChatClient:
    """微信客户端"""
    
    def __init__(self):
        self.appid = settings.WECHAT_APPID
        self.secret = settings.WECHAT_SECRET
    
    async def get_access_token(self):
        """获取接口调用凭证"""
        if self.access_token:
            return self.access_token
            
        async with aiohttp.ClientSession() as session:
            url = f"https://api.weixin.qq.com/cgi-bin/token"
            params = {
                "grant_type": "client_credential",
                "appid": self.appid,
                "secret": self.secret
            }
            async with session.get(url, params=params) as response:
                result = await response.json()
                if "access_token" in result:
                    self.access_token = result["access_token"]
                    return self.access_token
                raise Exception(result.get("errmsg", "获取access_token失败"))
    
    async def get_phone_number(self, code: str):
        """获取用户手机号"""
        access_token = await self.get_access_token()
        
        async with aiohttp.ClientSession() as session:
            url = f"https://api.weixin.qq.com/wxa/business/getuserphonenumber"
            params = {"access_token": access_token}
            data = {"code": code}
            
            async with session.post(url, params=params, json=data) as response:
                result = await response.json()
                if result.get("errcode") == 0:
                    return result.get("phone_info")
                raise Exception(result.get("errmsg", "获取手机号失败")) 
    
    
    async def code2session(self, code: str) -> dict:
        """通过 code 获取用户 openid
        
        Args:
            code: 登录凭证
        Returns:
            dict: 包含 openid 等信息
        """
        async with aiohttp.ClientSession() as session:
            url = "https://api.weixin.qq.com/sns/jscode2session"
            params = {
                "appid": self.appid,
                "secret": self.secret,
                "js_code": code,
                "grant_type": "authorization_code"
            }
            
            async with session.get(url, params=params) as response:
                result = await response.json()
                if "openid" in result:
                    return result
                raise Exception(result.get("errmsg", "获取openid失败"))