import requests
import json
from io import BytesIO


def upload_image_to_wechat(access_token, image_url):
    """
    上传图片到微信公众号素材库

    参数:
        access_token (str): 公众号的access_token
        image_url (str): 图片的URL地址

    返回:
        str: 成功时返回media_id
        None: 失败时返回None
    """
    if not access_token or not image_url:
        return None

    # 微信上传临时素材接口
    upload_url = f"https://api.weixin.qq.com/cgi-bin/media/upload?access_token={access_token}&type=image"

    try:
        # 先从URL下载图片
        image_response = requests.get(image_url, timeout=15)
        image_response.raise_for_status()  # 检查请求是否成功

        # 将图片内容转换为文件对象
        image_file = BytesIO(image_response.content)

        # 构造表单数据
        files = {
            'media': ('image.jpg', image_file, 'image/jpeg')
        }

        # 上传图片到微信服务器
        response = requests.post(upload_url, files=files, timeout=15)
        result = json.loads(response.text)

        # 检查是否返回错误
        if "errcode" in result and result["errcode"] != 0:
            return None

        # 返回media_id
        media_id = result.get("media_id")
        if media_id:
            return media_id
        else:
            return None

    except requests.exceptions.RequestException:
        return None
    except json.JSONDecodeError:
        return None
    except Exception:
        return None