from fastapi import APIRouter, Request, Response, Query
from app.core.wecombot import WecomBot
from app.models.database import get_db
from app.models.community import CommunityDB
from app.core.config import settings
import xml.etree.ElementTree as ET
import logging
import hashlib
import base64
from Crypto.Cipher import AES
import typing
import struct

router = APIRouter()

def decrypt_msg(msg_encrypt: str, signature: str, timestamp: str, nonce: str) -> typing.Optional[str]:
    """解密企业微信消息"""
    try:
        token = settings.WECHAT_CORP_TOKEN
        encoding_aes_key = settings.WECHAT_CORP_ENCODING_AES_KEY
        corpid = settings.WECHAT_CORP_ID
        
        # 1. 验证签名
        sort_list = [token, timestamp, nonce, msg_encrypt]
        sort_list.sort()
        sha1 = hashlib.sha1()
        sha1.update("".join(sort_list).encode())
        calc_signature = sha1.hexdigest()
        if calc_signature != signature:
            return None
            
        # 2. 解密消息
        aes_key = base64.b64decode(encoding_aes_key + "=")
        aes = AES.new(aes_key, AES.MODE_CBC, aes_key[:16])
        
        # 解密
        text = base64.b64decode(msg_encrypt)
        decrypted_text = aes.decrypt(text)
        
        # 去除补位
        pad = decrypted_text[-1]
        if not isinstance(pad, int):
            pad = ord(pad)
        content = decrypted_text[:-pad]
        
        # 验证corpid
        xml_len = struct.unpack('!I', content[16:20])[0]
        xml_content = content[20 : 20 + xml_len]
        from_corpid = content[20 + xml_len:]
        
        if from_corpid.decode() != corpid:
            return None
            
        return xml_content.decode()
        
    except Exception as e:
        logging.exception("解密企业微信消息失败")
        return None

@router.get("/callback")
async def verify_callback(
    msg_signature: str = Query(..., description="签名"),
    timestamp: str = Query(..., description="时间戳"),
    nonce: str = Query(..., description="随机数"),
    echostr: str = Query(..., description="随机字符串")
):
    """验证回调配置"""
    try:
        # 解密echostr
        decrypted_str = decrypt_msg(echostr, msg_signature, timestamp, nonce)
        if not decrypted_str:
            return Response(status_code=403)
            
        return Response(content=decrypted_str, media_type="text/plain")
        
    except Exception as e:
        logging.exception("验证回调配置失败")
        return Response(status_code=403)

@router.post("/callback")
async def wechat_corp_callback(
    request: Request,
    msg_signature: str = Query(..., description="签名"),
    timestamp: str = Query(..., description="时间戳"),
    nonce: str = Query(..., description="随机数")
):
    """处理企业微信回调消息"""
    try:
        # 读取原始XML数据
        body = await request.body()
        body_str = body.decode()
        
        # 解析XML获取加密消息
        root = ET.fromstring(body_str)
        encrypt_msg = root.find('Encrypt').text
        
        # 解密消息
        decrypted_msg = decrypt_msg(encrypt_msg, msg_signature, timestamp, nonce)
        if not decrypted_msg:
            return Response(content="success", media_type="text/plain")
            
        # 解析解密后的XML
        msg_root = ET.fromstring(decrypted_msg)
        
        print(f"企业微信回调消息：{decrypted_msg}")
        
        # 解析基本信息
        msg_type = msg_root.find('MsgType').text
        
        # 处理事件消息
        if msg_type == 'event':
            event = msg_root.find('Event').text
            
            # 处理进群事件
            if event == 'change_external_chat':
                chat_id = msg_root.find('ChatId').text
                change_type = msg_root.find('ChangeType').text
                
                if change_type == 'add_member':
                    # 获取数据库会话
                    db = next(get_db())
                    
                    # 查找对应的小区
                    community = db.query(CommunityDB).filter(
                        CommunityDB.webot_webhook.isnot(None)
                    ).first()
                    
                    if community and community.webot_webhook:
                        # 发送欢迎消息
                        wecom_bot = WecomBot()
                        await wecom_bot.send_welcome_message(community.webot_webhook)
        
        return Response(content="success", media_type="text/plain")
        
    except Exception as e:
        logging.exception("处理企业微信回调消息异常")
        return Response(content="success", media_type="text/plain")