from __future__ import annotations

import hashlib
import hmac
import base64
import time
from urllib.parse import quote_plus

import httpx

from app.config import settings
from app.schemas import IMPublishRequest, PublishResponse


class IMPublisher:
    async def publish(self, req: IMPublishRequest) -> PublishResponse:
        if not settings.im_webhook_url:
            return PublishResponse(ok=False, detail="缺少 IM_WEBHOOK_URL 配置")

        webhook = self._with_signature(settings.im_webhook_url, settings.im_secret)
        payload = {
            "msg_type": "post",
            "content": {
                "post": {
                    "zh_cn": {
                        "title": req.title,
                        "content": [[{"tag": "text", "text": req.body_markdown[:3800]}]],
                    }
                }
            },
        }

        async with httpx.AsyncClient(timeout=20) as client:
            r = await client.post(webhook, json=payload)
            try:
                data = r.json()
            except Exception:
                data = {"status_code": r.status_code, "text": r.text}

        if r.status_code >= 400:
            return PublishResponse(ok=False, detail=f"IM 推送失败: {data}", data=data)

        return PublishResponse(ok=True, detail="IM 推送成功", data=data)

    def _with_signature(self, webhook: str, secret: str | None) -> str:
        # 兼容飞书 webhook 签名参数：timestamp/sign
        if not secret:
            return webhook

        ts = str(int(time.time()))
        string_to_sign = f"{ts}\n{secret}".encode("utf-8")
        sign = base64.b64encode(hmac.new(string_to_sign, b"", hashlib.sha256).digest()).decode("utf-8")
        connector = "&" if "?" in webhook else "?"
        return f"{webhook}{connector}timestamp={ts}&sign={quote_plus(sign)}"