/**
 * AIBOT 长连接桥（骨架 + HTTP 转发）
 *
 * 本文件职责：
 * - /health 存活
 * - POST /forward 把已解析消息转到智能体 WECOM_AIBOT_INGRESS_URL（默认 8910/internal/aibot/inbound）
 * - 默认不连企微 Bot 长连接（并存期禁止双连）；WECOM_AIBOT_ENABLED=true 时仅打警告
 *
 * 禁止：在本进程写工单/六态/Graph。
 */

"use strict";

const http = require("http");
const { URL } = require("url");
const { startLongConnectionLoop } = require("./long_connection.cjs");

const port = Number(process.env.AIBOT_BRIDGE_PORT || 8913);
const bind = process.env.AIBOT_BRIDGE_BIND || "127.0.0.1";
const enabled = String(process.env.WECOM_AIBOT_ENABLED || "false").toLowerCase() === "true";
const ingressUrl =
  process.env.WECOM_AIBOT_INGRESS_URL ||
  "http://127.0.0.1:8910/internal/aibot/inbound";
const bridgeToken = process.env.WECOM_AIBOT_BRIDGE_TOKEN || "";

function readBody(req) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    req.on("data", (c) => chunks.push(c));
    req.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")));
    req.on("error", reject);
  });
}

function sendJson(res, code, obj) {
  const body = JSON.stringify(obj);
  res.writeHead(code, { "Content-Type": "application/json; charset=utf-8" });
  res.end(body);
}

function forwardToAgent(payloadText) {
  return new Promise((resolve, reject) => {
    let target;
    try {
      target = new URL(ingressUrl);
    } catch (e) {
      reject(e);
      return;
    }
    const data = Buffer.from(payloadText, "utf8");
    const req = http.request(
      {
        protocol: target.protocol,
        hostname: target.hostname,
        port: target.port || 80,
        path: target.pathname + (target.search || ""),
        method: "POST",
        headers: {
          "Content-Type": "application/json; charset=utf-8",
          "Content-Length": data.length,
          "X-Aibot-Bridge-Token": bridgeToken,
        },
        timeout: 5000,
      },
      (res) => {
        const chunks = [];
        res.on("data", (c) => chunks.push(c));
        res.on("end", () => {
          resolve({
            status: res.statusCode,
            body: Buffer.concat(chunks).toString("utf8"),
          });
        });
      }
    );
    req.on("error", reject);
    req.on("timeout", () => {
      req.destroy();
      reject(new Error("ingress_timeout"));
    });
    req.write(data);
    req.end();
  });
}

const server = http.createServer(async (req, res) => {
  const url = (req.url || "").split("?")[0];

  if (req.method === "GET" && (url === "/health" || url === "/health/")) {
    sendJson(res, 200, {
      status: "UP",
      service: "aibot-bridge",
      bind,
      port,
      wecomAibotEnabled: enabled,
      ingressUrl,
      longConnectionShell: true,
      note: enabled
        ? "enabled：长连接帧循环壳已起（默认无 Bot SDK）；勿与现网双连"
        : "Bot 长连接默认关闭；可用 POST /forward 测转发",
    });
    return;
  }

  // 测试/后续 Bot 回调：把 JSON 原样转到智能体（不做业务）
  if (req.method === "POST" && (url === "/forward" || url === "/forward/")) {
    try {
      const raw = await readBody(req);
      if (!raw) {
        sendJson(res, 400, { error: "empty_body" });
        return;
      }
      // 轻量校验 JSON
      JSON.parse(raw);
      const out = await forwardToAgent(raw);
      sendJson(res, 200, {
        status: "forwarded",
        ingressStatus: out.status,
        ingressBody: (() => {
          try {
            return JSON.parse(out.body);
          } catch (_) {
            return out.body;
          }
        })(),
      });
    } catch (e) {
      sendJson(res, 502, { error: "forward_failed", message: String(e && e.message ? e.message : e) });
    }
    return;
  }

  sendJson(res, 404, { error: "not_found", path: req.url });
});

server.listen(port, bind, () => {
  // eslint-disable-next-line no-console
  console.log(
    `[aibot-bridge] http://${bind}:${port}/health forward→${ingressUrl} enabled=${enabled}`
  );
  if (enabled) {
    // eslint-disable-next-line no-console
    console.warn(
      "[aibot-bridge] WECOM_AIBOT_ENABLED=true：请确认已停现网桥且不会双连同一 Bot"
    );
  }
  // 传输壳：enabled 时跑心跳循环；未接 SDK 前不会产生入站帧
  startLongConnectionLoop({
    enabled,
    forwardToAgent,
  });
});