/**
 * AIBOT 长连接（只传输，无工单状态）。
 *
 * 本文件职责：
 * - WECOM_AIBOT_ENABLED=true 时连 wss://openws.work.weixin.qq.com
 * - 订阅后：入站 aibot_msg_callback 转发智能体；出站 /send-group 走 aibot_send_msg
 * - 同一 Bot 只能一条长连接；并存期默认关，勿与现网 8813 双连
 *
 * 禁止：写工单/六态/Graph。密钥只读环境变量，不打日志。
 */

"use strict";

const crypto = require("crypto");
const { buildGroupMessageFrame, pickReplyReqId } = require("./group_message_frame.cjs");

function generateReqId(prefix) {
  const timestamp = Date.now();
  const random = crypto.randomBytes(4).toString("hex");
  return `${prefix}_${timestamp}_${random}`;
}

function loadWs() {
  try {
    return require("ws");
  } catch (_) {
    return null;
  }
}

/**
 * @param {object} opts
 * @param {boolean} opts.enabled
 * @param {(payloadText: string) => Promise<object>} opts.forwardToAgent
 * @param {() => boolean} [opts.shouldStop]
 */
function startLongConnectionLoop(opts) {
  const enabled = !!opts.enabled;
  const forwardToAgent = opts.forwardToAgent;
  const shouldStop = opts.shouldStop || (() => false);
  const botId = String(process.env.WECOM_AIBOT_BOT_ID || "").trim();
  const secret = String(process.env.WECOM_AIBOT_SECRET || "").trim();
  const wsUrl =
    process.env.WECOM_AIBOT_WS_URL || "wss://openws.work.weixin.qq.com";

  const state = {
    ws: null,
    connected: false,
    subscribed: false,
    lastError: "",
    pending: new Map(),
    lastCallback: new Map(),
    lastAnyReq: "",
    heartbeatTimer: null,
    reconnectTimer: null,
    stop: () => {},
  };

  function status() {
    return {
      enabled,
      connected: state.connected,
      subscribed: state.subscribed,
      lastError: state.lastError,
      hasCredentials: Boolean(botId && secret),
    };
  }

  function sendWs(payload, reqId) {
    return new Promise((resolve, reject) => {
      if (!state.ws || state.ws.readyState !== 1 || !state.subscribed) {
        const err = new Error("ws_offline");
        err.code = "ws_offline";
        reject(err);
        return;
      }
      const timer = setTimeout(() => {
        state.pending.delete(reqId);
        const err = new Error("send_timeout");
        err.code = "send_timeout";
        reject(err);
      }, 8000);
      state.pending.set(reqId, { resolve, reject, timer });
      state.ws.send(JSON.stringify(payload));
    });
  }

  function sendGroupMessage({ chatId, content, callbackReqId }) {
    const text = String(content || "");
    const fromCaller = String(callbackReqId || "").trim();
    const chatKey = String(chatId || "").trim();
    const fromChat = state.lastCallback.get(chatKey) || "";
    const replyReqId = pickReplyReqId({
      fromCaller,
      fromChat,
      lastAny: state.lastAnyReq || "",
    });
    // 用这次 @ 的 req_id 回 aibot_respond_msg，群里才会引用原消息。
    const reqId = replyReqId || generateReqId("aibot_send_msg");
    const frame = buildGroupMessageFrame({
      chatId,
      content: text,
      callbackReqId: replyReqId,
      reqId,
    });
    // eslint-disable-next-line no-console
    console.log(
      "[aibot-long-connection] 出站 cmd=",
      frame.cmd,
      "chat=",
      chatKey || "-",
      "hasReq=",
      Boolean(replyReqId)
    );
    return sendWs(frame, reqId);
  }

  /**
   * 空运群发报价模板：分片上传后 aibot_send_msg file。
   * 单个分片不超过 512KB（编码前）。
   */
  async function sendGroupFile({ chatId, filename, fileB64, fileBytes }) {
    const buf = Buffer.isBuffer(fileBytes)
      ? fileBytes
      : Buffer.from(String(fileB64 || ""), "base64");
    const name = String(filename || "quote.xlsx").trim() || "quote.xlsx";
    if (!chatId || !buf.length) {
      const err = new Error("file_empty");
      err.code = "file_empty";
      throw err;
    }
    const chunkSize = 400 * 1024;
    const totalChunks = Math.max(1, Math.ceil(buf.length / chunkSize));
    const md5 = crypto.createHash("md5").update(buf).digest("hex");
    const initReq = generateReqId("aibot_upload_media_init");
    const init = await sendWs(
      {
        cmd: "aibot_upload_media_init",
        headers: { req_id: initReq },
        body: {
          type: "file",
          filename: name,
          total_size: buf.length,
          total_chunks: totalChunks,
          md5,
        },
      },
      initReq
    );
    const uploadId = String((init.body && init.body.upload_id) || "").trim();
    if (!uploadId) {
      const err = new Error("upload_init_failed");
      err.code = "upload_init_failed";
      throw err;
    }
    for (let i = 0; i < totalChunks; i += 1) {
      const slice = buf.subarray(i * chunkSize, Math.min(buf.length, (i + 1) * chunkSize));
      const chunkReq = generateReqId("aibot_upload_media_chunk");
      await sendWs(
        {
          cmd: "aibot_upload_media_chunk",
          headers: { req_id: chunkReq },
          body: {
            upload_id: uploadId,
            chunk_index: i,
            base64_data: slice.toString("base64"),
          },
        },
        chunkReq
      );
    }
    const finishReq = generateReqId("aibot_upload_media_finish");
    const finished = await sendWs(
      {
        cmd: "aibot_upload_media_finish",
        headers: { req_id: finishReq },
        body: { upload_id: uploadId },
      },
      finishReq
    );
    const mediaId = String((finished.body && finished.body.media_id) || "").trim();
    if (!mediaId) {
      const err = new Error("upload_finish_failed");
      err.code = "upload_finish_failed";
      throw err;
    }
    const sendReq = generateReqId("aibot_send_msg");
    return sendWs(
      {
        cmd: "aibot_send_msg",
        headers: { req_id: sendReq },
        body: {
          chatid: chatId,
          chat_type: 2,
          msgtype: "file",
          file: { media_id: mediaId },
        },
      },
      sendReq
    );
  }

  if (!enabled) {
    // eslint-disable-next-line no-console
    console.log("[aibot-long-connection] 未启用（WECOM_AIBOT_ENABLED=false），不连企微");
    return { stop: () => {}, sendGroupMessage, sendGroupFile, status };
  }
  if (!botId || !secret) {
    state.lastError = "missing_bot_credentials";
    // eslint-disable-next-line no-console
    console.warn(
      "[aibot-long-connection] 已启用但缺少 WECOM_AIBOT_BOT_ID / WECOM_AIBOT_SECRET，无法订阅"
    );
    return { stop: () => {}, sendGroupMessage, sendGroupFile, status };
  }

  const WebSocket = loadWs();
  if (!WebSocket) {
    state.lastError = "ws_package_missing";
    // eslint-disable-next-line no-console
    console.warn("[aibot-long-connection] 未安装 ws 包，请在 aibot-bridge 目录执行 npm install");
    return { stop: () => {}, sendGroupMessage, sendGroupFile, status };
  }

  function startHeartbeat() {
    stopHeartbeat();
    state.heartbeatTimer = setInterval(() => {
      if (!state.ws || state.ws.readyState !== 1) {
        return;
      }
      try {
        state.ws.send(
          JSON.stringify({
            cmd: "ping",
            headers: { req_id: generateReqId("ping") },
          })
        );
      } catch (_) {
        /* ignore */
      }
    }, 25000);
  }

  function stopHeartbeat() {
    if (state.heartbeatTimer) {
      clearInterval(state.heartbeatTimer);
      state.heartbeatTimer = null;
    }
  }

  function scheduleReconnect() {
    if (shouldStop() || state.reconnectTimer) {
      return;
    }
    state.reconnectTimer = setTimeout(() => {
      state.reconnectTimer = null;
      connect();
    }, 5000);
  }

  function settlePending(reqId, errcode, errmsg, frame) {
    const wait = state.pending.get(reqId);
    if (!wait) {
      return;
    }
    clearTimeout(wait.timer);
    state.pending.delete(reqId);
    if (Number(errcode) === 0) {
      wait.resolve({ ok: true, body: (frame && frame.body) || {}, frame: frame || {} });
      return;
    }
    const err = new Error(errmsg || "send_failed");
    err.code = "wecom_error";
    err.errcode = errcode;
    wait.reject(err);
  }

  function normalizeInbound(frame) {
    const body = frame.body || {};
    const from = body.from || {};
    const text = (body.text && body.text.content) || "";
    return {
      sender_id: String(from.userid || "").trim(),
      message_id: String(body.msgid || (frame.headers && frame.headers.req_id) || "").trim(),
      content: text,
      msg_type: String(body.msgtype || "text"),
      chat_id: String(body.chatid || "").trim(),
      chat_type: body.chattype === "single" ? "c2c" : "group",
      raw: {
        source: "aibot",
        aibot_req_id: frame.headers && frame.headers.req_id,
      },
    };
  }

  function handleFrame(raw) {
    let frame;
    try {
      frame = JSON.parse(raw);
    } catch (_) {
      return;
    }
    const reqId = frame.headers && frame.headers.req_id;
    // 出站 ACK 带 chatid，不能当成入站，否则会盖掉这次 @ 的 req_id，群里就没有引用。
    if (reqId && state.pending.has(reqId)) {
      settlePending(reqId, frame.errcode, frame.errmsg, frame);
      return;
    }
    if (frame.cmd === "aibot_event_callback") {
      const ev = (frame.body && frame.body.event && frame.body.event.eventtype) || "";
      // eslint-disable-next-line no-console
      console.warn("[aibot-long-connection] 事件", ev || "-");
      if (ev === "disconnected_event") {
        state.lastError = "kicked_by_new_connection";
      }
      return;
    }
    const bodyHint = frame.body || {};
    const looksLikeInbound = Boolean(
      frame.cmd === "aibot_msg_callback" ||
        (bodyHint.msgid && (bodyHint.from || (bodyHint.text && bodyHint.text.content)))
    );
    if (looksLikeInbound) {
      // eslint-disable-next-line no-console
      console.log(
        "[aibot-long-connection] 收到入站 cmd=",
        frame.cmd || "-",
        "msgid=",
        bodyHint.msgid || "-",
        "chat=",
        bodyHint.chatid || "-"
      );
      const inbound = normalizeInbound(frame);
      const chatKey = inbound.chat_id || String(bodyHint.chatid || "").trim();
      if (reqId && chatKey) {
        state.lastCallback.set(chatKey, reqId);
      }
      if (reqId) {
        state.lastAnyReq = reqId;
      }
      const officialBody = Object.assign({}, frame.body || {}, {
        aibot_direct: true,
        aibot_req_id: reqId || "",
      });
      const payload = inbound.sender_id
        ? Object.assign({}, officialBody, {
            sender_id: inbound.sender_id,
            message_id: inbound.message_id,
            content: inbound.content,
            chat_id: inbound.chat_id,
            chat_type: inbound.chat_type,
          })
        : officialBody;
      if (!payload.sender_id && !payload.from) {
        return;
      }
      Promise.resolve(forwardToAgent(JSON.stringify(payload))).catch((e) => {
        // eslint-disable-next-line no-console
        console.warn("[aibot-long-connection] 转发入站失败", String(e && e.message ? e.message : e));
      });
    }
  }

  function connect() {
    if (shouldStop()) {
      return;
    }
    // eslint-disable-next-line no-console
    console.warn(
      "[aibot-long-connection] 即将连接企微长连接；请确认现网 8813 已停，避免双连"
    );
    const ws = new WebSocket(wsUrl);
    state.ws = ws;
    ws.on("open", () => {
      state.connected = true;
      state.lastError = "";
      const reqId = generateReqId("aibot_subscribe");
      ws.send(
        JSON.stringify({
          cmd: "aibot_subscribe",
          headers: { req_id: reqId },
          body: { bot_id: botId, secret },
        })
      );
      // eslint-disable-next-line no-console
      console.log("[aibot-long-connection] 已发订阅 req_id前缀=aibot_subscribe");
    });
    ws.on("message", (buf) => {
      const text = Buffer.isBuffer(buf) ? buf.toString("utf8") : String(buf);
      let frame;
      try {
        frame = JSON.parse(text);
      } catch (_) {
        // eslint-disable-next-line no-console
        console.warn("[aibot-long-connection] 非JSON帧 len=", text.length);
        handleFrame(text);
        return;
      }
      // eslint-disable-next-line no-console
      const reqPrefix = String((frame.headers && frame.headers.req_id) || "").split("_").slice(0, 2).join("_");
      console.log(
        "[aibot-long-connection] 帧 cmd=",
        frame.cmd || "-",
        "req=",
        reqPrefix || "-",
        "keys=",
        Object.keys(frame).join(","),
        "errcode=",
        frame.errcode,
        "errmsg=",
        frame.errmsg || ""
      );
      if (frame.cmd === "ping") {
        try {
          ws.send(
            JSON.stringify({
              cmd: "pong",
              headers: frame.headers || {},
            })
          );
        } catch (_) {
          /* ignore */
        }
      }
      const ackReq = String((frame.headers && frame.headers.req_id) || "");
      if (ackReq.startsWith("aibot_subscribe") && Number(frame.errcode) === 0 && !state.subscribed) {
        state.subscribed = true;
        startHeartbeat();
        // eslint-disable-next-line no-console
        console.log("[aibot-long-connection] 订阅成功");
      } else if (
        ackReq.startsWith("aibot_subscribe") &&
        frame.errcode !== undefined &&
        Number(frame.errcode) !== 0
      ) {
        state.lastError = "subscribe_failed_" + String(frame.errcode);
        // eslint-disable-next-line no-console
        console.warn("[aibot-long-connection] 订阅失败 errcode=", frame.errcode);
      }
      handleFrame(text);
    });
    ws.on("close", (code, reason) => {
      stopHeartbeat();
      state.connected = false;
      state.subscribed = false;
      state.ws = null;
      // eslint-disable-next-line no-console
      console.warn(
        "[aibot-long-connection] 连接关闭 code=",
        code,
        "reason=",
        reason ? String(reason).slice(0, 120) : ""
      );
      if (!shouldStop()) {
        scheduleReconnect();
      }
    });
    ws.on("error", (e) => {
      state.lastError = "ws_error";
      // eslint-disable-next-line no-console
      console.warn("[aibot-long-connection] 连接错误", String(e && e.message ? e.message : e));
    });
    ws.on("ping", () => {
      try {
        ws.pong();
      } catch (_) {
        /* ignore */
      }
    });
  }

  connect();

  state.stop = () => {
    stopHeartbeat();
    if (state.reconnectTimer) {
      clearTimeout(state.reconnectTimer);
      state.reconnectTimer = null;
    }
    if (state.ws) {
      try {
        state.ws.close();
      } catch (_) {
        /* ignore */
      }
      state.ws = null;
    }
    state.connected = false;
    state.subscribed = false;
  };

  return {
    stop: state.stop,
    sendGroupMessage,
    sendGroupFile,
    status,
    /**
     * 测试注入：模拟 SDK 收到一帧已解析 JSON，只做转发。
     * @param {object|string} frame
     */
    injectFrameForTest: async (frame) => {
      const text = typeof frame === "string" ? frame : JSON.stringify(frame);
      return forwardToAgent(text);
    },
  };
}

module.exports = { startLongConnectionLoop };