"use strict";

/**
 * 巡检执行器 - 用 ssh2 临时建立 SSH 连接执行命令
 *
 * 用于设备巡检的命令执行：每次巡检临时建立连接，执行完即释放，
 * 不占用 terminalWorker 的连接池（巡检是低频后台任务）。
 */

const { Client: SSHClient } = require("ssh2");
const { buildAlgorithms } = require("../sshAlgorithms.cjs");

const DEFAULT_CONNECT_TIMEOUT_MS = 10_000;
const DEFAULT_EXEC_TIMEOUT_MS = 30_000;
const DEFAULT_MAX_OUTPUT_BYTES = 100 * 1024; // 100KB

/**
 * 执行单条 SSH 命令（使用 pty shell 方式，兼容交换机等需要交互式 shell 的设备）
 * @param {object} connConfig - ssh2 连接配置（host/port/username/password/privateKey 等）
 * @param {string} command - 要执行的命令
 * @param {object} [options]
 * @param {number} [options.connectTimeoutMs]
 * @param {number} [options.execTimeoutMs]
 * @param {number} [options.maxOutputBytes]
 * @returns {Promise<string>} 命令输出
 */
function execSshCommand(connConfig, command, options = {}) {
  const connectTimeoutMs = options.connectTimeoutMs || DEFAULT_CONNECT_TIMEOUT_MS;
  const execTimeoutMs = options.execTimeoutMs || DEFAULT_EXEC_TIMEOUT_MS;
  const maxOutputBytes = options.maxOutputBytes || DEFAULT_MAX_OUTPUT_BYTES;

  const DEBUG = process.env.INSPECTION_DEBUG === "1";
  if (DEBUG) {
    console.log("[InspectExec] SSH host:", connConfig.host, "| cmd:", command.slice(0, 100));
  }

  return new Promise((resolve, reject) => {
    const client = new SSHClient();
    let settled = false;
    let stdout = "";
    let execTimer = null;
    let connectTimer = null;
    let commandSent = false;

    if (DEBUG) {
      client.on("banner", (msg) => console.log("[InspectExec] banner:", msg.slice(0, 100)));
      client.on("handshake", () => console.log("[InspectExec] handshake OK"));
      client.on("error", (err) => console.error("[InspectExec] client error:", err.message));
      client.on("close", () => console.log("[InspectExec] client closed"));
    }

    const cleanup = () => {
      if (execTimer) clearTimeout(execTimer);
      if (connectTimer) clearTimeout(connectTimer);
      try { client.end(); } catch (e) { /* ignore */ }
    };

    const done = (err, result) => {
      if (settled) return;
      settled = true;
      cleanup();
      if (err) reject(err);
      else resolve(result);
    };

    // 连接超时
    connectTimer = setTimeout(() => {
      console.error("[InspectExec] 连接超时，host:", connConfig.host);
      done(new Error("SSH 连接超时（" + connectTimeoutMs / 1000 + "s）"));
    }, connectTimeoutMs);

    client.on("ready", () => {
      if (DEBUG) console.log("[InspectExec] SSH ready，打开 pty shell...");
      clearTimeout(connectTimer);

      // 使用 pty shell（交互式）执行命令
      client.shell({ term: "vt100", cols: 80, rows: 24 }, (err, stream) => {
        if (err) {
          console.error("[InspectExec] shell 失败:", err.message);
          done(new Error("打开 shell 失败: " + err.message));
          return;
        }

        // 执行超时
        execTimer = setTimeout(() => {
          console.error("[InspectExec] 命令执行超时（" + execTimeoutMs / 1000 + "s）");
          done(new Error("命令执行超时"));
        }, execTimeoutMs);

        let outputBuffer = "";

        let lastLogTime = 0;
        stream.on("data", (data) => {
          const chunk = data.toString("utf-8");
          outputBuffer += chunk;

          // 检测是否出现命令提示符
          if (!commandSent) {
            // 交换机提示符格式: <hostname> 或 hostname>
            if (chunk.includes(">") || chunk.includes("<")) {
              commandSent = true;
              stream.write(command + "\n");
              if (DEBUG) console.log("[InspectExec] 已发送命令:", command);
            }
          }

          // 命令发送后，收集输出
          if (commandSent) {
            // 检测分页提示，发送 'q' 退出
            if (outputBuffer.includes("-- More --") || outputBuffer.includes("---- More ----")) {
              if (!outputBuffer.includes("__sent_q__")) {
                stream.write("q");
                outputBuffer += "__sent_q__"; // 避免重复发送
                if (DEBUG) console.log("[InspectExec] 检测到分页，发送 q");
              }
            }

            // 检测输出完成：出现新提示符
            const lines = outputBuffer.split("\n");
            if (lines.length > 5) {
              // 检查倒数第二行是否是提示符（因为最后一行为空）
              const lastContentLine = lines[lines.length - 2]?.trim() || "";
              if (lastContentLine.includes(">") || lastContentLine.includes("#")) {
                stdout = outputBuffer.replace(/__sent_q__/g, "");
                clearTimeout(execTimer);
                if (DEBUG) console.log("[InspectExec] 命令完成，行数:", lines.length);
                done(null, stdout);
              }
            }
          }

          // 防止缓冲区过大
          if (outputBuffer.length > maxOutputBytes * 2) {
            stdout = outputBuffer.replace(/__sent_q__/g, "");
            clearTimeout(execTimer);
            if (DEBUG) console.log("[InspectExec] 缓冲区满，强制返回");
            done(null, stdout);
          }
        });

        stream.stderr.on("data", (data) => {
          // stderr 通常为空
        });

        stream.on("close", () => {
          clearTimeout(execTimer);
          if (!commandSent) {
            // 没等到提示符就关闭了，再试一次发送命令
            commandSent = true;
            stream.write(command + "\n");
          } else if (stdout) {
            // 已有输出，正常结束
            done(null, stdout);
          } else {
            done(new Error("连接意外关闭"));
          }
        });

        stream.on("error", (e) => {
          console.error("[InspectExec] stream error:", e.message);
          done(new Error("流错误: " + e.message));
        });
      });
    });

    client.on("error", (err) => {
      clearTimeout(connectTimer);
      console.error("[InspectExec] SSH 连接失败:", err.message);
      done(new Error("SSH 连接失败: " + err.message));
    });

    try {
      client.connect({
        host: connConfig.host,
        port: connConfig.port || 22,
        username: connConfig.username,
        password: connConfig.password || undefined,
        privateKey: connConfig.privateKey || undefined,
        passphrase: connConfig.passphrase || undefined,
        readyTimeout: connectTimeoutMs,
        // 跳过主机密钥验证
        hostVerifier: () => true,
        // 使用 NetMesh 的算法构建器，启用旧算法兼容，跳过 ECDSA 主机密钥
        algorithms: buildAlgorithms(true, { skipEcdsaHostKey: true }),
      });
    } catch (e) {
      clearTimeout(connectTimer);
      done(e);
    }
  });
}

/**
 * 批量执行多条 SSH 命令（一次连接，执行多条命令）
 * @param {object} connConfig - ssh2 连接配置
 * @param {string[]} commands - 命令数组
 * @param {object} [options]
 * @returns {Promise<object>} { outputs: { command, stdout }[] }
 */
function execSshCommands(connConfig, commands, options = {}) {
  const connectTimeoutMs = options.connectTimeoutMs || DEFAULT_CONNECT_TIMEOUT_MS;
  const totalTimeoutMs = options.totalTimeoutMs || 180000; // 总超时 3 分钟
  const maxOutputBytes = options.maxOutputBytes || DEFAULT_MAX_OUTPUT_BYTES;

  const DEBUG = process.env.INSPECTION_DEBUG === "1";
  if (DEBUG) {
    console.log("[InspectExec] 批量执行:", connConfig.host, "| 命令数:", commands.length);
  }

  return new Promise((resolve, reject) => {
    const client = new SSHClient();
    let settled = false;
    let connectTimer = null;
    let totalTimer = null;
    let cmdTimeout = null;
    let outputBuffer = "";
    let commandIndex = 0;
    let phase = "wait-login"; // wait-login → disable-paging → idle → waiting-output → done
    let disableRetries = 0;
    const results = [];

    const cleanup = () => {
      if (connectTimer) clearTimeout(connectTimer);
      if (totalTimer) clearTimeout(totalTimer);
      if (cmdTimeout) clearTimeout(cmdTimeout);
      try { client.end(); } catch (e) { /* ignore */ }
    };

    const done = (err, result) => {
      if (settled) return;
      settled = true;
      cleanup();
      if (err) reject(err);
      else resolve(result);
    };

    // 总超时
    totalTimer = setTimeout(() => {
      done(new Error("批量命令执行超时（" + totalTimeoutMs / 1000 + "s）"));
    }, totalTimeoutMs);

    // 匹配网络设备提示符: 取最后一行，检查是 <hostname> 或 hostname>/hostname# 格式
    function hasPrompt(text) {
      const lines = (text || '').split('\n');
      // 从后往前找非空行
      let lastLine = '';
      for (let i = lines.length - 1; i >= 0; i--) {
        const trimmed = lines[i].trimEnd();
        if (trimmed.length > 0) {
          lastLine = trimmed;
          break;
        }
      }
      if (DEBUG) {
        console.log("[InspectExec] hasPrompt check:", JSON.stringify(lastLine.slice(-100)));
      }
      // <hostname> 格式（H3C/华为 VRP）
      if (/<[\w\-./]+>\s*$/.test(lastLine)) return true;
      // hostname> 或 hostname# 格式
      if (/[\w\-./]+[>#]\s*$/.test(lastLine)) return true;
      return false;
    }

    client.on("ready", () => {
      if (DEBUG) console.log("[InspectExec] SSH ready，打开 shell...");
      clearTimeout(connectTimer);

      client.shell({ term: "vt100", cols: 200, rows: 24 }, (err, stream) => {
        if (err) {
          done(new Error("打开 shell 失败: " + err.message));
          return;
        }

        let phase = "wait-login"; // wait-login → disable-paging → idle → waiting-output → done
        let disableRetries = 0;

        stream.on("data", (data) => {
          const chunk = data.toString("utf-8");
          outputBuffer += chunk;

          if (DEBUG && outputBuffer.length % 1000 < 100) {
            // 每隔约 1KB 打印一次状态（避免刷屏）
            const lines = outputBuffer.split('\n');
            console.log(`[InspectExec] phase=${phase} bufLen=${outputBuffer.length} lastLines=${JSON.stringify(lines.slice(-3))}`);
          }

          if (phase === "wait-login") {
            if (hasPrompt(outputBuffer)) {
              phase = "disable-paging";
              outputBuffer = "";
              if (DEBUG) console.log("[InspectExec] 登录成功，发送 screen-length 0 关闭分页");
              stream.write("screen-length 0 temporary\n");
            }
          } else if (phase === "disable-paging") {
            if (hasPrompt(outputBuffer)) {
              phase = "idle";
              outputBuffer = "";
              if (DEBUG) console.log("[InspectExec] 分页已关闭");
              sendNextCommand();
            } else if (outputBuffer.length > 500 && disableRetries < 1) {
              disableRetries++;
              outputBuffer = "";
              stream.write("screen-length 0 temporary\n");
              if (DEBUG) console.log("[InspectExec] 重试关闭分页");
            }
          } else if (phase === "waiting-output") {
            // 处理分页提示符：H3C/华为交换机可能在输出中途显示 "-- More --"
            // 注意：如果 switch 不认识 screen-length 0，分页仍然会发生
            const moreIdx = outputBuffer.indexOf("-- More --");
            if (moreIdx !== -1 || outputBuffer.indexOf("---- More ----") !== -1) {
              if (DEBUG) console.log("[InspectExec] 检测到分页，发送空格继续");
              stream.write(" ");
              // 把分页提示符从缓冲区移除，避免干扰
              outputBuffer = outputBuffer.replace(/--\s*More\s*--/gi, "").replace(/----\s*More\s*----/gi, "");
              return;
            }
            if (hasPrompt(outputBuffer)) {
              // 命令输出完整，保存
              const cmdOutput = cleanOutput(outputBuffer);
              results[results.length - 1].output = cmdOutput;
              outputBuffer = "";
              phase = "idle";
              if (DEBUG) console.log("[InspectExec] 命令输出完成，进入 idle");
              sendNextCommand();
            }
          }
        });

        stream.on("close", () => {
          if (phase === "done") {
            // 主动 quit 关闭的，正常 resolve
            if (!settled) done(null, { results });
            return;
          }
          if (!settled) {
            done(new Error("连接意外关闭"));
          }
        });

        stream.on("error", (e) => {
          done(new Error("流错误: " + e.message));
        });

        function sendNextCommand() {
          if (commandIndex >= commands.length) {
            if (DEBUG) console.log("[InspectExec] 所有命令执行完毕");
            phase = "done";
            stream.write("quit\n");
            setTimeout(() => done(null, { results }), 500);
            return;
          }

          const cmd = commands[commandIndex];
          if (DEBUG) console.log("[InspectExec] 发送命令 " + (commandIndex + 1) + "/" + commands.length + ":", cmd.slice(0, 50));

          stream.write(cmd + "\n");
          results.push({ command: cmd, output: "" });
          commandIndex++;
          phase = "waiting-output";

          // 每个命令 15 秒超时，防止卡住
          if (cmdTimeout) clearTimeout(cmdTimeout);
          cmdTimeout = setTimeout(() => {
            if (phase === "waiting-output") {
              if (DEBUG) console.log("[InspectExec] 命令超时，强制完成");
              const cmdOutput = cleanOutput(outputBuffer);
              results[results.length - 1].output = cmdOutput;
              outputBuffer = "";
              phase = "idle";
              sendNextCommand();
            }
          }, 15000);
        }

        function cleanOutput(text) {
          return (text || "")
            .replace(/<[^>]+>/g, "")
            .replace(/--\s*More\s*--/gi, "")
            .replace(/----\s*More\s*----/gi, "")
            .replace(/\r/g, "")
            .trim();
        }
      });
    });

    client.on("error", (err) => {
      clearTimeout(connectTimer);
      done(new Error("SSH 连接失败: " + err.message));
    });

    try {
      client.connect({
        host: connConfig.host,
        port: connConfig.port || 22,
        username: connConfig.username,
        password: connConfig.password || undefined,
        privateKey: connConfig.privateKey || undefined,
        passphrase: connConfig.passphrase || undefined,
        readyTimeout: connectTimeoutMs,
        hostVerifier: () => true,
        algorithms: buildAlgorithms(true, { skipEcdsaHostKey: true }),
        // 保活配置，防止交换机 VTY 超时断开
        keepaliveInterval: 30000, // 每 30 秒发送一次心跳
        keepaliveCountMax: 3,      // 最多重试 3 次
      });
    } catch (e) {
      done(e);
    }
  });
}

module.exports = {
  execSshCommand,
  execSshCommands,
  DEFAULT_CONNECT_TIMEOUT_MS,
  DEFAULT_EXEC_TIMEOUT_MS,
};