nupst/ts/daemon.ts

import process from 'node:process';
import * as fs from 'node:fs';
import * as path from 'node:path';
import { exec, execFile } from 'node:child_process';
import { promisify } from 'node:util';
import { NupstSnmp } from './snmp/manager.ts';
import type { ISnmpConfig } from './snmp/types.ts';
import { logger } from './logger.ts';
import { MigrationRunner } from './migrations/index.ts';

const execAsync = promisify(exec);
const execFileAsync = promisify(execFile);

/**
 * UPS configuration interface
 */
export interface IUpsConfig {
  /** Unique ID for the UPS */
  id: string;
  /** Friendly name for the UPS */
  name: string;
  /** SNMP configuration settings */
  snmp: ISnmpConfig;
  /** Threshold settings for initiating shutdown */
  thresholds: {
    /** Shutdown when battery below this percentage */
    battery: number;
    /** Shutdown when runtime below this minutes */
    runtime: number;
  };
  /** Group IDs this UPS belongs to */
  groups: string[];
}

/**
 * Group configuration interface
 */
export interface IGroupConfig {
  /** Unique ID for the group */
  id: string;
  /** Friendly name for the group */
  name: string;
  /** Group operation mode */
  mode: 'redundant' | 'nonRedundant';
  /** Optional description */
  description?: string;
}

/**
 * Configuration interface for the daemon
 */
export interface INupstConfig {
  /** Configuration format version */
  version?: string;
  /** UPS devices configuration */
  upsDevices: IUpsConfig[];
  /** Groups configuration */
  groups: IGroupConfig[];
  /** Check interval in milliseconds */
  checkInterval: number;

  // Legacy fields for backward compatibility (will be migrated away)
  /** UPS list (v3 format - legacy) */
  upsList?: IUpsConfig[];
  /** SNMP configuration settings (v1 format - legacy) */
  snmp?: ISnmpConfig;
  /** Threshold settings (v1 format - legacy) */
  thresholds?: {
    /** Shutdown when battery below this percentage */
    battery: number;
    /** Shutdown when runtime below this minutes */
    runtime: number;
  };
}

/**
 * UPS status tracking interface
 */
interface IUpsStatus {
  id: string;
  name: string;
  powerStatus: 'online' | 'onBattery' | 'unknown';
  batteryCapacity: number;
  batteryRuntime: number;
  lastStatusChange: number;
  lastCheckTime: number;
}

/**
 * Daemon class for monitoring UPS and handling shutdown
 * Responsible for loading/saving config and monitoring the UPS status
 */
export class NupstDaemon {
  /** Default configuration path */
  private readonly CONFIG_PATH = '/etc/nupst/config.json';

  /** Default configuration */
  private readonly DEFAULT_CONFIG: INupstConfig = {
    version: '4.0',
    upsDevices: [
      {
        id: 'default',
        name: 'Default UPS',
        snmp: {
          host: '127.0.0.1',
          port: 161,
          community: 'public',
          version: 1,
          timeout: 5000,
          // SNMPv3 defaults (used only if version === 3)
          securityLevel: 'authPriv',
          username: '',
          authProtocol: 'SHA',
          authKey: '',
          privProtocol: 'AES',
          privKey: '',
          // UPS model for OID selection
          upsModel: 'cyberpower',
        },
        thresholds: {
          battery: 60, // Shutdown when battery below 60%
          runtime: 20, // Shutdown when runtime below 20 minutes
        },
        groups: [],
      },
    ],
    groups: [],
    checkInterval: 30000, // Check every 30 seconds
  };

  private config: INupstConfig;
  private snmp: NupstSnmp;
  private isRunning: boolean = false;
  private upsStatus: Map<string, IUpsStatus> = new Map();

  /**
   * Create a new daemon instance with the given SNMP manager
   */
  constructor(snmp: NupstSnmp) {
    this.snmp = snmp;
    this.config = this.DEFAULT_CONFIG;
  }

  /**
   * Load configuration from file
   * @throws Error if configuration file doesn't exist
   */
  public async loadConfig(): Promise<INupstConfig> {
    try {
      // Check if config file exists
      const configExists = fs.existsSync(this.CONFIG_PATH);
      if (!configExists) {
        const errorMsg = `No configuration found at ${this.CONFIG_PATH}`;
        this.logConfigError(errorMsg);
        throw new Error(errorMsg);
      }

      // Read and parse config
      const configData = fs.readFileSync(this.CONFIG_PATH, 'utf8');
      const parsedConfig = JSON.parse(configData);

      // Run migrations to upgrade config format if needed
      const migrationRunner = new MigrationRunner();
      const { config: migratedConfig, migrated } = await migrationRunner.run(parsedConfig);

      // Save migrated config back to disk if any migrations ran
      if (migrated) {
        this.config = migratedConfig;
        await this.saveConfig(this.config);
      } else {
        this.config = migratedConfig;
      }

      return this.config;
    } catch (error) {
      if (
        error instanceof Error && error.message && error.message.includes('No configuration found')
      ) {
        throw error; // Re-throw the no configuration error
      }

      this.logConfigError(
        `Error loading configuration: ${error instanceof Error ? error.message : String(error)}`,
      );
      throw new Error('Failed to load configuration');
    }
  }

  /**
   * Save configuration to file
   */
  public saveConfig(config: INupstConfig): void {
    try {
      const configDir = path.dirname(this.CONFIG_PATH);
      if (!fs.existsSync(configDir)) {
        fs.mkdirSync(configDir, { recursive: true });
      }

      // Ensure version is always set and remove legacy fields before saving
      const configToSave: INupstConfig = {
        version: '4.0',
        upsDevices: config.upsDevices,
        groups: config.groups,
        checkInterval: config.checkInterval,
      };

      fs.writeFileSync(this.CONFIG_PATH, JSON.stringify(configToSave, null, 2));
      this.config = configToSave;

      logger.logBox('Configuration Saved', [`Location: ${this.CONFIG_PATH}`], 45, 'success');
    } catch (error) {
      logger.error(`Error saving configuration: ${error}`);
    }
  }

  /**
   * Helper method to log configuration errors consistently
   */
  private logConfigError(message: string): void {
    logger.logBox('Configuration Error', [message, "Please run 'nupst setup' first to create a configuration."], 45, 'error');
  }

  /**
   * Get the current configuration
   */
  public getConfig(): INupstConfig {
    return this.config;
  }

  /**
   * Get the SNMP instance
   */
  public getNupstSnmp(): NupstSnmp {
    return this.snmp;
  }

  /**
   * Start the monitoring daemon
   */
  public async start(): Promise<void> {
    if (this.isRunning) {
      logger.log('Daemon is already running');
      return;
    }

    logger.log('Starting NUPST daemon...');

    try {
      // Load configuration - this will throw an error if config doesn't exist
      await this.loadConfig();
      this.logConfigLoaded();

      // Log version information
      this.snmp.getNupst().logVersionInfo(false); // Don't check for updates immediately on startup

      // Check for updates in the background
      this.snmp.getNupst().checkForUpdates().then((updateAvailable: boolean) => {
        if (updateAvailable) {
          const updateStatus = this.snmp.getNupst().getUpdateStatus();
          const boxWidth = 45;
          logger.logBoxTitle('Update Available', boxWidth);
          logger.logBoxLine(`Current Version: ${updateStatus.currentVersion}`);
          logger.logBoxLine(`Latest Version: ${updateStatus.latestVersion}`);
          logger.logBoxLine('Run "sudo nupst update" to update');
          logger.logBoxEnd();
        }
      }).catch(() => {}); // Ignore errors checking for updates

      // Initialize UPS status tracking
      this.initializeUpsStatus();

      // Start UPS monitoring
      this.isRunning = true;
      await this.monitor();
    } catch (error) {
      this.isRunning = false;
      logger.error(
        `Daemon failed to start: ${error instanceof Error ? error.message : String(error)}`,
      );
      process.exit(1); // Exit with error
    }
  }

  /**
   * Initialize UPS status tracking for all UPS devices
   */
  private initializeUpsStatus(): void {
    this.upsStatus.clear();

    if (this.config.upsDevices && this.config.upsDevices.length > 0) {
      for (const ups of this.config.upsDevices) {
        this.upsStatus.set(ups.id, {
          id: ups.id,
          name: ups.name,
          powerStatus: 'unknown',
          batteryCapacity: 100,
          batteryRuntime: 999, // High value as default
          lastStatusChange: Date.now(),
          lastCheckTime: 0,
        });
      }

      logger.log(`Initialized status tracking for ${this.config.upsDevices.length} UPS devices`);
    } else {
      logger.error('No UPS devices found in configuration');
    }
  }

  /**
   * Log the loaded configuration settings
   */
  private logConfigLoaded(): void {
    const boxWidth = 50;
    logger.logBoxTitle('Configuration Loaded', boxWidth);

    if (this.config.upsDevices && this.config.upsDevices.length > 0) {
      logger.logBoxLine(`UPS Devices: ${this.config.upsDevices.length}`);
      for (const ups of this.config.upsDevices) {
        logger.logBoxLine(`  - ${ups.name} (${ups.id}): ${ups.snmp.host}:${ups.snmp.port}`);
      }
    } else {
      logger.logBoxLine('No UPS devices configured');
    }

    if (this.config.groups && this.config.groups.length > 0) {
      logger.logBoxLine(`Groups: ${this.config.groups.length}`);
      for (const group of this.config.groups) {
        logger.logBoxLine(`  - ${group.name} (${group.id}): ${group.mode} mode`);
      }
    } else {
      logger.logBoxLine('No Groups configured');
    }

    logger.logBoxLine(`Check Interval: ${this.config.checkInterval / 1000} seconds`);
    logger.logBoxEnd();
  }

  /**
   * Stop the monitoring daemon
   */
  public stop(): void {
    logger.log('Stopping NUPST daemon...');
    this.isRunning = false;
  }

  /**
   * Monitor the UPS status and trigger shutdown when necessary
   */
  private async monitor(): Promise<void> {
    logger.log('Starting UPS monitoring...');

    if (!this.config.upsDevices || this.config.upsDevices.length === 0) {
      logger.warn('No UPS devices found in configuration. Daemon will remain idle...');
      // Don't exit - enter idle monitoring mode instead
      await this.idleMonitoring();
      return;
    }

    let lastLogTime = 0; // Track when we last logged status
    const LOG_INTERVAL = 5 * 60 * 1000; // Log at least every 5 minutes (300000ms)

    // Monitor continuously
    while (this.isRunning) {
      try {
        // Check all UPS devices
        await this.checkAllUpsDevices();

        // Log periodic status update
        const currentTime = Date.now();
        if (currentTime - lastLogTime >= LOG_INTERVAL) {
          this.logAllUpsStatus();
          lastLogTime = currentTime;
        }

        // Check if shutdown is required based on group configurations
        await this.evaluateGroupShutdownConditions();

        // Wait before next check
        await this.sleep(this.config.checkInterval);
      } catch (error) {
        logger.error(
          `Error during UPS monitoring: ${error instanceof Error ? error.message : String(error)}`,
        );
        await this.sleep(this.config.checkInterval);
      }
    }

    logger.log('UPS monitoring stopped');
  }

  /**
   * Check status of all UPS devices
   */
  private async checkAllUpsDevices(): Promise<void> {
    for (const ups of this.config.upsDevices) {
      try {
        const upsStatus = this.upsStatus.get(ups.id);
        if (!upsStatus) {
          // Initialize status for this UPS if not exists
          this.upsStatus.set(ups.id, {
            id: ups.id,
            name: ups.name,
            powerStatus: 'unknown',
            batteryCapacity: 100,
            batteryRuntime: 999,
            lastStatusChange: Date.now(),
            lastCheckTime: 0,
          });
        }

        // Check UPS status
        const status = await this.snmp.getUpsStatus(ups.snmp);
        const currentTime = Date.now();

        // Get the current status from the map
        const currentStatus = this.upsStatus.get(ups.id);

        // Update status with new values
        const updatedStatus: IUpsStatus = {
          id: ups.id,
          name: ups.name,
          powerStatus: status.powerStatus,
          batteryCapacity: status.batteryCapacity,
          batteryRuntime: status.batteryRuntime,
          lastCheckTime: currentTime,
          lastStatusChange: currentStatus?.lastStatusChange || currentTime,
        };

        // Check if power status changed
        if (currentStatus && currentStatus.powerStatus !== status.powerStatus) {
          logger.logBoxTitle(`Power Status Change: ${ups.name}`, 50);
          logger.logBoxLine(`Status changed: ${currentStatus.powerStatus} → ${status.powerStatus}`);
          logger.logBoxEnd();

          updatedStatus.lastStatusChange = currentTime;
        }

        // Update the status in the map
        this.upsStatus.set(ups.id, updatedStatus);
      } catch (error) {
        logger.error(
          `Error checking UPS ${ups.name} (${ups.id}): ${
            error instanceof Error ? error.message : String(error)
          }`,
        );
      }
    }
  }

  /**
   * Log status of all UPS devices
   */
  private logAllUpsStatus(): void {
    const timestamp = new Date().toISOString();
    const boxWidth = 60;
    logger.logBoxTitle('Periodic Status Update', boxWidth);
    logger.logBoxLine(`Timestamp: ${timestamp}`);
    logger.logBoxLine('');

    for (const [id, status] of this.upsStatus.entries()) {
      logger.logBoxLine(`UPS: ${status.name} (${id})`);
      logger.logBoxLine(`  Power Status: ${status.powerStatus}`);
      logger.logBoxLine(
        `  Battery: ${status.batteryCapacity}% | Runtime: ${status.batteryRuntime} min`,
      );
      logger.logBoxLine('');
    }

    logger.logBoxEnd();
  }

  /**
   * Evaluate if shutdown is required based on group configurations
   */
  private async evaluateGroupShutdownConditions(): Promise<void> {
    if (!this.config.groups || this.config.groups.length === 0) {
      // No groups defined, check individual UPS conditions
      for (const [id, status] of this.upsStatus.entries()) {
        if (status.powerStatus === 'onBattery') {
          // Find the UPS config
          const ups = this.config.upsDevices.find((u) => u.id === id);
          if (ups) {
            await this.evaluateUpsShutdownCondition(ups, status);
          }
        }
      }
      return;
    }

    // Evaluate each group
    for (const group of this.config.groups) {
      // Find all UPS devices in this group
      const upsDevicesInGroup = this.config.upsDevices.filter((ups) =>
        ups.groups && ups.groups.includes(group.id)
      );

      if (upsDevicesInGroup.length === 0) {
        // No UPS devices in this group
        continue;
      }

      if (group.mode === 'redundant') {
        // Redundant mode: only shutdown if ALL UPS devices in the group are in critical condition
        await this.evaluateRedundantGroup(group, upsDevicesInGroup);
      } else {
        // Non-redundant mode: shutdown if ANY UPS device in the group is in critical condition
        await this.evaluateNonRedundantGroup(group, upsDevicesInGroup);
      }
    }
  }

  /**
   * Evaluate a redundant group for shutdown conditions
   * In redundant mode, we only shut down if ALL UPS devices are in critical condition
   */
  private async evaluateRedundantGroup(
    group: IGroupConfig,
    upsDevices: IUpsConfig[],
  ): Promise<void> {
    // Count UPS devices on battery and in critical condition
    let upsOnBattery = 0;
    let upsInCriticalCondition = 0;

    for (const ups of upsDevices) {
      const status = this.upsStatus.get(ups.id);
      if (!status) continue;

      if (status.powerStatus === 'onBattery') {
        upsOnBattery++;

        // Check if this UPS is in critical condition
        if (
          status.batteryCapacity < ups.thresholds.battery ||
          status.batteryRuntime < ups.thresholds.runtime
        ) {
          upsInCriticalCondition++;
        }
      }
    }

    // All UPS devices must be online for a redundant group to be considered healthy
    const allUpsCount = upsDevices.length;

    // If all UPS are on battery and in critical condition, shutdown
    if (upsOnBattery === allUpsCount && upsInCriticalCondition === allUpsCount) {
      logger.logBoxTitle(`Group Shutdown Required: ${group.name}`, 50);
      logger.logBoxLine(`Mode: Redundant`);
      logger.logBoxLine(`All ${allUpsCount} UPS devices in critical condition`);
      logger.logBoxEnd();

      await this.initiateShutdown(
        `All UPS devices in redundant group "${group.name}" in critical condition`,
      );
    }
  }

  /**
   * Evaluate a non-redundant group for shutdown conditions
   * In non-redundant mode, we shut down if ANY UPS device is in critical condition
   */
  private async evaluateNonRedundantGroup(
    group: IGroupConfig,
    upsDevices: IUpsConfig[],
  ): Promise<void> {
    for (const ups of upsDevices) {
      const status = this.upsStatus.get(ups.id);
      if (!status) continue;

      if (status.powerStatus === 'onBattery') {
        // Check if this UPS is in critical condition
        if (
          status.batteryCapacity < ups.thresholds.battery ||
          status.batteryRuntime < ups.thresholds.runtime
        ) {
          logger.logBoxTitle(`Group Shutdown Required: ${group.name}`, 50);
          logger.logBoxLine(`Mode: Non-Redundant`);
          logger.logBoxLine(`UPS ${ups.name} in critical condition`);
          logger.logBoxLine(
            `Battery: ${status.batteryCapacity}% (threshold: ${ups.thresholds.battery}%)`,
          );
          logger.logBoxLine(
            `Runtime: ${status.batteryRuntime} min (threshold: ${ups.thresholds.runtime} min)`,
          );
          logger.logBoxEnd();

          await this.initiateShutdown(
            `UPS "${ups.name}" in non-redundant group "${group.name}" in critical condition`,
          );
          return; // Exit after initiating shutdown
        }
      }
    }
  }

  /**
   * Evaluate an individual UPS for shutdown conditions
   */
  private async evaluateUpsShutdownCondition(ups: IUpsConfig, status: IUpsStatus): Promise<void> {
    // Only evaluate UPS devices not in any group
    if (ups.groups && ups.groups.length > 0) {
      return;
    }

    // Check threshold conditions
    if (
      status.batteryCapacity < ups.thresholds.battery ||
      status.batteryRuntime < ups.thresholds.runtime
    ) {
      logger.logBoxTitle(`UPS Shutdown Required: ${ups.name}`, 50);
      logger.logBoxLine(
        `Battery: ${status.batteryCapacity}% (threshold: ${ups.thresholds.battery}%)`,
      );
      logger.logBoxLine(
        `Runtime: ${status.batteryRuntime} min (threshold: ${ups.thresholds.runtime} min)`,
      );
      logger.logBoxEnd();

      await this.initiateShutdown(`UPS "${ups.name}" battery or runtime below threshold`);
    }
  }

  /**
   * Initiate system shutdown with UPS monitoring during shutdown
   * @param reason Reason for shutdown
   */
  public async initiateShutdown(reason: string): Promise<void> {
    logger.log(`Initiating system shutdown due to: ${reason}`);

    // Set a longer delay for shutdown to allow VMs and services to close
    const shutdownDelayMinutes = 5;

    try {
      // Find shutdown command in common system paths
      const shutdownPaths = [
        '/sbin/shutdown',
        '/usr/sbin/shutdown',
        '/bin/shutdown',
        '/usr/bin/shutdown',
      ];

      let shutdownCmd = '';
      for (const path of shutdownPaths) {
        try {
          if (fs.existsSync(path)) {
            shutdownCmd = path;
            logger.log(`Found shutdown command at: ${shutdownCmd}`);
            break;
          }
        } catch (e) {
          // Continue checking other paths
        }
      }

      if (shutdownCmd) {
        // Execute shutdown command with delay to allow for VM graceful shutdown
        logger.log(
          `Executing: ${shutdownCmd} -h +${shutdownDelayMinutes} "UPS battery critical..."`,
        );
        const { stdout } = await execFileAsync(shutdownCmd, [
          '-h',
          `+${shutdownDelayMinutes}`,
          `UPS battery critical, shutting down in ${shutdownDelayMinutes} minutes`,
        ]);
        logger.log(`Shutdown initiated: ${stdout}`);
        logger.log(`Allowing ${shutdownDelayMinutes} minutes for VMs to shut down safely`);
      } else {
        // Try using the PATH to find shutdown
        try {
          logger.log('Shutdown command not found in common paths, trying via PATH...');
          const { stdout } = await execAsync(
            `shutdown -h +${shutdownDelayMinutes} "UPS battery critical, shutting down in ${shutdownDelayMinutes} minutes"`,
            {
              env: process.env, // Pass the current environment
            },
          );
          logger.log(`Shutdown initiated: ${stdout}`);
        } catch (e) {
          throw new Error(
            `Shutdown command not found: ${e instanceof Error ? e.message : String(e)}`,
          );
        }
      }

      // Monitor UPS during shutdown and force immediate shutdown if battery gets too low
      logger.log('Monitoring UPS during shutdown process...');
      await this.monitorDuringShutdown();
    } catch (error) {
      logger.error(`Failed to initiate shutdown: ${error}`);

      // Try alternative shutdown methods
      const alternatives = [
        { cmd: 'poweroff', args: ['--force'] },
        { cmd: 'halt', args: ['-p'] },
        { cmd: 'systemctl', args: ['poweroff'] },
        { cmd: 'reboot', args: ['-p'] }, // Some systems allow reboot -p for power off
      ];

      for (const alt of alternatives) {
        try {
          // First check if command exists in common system paths
          const paths = [
            `/sbin/${alt.cmd}`,
            `/usr/sbin/${alt.cmd}`,
            `/bin/${alt.cmd}`,
            `/usr/bin/${alt.cmd}`,
          ];

          let cmdPath = '';
          for (const path of paths) {
            if (fs.existsSync(path)) {
              cmdPath = path;
              break;
            }
          }

          if (cmdPath) {
            logger.log(`Trying alternative shutdown method: ${cmdPath} ${alt.args.join(' ')}`);
            await execFileAsync(cmdPath, alt.args);
            return; // Exit if successful
          } else {
            // Try using PATH environment
            logger.log(`Trying alternative via PATH: ${alt.cmd} ${alt.args.join(' ')}`);
            await execAsync(`${alt.cmd} ${alt.args.join(' ')}`, {
              env: process.env, // Pass the current environment
            });
            return; // Exit if successful
          }
        } catch (altError) {
          logger.error(`Alternative method ${alt.cmd} failed: ${altError}`);
          // Continue to next method
        }
      }

      logger.error('All shutdown methods failed');
    }
  }

  /**
   * Monitor UPS during system shutdown
   * Force immediate shutdown if any UPS gets critically low
   */
  private async monitorDuringShutdown(): Promise<void> {
    const EMERGENCY_RUNTIME_THRESHOLD = 5; // 5 minutes remaining is critical
    const CHECK_INTERVAL = 30000; // Check every 30 seconds during shutdown
    const MAX_MONITORING_TIME = 5 * 60 * 1000; // Max 5 minutes of monitoring
    const startTime = Date.now();

    logger.log(
      `Emergency shutdown threshold: ${EMERGENCY_RUNTIME_THRESHOLD} minutes remaining battery runtime`,
    );

    // Continue monitoring until max monitoring time is reached
    while (Date.now() - startTime < MAX_MONITORING_TIME) {
      try {
        logger.log('Checking UPS status during shutdown...');

        // Check all UPS devices
        for (const ups of this.config.upsDevices) {
          try {
            const status = await this.snmp.getUpsStatus(ups.snmp);

            logger.log(
              `UPS ${ups.name}: Battery ${status.batteryCapacity}%, Runtime: ${status.batteryRuntime} minutes`,
            );

            // If any UPS battery runtime gets critically low, force immediate shutdown
            if (status.batteryRuntime < EMERGENCY_RUNTIME_THRESHOLD) {
              logger.logBoxTitle('EMERGENCY SHUTDOWN', 50);
              logger.logBoxLine(
                `UPS ${ups.name} runtime critically low: ${status.batteryRuntime} minutes`,
              );
              logger.logBoxLine('Forcing immediate shutdown!');
              logger.logBoxEnd();

              // Force immediate shutdown
              await this.forceImmediateShutdown();
              return;
            }
          } catch (upsError) {
            logger.error(
              `Error checking UPS ${ups.name} during shutdown: ${
                upsError instanceof Error ? upsError.message : String(upsError)
              }`,
            );
          }
        }

        // Wait before checking again
        await this.sleep(CHECK_INTERVAL);
      } catch (error) {
        logger.error(
          `Error monitoring UPS during shutdown: ${
            error instanceof Error ? error.message : String(error)
          }`,
        );
        await this.sleep(CHECK_INTERVAL);
      }
    }

    logger.log('UPS monitoring during shutdown completed');
  }

  /**
   * Force an immediate system shutdown
   */
  private async forceImmediateShutdown(): Promise<void> {
    try {
      // Find shutdown command in common system paths
      const shutdownPaths = [
        '/sbin/shutdown',
        '/usr/sbin/shutdown',
        '/bin/shutdown',
        '/usr/bin/shutdown',
      ];

      let shutdownCmd = '';
      for (const path of shutdownPaths) {
        if (fs.existsSync(path)) {
          shutdownCmd = path;
          logger.log(`Found shutdown command at: ${shutdownCmd}`);
          break;
        }
      }

      if (shutdownCmd) {
        logger.log(`Executing emergency shutdown: ${shutdownCmd} -h now`);
        await execFileAsync(shutdownCmd, [
          '-h',
          'now',
          'EMERGENCY: UPS battery critically low, shutting down NOW',
        ]);
      } else {
        // Try using the PATH to find shutdown
        logger.log('Shutdown command not found in common paths, trying via PATH...');
        await execAsync(
          'shutdown -h now "EMERGENCY: UPS battery critically low, shutting down NOW"',
          {
            env: process.env, // Pass the current environment
          },
        );
      }
    } catch (error) {
      logger.error('Emergency shutdown failed, trying alternative methods...');

      // Try alternative shutdown methods in sequence
      const alternatives = [
        { cmd: 'poweroff', args: ['--force'] },
        { cmd: 'halt', args: ['-p'] },
        { cmd: 'systemctl', args: ['poweroff'] },
      ];

      for (const alt of alternatives) {
        try {
          // Check common paths
          const paths = [
            `/sbin/${alt.cmd}`,
            `/usr/sbin/${alt.cmd}`,
            `/bin/${alt.cmd}`,
            `/usr/bin/${alt.cmd}`,
          ];

          let cmdPath = '';
          for (const path of paths) {
            if (fs.existsSync(path)) {
              cmdPath = path;
              break;
            }
          }

          if (cmdPath) {
            logger.log(`Emergency: using ${cmdPath} ${alt.args.join(' ')}`);
            await execFileAsync(cmdPath, alt.args);
            return; // Exit if successful
          } else {
            // Try using PATH
            logger.log(`Emergency: trying ${alt.cmd} via PATH`);
            await execAsync(`${alt.cmd} ${alt.args.join(' ')}`, {
              env: process.env,
            });
            return; // Exit if successful
          }
        } catch (altError) {
          // Continue to next method
        }
      }

      logger.error('All emergency shutdown methods failed');
    }
  }

  /**
   * Idle monitoring loop when no UPS devices are configured
   * Watches for config changes and reloads when detected
   */
  private async idleMonitoring(): Promise<void> {
    const IDLE_CHECK_INTERVAL = 60000; // Check every 60 seconds
    let lastConfigCheck = Date.now();
    const CONFIG_CHECK_INTERVAL = 60000; // Check config every minute

    logger.log('Entering idle monitoring mode...');
    logger.log('Daemon will check for config changes every 60 seconds');

    // Start file watcher for hot-reload
    this.watchConfigFile();

    while (this.isRunning) {
      try {
        const currentTime = Date.now();

        // Periodically check if config has been updated
        if (currentTime - lastConfigCheck >= CONFIG_CHECK_INTERVAL) {
          try {
            // Try to load config
            const newConfig = await this.loadConfig();

            // Check if we now have UPS devices configured
            if (newConfig.upsDevices && newConfig.upsDevices.length > 0) {
              logger.success('Configuration updated! UPS devices found. Starting monitoring...');
              this.initializeUpsStatus();
              // Exit idle mode and start monitoring
              await this.monitor();
              return;
            }
          } catch (error) {
            // Config still doesn't exist or invalid, continue waiting
          }

          lastConfigCheck = currentTime;
        }

        await this.sleep(IDLE_CHECK_INTERVAL);
      } catch (error) {
        logger.error(
          `Error during idle monitoring: ${error instanceof Error ? error.message : String(error)}`,
        );
        await this.sleep(IDLE_CHECK_INTERVAL);
      }
    }

    logger.log('Idle monitoring stopped');
  }

  /**
   * Watch config file for changes and reload automatically
   */
  private watchConfigFile(): void {
    try {
      // Use Deno's file watcher to monitor config file
      const configDir = path.dirname(this.CONFIG_PATH);

      // Spawn a background watcher (non-blocking)
      (async () => {
        try {
          const watcher = Deno.watchFs(configDir);

          logger.log('Config file watcher started');

          for await (const event of watcher) {
            // Only respond to modify events on the config file
            if (
              event.kind === 'modify' &&
              event.paths.some((p) => p.includes('config.json'))
            ) {
              logger.info('Config file changed, reloading...');
              await this.reloadConfig();
            }

            // Stop watching if daemon stopped
            if (!this.isRunning) {
              break;
            }
          }
        } catch (error) {
          // Watcher error - not critical, just log it
          logger.dim(
            `Config watcher stopped: ${error instanceof Error ? error.message : String(error)}`,
          );
        }
      })();
    } catch (error) {
      // If we can't start the watcher, just log and continue
      // The periodic check will still work
      logger.dim('Could not start config file watcher, using periodic checks only');
    }
  }

  /**
   * Reload configuration and restart monitoring if needed
   */
  private async reloadConfig(): Promise<void> {
    try {
      const oldDeviceCount = this.config.upsDevices?.length || 0;

      // Load the new configuration
      await this.loadConfig();
      const newDeviceCount = this.config.upsDevices?.length || 0;

      if (newDeviceCount > 0 && oldDeviceCount === 0) {
        logger.success(`Configuration reloaded! Found ${newDeviceCount} UPS device(s)`);
        logger.info('Monitoring will start automatically...');
      } else if (newDeviceCount !== oldDeviceCount) {
        logger.success(
          `Configuration reloaded! UPS devices: ${oldDeviceCount} → ${newDeviceCount}`,
        );

        // Reinitialize UPS status tracking
        this.initializeUpsStatus();
      } else {
        logger.success('Configuration reloaded successfully');
      }
    } catch (error) {
      logger.warn(
        `Failed to reload config: ${error instanceof Error ? error.message : String(error)}`,
      );
    }
  }

  /**
   * Sleep for the specified milliseconds
   */
  private sleep(ms: number): Promise<void> {
    return new Promise((resolve) => setTimeout(resolve, ms));
  }
}