import process from 'node:process';
import { promises as fs } from 'node:fs';
import { execSync } from 'node:child_process';
import { NupstDaemon } from './daemon.ts';
import { logger } from './logger.ts';
import { theme, symbols, getBatteryColor, getRuntimeColor, formatPowerStatus } from './colors.ts';

/**
 * Class for managing systemd service
 * Handles installation, removal, and control of the NUPST systemd service
 */
export class NupstSystemd {
  /** Path to the systemd service file */
  private readonly serviceFilePath = '/etc/systemd/system/nupst.service';
  private readonly daemon: NupstDaemon;

  /** Template for the systemd service file */
  private readonly serviceTemplate = `[Unit]
Description=NUPST - Deno-powered UPS Monitoring Tool
After=network.target

[Service]
ExecStart=/usr/local/bin/nupst service start-daemon
Restart=always
RestartSec=10
User=root
Group=root
Environment=PATH=/usr/bin:/usr/local/bin
WorkingDirectory=/opt/nupst

[Install]
WantedBy=multi-user.target
`;

  /**
   * Create a new systemd manager
   * @param daemon The daemon instance to manage
   */
  constructor(daemon: NupstDaemon) {
    this.daemon = daemon;
  }

  /**
   * Check if a configuration file exists
   * @private
   * @throws Error if configuration not found
   */
  private async checkConfigExists(): Promise<void> {
    const configPath = '/etc/nupst/config.json';
    try {
      await fs.access(configPath);
    } catch (error) {
      const boxWidth = 50;
      logger.logBoxTitle('Configuration Error', boxWidth);
      logger.logBoxLine(`No configuration file found at ${configPath}`);
      logger.logBoxLine("Please run 'nupst add' first to create a UPS configuration.");
      logger.logBoxEnd();
      throw new Error('Configuration not found');
    }
  }

  /**
   * Install the systemd service file
   * @throws Error if installation fails
   */
  public async install(): Promise<void> {
    try {
      // Check if configuration exists before installing
      await this.checkConfigExists();

      // Write the service file
      await fs.writeFile(this.serviceFilePath, this.serviceTemplate);
      const boxWidth = 50;
      logger.logBoxTitle('Service Installation', boxWidth);
      logger.logBoxLine(`Service file created at ${this.serviceFilePath}`);

      // Reload systemd daemon
      execSync('systemctl daemon-reload');
      logger.logBoxLine('Systemd daemon reloaded');

      // Enable the service
      execSync('systemctl enable nupst.service');
      logger.logBoxLine('Service enabled to start on boot');
      logger.logBoxEnd();
    } catch (error) {
      if (error instanceof Error && error.message === 'Configuration not found') {
        // Just rethrow the error as the message has already been displayed
        throw error;
      }
      logger.error(`Failed to install systemd service: ${error}`);
      throw error;
    }
  }

  /**
   * Start the systemd service
   * @throws Error if start fails
   */
  public async start(): Promise<void> {
    try {
      // Check if configuration exists before starting
      await this.checkConfigExists();

      execSync('systemctl start nupst.service');
      const boxWidth = 45;
      logger.logBoxTitle('Service Status', boxWidth);
      logger.logBoxLine('NUPST service started successfully');
      logger.logBoxEnd();
    } catch (error) {
      if (error instanceof Error && error.message === 'Configuration not found') {
        // Exit with error code since configuration is required
        process.exit(1);
      }
      logger.error(`Failed to start service: ${error}`);
      throw error;
    }
  }

  /**
   * Stop the systemd service
   * @throws Error if stop fails
   */
  public stop(): void {
    try {
      execSync('systemctl stop nupst.service');
      logger.success('NUPST service stopped');
    } catch (error) {
      logger.error(`Failed to stop service: ${error}`);
      throw error;
    }
  }

  /**
   * Get status of the systemd service and UPS
   * @param debugMode Whether to enable debug mode for SNMP
   */
  public async getStatus(debugMode: boolean = false): Promise<void> {
    try {
      // Enable debug mode if requested
      if (debugMode) {
        const boxWidth = 45;
        logger.logBoxTitle('Debug Mode', boxWidth);
        logger.logBoxLine('SNMP debugging enabled - detailed logs will be shown');
        logger.logBoxEnd();
        this.daemon.getNupstSnmp().enableDebug();
      }

      // Display version information
      this.daemon.getNupstSnmp().getNupst().logVersionInfo();

      // Check if config exists first
      try {
        await this.checkConfigExists();
      } catch (error) {
        // Error message already displayed by checkConfigExists
        return;
      }

      await this.displayServiceStatus();
      await this.displayAllUpsStatus();
    } catch (error) {
      logger.error(
        `Failed to get status: ${error instanceof Error ? error.message : String(error)}`,
      );
    }
  }

  /**
   * Display the systemd service status
   * @private
   */
  private displayServiceStatus(): void {
    try {
      const serviceStatus = execSync('systemctl status nupst.service').toString();
      const lines = serviceStatus.split('\n');

      // Parse key information from systemctl output
      let isActive = false;
      let pid = '';
      let memory = '';
      let cpu = '';

      for (const line of lines) {
        if (line.includes('Active:')) {
          isActive = line.includes('active (running)');
        } else if (line.includes('Main PID:')) {
          const match = line.match(/Main PID:\s+(\d+)/);
          if (match) pid = match[1];
        } else if (line.includes('Memory:')) {
          const match = line.match(/Memory:\s+([\d.]+[A-Z])/);
          if (match) memory = match[1];
        } else if (line.includes('CPU:')) {
          const match = line.match(/CPU:\s+([\d.]+(?:ms|s))/);
          if (match) cpu = match[1];
        }
      }

      // Display beautiful status
      console.log('');
      if (isActive) {
        console.log(`${symbols.running} ${theme.success('Service:')} ${theme.statusActive('active (running)')}`);
      } else {
        console.log(`${symbols.stopped} ${theme.dim('Service:')} ${theme.statusInactive('inactive')}`);
      }

      if (pid || memory || cpu) {
        const details = [];
        if (pid) details.push(`PID: ${theme.dim(pid)}`);
        if (memory) details.push(`Memory: ${theme.dim(memory)}`);
        if (cpu) details.push(`CPU: ${theme.dim(cpu)}`);
        console.log(`  ${details.join('  ')}`);
      }
      console.log('');

    } catch (error) {
      console.log('');
      console.log(`${symbols.stopped} ${theme.dim('Service:')} ${theme.statusInactive('not installed')}`);
      console.log('');
    }
  }

  /**
   * Display all UPS statuses
   * @private
   */
  private async displayAllUpsStatus(): Promise<void> {
    try {
      // Explicitly load the configuration first to ensure it's up-to-date
      await this.daemon.loadConfig();
      const config = this.daemon.getConfig();
      const snmp = this.daemon.getNupstSnmp();

      // Check if we have the new multi-UPS config format
      if (config.upsDevices && Array.isArray(config.upsDevices) && config.upsDevices.length > 0) {
        console.log(theme.info(`UPS Devices (${config.upsDevices.length}):`));

        // Show status for each UPS
        for (const ups of config.upsDevices) {
          await this.displaySingleUpsStatus(ups, snmp);
        }
      } else if (config.snmp) {
        // Legacy single UPS configuration
        console.log(theme.info('UPS Devices (1):'));
        const legacyUps = {
          id: 'default',
          name: 'Default UPS',
          snmp: config.snmp,
          thresholds: config.thresholds,
          groups: [],
        };

        await this.displaySingleUpsStatus(legacyUps, snmp);
      } else {
        console.log('');
        console.log(`${symbols.warning} ${theme.warning('No UPS devices configured')}`);
        console.log(`  ${theme.dim('Run')} ${theme.command('nupst ups add')} ${theme.dim('to add a device')}`);
        console.log('');
      }
    } catch (error) {
      console.log('');
      console.log(`${symbols.error} ${theme.error('Failed to retrieve UPS status')}`);
      console.log(`  ${theme.dim(error instanceof Error ? error.message : String(error))}`);
      console.log('');
    }
  }

  /**
   * Display status of a single UPS
   * @param ups UPS configuration
   * @param snmp SNMP manager
   */
  private async displaySingleUpsStatus(ups: any, snmp: any): Promise<void> {
    try {
      // Create a test config with a short timeout
      const testConfig = {
        ...ups.snmp,
        timeout: Math.min(ups.snmp.timeout, 10000), // Use at most 10 seconds for status check
      };

      const status = await snmp.getUpsStatus(testConfig);

      // Determine status symbol based on power status
      let statusSymbol = symbols.unknown;
      if (status.powerStatus === 'online') {
        statusSymbol = symbols.running;
      } else if (status.powerStatus === 'onBattery') {
        statusSymbol = symbols.warning;
      }

      // Display UPS name and power status
      console.log(`  ${statusSymbol} ${theme.highlight(ups.name)} - ${formatPowerStatus(status.powerStatus)}`);

      // Display battery with color coding
      const batteryColor = getBatteryColor(status.batteryCapacity);
      const batterySymbol = status.batteryCapacity >= ups.thresholds.battery ? symbols.success : symbols.warning;
      console.log(`    Battery: ${batteryColor(status.batteryCapacity + '%')} ${batterySymbol}  Runtime: ${getRuntimeColor(status.batteryRuntime)(status.batteryRuntime + ' min')}`);

      // Display host info
      console.log(`    ${theme.dim(`Host: ${ups.snmp.host}:${ups.snmp.port}`)}`);

      // Display groups if any
      if (ups.groups && ups.groups.length > 0) {
        const config = this.daemon.getConfig();
        const groupNames = ups.groups.map((groupId: string) => {
          const group = config.groups?.find((g: { id: string }) => g.id === groupId);
          return group ? group.name : groupId;
        });
        console.log(`    ${theme.dim(`Groups: ${groupNames.join(', ')}`)}`);
      }

      console.log('');

    } catch (error) {
      // Display error for this UPS
      console.log(`  ${symbols.error} ${theme.highlight(ups.name)} - ${theme.error('Connection failed')}`);
      console.log(`    ${theme.dim(error instanceof Error ? error.message : String(error))}`);
      console.log(`    ${theme.dim(`Host: ${ups.snmp.host}:${ups.snmp.port}`)}`);
      console.log('');
    }
  }

  /**
   * Disable and uninstall the systemd service
   * @throws Error if disabling fails
   */
  public async disable(): Promise<void> {
    try {
      await this.stopService();
      await this.disableService();
      await this.removeServiceFile();

      // Reload systemd daemon
      execSync('systemctl daemon-reload');
      logger.log('Systemd daemon reloaded');
      logger.success('NUPST service has been successfully uninstalled');
    } catch (error) {
      logger.error(`Failed to disable and uninstall service: ${error}`);
      throw error;
    }
  }

  /**
   * Stop the service if it's running
   * @private
   */
  private stopService(): void {
    try {
      logger.log('Stopping NUPST service...');
      execSync('systemctl stop nupst.service');
    } catch (error) {
      // Service might not be running, that's okay
      logger.log('Service was not running or could not be stopped');
    }
  }

  /**
   * Disable the service
   * @private
   */
  private disableService(): void {
    try {
      logger.log('Disabling NUPST service...');
      execSync('systemctl disable nupst.service');
    } catch (error) {
      logger.log('Service was not enabled or could not be disabled');
    }
  }

  /**
   * Remove the service file if it exists
   * @private
   */
  private async removeServiceFile(): Promise<void> {
    if (await fs.stat(this.serviceFilePath).catch(() => null)) {
      logger.log(`Removing service file ${this.serviceFilePath}...`);
      await fs.unlink(this.serviceFilePath);
      logger.log('Service file removed');
    } else {
      logger.log('Service file did not exist');
    }
  }
}