/**
 * Daemon Manager for Onebox
 *
 * Handles background monitoring, metrics collection, and automatic tasks
 */

import * as plugins from '../plugins.ts';
import { logger } from '../logging.ts';
import { projectInfo } from '../info.ts';
import type { Onebox } from './onebox.ts';

// PID file constants
const PID_FILE_PATH = '/var/run/onebox/onebox.pid';
const PID_DIR = '/var/run/onebox';
const FALLBACK_PID_DIR = `${Deno.env.get('HOME')}/.onebox`;
const FALLBACK_PID_FILE = `${FALLBACK_PID_DIR}/onebox.pid`;

export class OneboxDaemon {
  private oneboxRef: Onebox;
  private smartdaemon: plugins.smartdaemon.SmartDaemon | null = null;
  private running = false;
  private monitoringInterval: number | null = null;
  private metricsInterval = 60000; // 1 minute
  private pidFilePath: string = PID_FILE_PATH;

  constructor(oneboxRef: Onebox) {
    this.oneboxRef = oneboxRef;
  }

  /**
   * Load settings from database (call after database init)
   */
  private loadSettings(): void {
    try {
      const customInterval = this.oneboxRef.database.getSetting('metricsInterval');
      if (customInterval) {
        this.metricsInterval = parseInt(customInterval, 10);
      }
    } catch {
      // Database not initialized yet - use defaults
    }
  }

  /**
   * Install systemd service
   */
  async installService(): Promise<void> {
    try {
      logger.info('Installing Onebox daemon service...');

      // Initialize smartdaemon if needed
      if (!this.smartdaemon) {
        this.smartdaemon = new plugins.smartdaemon.SmartDaemon();
      }

      // Get installation directory
      const execPath = Deno.execPath();

      const service = await this.smartdaemon.addService({
        name: 'onebox',
        version: projectInfo.version,
        command: `${execPath} run --allow-all ${Deno.cwd()}/mod.ts daemon start`,
        description: 'Onebox - Self-hosted container platform',
        workingDir: Deno.cwd(),
      });

      await service.save();
      await service.enable();

      logger.success('Onebox daemon service installed');
      logger.info('Start with: sudo systemctl start smartdaemon_onebox');
    } catch (error) {
      logger.error(`Failed to install daemon service: ${error.message}`);
      throw error;
    }
  }

  /**
   * Uninstall systemd service
   */
  async uninstallService(): Promise<void> {
    try {
      logger.info('Uninstalling Onebox daemon service...');

      // Initialize smartdaemon if needed
      if (!this.smartdaemon) {
        this.smartdaemon = new plugins.smartdaemon.SmartDaemon();
      }

      const service = await this.smartdaemon.getService('onebox');

      if (service) {
        await service.stop();
        await service.disable();
        await service.delete();
      }

      logger.success('Onebox daemon service uninstalled');
    } catch (error) {
      logger.error(`Failed to uninstall daemon service: ${error.message}`);
      throw error;
    }
  }

  /**
   * Start daemon mode (background monitoring)
   */
  async start(): Promise<void> {
    try {
      if (this.running) {
        logger.warn('Daemon already running');
        return;
      }

      logger.info('Starting Onebox daemon...');

      this.running = true;

      // Load settings from database
      this.loadSettings();

      // Write PID file
      await this.writePidFile();

      // Start monitoring loop
      this.startMonitoring();

      // Start HTTP server
      const httpPort = parseInt(this.oneboxRef.database.getSetting('httpPort') || '3000', 10);
      await this.oneboxRef.httpServer.start(httpPort);

      logger.success('Onebox daemon started');
      logger.info(`Web UI available at http://localhost:${httpPort}`);

      // Keep process alive
      await this.keepAlive();
    } catch (error) {
      logger.error(`Failed to start daemon: ${error.message}`);
      this.running = false;
      throw error;
    }
  }

  /**
   * Stop daemon mode
   */
  async stop(): Promise<void> {
    try {
      if (!this.running) {
        return;
      }

      logger.info('Stopping Onebox daemon...');

      this.running = false;

      // Stop monitoring
      this.stopMonitoring();

      // Stop HTTP server
      await this.oneboxRef.httpServer.stop();

      // Remove PID file
      await this.removePidFile();

      logger.success('Onebox daemon stopped');
    } catch (error) {
      logger.error(`Failed to stop daemon: ${error.message}`);
      throw error;
    }
  }

  /**
   * Start monitoring loop
   */
  public startMonitoring(): void {
    logger.info('Starting monitoring loop...');

    this.monitoringInterval = setInterval(async () => {
      await this.monitoringTick();
    }, this.metricsInterval);

    // Run first tick immediately
    this.monitoringTick();
  }

  /**
   * Stop monitoring loop
   */
  public stopMonitoring(): void {
    if (this.monitoringInterval !== null) {
      clearInterval(this.monitoringInterval);
      this.monitoringInterval = null;
      logger.debug('Monitoring loop stopped');
    }
  }

  /**
   * Single monitoring tick
   */
  private async monitoringTick(): Promise<void> {
    try {
      logger.debug('Running monitoring tick...');

      // Collect metrics for all services
      await this.collectMetrics();

      // Sync service statuses
      await this.oneboxRef.services.syncAllServiceStatuses();

      // Check SSL certificate expiration
      await this.checkSSLExpiration();

      // Check service health (TODO: implement health checks)

      logger.debug('Monitoring tick complete');
    } catch (error) {
      logger.error(`Monitoring tick failed: ${error.message}`);
    }
  }

  /**
   * Collect metrics for all services
   */
  private async collectMetrics(): Promise<void> {
    try {
      const services = this.oneboxRef.services.listServices();

      for (const service of services) {
        if (service.status === 'running' && service.containerID) {
          try {
            const stats = await this.oneboxRef.docker.getContainerStats(service.containerID);

            if (stats) {
              this.oneboxRef.database.addMetric({
                serviceId: service.id!,
                timestamp: Date.now(),
                cpuPercent: stats.cpuPercent,
                memoryUsed: stats.memoryUsed,
                memoryLimit: stats.memoryLimit,
                networkRxBytes: stats.networkRx,
                networkTxBytes: stats.networkTx,
              });
            }
          } catch (error) {
            logger.debug(`Failed to collect metrics for ${service.name}: ${error.message}`);
          }
        }
      }
    } catch (error) {
      logger.error(`Failed to collect metrics: ${error.message}`);
    }
  }

  /**
   * Check SSL certificate expiration
   */
  private async checkSSLExpiration(): Promise<void> {
    try {
      if (!this.oneboxRef.ssl.isConfigured()) {
        return;
      }

      await this.oneboxRef.ssl.renewExpiring();
    } catch (error) {
      logger.error(`Failed to check SSL expiration: ${error.message}`);
    }
  }

  /**
   * Keep process alive
   */
  private async keepAlive(): Promise<void> {
    // Set up signal handlers
    const signalHandler = () => {
      logger.info('Received shutdown signal');
      this.stop().then(() => {
        Deno.exit(0);
      });
    };

    Deno.addSignalListener('SIGINT', signalHandler);
    Deno.addSignalListener('SIGTERM', signalHandler);

    // Keep event loop alive
    while (this.running) {
      await new Promise((resolve) => setTimeout(resolve, 1000));
    }
  }

  /**
   * Get daemon status
   */
  isRunning(): boolean {
    return this.running;
  }

  /**
   * Write PID file
   */
  private async writePidFile(): Promise<void> {
    try {
      // Try primary location first
      try {
        await Deno.mkdir(PID_DIR, { recursive: true });
        await Deno.writeTextFile(PID_FILE_PATH, Deno.pid.toString());
        this.pidFilePath = PID_FILE_PATH;
        logger.debug(`PID file written: ${PID_FILE_PATH}`);
        return;
      } catch (error) {
        // Permission denied - try fallback location
        logger.debug(`Cannot write to ${PID_DIR}, using fallback location`);
      }

      // Fallback to user directory
      await Deno.mkdir(FALLBACK_PID_DIR, { recursive: true });
      await Deno.writeTextFile(FALLBACK_PID_FILE, Deno.pid.toString());
      this.pidFilePath = FALLBACK_PID_FILE;
      logger.debug(`PID file written: ${FALLBACK_PID_FILE}`);
    } catch (error) {
      logger.warn(`Failed to write PID file: ${error.message}`);
      // Non-fatal - daemon can still run
    }
  }

  /**
   * Remove PID file
   */
  private async removePidFile(): Promise<void> {
    try {
      await Deno.remove(this.pidFilePath);
      logger.debug(`PID file removed: ${this.pidFilePath}`);
    } catch (error) {
      // Ignore errors - file might not exist
      logger.debug(`Could not remove PID file: ${error.message}`);
    }
  }

  /**
   * Check if daemon is running
   */
  static async isDaemonRunning(): Promise<boolean> {
    const pid = await OneboxDaemon.getDaemonPid();
    if (!pid) {
      return false;
    }

    try {
      // Check if process exists
      await Deno.stat(`/proc/${pid}`);
      return true;
    } catch {
      // Process doesn't exist - clean up stale PID file
      logger.debug(`Cleaning up stale PID file`);
      try {
        await Deno.remove(PID_FILE_PATH);
      } catch {
        try {
          await Deno.remove(FALLBACK_PID_FILE);
        } catch {
          // Ignore
        }
      }
      return false;
    }
  }

  /**
   * Get daemon PID
   */
  static async getDaemonPid(): Promise<number | null> {
    try {
      // Try primary location
      try {
        const pidText = await Deno.readTextFile(PID_FILE_PATH);
        return parseInt(pidText.trim(), 10);
      } catch {
        // Try fallback location
        const pidText = await Deno.readTextFile(FALLBACK_PID_FILE);
        return parseInt(pidText.trim(), 10);
      }
    } catch {
      return null;
    }
  }

  /**
   * Ensure no daemon is running
   */
  static async ensureNoDaemon(): Promise<void> {
    const running = await OneboxDaemon.isDaemonRunning();
    if (running) {
      throw new Error('Daemon is already running. Please stop it first with: onebox daemon stop');
    }
  }

  /**
   * Get service status from systemd
   */
  async getServiceStatus(): Promise<string> {
    try {
      // Don't need smartdaemon to check status, just use systemctl directly
      const command = new Deno.Command('systemctl', {
        args: ['status', 'smartdaemon_onebox'],
        stdout: 'piped',
        stderr: 'piped',
      });

      const { code, stdout } = await command.output();
      const output = new TextDecoder().decode(stdout);

      if (code === 0 || output.includes('active (running)')) {
        return 'running';
      } else if (output.includes('inactive') || output.includes('dead')) {
        return 'stopped';
      } else if (output.includes('failed')) {
        return 'failed';
      } else {
        return 'unknown';
      }
    } catch (error) {
      return 'not-installed';
    }
  }
}