const axios = require('axios');
const WebSocket = require('ws');
const { exec } = require('child_process');
const { promisify } = require('util');
const os = require('os');
const crypto = require('crypto');
require('dotenv').config();

const execAsync = promisify(exec);

class PulseWorker {
  constructor() {
    this.workerId = crypto.randomUUID();
    this.workerName = process.env.WORKER_NAME || os.hostname();
    this.serverUrl = process.env.PULSE_SERVER || 'http://localhost:8080';
    this.wsUrl = process.env.PULSE_WS || 'ws://localhost:8080';
    this.apiKey = process.env.WORKER_API_KEY;
    this.heartbeatInterval = parseInt(process.env.HEARTBEAT_INTERVAL || '30') * 1000;
    this.maxConcurrentTasks = parseInt(process.env.MAX_CONCURRENT_TASKS || '5');
    this.activeTasks = 0;
    this.ws = null;
    this.heartbeatTimer = null;
  }

  async start() {
    console.log(`[PULSE Worker] Starting worker: ${this.workerName}`);
    console.log(`[PULSE Worker] Worker ID: ${this.workerId}`);
    console.log(`[PULSE Worker] Server: ${this.serverUrl}`);

    // Send initial heartbeat
    await this.sendHeartbeat();

    // Start heartbeat timer
    this.startHeartbeat();

    // Connect to WebSocket for real-time commands
    this.connectWebSocket();

    console.log(`[PULSE Worker] Worker started successfully`);
  }

  startHeartbeat() {
    this.heartbeatTimer = setInterval(async () => {
      try {
        await this.sendHeartbeat();
      } catch (error) {
        console.error('[PULSE Worker] Heartbeat failed:', error.message);
      }
    }, this.heartbeatInterval);
  }

  async sendHeartbeat() {
    const metadata = {
      hostname: os.hostname(),
      platform: os.platform(),
      arch: os.arch(),
      cpus: os.cpus().length,
      totalMem: os.totalmem(),
      freeMem: os.freemem(),
      uptime: os.uptime(),
      loadavg: os.loadavg(),
      activeTasks: this.activeTasks,
      maxConcurrentTasks: this.maxConcurrentTasks
    };

    try {
      const response = await axios.post(
        `${this.serverUrl}/api/workers/heartbeat`,
        {
          worker_id: this.workerId,
          name: this.workerName,
          metadata: metadata
        },
        {
          headers: {
            'X-API-Key': this.apiKey,
            'Content-Type': 'application/json'
          }
        }
      );

      console.log(`[PULSE Worker] Heartbeat sent - Status: online`);
      return response.data;
    } catch (error) {
      console.error('[PULSE Worker] Heartbeat error:', error.message);
      throw error;
    }
  }

  connectWebSocket() {
    console.log(`[PULSE Worker] Connecting to WebSocket...`);
    
    this.ws = new WebSocket(this.wsUrl);

    this.ws.on('open', () => {
      console.log('[PULSE Worker] WebSocket connected');
      // Identify this worker
      this.ws.send(JSON.stringify({
        type: 'worker_connect',
        worker_id: this.workerId,
        worker_name: this.workerName
      }));
    });

    this.ws.on('message', async (data) => {
      try {
        const message = JSON.parse(data.toString());
        await this.handleMessage(message);
      } catch (error) {
        console.error('[PULSE Worker] Message handling error:', error);
      }
    });

    this.ws.on('close', () => {
      console.log('[PULSE Worker] WebSocket disconnected, reconnecting...');
      setTimeout(() => this.connectWebSocket(), 5000);
    });

    this.ws.on('error', (error) => {
      console.error('[PULSE Worker] WebSocket error:', error.message);
    });
  }

  async handleMessage(message) {
    console.log(`[PULSE Worker] Received message:`, message.type);

    switch (message.type) {
      case 'execute_command':
        await this.executeCommand(message);
        break;
      case 'execute_workflow':
        await this.executeWorkflow(message);
        break;
      case 'ping':
        this.sendPong();
        break;
      default:
        console.log(`[PULSE Worker] Unknown message type: ${message.type}`);
    }
  }

  async executeCommand(message) {
    const { command, execution_id, command_id, timeout = 300000 } = message;

    if (this.activeTasks >= this.maxConcurrentTasks) {
      console.log(`[PULSE Worker] Max concurrent tasks reached, rejecting command`);
      return;
    }

    this.activeTasks++;
    console.log(`[PULSE Worker] Executing command (active tasks: ${this.activeTasks})`);

    try {
      const startTime = Date.now();
      const { stdout, stderr } = await execAsync(command, {
        timeout: timeout,
        maxBuffer: 10 * 1024 * 1024 // 10MB buffer
      });
      const duration = Date.now() - startTime;

      const result = {
        type: 'command_result',
        execution_id,
        worker_id: this.workerId,
        command_id,
        success: true,
        stdout: stdout,
        stderr: stderr,
        duration: duration,
        timestamp: new Date().toISOString()
      };

      this.sendResult(result);
      console.log(`[PULSE Worker] Command completed in ${duration}ms`);
    } catch (error) {
      const result = {
        type: 'command_result',
        execution_id,
        worker_id: this.workerId,
        command_id,
        success: false,
        error: error.message,
        stdout: error.stdout || '',
        stderr: error.stderr || '',
        timestamp: new Date().toISOString()
      };

      this.sendResult(result);
      console.error(`[PULSE Worker] Command failed:`, error.message);
    } finally {
      this.activeTasks--;
    }
  }

  async executeWorkflow(message) {
    const { workflow, execution_id } = message;
    
    console.log(`[PULSE Worker] Executing workflow: ${workflow.name}`);
    
    // Workflow execution will be implemented in phase 2
    // For now, just acknowledge receipt
    this.sendResult({
      type: 'workflow_result',
      execution_id,
      worker_id: this.workerId,
      success: true,
      message: 'Workflow execution not yet implemented',
      timestamp: new Date().toISOString()
    });
  }

  sendResult(result) {
    if (this.ws && this.ws.readyState === WebSocket.OPEN) {
      this.ws.send(JSON.stringify(result));
    }
  }

  sendPong() {
    if (this.ws && this.ws.readyState === WebSocket.OPEN) {
      this.ws.send(JSON.stringify({ type: 'pong', worker_id: this.workerId }));
    }
  }

  async stop() {
    console.log('[PULSE Worker] Shutting down...');
    
    if (this.heartbeatTimer) {
      clearInterval(this.heartbeatTimer);
    }

    if (this.ws) {
      this.ws.close();
    }

    console.log('[PULSE Worker] Shutdown complete');
  }
}

// Start worker
const worker = new PulseWorker();

// Handle graceful shutdown
process.on('SIGTERM', async () => {
  await worker.stop();
  process.exit(0);
});

process.on('SIGINT', async () => {
  await worker.stop();
  process.exit(0);
});

// Start the worker
worker.start().catch((error) => {
  console.error('[PULSE Worker] Fatal error:', error);
  process.exit(1);
});