import * as plugins from './plugins.js';
import type { IFirecrackerProcessOptions } from './interfaces/index.js';
import { SmartVMError } from './interfaces/index.js';
import { SocketClient } from './classes.socketclient.js';

/**
 * Manages a single Firecracker child process, including startup, readiness polling, and shutdown.
 */
export class FirecrackerProcess {
  private options: IFirecrackerProcessOptions;
  private streaming: any | null = null;
  private shell: InstanceType<typeof plugins.smartshell.Smartshell>;
  private smartExitInstance: InstanceType<typeof plugins.smartexit.SmartExit> | null = null;
  public socketClient: SocketClient;

  constructor(options: IFirecrackerProcessOptions) {
    this.options = options;
    this.shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
    this.socketClient = new SocketClient({ socketPath: options.socketPath });
  }

  /**
   * Start the Firecracker process and wait for the API socket to become ready.
   */
  public async start(): Promise<void> {
    // Remove any stale socket file
    if (plugins.fs.existsSync(this.options.socketPath)) {
      plugins.fs.unlinkSync(this.options.socketPath);
    }

    // Build the command
    let cmd = `${this.options.binaryPath} --api-sock ${this.options.socketPath}`;
    if (this.options.logLevel) {
      cmd += ` --level ${this.options.logLevel}`;
    }

    // Spawn the process
    this.streaming = await this.shell.execStreaming(cmd, true);

    // Register with smartexit for automatic cleanup
    if (this.streaming?.childProcess) {
      this.smartExitInstance = new plugins.smartexit.SmartExit({ silent: true });
      this.smartExitInstance.addProcess(this.streaming.childProcess);
    }

    // Wait for the socket file to appear
    const socketReady = await this.waitForSocket(10000);
    if (!socketReady) {
      await this.stop();
      throw new SmartVMError(
        'Firecracker socket did not become ready within timeout',
        'SOCKET_TIMEOUT',
      );
    }

    // Wait for the API to be responsive
    const apiReady = await this.socketClient.isReady(5000);
    if (!apiReady) {
      await this.stop();
      throw new SmartVMError(
        'Firecracker API did not become responsive within timeout',
        'API_TIMEOUT',
      );
    }
  }

  /**
   * Poll for the socket file to appear on disk.
   */
  private async waitForSocket(timeoutMs: number): Promise<boolean> {
    const start = Date.now();
    while (Date.now() - start < timeoutMs) {
      if (plugins.fs.existsSync(this.options.socketPath)) {
        return true;
      }
      await plugins.smartdelay.delayFor(100);
    }
    return false;
  }

  /**
   * Gracefully stop the Firecracker process with SIGTERM, then SIGKILL after timeout.
   */
  public async stop(): Promise<void> {
    if (!this.streaming) return;

    try {
      // Try graceful termination first
      await this.streaming.terminate();

      // Wait up to 5 seconds for the process to exit
      const exitPromise = Promise.race([
        this.streaming.finalPromise,
        plugins.smartdelay.delayFor(5000),
      ]);
      await exitPromise;
    } catch {
      // If termination fails, force kill
      try {
        await this.streaming.kill();
      } catch {
        // Process may already be dead
      }
    }

    this.streaming = null;
  }

  /**
   * Clean up the socket file.
   */
  public async cleanup(): Promise<void> {
    await this.stop();

    // Remove the socket file
    if (plugins.fs.existsSync(this.options.socketPath)) {
      plugins.fs.unlinkSync(this.options.socketPath);
    }
  }

  /**
   * Check if the process is currently running.
   */
  public isRunning(): boolean {
    if (!this.streaming?.childProcess) return false;
    try {
      // Sending signal 0 tests if process exists without actually sending a signal
      process.kill(this.streaming.childProcess.pid, 0);
      return true;
    } catch {
      return false;
    }
  }

  /**
   * Get the child process PID.
   */
  public getPid(): number | null {
    return this.streaming?.childProcess?.pid ?? null;
  }
}