# All files / src/process manager.ts

77.41% Statements 72/93
83.78% Branches 31/37
60% Functions 12/20
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     /**
     * Process Manager
     *
     * Manages spawning, stopping, and lifecycle of child processes.
     * Uses execa for process spawning with detached mode support.
     * Emits domain events via optional EventBus for coordination.
     */

    import { execa, type ResultPromise } from 'execa';
    import type { ProcessInfo, SpawnOptions } from './types.js';
    import type { ProcessRegistry } from './registry.js';
    import type { EventBus, ProcessSpawnedEvent, ProcessStoppedEvent, ProcessCrashedEvent } from '../events/index.js';

    /** Stop timeout in milliseconds before sending SIGKILL */
    const STOP_TIMEOUT_MS = 5000;

    /**
     * Internal tracking for spawned process handles.
     * Maps process ID to execa subprocess for control operations.
     */
    interface ProcessHandle {
      subprocess: ResultPromise;
      options: SpawnOptions;
    }

    /**
     * Manager for spawning, tracking, and controlling child processes.
     */
    export class ProcessManager {
      private handles: Map<string, ProcessHandle> = new Map();

      /**
       * Create a new ProcessManager.
       * @param registry - Registry for tracking process metadata
       * @param eventBus - Optional event bus for emitting domain events
       */
      constructor(
        private registry: ProcessRegistry,
        private eventBus?: EventBus
      ) {}

      /**
       * Spawn a new child process.
       * @param options - Spawn configuration
       * @returns Process info for the spawned process
       * @throws If process fails to start
       */
      async spawn(options: SpawnOptions): Promise<ProcessInfo> {
        const { id, command, args = [], cwd, env } = options;

        // Check if process with this ID already exists
        const existing = this.registry.get(id);
        if (existing && existing.status === 'running') {
          throw new Error(`Process with id '${id}' is already running`);
        }

        // Spawn the process in detached mode
        const subprocess = execa(command, args, {
          cwd,
          env: env ? { ...process.env, ...env } : undefined,
          detached: true,
          stdio: 'ignore', // Don't inherit stdio for background processes
        });

        // Ensure we have a PID
        const pid = subprocess.pid;
        if (pid === undefined) {
          throw new Error(`Failed to get PID for process '${id}'`);
        }

        // Create process info
        const info: ProcessInfo = {
          id,
          pid,
          command,
          args,
          startedAt: new Date(),
          status: 'running',
        };

        // Store handle for later control
        this.handles.set(id, { subprocess, options });

        // Register in registry
        this.registry.register(info);

        // Emit ProcessSpawned event
        if (this.eventBus) {
          const event: ProcessSpawnedEvent = {
            type: 'process:spawned',
            timestamp: new Date(),
            payload: {
              processId: id,
              pid,
              command,
            },
          };
          this.eventBus.emit(event);
        }

        // Set up exit handler to update status and emit events
        subprocess.on('exit', (code, signal) => {
          const status = code === 0 ? 'stopped' : 'crashed';
          this.registry.updateStatus(id, status);
          this.handles.delete(id);

          // Emit appropriate event based on exit status
          if (this.eventBus) {
            if (status === 'stopped') {
              const event: ProcessStoppedEvent = {
                type: 'process:stopped',
                timestamp: new Date(),
                payload: {
                  processId: id,
                  pid,
                  exitCode: code,
                },
              };
              this.eventBus.emit(event);
            } else {
              const event: ProcessCrashedEvent = {
                type: 'process:crashed',
                timestamp: new Date(),
                payload: {
                  processId: id,
                  pid,
                  exitCode: code,
                  signal,
                },
              };
              this.eventBus.emit(event);
            }
          }
        });

        // Suppress unhandled rejection when process is killed
        // This is expected behavior - we're intentionally killing processes
        subprocess.catch(() => {
          // Intentionally ignored - we handle exit via the 'exit' event
        });

        // Unref the subprocess so it doesn't keep the parent alive
        subprocess.unref();

        return info;
      }

      /**
       * Stop a running process.
       * Sends SIGTERM first, then SIGKILL after timeout if needed.
       * @param id - Process ID to stop
       * @throws If process not found
       */
      async stop(id: string): Promise<void> {
        const handle = this.handles.get(id);
        const info = this.registry.get(id);

        if (!info) {
          throw new Error(`Process with id '${id}' not found`);
        }

        if (info.status !== 'running') {
          // Already stopped, just clean up
          this.handles.delete(id);
          return;
        }

        Iif (!handle) {
          // Process exists in registry but we don't have a handle
          // Try to kill by PID directly
          try {
            process.kill(info.pid, 'SIGTERM');
            await this.waitForExit(info.pid, STOP_TIMEOUT_MS);
          } catch {
            // Process might already be dead
          }
          this.registry.updateStatus(id, 'stopped');
          return;
        }

        // Send SIGTERM
        handle.subprocess.kill('SIGTERM');

        // Wait for graceful shutdown
        const exited = await this.waitForProcessExit(handle.subprocess, STOP_TIMEOUT_MS);

        Iif (!exited) {
          // Force kill with SIGKILL
          handle.subprocess.kill('SIGKILL');
          await this.waitForProcessExit(handle.subprocess, 1000).catch(() => {});
        }

        // Update status (exit handler should have done this, but ensure it)
        this.registry.updateStatus(id, 'stopped');
        this.handles.delete(id);
      }

      /**
       * Stop all running processes.
       */
      async stopAll(): Promise<void> {
        const processes = this.registry.getAll().filter(p => p.status === 'running');
        await Promise.all(processes.map(p => this.stop(p.id).catch(() => {})));
      }

      /**
       * Restart a process with the same configuration.
       * @param id - Process ID to restart
       * @returns New process info
       * @throws If process not found or original config unavailable
       */
      async restart(id: string): Promise<ProcessInfo> {
        const handle = this.handles.get(id);
        const info = this.registry.get(id);

        if (!info) {
          throw new Error(`Process with id '${id}' not found`);
        }

        // Get original spawn options
        let options: SpawnOptions;
        if (handle) {
          options = handle.options;
        } else E{
          // Reconstruct options from process info
          options = {
            id,
            command: info.command,
            args: info.args,
          };
        }

        // Stop if running
        Eif (info.status === 'running') {
          await this.stop(id);
        }

        // Unregister old process
        this.registry.unregister(id);

        // Spawn with same options
        return this.spawn(options);
      }

      /**
       * Check if a process is currently running.
       * @param id - Process ID to check
       * @returns true if process exists and is running
       */
      isRunning(id: string): boolean {
        const info = this.registry.get(id);
        if (!info || info.status !== 'running') {
          return false;
        }

        // Double-check by probing the actual process
        try {
          process.kill(info.pid, 0);
          return true;
        } catch {
          // Process is dead, update registry
          this.registry.updateStatus(id, 'crashed');
          this.handles.delete(id);
          return false;
        }
      }

      /**
       * Wait for a subprocess to exit within a timeout.
       * @returns true if process exited, false if timeout
       */
      private waitForProcessExit(subprocess: ResultPromise, timeoutMs: number): Promise<boolean> {
        return new Promise(resolve => {
          const timeout = setTimeout(() => {
            resolve(false);
          }, timeoutMs);

          // Use both then and catch to handle success and kill scenarios
          subprocess
            .then(() => {
              clearTimeout(timeout);
              resolve(true);
            })
            .catch(() => {
              // Process was killed (expected) - this is success for our purposes
              clearTimeout(timeout);
              resolve(true);
            });
        });
      }

      /**
       * Wait for a PID to exit within a timeout.
       * @returns true if process exited, false if timeout
       */
      private waitForExit(pid: number, timeoutMs: number): Promise<boolean> {
        return new Promise(resolve => {
          const start = Date.now();
          const check = () => {
            try {
              process.kill(pid, 0);
              // Still alive
              if (Date.now() - start >= timeoutMs) {
                resolve(false);
              } else {
                setTimeout(check, 100);
              }
            } catch {
              // Dead
              resolve(true);
            }
          };
          check();
        });
      }
    }