tswatch/ts/tswatch.classes.watcher.ts

import * as plugins from './tswatch.plugins.js';
import * as interfaces from './interfaces/index.js';
import { logger } from './tswatch.logging.js';

export interface IWatcherConstructorOptions {
  /** Name for this watcher (used in logging) */
  name?: string;
  /** Path(s) to watch - can be a single path or array */
  filePathToWatch: string | string[];
  /** Shell command to execute on changes */
  commandToExecute?: string;
  /** Function to call on changes */
  functionToCall?: () => Promise<any>;
  /** Timeout for the watcher */
  timeout?: number;
  /** If true, kill previous process before restarting (default: true) */
  restart?: boolean;
  /** Debounce delay in ms (default: 300) */
  debounce?: number;
  /** If true, run the command immediately on start (default: true) */
  runOnStart?: boolean;
}

/**
 * A watcher keeps track of one child execution
 */
export class Watcher {
  /**
   * used to execute shell commands
   */
  private smartshellInstance = new plugins.smartshell.Smartshell({
    executor: 'bash',
  });

  private currentExecution: plugins.smartshell.IExecResultStreaming;
  private smartwatchInstance = new plugins.smartwatch.Smartwatch([]);
  private options: IWatcherConstructorOptions;
  private debounceTimer: NodeJS.Timeout | null = null;
  private isExecuting = false;
  private pendingExecution = false;

  constructor(optionsArg: IWatcherConstructorOptions) {
    this.options = {
      restart: true,
      debounce: 300,
      runOnStart: true,
      ...optionsArg,
    };
  }

  /**
   * Create a Watcher from config
   */
  public static fromConfig(config: interfaces.IWatcherConfig): Watcher {
    const watchPaths = Array.isArray(config.watch) ? config.watch : [config.watch];
    return new Watcher({
      name: config.name,
      filePathToWatch: watchPaths,
      commandToExecute: config.command,
      restart: config.restart ?? true,
      debounce: config.debounce ?? 300,
      runOnStart: config.runOnStart ?? true,
    });
  }

  /**
   * Get the watcher name for logging
   */
  private getName(): string {
    return this.options.name || 'unnamed';
  }

  /**
   * start the file
   */
  public async start() {
    const name = this.getName();
    logger.log('info', `[${name}] starting watcher`);
    await this.setupCleanup();

    // Convert paths to glob patterns
    const paths = Array.isArray(this.options.filePathToWatch)
      ? this.options.filePathToWatch
      : [this.options.filePathToWatch];

    const watchPatterns = paths.map((p) => {
      // Convert directory path to glob pattern for smartwatch
      if (p.endsWith('/')) {
        return `${p}**/*`;
      }
      // If it's already a glob pattern, use as-is
      if (p.includes('*')) {
        return p;
      }
      // Otherwise assume it's a directory
      return `${p}/**/*`;
    });

    logger.log('info', `[${name}] watching patterns: ${watchPatterns.join(', ')}`);
    this.smartwatchInstance.add(watchPatterns);
    await this.smartwatchInstance.start();

    const changeObservable = await this.smartwatchInstance.getObservableFor('change');
    changeObservable.subscribe(() => {
      this.handleChange();
    });

    // Run on start if configured
    if (this.options.runOnStart) {
      await this.executeCommand();
    }

    logger.log('info', `[${name}] watcher started`);
  }

  /**
   * Handle file change with debouncing
   */
  private handleChange() {
    const name = this.getName();

    // Clear existing debounce timer
    if (this.debounceTimer) {
      clearTimeout(this.debounceTimer);
    }

    // Set new debounce timer
    this.debounceTimer = setTimeout(async () => {
      this.debounceTimer = null;

      // If currently executing and not in restart mode, mark pending
      if (this.isExecuting && !this.options.restart) {
        logger.log('info', `[${name}] change detected, queuing execution`);
        this.pendingExecution = true;
        return;
      }

      await this.executeCommand();

      // If there was a pending execution, run it
      if (this.pendingExecution) {
        this.pendingExecution = false;
        await this.executeCommand();
      }
    }, this.options.debounce);
  }

  /**
   * Execute the command or function
   */
  private async executeCommand() {
    const name = this.getName();

    if (this.options.commandToExecute) {
      if (this.currentExecution && this.options.restart) {
        logger.log('ok', `[${name}] restarting: ${this.options.commandToExecute}`);
        this.currentExecution.kill();
      } else if (!this.currentExecution) {
        logger.log('ok', `[${name}] executing: ${this.options.commandToExecute}`);
      }

      this.isExecuting = true;
      this.currentExecution = await this.smartshellInstance.execStreaming(
        this.options.commandToExecute,
      );

      // Track when execution completes
      this.currentExecution.childProcess.on('exit', () => {
        this.isExecuting = false;
      });
    }

    if (this.options.functionToCall) {
      this.isExecuting = true;
      try {
        await this.options.functionToCall();
      } finally {
        this.isExecuting = false;
      }
    }
  }

  /**
   * this method sets up a clean exit strategy
   */
  private async setupCleanup() {
    process.on('exit', () => {
      console.log('');
      console.log('now exiting!');
      this.stop();
      process.exit(0);
    });
    process.on('SIGINT', () => {
      console.log('');
      console.log('ok! got SIGINT We are exiting! Just cleaning up to exit neatly :)');
      this.stop();
      process.exit(0);
    });

    // handle timeout
    if (this.options.timeout) {
      plugins.smartdelay.delayFor(this.options.timeout).then(() => {
        console.log(`timed out afer ${this.options.timeout} milliseconds! exiting!`);
        this.stop();
        process.exit(0);
      });
    }
  }

  /**
   * stops the watcher
   */
  public async stop() {
    if (this.debounceTimer) {
      clearTimeout(this.debounceTimer);
    }
    await this.smartwatchInstance.stop();
    if (this.currentExecution && !this.currentExecution.childProcess.killed) {
      this.currentExecution.kill();
    }
  }
}