meld/services/pipeline/DirectiveService/handlers/execution/RunDirectiveHandler.ts

Meld: A template language for LLM prompts

import type { DirectiveNode, DirectiveContext, MeldNode, TextNode, StructuredPath } from 'meld-spec';
import type { IValidationService } from '@services/resolution/ValidationService/IValidationService.js';
import type { IStateService } from '@services/state/StateService/IStateService.js';
import type { IResolutionService } from '@services/resolution/ResolutionService/IResolutionService.js';
import type { IFileSystemService } from '@services/fs/FileSystemService/IFileSystemService.js';
import { DirectiveError, DirectiveErrorCode, DirectiveErrorSeverity } from '@services/pipeline/DirectiveService/errors/DirectiveError.js';
import { directiveLogger } from '../../../../../core/utils/logger.js';
import type { DirectiveResult } from '@services/pipeline/DirectiveService/types.js';
import type { IDirectiveHandler } from '@services/pipeline/DirectiveService/IDirectiveService.js';
import { ErrorSeverity } from '@core/errors/MeldError.js';

/**
 * Handler for @run directives
 * Executes commands and stores their output in state
 */
export class RunDirectiveHandler implements IDirectiveHandler {
  readonly kind = 'run';

  constructor(
    private validationService: IValidationService,
    private resolutionService: IResolutionService,
    private stateService: IStateService,
    private fileSystemService: IFileSystemService
  ) {}

  async execute(node: DirectiveNode, context: DirectiveContext): Promise<DirectiveResult> {
    const { directive } = node;
    const { state } = context;
    const clonedState = state.clone();

    try {
      // Validate the directive
      await this.validationService.validate(node);

      // Properly handle both string commands and command objects from AST
      const rawCommand = typeof directive.command === 'string' 
        ? directive.command 
        : directive.command.raw;

      // Resolve the command
      const resolvedCommand = await this.resolutionService.resolveInContext(
        rawCommand,
        context
      );

      // Show feedback that command is running (skips in test env)
      this.showRunningCommandFeedback(resolvedCommand);
      
      try {
        // Execute the command
        const { stdout, stderr } = await this.fileSystemService.executeCommand(
          resolvedCommand,
          {
            cwd: context.workingDirectory || this.fileSystemService.getCwd()
          }
        );
        
        // Clear the animated feedback after command completes
        this.clearCommandFeedback();

        // Store the output in state variables
        if (node.directive.output) {
          clonedState.setTextVar(node.directive.output, stdout);
        } else {
          clonedState.setTextVar('stdout', stdout);
        }
        if (stderr) {
          clonedState.setTextVar('stderr', stderr);
        }

        // In transformation mode, return a replacement node with the command output
        if (clonedState.isTransformationEnabled()) {
          const content = stdout && stderr ? `${stdout}\n${stderr}` : stdout || stderr || '';
          const replacement: TextNode = {
            type: 'Text',
            content,
            location: node.location
          };
          
          // Copy variables from cloned state to context state
          if (node.directive.output) {
            context.state.setTextVar(node.directive.output, stdout);
          } else {
            context.state.setTextVar('stdout', stdout);
          }
          if (stderr) {
            context.state.setTextVar('stderr', stderr);
          }
          
          clonedState.transformNode(node, replacement);
          return { state: clonedState, replacement };
        }

        // In normal mode, return a placeholder node
        const placeholder: TextNode = {
          type: 'Text',
          content: '[run directive output placeholder]',
          location: node.location
        };
        return { state: clonedState, replacement: placeholder };
      } catch (error) {
        // Make sure to clear animation on command execution error
        this.clearCommandFeedback();
        throw error;
      }
    } catch (error) {
      // Clear any animation if there's an error
      this.clearCommandFeedback();
      
      directiveLogger.error('Error executing run directive:', error);
      
      // If it's already a DirectiveError, just rethrow it
      if (error instanceof DirectiveError) {
        throw error;
      }

      // Otherwise wrap it with more context
      const message = error instanceof Error ? 
        `Failed to execute command: ${error.message}` :
        'Failed to execute command';

      throw new DirectiveError(
        message,
        this.kind,
        DirectiveErrorCode.EXECUTION_FAILED,
        { 
          node, 
          error,
          severity: DirectiveErrorSeverity[DirectiveErrorCode.EXECUTION_FAILED]
        }
      );
    }
  }
  
  // Reference to the interval for the animation
  private animationInterval: NodeJS.Timeout | null = null;
  
  // Determine if we're in a test environment
  private isTestEnvironment: boolean = process.env.NODE_ENV === 'test' || process.env.VITEST;
  
  /**
   * Display animated feedback that a command is running
   */
  private showRunningCommandFeedback(command: string): void {
    // Skip animation in test environments
    if (this.isTestEnvironment) {
      return;
    }
    
    // Clear any existing animation
    this.clearCommandFeedback();
    
    // Start position for the ellipses
    let count = 0;
    
    // Function to update the animation
    const updateAnimation = () => {
      // Create the ellipses string with the appropriate number of dots
      const ellipses = '.'.repeat(count % 4);
      
      // Clear the current line and print the message with animated ellipses
      process.stdout.write(`\r\x1b[K`); // Clear the line
      process.stdout.write(`Running \`${command}\`${ellipses}`);
      
      count++;
    };
    
    // Initial display
    updateAnimation();
    
    // Update the animation every 500ms
    this.animationInterval = setInterval(updateAnimation, 500);
  }
  
  /**
   * Clear the command feedback animation
   */
  private clearCommandFeedback(): void {
    // Skip in test environments
    if (this.isTestEnvironment) {
      return;
    }
    
    if (this.animationInterval) {
      clearInterval(this.animationInterval);
      this.animationInterval = null;
      
      // Clear the line
      process.stdout.write(`\r\x1b[K`);
    }
  }
}