stock-bot/libs/core/handlers/src/base/BaseHandler.ts

import { getLogger } from '@stock-bot/logger';
import type { IHandler, ExecutionContext } from '../types/types';
import type { IServiceContainer } from '../types/service-container';
import { handlerRegistry, createJobHandler, type HandlerConfigWithSchedule } from '@stock-bot/types';

/**
 * Abstract base class for all handlers with improved DI
 * Provides common functionality and structure for queue/event operations
 */
export abstract class BaseHandler implements IHandler {
  protected readonly logger;
  private handlerName: string;

  constructor(protected readonly services: IServiceContainer, handlerName?: string) {
    this.logger = getLogger(this.constructor.name);
    // Read handler name from decorator first, then fallback to parameter or class name
    const constructor = this.constructor as any;
    this.handlerName = constructor.__handlerName || handlerName || this.constructor.name.toLowerCase();
  }

  // Convenience getters for common services
  protected get mongodb() { return this.services.mongodb; }
  protected get postgres() { return this.services.postgres; }
  protected get questdb() { return this.services.questdb; }
  protected get cache() { return this.services.cache; }
  protected get queue() { return this.services.queue; }
  protected get http() { return this.services.http; }

  /**
   * Main execution method - automatically routes to decorated methods
   * Works with queue (events commented for future)
   */
  async execute(operation: string, input: unknown, context: ExecutionContext): Promise<unknown> {
    const constructor = this.constructor as any;
    const operations = constructor.__operations || [];
    
    // Debug logging
    this.logger.debug('Handler execute called', {
      handler: this.handlerName,
      operation,
      availableOperations: operations.map((op: any) => ({ name: op.name, method: op.method }))
    });
    
    // Find the operation metadata
    const operationMeta = operations.find((op: any) => op.name === operation);
    if (!operationMeta) {
      this.logger.error('Operation not found', {
        requestedOperation: operation,
        availableOperations: operations.map((op: any) => op.name)
      });
      throw new Error(`Unknown operation: ${operation}`);
    }
    
    // Get the method from the instance and call it
    const method = (this as any)[operationMeta.method];
    if (typeof method !== 'function') {
      throw new Error(`Operation method '${operationMeta.method}' not found on handler`);
    }
    
    this.logger.debug('Executing operation method', {
      operation,
      method: operationMeta.method
    });
    
    return await method.call(this, input, context);
  }

  /**
   * Queue helper methods - now type-safe and direct
   */
  protected async scheduleOperation(operation: string, payload: unknown, delay?: number): Promise<void> {
    const queue = this.services.queue.getQueue(this.handlerName);
    const jobData = {
      handler: this.handlerName,
      operation,
      payload
    };
    await queue.add(operation, jobData, { delay });
  }

  /**
   * Create execution context for operations
   */
  protected createExecutionContext(type: 'http' | 'queue' | 'scheduled', metadata: Record<string, any> = {}): ExecutionContext {
    return {
      type,
      metadata: {
        ...metadata,
        timestamp: Date.now(),
        traceId: `${this.constructor.name}-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`
      }
    };
  }

  /**
   * Event methods - commented for future
   */
  // protected async publishEvent(eventName: string, payload: unknown): Promise<void> {
  //   const eventBus = await this.container.resolveAsync('eventBus');
  //   await eventBus.publish(eventName, payload);
  // }

  /**
   * Register this handler using decorator metadata
   * Automatically reads @Handler, @Operation, and @QueueSchedule decorators
   */
  register(): void {
    const constructor = this.constructor as any;
    const handlerName = constructor.__handlerName || this.handlerName;
    const operations = constructor.__operations || [];
    const schedules = constructor.__schedules || [];

    // Create operation handlers from decorator metadata
    const operationHandlers: Record<string, any> = {};
    for (const op of operations) {
      operationHandlers[op.name] = createJobHandler(async (payload) => {
        const context: ExecutionContext = {
          type: 'queue',
          metadata: { source: 'queue', timestamp: Date.now() }
        };
        return await this.execute(op.name, payload, context);
      });
    }

    // Create scheduled jobs from decorator metadata
    const scheduledJobs = schedules.map((schedule: any) => {
      // Find the operation name from the method name
      const operation = operations.find((op: any) => op.method === schedule.operation);
      return {
        type: `${handlerName}-${schedule.operation}`,
        operation: operation?.name || schedule.operation,
        cronPattern: schedule.cronPattern,
        priority: schedule.priority || 5,
        immediately: schedule.immediately || false,
        description: schedule.description || `${handlerName} ${schedule.operation}`,
        payload: this.getScheduledJobPayload?.(schedule.operation),
      };
    });

    const config: HandlerConfigWithSchedule = {
      name: handlerName,
      operations: operationHandlers,
      scheduledJobs,
    };

    handlerRegistry.registerWithSchedule(config);
    this.logger.info('Handler registered using decorator metadata', { 
      handlerName, 
      operations: operations.map((op: any) => ({ name: op.name, method: op.method })),
      scheduledJobs: scheduledJobs.map((job: any) => ({ 
        operation: job.operation, 
        cronPattern: job.cronPattern,
        immediately: job.immediately 
      }))
    });
  }

  /**
   * Override this method to provide payloads for scheduled jobs
   * @param operation The operation name that needs a payload
   * @returns The payload for the scheduled job, or undefined
   */
  protected getScheduledJobPayload?(operation: string): any;

  /**
   * Lifecycle hooks - can be overridden by subclasses
   */
  async onInit?(): Promise<void>;
  async onStart?(): Promise<void>;
  async onStop?(): Promise<void>;
  async onDispose?(): Promise<void>;
}


/**
 * Specialized handler for operations that have scheduled jobs
 */
export abstract class ScheduledHandler extends BaseHandler {
  /**
   * Get scheduled job configurations for this handler
   * Override in subclasses to define schedules
   */
  getScheduledJobs?(): Array<{
    operation: string;
    cronPattern: string;
    priority?: number;
    immediately?: boolean;
    description?: string;
  }>;
}