import { ToolDiscoveryEngine, DiscoveredTool } from './tool-discovery';
import { Logger } from '../../utils/logger';

/**
 * @class ToolExecutor
 * @description Creates a robust tool execution infrastructure with async execution, error handling, and chaining.
 */
export class ToolExecutor {
  private toolDiscovery: ToolDiscoveryEngine;
  private logger: Logger;

  constructor(toolDiscovery: ToolDiscoveryEngine) {
    this.toolDiscovery = toolDiscovery;
    this.logger = new Logger('ToolExecutor');
  }

  /**
   * Executes a tool asynchronously with timeout management and retry mechanisms.
   * @param {string} toolName The name of the tool to execute.
   * @param {string} methodName The method name to call on the tool instance.
   * @param {any[]} args Arguments to pass to the tool method.
   * @param {object} [options] Execution options.
   * @param {number} [options.timeout=60000] Timeout in milliseconds.
   * @param {number} [options.retries=3] Number of retry attempts.
   * @param {number} [options.backoff=1000] Initial backoff delay in milliseconds.
   * @returns {Promise<any>} The result of the tool execution.
   */
  public async executeTool(
    toolName: string,
    methodName: string,
    args: any[],
    options?: { timeout?: number; retries?: number; backoff?: number }
  ): Promise<any> {
    const { timeout = 60000, retries = 3, backoff = 1000 } = options || {};

    const tool = this.toolDiscovery.getTool(toolName);
    if (!tool) {
      throw new Error(`Tool "${toolName}" not found in discovery engine.`);
    }

    // Instantiate the tool if not already done
    if (!tool.instance) {
      try {
        // Dynamically import the tool module again to get the class constructor
        const module = await import(tool.filePath);
        const ToolClass = module[`${tool.name.charAt(0).toUpperCase() + tool.name.slice(1)}Tool`];
        if (!ToolClass) {
          throw new Error(`Tool class not found for ${toolName} at ${tool.filePath}`);
        }
        // Assuming tool constructors take a config object. This needs to be generalized.
        // For now, we'll pass a dummy config or assume no config for simplicity.
        tool.instance = new ToolClass({}); // TODO: Pass actual config based on tool type
      } catch (instantiationError: any) {
        throw new Error(`Failed to instantiate tool ${toolName}: ${instantiationError.message}`);
      }
    }

    if (typeof tool.instance[methodName] !== 'function') {
      throw new Error(`Method "${methodName}" not found on tool "${toolName}".`);
    }

    for (let attempt = 1; attempt <= retries + 1; attempt++) {
      try {
        this.logger.info(`Executing tool ${toolName}.${methodName} (Attempt ${attempt}/${retries + 1})`);
        const executionPromise = tool.instance[methodName](...args);

        const result = await Promise.race([
          executionPromise,
          new Promise((_, reject) =>
            setTimeout(() => reject(new Error(`Tool execution timed out after ${timeout}ms`)), timeout)
          ),
        ]);
        this.logger.info(`Tool ${toolName}.${methodName} executed successfully.`);
        return result;
      } catch (error: any) {
        this.logger.warn(`Tool ${toolName}.${methodName} failed (Attempt ${attempt}/${retries + 1}): ${error.message}`);
        if (attempt <= retries) {
          const delay = backoff * Math.pow(2, attempt - 1);
          this.logger.info(`Retrying in ${delay}ms...`);
          await new Promise((resolve) => setTimeout(resolve, delay));
        } else {
          throw new Error(`Tool ${toolName}.${methodName} failed after ${retries + 1} attempts: ${error.message}`);
        }
      }
    }
    throw new Error('Unexpected error: Should not reach here.'); // Should be unreachable
  }

  /**
   * Supports tool chaining and workflow orchestration (conceptual at this layer).
   * @param {Array<{ toolName: string, methodName: string, args: any[] }>} chain A sequence of tool calls.
   * @returns {Promise<any[]>} Results of each step in the chain.
   */
  public async executeToolChain(chain: Array<{ toolName: string, methodName: string, args: any[] }>): Promise<any[]> {
    this.logger.info('Executing tool chain...');
    const results: any[] = [];
    for (const step of chain) {
      const result = await this.executeTool(step.toolName, step.methodName, step.args);
      results.push(result);
    }
    this.logger.info('Tool chain execution complete.');
    return results;
  }

  /**
   * Manages resources and connection pooling (conceptual).
   * @returns {Promise<void>}
   */
  public async manageResources(): Promise<void> {
    this.logger.info('Managing tool resources and connection pooling (conceptual)...');
    // This would involve:
    // - Initializing and managing connection pools for various GCP services.
    // - Ensuring efficient resource allocation and deallocation.
    // - Implementing graceful shutdown of connections.
  }

  /**
   * Monitors tool performance and provides optimization insights (conceptual).
   * @returns {Promise<void>}
   */
  public async monitorPerformance(): Promise<void> {
    this.logger.info('Monitoring tool performance and providing optimization insights (conceptual)...');
    // This would involve:
    // - Collecting metrics during tool execution (latency, error rate, resource usage).
    // - Analyzing trends and identifying bottlenecks.
    // - Suggesting optimizations (e.g., caching, parallelization).
  }
}