import { Queue as BullQueue, type Job } from 'bullmq';
import { createCache } from '@stock-bot/cache';
import type { CacheProvider } from '@stock-bot/cache';
import type { HandlerRegistry } from '@stock-bot/handler-registry';
import { getLogger } from '@stock-bot/logger';
import { Queue, type QueueWorkerConfig } from './queue';
import { QueueRateLimiter } from './rate-limiter';
import { getFullQueueName, parseQueueName } from './service-utils';
import type {
  GlobalStats,
  JobData,
  JobOptions,
  QueueManagerConfig,
  QueueOptions,
  QueueRoute,
  QueueStats,
  RateLimitRule,
} from './types';
import { getRedisConnection } from './utils';

// Logger interface for type safety
interface Logger {
  info(message: string, meta?: Record<string, unknown>): void;
  error(message: string, meta?: Record<string, unknown>): void;
  warn(message: string, meta?: Record<string, unknown>): void;
  debug(message: string, meta?: Record<string, unknown>): void;
  trace(message: string, meta?: Record<string, unknown>): void;
  child?(name: string, context?: Record<string, unknown>): Logger;
}

/**
 * QueueManager provides unified queue and cache management with service discovery
 * Handles both local and cross-service queue operations
 */
export class QueueManager {
  private queues = new Map<string, Queue>();
  private caches = new Map<string, CacheProvider>();
  private rateLimiter?: QueueRateLimiter;
  private redisConnection: ReturnType<typeof getRedisConnection>;
  private isShuttingDown = false;
  private shutdownPromise: Promise<void> | null = null;
  private config: QueueManagerConfig;
  private readonly logger: Logger;
  
  // Service discovery features
  private serviceName?: string;
  private queueRoutes = new Map<string, QueueRoute>();
  private producerQueues = new Map<string, BullQueue>(); // For cross-service sending
  private handlerRegistry?: HandlerRegistry;

  constructor(config: QueueManagerConfig, handlerRegistry?: HandlerRegistry, logger?: Logger) {
    // Always use DB 0 for queues if service name is provided
    if (config.serviceName) {
      config = {
        ...config,
        redis: {
          ...config.redis,
          db: 0, // All queues in DB 0 for cross-service communication
        },
      };
    }
    
    this.config = config;
    this.serviceName = config.serviceName;
    this.handlerRegistry = handlerRegistry;
    this.logger = logger || getLogger('QueueManager');
    this.redisConnection = getRedisConnection(config.redis);

    // Initialize rate limiter if rules are provided
    if (config.rateLimitRules && config.rateLimitRules.length > 0) {
      this.rateLimiter = new QueueRateLimiter(this.redisConnection, this.logger);
      config.rateLimitRules.forEach(rule => {
        if (this.rateLimiter) {
          this.rateLimiter.addRule(rule);
        }
      });
    }

    // Auto-discover routes if enabled and registry provided
    if (config.serviceName && config.autoDiscoverHandlers !== false && handlerRegistry) {
      this.discoverQueueRoutes();
    }
    
    this.logger.info('QueueManager initialized', {
      redis: `${config.redis.host}:${config.redis.port}`,
      service: this.serviceName,
      discoveredRoutes: this.queueRoutes.size,
      hasRegistry: !!handlerRegistry,
    });
  }

  /**
   * Get or create a queue - unified method that handles both scenarios
   * This is the main method for accessing queues
   * If serviceName is configured, automatically handles namespacing
   */
  getQueue(queueName: string, options: QueueOptions = {}): Queue {
    let fullQueueName = queueName;
    let isOwnQueue = true;
    
    // Handle service namespacing if service name is configured
    if (this.serviceName) {
      const parsed = parseQueueName(queueName);
      
      if (parsed) {
        // Already in service:handler format
        fullQueueName = queueName;
        isOwnQueue = parsed.service === this.serviceName;
      } else {
        // Just handler name, assume it's for current service
        fullQueueName = getFullQueueName(this.serviceName, queueName);
        isOwnQueue = true;
      }
      
      // For cross-service queues, create without workers (producer-only)
      if (!isOwnQueue) {
        options = {
          ...options,
          workers: 0, // No workers for other services' queues
        };
      } else {
        // For own service queues, include handler registry
        options = {
          ...options,
          handlerRegistry: this.handlerRegistry
        };
      }
      
      queueName = fullQueueName;
    }
    // Return existing queue if it exists
    if (this.queues.has(queueName)) {
      const existingQueue = this.queues.get(queueName);
      if (existingQueue) {
        return existingQueue;
      }
    }

    // Create new queue with merged options
    const mergedOptions = {
      ...this.config.defaultQueueOptions,
      ...options,
    };

    // Prepare queue configuration
    const workers = mergedOptions.workers ?? this.config.defaultQueueOptions?.workers ?? 1;
    const concurrency =
      mergedOptions.concurrency ?? this.config.defaultQueueOptions?.concurrency ?? 1;

    const queueConfig: QueueWorkerConfig = {
      workers,
      concurrency,
      startWorker: workers > 0 && !this.config.delayWorkerStart,
      handlerRegistry: options.handlerRegistry || this.handlerRegistry,
    };

    const queue = new Queue(
      queueName,
      this.config.redis,
      mergedOptions.defaultJobOptions || {},
      queueConfig,
      this.logger
    );

    // Store the queue
    this.queues.set(queueName, queue);

    // Automatically initialize batch cache for the queue
    this.initializeBatchCacheSync(queueName);

    // Add queue-specific rate limit rules
    if (this.rateLimiter && mergedOptions.rateLimitRules) {
      mergedOptions.rateLimitRules.forEach(rule => {
        // Ensure queue name is set for queue-specific rules
        const ruleWithQueue = { ...rule, queueName };
        if (this.rateLimiter) {
          this.rateLimiter.addRule(ruleWithQueue);
        }
      });
    }

    this.logger.info('Queue created with batch cache', {
      queueName,
      originalQueueName: options.handlerRegistry ? 'has-handler-registry' : 'no-handler-registry',
      workers: workers,
      concurrency: concurrency,
      handlerRegistryProvided: !!this.handlerRegistry,
      willStartWorkers: workers > 0 && !this.config.delayWorkerStart,
      isOwnQueue,
      serviceName: this.serviceName,
    });

    return queue;
  }

  /**
   * Check if a queue exists
   */
  hasQueue(queueName: string): boolean {
    return this.queues.has(queueName);
  }

  /**
   * Get all queue names
   */
  getQueueNames(): string[] {
    return Array.from(this.queues.keys());
  }

  /**
   * Get or create a cache for a queue
   */
  getCache(queueName: string): CacheProvider {
    if (!this.caches.has(queueName)) {
      const cacheProvider = createCache({
        redisConfig: this.config.redis,
        keyPrefix: `batch:${queueName}:`,
        ttl: 86400, // 24 hours default
        enableMetrics: true,
        logger: this.logger,
      });
      this.caches.set(queueName, cacheProvider);
      this.logger.trace('Cache created for queue', { queueName });
    }
    const cache = this.caches.get(queueName);
    if (!cache) {
      throw new Error(`Expected cache for queue ${queueName} to exist`);
    }
    return cache;
  }

  /**
   * Initialize cache for a queue (ensures it's ready)
   */
  async initializeCache(queueName: string): Promise<void> {
    const cache = this.getCache(queueName);
    await cache.waitForReady(10000);
    this.logger.info('Cache initialized for queue', { queueName });
  }

  /**
   * Initialize batch cache synchronously (for automatic initialization)
   * The cache will be ready for use, but we don't wait for Redis connection
   */
  private initializeBatchCacheSync(queueName: string): void {
    // Just create the cache - it will connect automatically when first used
    this.getCache(queueName);
    this.logger.trace('Batch cache initialized synchronously for queue', { queueName });
  }

  /**
   * Get the queues map (for subclasses)
   */
  protected getQueues(): Map<string, Queue> {
    return this.queues;
  }

  /**
   * Get statistics for all queues
   */
  async getGlobalStats(): Promise<GlobalStats> {
    const queueStats: Record<string, QueueStats> = {};
    let totalJobs = 0;
    let totalWorkers = 0;

    for (const [queueName, queue] of this.queues) {
      const stats = await queue.getStats();
      queueStats[queueName] = stats;

      totalJobs += stats.waiting + stats.active + stats.completed + stats.failed + stats.delayed;
      totalWorkers += stats.workers || 0;
    }

    return {
      queues: queueStats,
      totalJobs,
      totalWorkers,
      uptime: process.uptime(),
    };
  }

  /**
   * Get statistics for a specific queue
   */
  async getQueueStats(queueName: string): Promise<QueueStats | undefined> {
    const queue = this.queues.get(queueName);
    if (!queue) {
      return undefined;
    }
    return await queue.getStats();
  }

  /**
   * Add a rate limit rule
   */
  addRateLimitRule(rule: RateLimitRule): void {
    if (!this.rateLimiter) {
      this.rateLimiter = new QueueRateLimiter(this.redisConnection, this.logger);
    }
    this.rateLimiter.addRule(rule);
  }

  /**
   * Check rate limits for a job
   */
  async checkRateLimit(
    queueName: string,
    handler: string,
    operation: string
  ): Promise<{
    allowed: boolean;
    retryAfter?: number;
    remainingPoints?: number;
    appliedRule?: RateLimitRule;
  }> {
    if (!this.rateLimiter) {
      return { allowed: true };
    }

    return await this.rateLimiter.checkLimit(queueName, handler, operation);
  }

  /**
   * Get rate limit status
   */
  async getRateLimitStatus(queueName: string, handler: string, operation: string) {
    if (!this.rateLimiter) {
      return {
        queueName,
        handler,
        operation,
      };
    }

    return await this.rateLimiter.getStatus(queueName, handler, operation);
  }

  /**
   * Pause all queues
   */
  async pauseAll(): Promise<void> {
    const pausePromises = Array.from(this.queues.values()).map(queue => queue.pause());
    await Promise.all(pausePromises);
    this.logger.info('All queues paused');
  }

  /**
   * Resume all queues
   */
  async resumeAll(): Promise<void> {
    const resumePromises = Array.from(this.queues.values()).map(queue => queue.resume());
    await Promise.all(resumePromises);
    this.logger.info('All queues resumed');
  }

  /**
   * Pause a specific queue
   */
  async pauseQueue(queueName: string): Promise<boolean> {
    const queue = this.queues.get(queueName);
    if (!queue) {
      return false;
    }

    await queue.pause();
    return true;
  }

  /**
   * Resume a specific queue
   */
  async resumeQueue(queueName: string): Promise<boolean> {
    const queue = this.queues.get(queueName);
    if (!queue) {
      return false;
    }

    await queue.resume();
    return true;
  }

  /**
   * Drain all queues
   */
  async drainAll(delayed = false): Promise<void> {
    const drainPromises = Array.from(this.queues.values()).map(queue => queue.drain(delayed));
    await Promise.all(drainPromises);
    this.logger.info('All queues drained', { delayed });
  }

  /**
   * Clean all queues
   */
  async cleanAll(
    grace: number = 0,
    limit: number = 100,
    type: 'completed' | 'failed' = 'completed'
  ): Promise<void> {
    const cleanPromises = Array.from(this.queues.values()).map(queue =>
      queue.clean(grace, limit, type)
    );
    await Promise.all(cleanPromises);
    this.logger.info('All queues cleaned', { type, grace, limit });
  }

  /**
   * Shutdown all queues and workers (thread-safe)
   */
  async shutdown(): Promise<void> {
    // If already shutting down, return the existing promise
    if (this.shutdownPromise) {
      return this.shutdownPromise;
    }

    if (this.isShuttingDown) {
      return;
    }

    this.isShuttingDown = true;
    this.logger.info('Shutting down QueueManager...');

    // Create shutdown promise
    this.shutdownPromise = this.performShutdown();
    return this.shutdownPromise;
  }

  /**
   * Perform the actual shutdown
   */
  private async performShutdown(): Promise<void> {
    try {
      // Close all queues (this now includes workers since they're managed by Queue class)
      const queueShutdownPromises = Array.from(this.queues.values()).map(async queue => {
        try {
          // Add timeout to queue.close() to prevent hanging
          await queue.close();
          // const timeoutPromise = new Promise<never>((_, reject) =>
          //   setTimeout(() => reject(new Error('Queue close timeout')), 100)
          // );

          // await Promise.race([closePromise, timeoutPromise]);
        } catch (error) {
          this.logger.warn('Error closing queue', { error: (error as Error).message });
        }
      });

      await Promise.all(queueShutdownPromises);

      // Close all caches
      const cacheShutdownPromises = Array.from(this.caches.values()).map(async cache => {
        try {
          // Clear cache before shutdown
          await cache.clear();
        } catch (error) {
          this.logger.warn('Error clearing cache', { error: (error as Error).message });
        }
      });

      await Promise.all(cacheShutdownPromises);

      // Clear collections
      this.queues.clear();
      this.caches.clear();

      this.logger.info('QueueManager shutdown complete');
    } catch (error) {
      this.logger.error('Error during shutdown', { error: (error as Error).message });
      throw error;
    } finally {
      // Reset shutdown state
      this.shutdownPromise = null;
      this.isShuttingDown = false;
    }
  }

  /**
   * Start workers for all queues (used when delayWorkerStart is enabled)
   */
  startAllWorkers(): void {
    if (!this.config.delayWorkerStart) {
      this.logger.info(
        'startAllWorkers() called but workers already started automatically (delayWorkerStart is false)'
      );
      return;
    }

    let workersStarted = 0;
    const queues = this.queues;
    
    this.logger.info(`Starting workers for ${queues.size} queues: ${Array.from(queues.keys()).join(', ')} (service: ${this.serviceName})`);
    
    for (const [queueName, queue] of queues) {
      // If we have a service name, check if this queue belongs to us
      if (this.serviceName) {
        const parsed = parseQueueName(queueName);
        // Skip if not our service's queue
        if (parsed && parsed.service !== this.serviceName) {
          this.logger.trace('Skipping workers for cross-service queue', {
            queueName,
            ownerService: parsed.service,
            currentService: this.serviceName,
          });
          continue;
        }
      }
      
      const workerCount = this.config.defaultQueueOptions?.workers || 1;
      const concurrency = this.config.defaultQueueOptions?.concurrency || 1;

      if (workerCount > 0) {
        queue.startWorkersManually(workerCount, concurrency);
        workersStarted++;
        this.logger.debug('Started workers for queue', {
          queueName,
          workers: workerCount,
          concurrency,
        });
      }
    }

    this.logger.info('Service workers started', {
      service: this.serviceName || 'default',
      totalQueues: queues.size,
      queuesWithWorkers: workersStarted,
      delayWorkerStart: this.config.delayWorkerStart,
    });
  }

  /**
   * Wait for all queues to be ready
   */
  async waitUntilReady(): Promise<void> {
    const readyPromises = Array.from(this.queues.values()).map(queue => queue.waitUntilReady());
    await Promise.all(readyPromises);
  }

  /**
   * Get Redis configuration (for backward compatibility)
   */
  getRedisConfig() {
    return this.config.redis;
  }

  /**
   * Get the current configuration
   */
  getConfig(): Readonly<QueueManagerConfig> {
    return { ...this.config };
  }
  
  /**
   * Send a job to any queue (local or remote)
   * This is the main method for cross-service communication
   */
  async send(
    targetQueue: string,
    operation: string,
    payload: unknown,
    options: JobOptions = {}
  ): Promise<Job> {
    if (!this.serviceName) {
      // If no service name, just use regular queue
      const queue = this.getQueue(targetQueue);
      return queue.add(operation, { handler: targetQueue, operation, payload }, options);
    }
    
    // Resolve the target queue
    const route = this.resolveQueueRoute(targetQueue);
    if (!route) {
      throw new Error(`Unknown queue: ${targetQueue}`);
    }

    // Validate operation if we have metadata
    if (route.operations && !route.operations.includes(operation)) {
      this.logger.warn('Operation not found in handler metadata', {
        handler: route.handler,
        operation,
        availableOperations: route.operations,
      });
    }

    // Use a producer queue for cross-service sending
    const producerQueue = this.getProducerQueue(route.fullName);
    
    const jobData: JobData = {
      handler: route.handler,
      operation,
      payload,
    };

    this.logger.trace('Sending job to queue', {
      targetQueue: route.fullName,
      handler: route.handler,
      operation,
      fromService: this.serviceName,
      toService: route.service,
    });

    return producerQueue.add(operation, jobData, options);
  }
  
  /**
   * Resolve a queue name to a route
   */
  private resolveQueueRoute(queueName: string): QueueRoute | null {
    // Check if it's a full queue name with service prefix
    const parsed = parseQueueName(queueName);
    if (parsed) {
      // Try to find in discovered routes by handler name
      const route = this.queueRoutes.get(parsed.handler);
      if (route && route.service === parsed.service) {
        return route;
      }
      // Create a route on the fly
      return {
        fullName: queueName,
        service: parsed.service,
        handler: parsed.handler,
        db: 0, // All queues in DB 0
      };
    }

    // Check if it's just a handler name in our routes
    const route = this.queueRoutes.get(queueName);
    if (route) {
      return route;
    }

    // Try to find in handler registry
    const ownerService = this.handlerRegistry?.getHandlerService(queueName);
    if (ownerService) {
      return {
        fullName: getFullQueueName(ownerService, queueName),
        service: ownerService,
        handler: queueName,
        db: 0, // All queues in DB 0
      };
    }

    return null;
  }
  
  /**
   * Get a producer queue for sending to other services
   */
  private getProducerQueue(queueName: string): BullQueue {
    if (!this.producerQueues.has(queueName)) {
      const queue = new BullQueue(queueName, {
        connection: this.redisConnection,
        defaultJobOptions: this.config.defaultQueueOptions?.defaultJobOptions,
      });
      this.producerQueues.set(queueName, queue);
    }
    return this.producerQueues.get(queueName)!;
  }
  
  /**
   * Discover all available queue routes from handler registry
   */
  private discoverQueueRoutes(): void {
    if (!this.handlerRegistry) {
      this.logger.warn('No handler registry provided, skipping route discovery');
      return;
    }

    try {
      const handlers = this.handlerRegistry.getAllMetadata();
      for (const [handlerName, metadata] of handlers) {
        // Get the service that registered this handler
        const ownerService = metadata.service;
        if (ownerService) {
          const fullName = getFullQueueName(ownerService, handlerName);

          this.queueRoutes.set(handlerName, {
            fullName,
            service: ownerService,
            handler: handlerName,
            db: 0, // All queues in DB 0
            operations: metadata.operations.map((op: any) => op.name),
          });

          this.logger.trace('Discovered queue route', {
            handler: handlerName,
            service: ownerService,
            operations: metadata.operations.length,
          });
        }
      }

      // Also discover handlers registered by the current service
      if (this.serviceName) {
        const myHandlers = this.handlerRegistry.getServiceHandlers(this.serviceName);
        for (const metadata of myHandlers) {
          const handlerName = metadata.name;
          if (!this.queueRoutes.has(handlerName)) {
            const fullName = getFullQueueName(this.serviceName, handlerName);
            this.queueRoutes.set(handlerName, {
              fullName,
              service: this.serviceName,
              handler: handlerName,
              db: 0, // All queues in DB 0
            });
          }
        }
      }

      this.logger.info('Queue routes discovered', {
        totalRoutes: this.queueRoutes.size,
        routes: Array.from(this.queueRoutes.keys()),
      });
    } catch (error) {
      this.logger.error('Failed to discover queue routes', { error });
    }
  }
}