/**
 * Monitoring Service
 * Collects health and performance metrics from all system components
 */

import type { IServiceContainer } from '@stock-bot/handlers';
import { getLogger } from '@stock-bot/logger';
import type { 
  CacheStats, 
  QueueStats, 
  DatabaseStats, 
  SystemHealth,
  ServiceMetrics,
  MetricSnapshot
} from '../types/monitoring.types';

export class MonitoringService {
  private readonly logger = getLogger('monitoring-service');
  private startTime = Date.now();

  constructor(private readonly container: IServiceContainer) {}

  /**
   * Get cache/Dragonfly statistics
   */
  async getCacheStats(): Promise<CacheStats> {
    try {
      if (!this.container.cache) {
        return {
          provider: 'dragonfly',
          connected: false,
        };
      }

      // Get Redis/Dragonfly info
      const info = await this.container.cache.info();
      const dbSize = await this.container.cache.dbsize();
      
      // Parse memory stats from info
      const memoryUsed = this.parseInfoValue(info, 'used_memory');
      const memoryPeak = this.parseInfoValue(info, 'used_memory_peak');
      
      // Parse stats
      const hits = this.parseInfoValue(info, 'keyspace_hits');
      const misses = this.parseInfoValue(info, 'keyspace_misses');
      const evictedKeys = this.parseInfoValue(info, 'evicted_keys');
      const expiredKeys = this.parseInfoValue(info, 'expired_keys');
      
      return {
        provider: 'dragonfly',
        connected: true,
        uptime: this.parseInfoValue(info, 'uptime_in_seconds'),
        memoryUsage: {
          used: memoryUsed,
          peak: memoryPeak,
        },
        stats: {
          hits,
          misses,
          keys: dbSize,
          evictedKeys,
          expiredKeys,
        },
        info: this.parseRedisInfo(info),
      };
    } catch (error) {
      this.logger.error('Failed to get cache stats', { error });
      return {
        provider: 'dragonfly',
        connected: false,
      };
    }
  }

  /**
   * Get queue statistics
   */
  async getQueueStats(): Promise<QueueStats[]> {
    const stats: QueueStats[] = [];
    
    try {
      if (!this.container.queue) {
        return stats;
      }

      // Get all queue names from the queue manager
      const queueManager = this.container.queue;
      const queueNames = ['default', 'proxy', 'qm', 'ib', 'ceo', 'webshare']; // Add your queue names
      
      for (const queueName of queueNames) {
        try {
          const queue = queueManager.getQueue(queueName);
          if (!queue) continue;

          const [waiting, active, completed, failed, delayed, paused] = await Promise.all([
            queue.getWaitingCount(),
            queue.getActiveCount(),
            queue.getCompletedCount(),
            queue.getFailedCount(),
            queue.getDelayedCount(),
            queue.getPausedCount(),
          ]);

          // Get worker info if available
          const workers = queueManager.getWorker(queueName);
          const workerInfo = workers ? {
            count: 1, // Assuming single worker per queue
            concurrency: workers.concurrency || 1,
          } : undefined;

          stats.push({
            name: queueName,
            connected: true,
            jobs: {
              waiting,
              active,
              completed,
              failed,
              delayed,
              paused,
            },
            workers: workerInfo,
          });
        } catch (error) {
          this.logger.warn(`Failed to get stats for queue ${queueName}`, { error });
          stats.push({
            name: queueName,
            connected: false,
            jobs: {
              waiting: 0,
              active: 0,
              completed: 0,
              failed: 0,
              delayed: 0,
              paused: 0,
            },
          });
        }
      }
    } catch (error) {
      this.logger.error('Failed to get queue stats', { error });
    }

    return stats;
  }

  /**
   * Get database statistics
   */
  async getDatabaseStats(): Promise<DatabaseStats[]> {
    const stats: DatabaseStats[] = [];

    // PostgreSQL stats
    if (this.container.postgres) {
      try {
        const startTime = Date.now();
        const result = await this.container.postgres.query('SELECT 1');
        const latency = Date.now() - startTime;

        // Get pool stats
        const pool = (this.container.postgres as any).pool;
        const poolStats = pool ? {
          size: pool.totalCount || 0,
          active: pool.idleCount || 0,
          idle: pool.waitingCount || 0,
          max: pool.options?.max || 0,
        } : undefined;

        stats.push({
          type: 'postgres',
          name: 'PostgreSQL',
          connected: true,
          latency,
          pool: poolStats,
        });
      } catch (error) {
        this.logger.error('Failed to get PostgreSQL stats', { error });
        stats.push({
          type: 'postgres',
          name: 'PostgreSQL',
          connected: false,
        });
      }
    }

    // MongoDB stats
    if (this.container.mongodb) {
      try {
        const startTime = Date.now();
        const db = this.container.mongodb.db();
        await db.admin().ping();
        const latency = Date.now() - startTime;

        const serverStatus = await db.admin().serverStatus();
        
        stats.push({
          type: 'mongodb',
          name: 'MongoDB',
          connected: true,
          latency,
          stats: {
            version: serverStatus.version,
            uptime: serverStatus.uptime,
            connections: serverStatus.connections,
            opcounters: serverStatus.opcounters,
          },
        });
      } catch (error) {
        this.logger.error('Failed to get MongoDB stats', { error });
        stats.push({
          type: 'mongodb',
          name: 'MongoDB',
          connected: false,
        });
      }
    }

    // QuestDB stats
    if (this.container.questdb) {
      try {
        const startTime = Date.now();
        // QuestDB health check
        const response = await fetch(`http://${process.env.QUESTDB_HOST || 'localhost'}:9000/exec?query=SELECT%201`);
        const latency = Date.now() - startTime;
        
        stats.push({
          type: 'questdb',
          name: 'QuestDB',
          connected: response.ok,
          latency,
        });
      } catch (error) {
        this.logger.error('Failed to get QuestDB stats', { error });
        stats.push({
          type: 'questdb',
          name: 'QuestDB',
          connected: false,
        });
      }
    }

    return stats;
  }

  /**
   * Get system health summary
   */
  async getSystemHealth(): Promise<SystemHealth> {
    const [cacheStats, queueStats, databaseStats] = await Promise.all([
      this.getCacheStats(),
      this.getQueueStats(),
      this.getDatabaseStats(),
    ]);

    const memory = process.memoryUsage();
    const uptime = Date.now() - this.startTime;

    // Determine overall health status
    const errors: string[] = [];
    
    if (!cacheStats.connected) {
      errors.push('Cache service is disconnected');
    }
    
    const disconnectedQueues = queueStats.filter(q => !q.connected);
    if (disconnectedQueues.length > 0) {
      errors.push(`${disconnectedQueues.length} queue(s) are disconnected`);
    }
    
    const disconnectedDbs = databaseStats.filter(db => !db.connected);
    if (disconnectedDbs.length > 0) {
      errors.push(`${disconnectedDbs.length} database(s) are disconnected`);
    }

    const status = errors.length === 0 ? 'healthy' : 
                   errors.length < 3 ? 'degraded' : 'unhealthy';

    return {
      status,
      timestamp: new Date().toISOString(),
      uptime,
      memory: {
        used: memory.heapUsed,
        total: memory.heapTotal,
        percentage: (memory.heapUsed / memory.heapTotal) * 100,
      },
      services: {
        cache: cacheStats,
        queues: queueStats,
        databases: databaseStats,
      },
      errors: errors.length > 0 ? errors : undefined,
    };
  }

  /**
   * Get service metrics (placeholder for future implementation)
   */
  async getServiceMetrics(): Promise<ServiceMetrics> {
    const now = new Date().toISOString();
    
    return {
      requestsPerSecond: {
        timestamp: now,
        value: 0,
        unit: 'req/s',
      },
      averageResponseTime: {
        timestamp: now,
        value: 0,
        unit: 'ms',
      },
      errorRate: {
        timestamp: now,
        value: 0,
        unit: '%',
      },
      activeConnections: {
        timestamp: now,
        value: 0,
        unit: 'connections',
      },
    };
  }

  /**
   * Parse value from Redis INFO output
   */
  private parseInfoValue(info: string, key: string): number {
    const match = info.match(new RegExp(`${key}:(\\d+)`));
    return match ? parseInt(match[1], 10) : 0;
  }

  /**
   * Parse Redis INFO into structured object
   */
  private parseRedisInfo(info: string): Record<string, any> {
    const result: Record<string, any> = {};
    const sections = info.split('\r\n\r\n');
    
    for (const section of sections) {
      const lines = section.split('\r\n');
      const sectionName = lines[0]?.replace('# ', '') || 'general';
      result[sectionName] = {};
      
      for (let i = 1; i < lines.length; i++) {
        const [key, value] = lines[i].split(':');
        if (key && value) {
          result[sectionName][key] = value;
        }
      }
    }
    
    return result;
  }
}