/**
 * Distributed Memory System - Enterprise Edition
 * 
 * Enables cross-agent memory sharing, synchronization, and distributed storage
 * based on the original flowx distributed memory architecture with
 * modern enhancements for enterprise-grade performance.
 * 
 * Features:
 * - Cross-agent memory synchronization
 * - Vector clock conflict resolution
 * - Memory partitioning and sharding
 * - Eventual consistency with strong consistency options
 * - Enterprise-grade replication and backup
 * - Performance monitoring and analytics
 */

import { EventEmitter } from 'node:events';
import { ILogger } from '../core/logger.ts';
import { IEventBus } from '../core/event-bus.ts';
import { generateId } from '../utils/helpers.ts';
import { AdvancedMemoryManager, AdvancedMemoryEntry } from './advanced-memory-manager.ts';

// === INTERFACES ===

export interface DistributedMemoryConfig {
  namespace: string;
  distributed: boolean;
  consistency: ConsistencyLevel;
  replicationFactor: number;
  syncInterval: number;
  maxMemorySize: number;
  compressionEnabled: boolean;
  encryptionEnabled: boolean;
  backupEnabled: boolean;
  persistenceEnabled: boolean;
  shardingEnabled: boolean;
  cacheSize: number;
  cacheTtl: number;
  backend?: string;
  timeout?: number;
  retryAttempts?: number;
  enableCrossAgentLearning: boolean;
  enableConflictResolution: boolean;
  vectorClockSize: number;
  partitionStrategy: 'hash' | 'range' | 'round-robin';
  networkOptimization: boolean;
}

export type ConsistencyLevel = 'strong' | 'eventual' | 'session' | 'monotonic';
export type AccessLevel = 'private' | 'shared' | 'public' | 'restricted';

export interface MemoryPartition {
  id: string;
  name: string;
  type: string;
  namespace: string;
  maxSize: number;
  currentSize: number;
  readOnly: boolean;
  encrypted: boolean;
  compressed: boolean;
  replicationFactor: number;
  entries: AdvancedMemoryEntry[];
  lastSync: Date;
  nodeId: string;
  shardKey?: string;
  accessPolicy: AccessPolicy;
}

export interface AccessPolicy {
  allowedAgents: string[];
  allowedOperations: ('read' | 'write' | 'delete' | 'sync')[];
  timeRestrictions?: {
    startTime: string;
    endTime: string;
    timezone: string;
  };
  quotaLimits?: {
    maxEntries: number;
    maxSizeBytes: number;
    maxOperationsPerHour: number;
  };
}

export interface MemoryNode {
  id: string;
  address: string;
  port: number;
  status: 'online' | 'offline' | 'degraded' | 'syncing';
  lastSeen: Date;
  partitions: string[];
  load: number;
  capacity: number;
  region?: string;
  datacenter?: string;
  capabilities: NodeCapabilities;
  healthMetrics: NodeHealthMetrics;
}

export interface NodeCapabilities {
  storage: boolean;
  processing: boolean;
  networking: boolean;
  encryption: boolean;
  compression: boolean;
  analytics: boolean;
  machineLearning: boolean;
}

export interface NodeHealthMetrics {
  cpuUsage: number;
  memoryUsage: number;
  diskUsage: number;
  networkLatency: number;
  errorRate: number;
  responseTime: number;
  availability: number;
  lastHealthCheck: Date;
}

export interface SyncOperation {
  id: string;
  type: 'full' | 'incremental' | 'delta' | 'conflict-resolution';
  sourceNodeId: string;
  targetNodeId: string;
  partitionId: string;
  entries: string[];
  vectorClock: VectorClock;
  timestamp: Date;
  priority: number;
  retryCount: number;
  status: 'pending' | 'in-progress' | 'completed' | 'failed';
  metadata: Record<string, any>;
}

export interface VectorClock {
  [nodeId: string]: number;
}

export interface ConflictResolution {
  strategy: 'last-write-wins' | 'vector-clock' | 'semantic-merge' | 'user-defined';
  customResolver?: (local: AdvancedMemoryEntry, remote: AdvancedMemoryEntry) => AdvancedMemoryEntry;
  weightFactors?: {
    timestamp: number;
    cognitiveWeight: number;
    accessFrequency: number;
    sourceReliability: number;
  };
}

export interface MemoryStatistics {
  totalNodes: number;
  activeNodes: number;
  totalPartitions: number;
  totalEntries: number;
  totalSize: number;
  replicationFactor: number;
  syncOperations: {
    pending: number;
    completed: number;
    failed: number;
  };
  performanceMetrics: {
    averageLatency: number;
    throughput: number;
    errorRate: number;
    cacheHitRate: number;
  };
  distributionMetrics: {
    loadBalance: number;
    hotSpots: string[];
    underutilizedNodes: string[];
  };
}

export interface CrossAgentLearningData {
  agentId: string;
  learningPatterns: Record<string, any>;
  sharedKnowledge: AdvancedMemoryEntry[];
  collaborationHistory: CollaborationRecord[];
  performanceMetrics: AgentPerformanceMetrics;
}

export interface CollaborationRecord {
  id: string;
  participants: string[];
  task: string;
  outcome: 'success' | 'failure' | 'partial';
  lessons: string[];
  timestamp: Date;
  context: Record<string, any>;
}

export interface AgentPerformanceMetrics {
  taskCompletionRate: number;
  averageResponseTime: number;
  knowledgeContribution: number;
  collaborationEffectiveness: number;
  errorRate: number;
  learningVelocity: number;
}

// === MAIN CLASS ===

export class DistributedMemorySystem extends EventEmitter {
  private logger: ILogger;
  private eventBus: IEventBus;
  private config: DistributedMemoryConfig;
  
  // Storage components
  private localMemoryManager: AdvancedMemoryManager;
  private partitions = new Map<string, MemoryPartition>();
  private cache = new Map<string, { entry: AdvancedMemoryEntry; expiry: number; nodeId: string }>();
  
  // Distribution infrastructure
  private nodes = new Map<string, MemoryNode>();
  private localNodeId: string;
  private syncQueue: SyncOperation[] = [];
  private replicationMap = new Map<string, string[]>(); // entryId -> nodeIds
  
  // Synchronization and conflict resolution
  private syncInterval?: NodeJS.Timeout;
  private vectorClock: VectorClock = {};
  private conflictResolver: ConflictResolution;
  
  // Cross-agent learning
  private agentLearningData = new Map<string, CrossAgentLearningData>();
  private sharedKnowledgeIndex = new Map<string, Set<string>>();
  private collaborationGraph = new Map<string, Set<string>>();
  
  // Performance tracking
  private statistics: MemoryStatistics;
  private operationMetrics = new Map<string, { count: number; totalTime: number; errors: number }>();
  private healthMonitor?: NodeJS.Timeout;

  constructor(
    config: Partial<DistributedMemoryConfig>,
    logger: ILogger,
    eventBus: IEventBus,
    localMemoryManager: AdvancedMemoryManager
  ) {
    super();
    this.logger = logger;
    this.eventBus = eventBus;
    this.localMemoryManager = localMemoryManager;
    
    this.config = {
      namespace: 'distributed-memory',
      distributed: true,
      consistency: 'eventual',
      replicationFactor: 3,
      syncInterval: 10000, // 10 seconds
      maxMemorySize: 5 * 1024 * 1024 * 1024, // 5GB
      compressionEnabled: true,
      encryptionEnabled: false,
      backupEnabled: true,
      persistenceEnabled: true,
      shardingEnabled: true,
      cacheSize: 50000,
      cacheTtl: 600000, // 10 minutes
      timeout: 30000, // 30 seconds
      retryAttempts: 3,
      enableCrossAgentLearning: true,
      enableConflictResolution: true,
      vectorClockSize: 64,
      partitionStrategy: 'hash',
      networkOptimization: true,
      ...config
    };

    this.localNodeId = generateId('memory-node');
    this.statistics = this.initializeStatistics();
    
    this.conflictResolver = {
      strategy: 'vector-clock',
      weightFactors: {
        timestamp: 0.3,
        cognitiveWeight: 0.4,
        accessFrequency: 0.2,
        sourceReliability: 0.1
      }
    };
    
    this.setupEventHandlers();
  }

  // === INITIALIZATION ===

  async initialize(): Promise<void> {
    this.logger.info('Initializing Distributed Memory System', {
      nodeId: this.localNodeId,
      namespace: this.config.namespace,
      distributed: this.config.distributed
    });

    try {
      // Initialize vector clock
      this.vectorClock[this.localNodeId] = 0;

      // Register local node
      await this.registerLocalNode();

      // Initialize default partitions
      await this.initializeDefaultPartitions();

      // Start synchronization if distributed
      if (this.config.distributed) {
        this.startSynchronization();
      }

      // Start health monitoring
      this.startHealthMonitoring();

      // Load cross-agent learning data
      if (this.config.enableCrossAgentLearning) {
        await this.loadCrossAgentLearningData();
      }

      this.emit('distributed-memory:initialized', { 
        nodeId: this.localNodeId,
        partitions: this.partitions.size,
        distributed: this.config.distributed
      });

      this.logger.info('Distributed Memory System initialized successfully', {
        nodeId: this.localNodeId,
        partitions: this.partitions.size,
        nodes: this.nodes.size
      });

    } catch (error) {
      this.logger.error('Failed to initialize Distributed Memory System', { error });
      throw error;
    }
  }

  private async registerLocalNode(): Promise<void> {
    const localNode: MemoryNode = {
      id: this.localNodeId,
      address: 'localhost',
      port: 8080,
      status: 'online',
      lastSeen: new Date(),
      partitions: [],
      load: 0,
      capacity: this.config.maxMemorySize,
      capabilities: {
        storage: true,
        processing: true,
        networking: true,
        encryption: this.config.encryptionEnabled,
        compression: this.config.compressionEnabled,
        analytics: true,
        machineLearning: this.config.enableCrossAgentLearning
      },
      healthMetrics: {
        cpuUsage: 0,
        memoryUsage: 0,
        diskUsage: 0,
        networkLatency: 0,
        errorRate: 0,
        responseTime: 0,
        availability: 1.0,
        lastHealthCheck: new Date()
      }
    };

    this.nodes.set(this.localNodeId, localNode);
    this.logger.debug('Local node registered', { nodeId: this.localNodeId });
  }

  private async initializeDefaultPartitions(): Promise<void> {
    const defaultPartitions = [
      { name: 'knowledge', type: 'knowledge', namespace: 'agents' },
      { name: 'state', type: 'state', namespace: 'system' },
      { name: 'cache', type: 'cache', namespace: 'temporary' },
      { name: 'results', type: 'results', namespace: 'tasks' },
      { name: 'learning', type: 'learning', namespace: 'cross-agent' }
    ];

    for (const partitionConfig of defaultPartitions) {
      await this.createPartition(
        partitionConfig.name,
        partitionConfig.type,
        partitionConfig.namespace
      );
    }

    this.logger.debug('Default partitions initialized', { 
      count: defaultPartitions.length 
    });
  }

  private setupEventHandlers(): void {
    this.eventBus.on('memory:sync-request', (data) => {
      this.handleSyncRequest(data).catch(error =>
        this.logger.error('Failed to handle sync request', { error })
      );
    });

    this.eventBus.on('memory:node-joined', (data) => {
      this.handleNodeJoined(data).catch(error =>
        this.logger.error('Failed to handle node joined', { error })
      );
    });

    this.eventBus.on('memory:node-left', (data) => {
      this.handleNodeLeft(data).catch(error =>
        this.logger.error('Failed to handle node left', { error })
      );
    });

    this.eventBus.on('memory:conflict-detected', (data) => {
      this.handleConflict(data).catch(error =>
        this.logger.error('Failed to handle conflict', { error })
      );
    });

    this.eventBus.on('agent:learning-update', (data) => {
      this.handleAgentLearningUpdate(data).catch(error =>
        this.logger.error('Failed to handle learning update', { error })
      );
    });
  }

  // === CORE OPERATIONS ===

  async store(
    key: string,
    value: any,
    options: {
      type?: string;
      tags?: string[];
      owner?: string;
      accessLevel?: AccessLevel;
      partition?: string;
      ttl?: number;
      replicate?: boolean;
      consistency?: ConsistencyLevel;
      agentId?: string;
    } = {}
  ): Promise<string> {
    const startTime = Date.now();
    
    try {
      // Determine partition
      const partitionId = options.partition || this.selectPartition(options.type || 'knowledge');
      const partition = this.partitions.get(partitionId);
      
      if (!partition) {
        throw new Error(`Partition ${partitionId} not found`);
      }

      if (partition.readOnly) {
        throw new Error('Cannot write to read-only partition');
      }

      // Check access policy
      if (!this.checkAccessPolicy(partition, options.owner || 'system', 'write')) {
        throw new Error('Access denied by partition policy');
      }

      // Check partition capacity
      if (this.getPartitionSize(partitionId) >= partition.maxSize) {
        await this.evictOldEntries(partitionId);
      }

      // Store in local memory manager first
      const entryId = await this.localMemoryManager.store(key, value, {
        namespace: partition.namespace,
        type: options.type,
        tags: options.tags,
        owner: options.owner,
        accessLevel: options.accessLevel === 'restricted' ? 'shared' : options.accessLevel,
        ttl: options.ttl
      });

      // Get the stored entry
      const entry = await this.localMemoryManager.retrieve(key, {
        namespace: partition.namespace
      });

      if (!entry) {
        throw new Error('Failed to retrieve stored entry');
      }

      // Add to partition
      partition.entries.push(entry);

      // Update vector clock
      this.incrementVectorClock(this.localNodeId);

      // Handle replication if enabled
      if (options.replicate !== false && this.config.distributed) {
        await this.replicateEntry(entry, partition, options.consistency);
      }

      // Update cross-agent learning if applicable
      if (options.agentId && this.config.enableCrossAgentLearning) {
        await this.updateCrossAgentLearning(options.agentId, entry);
      }

      this.logger.debug('Distributed memory entry stored', { 
        entryId, 
        key, 
        partition: partitionId,
        replicated: options.replicate !== false
      });

      this.emit('distributed-memory:entry-stored', { entry, partition });
      this.recordMetric('store', Date.now() - startTime, false);
      
      return entryId;
      
    } catch (error) {
      this.recordMetric('store', Date.now() - startTime, true);
      this.logger.error('Failed to store distributed memory entry', { key, error });
      throw error;
    }
  }

  async retrieve(
    key: string,
    options: {
      partition?: string;
      consistency?: ConsistencyLevel;
      maxAge?: number;
      agentId?: string;
      bypassCache?: boolean;
    } = {}
  ): Promise<AdvancedMemoryEntry | null> {
    const startTime = Date.now();
    
    try {
      // Check cache first (unless bypassed)
      if (!options.bypassCache) {
        const cached = this.getCachedEntry(key);
        if (cached && this.isCacheValid(cached)) {
          this.recordMetric('retrieve-cache', Date.now() - startTime, false);
          return cached.entry;
        }
      }

      // Search in specified partition or all partitions
      const partitions = options.partition 
        ? [this.partitions.get(options.partition)].filter(Boolean)
        : Array.from(this.partitions.values());

      let foundEntry: AdvancedMemoryEntry | null = null;

      for (const partition of partitions) {
        if (!partition) continue;

        // Check access policy
        if (!this.checkAccessPolicy(partition, options.agentId || 'system', 'read')) {
          continue;
        }

        // Try local memory manager first
        const entry = await this.localMemoryManager.retrieve(key, {
          namespace: partition.namespace
        });

        if (entry) {
          // Check if entry is expired
          if (entry.expiresAt && entry.expiresAt < new Date()) {
            await this.deleteEntry(entry.id, partition.id);
            continue;
          }

          // Apply consistency model
          if (this.config.distributed && options.consistency === 'strong') {
            const latestEntry = await this.ensureConsistency(entry, partition);
            foundEntry = latestEntry;
          } else {
            foundEntry = entry;
          }
          break;
        }
      }

      // If not found locally and distributed, try remote nodes
      if (!foundEntry && this.config.distributed) {
        foundEntry = await this.retrieveFromRemote(key, options);
      }

      // Update cache if found
      if (foundEntry) {
        this.updateCache(key, foundEntry, this.localNodeId);
        
        // Update cross-agent learning
        if (options.agentId && this.config.enableCrossAgentLearning) {
          await this.recordAgentAccess(options.agentId, foundEntry);
        }
      }

      this.recordMetric('retrieve', Date.now() - startTime, foundEntry === null);
      return foundEntry;
      
    } catch (error) {
      this.recordMetric('retrieve', Date.now() - startTime, true);
      this.logger.error('Failed to retrieve distributed memory entry', { key, error });
      throw error;
    }
  }

  async shareKnowledge(
    agentId: string,
    knowledge: any,
    targetAgents?: string[]
  ): Promise<void> {
    if (!this.config.enableCrossAgentLearning) {
      throw new Error('Cross-agent learning is disabled');
    }

    try {
      // Store knowledge in learning partition
      const entryId = await this.store(`shared-knowledge-${Date.now()}`, knowledge, {
        partition: 'learning',
        type: 'shared-knowledge',
        owner: agentId,
        accessLevel: targetAgents ? 'restricted' : 'shared',
        agentId,
        replicate: true
      });

      // Update shared knowledge index
      const keywordSet = this.extractKeywords(knowledge);
      for (const keyword of keywordSet) {
        if (!this.sharedKnowledgeIndex.has(keyword)) {
          this.sharedKnowledgeIndex.set(keyword, new Set());
        }
        this.sharedKnowledgeIndex.get(keyword)!.add(entryId);
      }

      // Update collaboration graph
      if (targetAgents) {
        for (const targetAgent of targetAgents) {
          if (!this.collaborationGraph.has(agentId)) {
            this.collaborationGraph.set(agentId, new Set());
          }
          this.collaborationGraph.get(agentId)!.add(targetAgent);
        }
      }

      this.logger.debug('Knowledge shared', { 
        agentId, 
        entryId,
        targetAgents: targetAgents?.length || 'all'
      });

      this.emit('distributed-memory:knowledge-shared', { 
        agentId, 
        entryId, 
        targetAgents 
      });

    } catch (error) {
      this.logger.error('Failed to share knowledge', { agentId, error });
      throw error;
    }
  }

  async querySharedKnowledge(
    agentId: string,
    query: string | string[],
    options: {
      limit?: number;
      similarity?: number;
      timeRange?: { start: Date; end: Date };
    } = {}
  ): Promise<AdvancedMemoryEntry[]> {
    if (!this.config.enableCrossAgentLearning) {
      return [];
    }

    try {
      const keywords = Array.isArray(query) ? query : this.extractKeywords(query);
      const entryIds = new Set<string>();

      // Find entries by keywords
      for (const keyword of keywords) {
        const keywordEntries = this.sharedKnowledgeIndex.get(keyword);
        if (keywordEntries) {
          keywordEntries.forEach(id => entryIds.add(id));
        }
      }

      // Retrieve and filter entries
      const results: AdvancedMemoryEntry[] = [];
      
      for (const entryId of entryIds) {
        const entry = await this.localMemoryManager.retrieve(entryId, {
          namespace: 'cross-agent'
        });

        if (entry && this.checkAccessPolicy(
          this.partitions.get('learning')!, 
          agentId, 
          'read'
        )) {
          // Apply time filter
          if (options.timeRange) {
            if (entry.createdAt < options.timeRange.start || 
                entry.createdAt > options.timeRange.end) {
              continue;
            }
          }

          results.push(entry);
        }
      }

      // Sort by relevance (cognitive weight, recency)
      results.sort((a, b) => {
        const scoreA = a.cognitiveWeight + (1 / (Date.now() - a.createdAt.getTime()));
        const scoreB = b.cognitiveWeight + (1 / (Date.now() - b.createdAt.getTime()));
        return scoreB - scoreA;
      });

      return results.slice(0, options.limit || 20);

    } catch (error) {
      this.logger.error('Failed to query shared knowledge', { agentId, error });
      return [];
    }
  }

  // === PARTITION MANAGEMENT ===

  async createPartition(
    name: string,
    type: string,
    namespace: string,
    options: {
      maxSize?: number;
      readOnly?: boolean;
      encrypted?: boolean;
      compressed?: boolean;
      replicationFactor?: number;
      accessPolicy?: Partial<AccessPolicy>;
    } = {}
  ): Promise<string> {
    const partitionId = generateId('partition');
    
    const partition: MemoryPartition = {
      id: partitionId,
      name,
      type,
      namespace,
      maxSize: options.maxSize || 100 * 1024 * 1024, // 100MB default
      currentSize: 0,
      readOnly: options.readOnly || false,
      encrypted: options.encrypted || this.config.encryptionEnabled,
      compressed: options.compressed || this.config.compressionEnabled,
      replicationFactor: options.replicationFactor || this.config.replicationFactor,
      entries: [],
      lastSync: new Date(),
      nodeId: this.localNodeId,
      accessPolicy: {
        allowedAgents: options.accessPolicy?.allowedAgents || ['*'],
        allowedOperations: options.accessPolicy?.allowedOperations || ['read', 'write'],
        ...options.accessPolicy
      }
    };

    this.partitions.set(partitionId, partition);
    
    // Update local node's partition list
    const localNode = this.nodes.get(this.localNodeId);
    if (localNode) {
      localNode.partitions.push(partitionId);
    }

    this.logger.debug('Partition created', { 
      partitionId, 
      name, 
      type, 
      namespace 
    });

    this.emit('distributed-memory:partition-created', { partition });
    return partitionId;
  }

  // === SYNCHRONIZATION ===

  private startSynchronization(): void {
    if (this.syncInterval) {
      clearInterval(this.syncInterval);
    }

    this.syncInterval = setInterval(() => {
      this.performSynchronization().catch(error =>
        this.logger.error('Synchronization failed', { error })
      );
    }, this.config.syncInterval);

    this.logger.debug('Synchronization started', { 
      interval: this.config.syncInterval 
    });
  }

  private async performSynchronization(): Promise<void> {
    try {
      // Process pending sync operations
      await this.processSyncQueue();

      // Discover new nodes
      await this.discoverNodes();

      // Sync partitions with other nodes
      await this.syncPartitions();

      // Resolve conflicts
      if (this.config.enableConflictResolution) {
        await this.resolveConflicts();
      }

      // Update health metrics
      await this.updateHealthMetrics();

    } catch (error) {
      this.logger.error('Synchronization cycle failed', { error });
    }
  }

  private async processSyncQueue(): Promise<void> {
    while (this.syncQueue.length > 0) {
      const operation = this.syncQueue.shift()!;
      
      try {
        await this.executeSyncOperation(operation);
        this.statistics.syncOperations.completed++;
      } catch (error) {
        this.logger.error('Sync operation failed', { 
          operationId: operation.id, 
          error 
        });
        
        if (operation.retryCount < (this.config.retryAttempts || 3)) {
          operation.retryCount++;
          operation.status = 'pending';
          this.syncQueue.push(operation);
        } else {
          this.statistics.syncOperations.failed++;
        }
      }
    }
  }

  private async executeSyncOperation(operation: SyncOperation): Promise<void> {
    operation.status = 'in-progress';
    
    switch (operation.type) {
      case 'full':
        await this.performFullSync(operation);
        break;
      case 'incremental':
        await this.performIncrementalSync(operation);
        break;
      case 'delta':
        await this.performDeltaSync(operation);
        break;
      case 'conflict-resolution':
        await this.performConflictResolution(operation);
        break;
    }
    
    operation.status = 'completed';
  }

  // === CONFLICT RESOLUTION ===

  private async resolveConflicts(): Promise<void> {
    // Find entries with conflicting vector clocks
    const conflicts = await this.detectConflicts();
    
    for (const conflict of conflicts) {
      try {
        const resolved = await this.resolveConflict(conflict.local, conflict.remote);
        
        // Update local entry
        await this.localMemoryManager.store(resolved.key, resolved.value, {
          namespace: resolved.namespace,
          type: resolved.type
        });

        this.logger.debug('Conflict resolved', { 
          entryId: resolved.id,
          strategy: this.conflictResolver.strategy
        });

      } catch (error) {
        this.logger.error('Failed to resolve conflict', { error });
      }
    }
  }

  private async detectConflicts(): Promise<Array<{local: AdvancedMemoryEntry, remote: AdvancedMemoryEntry}>> {
    // This would implement conflict detection logic
    // For now, return empty array
    return [];
  }

  private async resolveConflict(
    local: AdvancedMemoryEntry, 
    remote: AdvancedMemoryEntry
  ): Promise<AdvancedMemoryEntry> {
    switch (this.conflictResolver.strategy) {
      case 'last-write-wins':
        return local.updatedAt > remote.updatedAt ? local : remote;
        
      case 'vector-clock':
        return this.resolveWithVectorClock(local, remote);
        
      case 'semantic-merge':
        return this.semanticMerge(local, remote);
        
      case 'user-defined':
        if (this.conflictResolver.customResolver) {
          return this.conflictResolver.customResolver(local, remote);
        }
        return local; // Fallback
        
      default:
        return local;
    }
  }

  private resolveWithVectorClock(
    local: AdvancedMemoryEntry, 
    remote: AdvancedMemoryEntry
  ): AdvancedMemoryEntry {
    // Implement vector clock comparison logic
    // For now, use cognitive weight as tiebreaker
    if (local.cognitiveWeight >= remote.cognitiveWeight) {
      return local;
    }
    return remote;
  }

  private semanticMerge(
    local: AdvancedMemoryEntry, 
    remote: AdvancedMemoryEntry
  ): AdvancedMemoryEntry {
    // Implement semantic merging logic
    // This would analyze content similarity and merge compatible changes
    
    // For now, return the entry with higher cognitive weight
    return local.cognitiveWeight >= remote.cognitiveWeight ? local : remote;
  }

  // === HELPER METHODS ===

  private selectPartition(type: string): string {
    // Select partition based on type and strategy
    const partitions = Array.from(this.partitions.values())
      .filter(p => p.type === type || p.type === 'general');

    if (partitions.length === 0) {
      return 'knowledge'; // Default partition
    }

    switch (this.config.partitionStrategy) {
      case 'hash':
        return partitions[Math.abs(this.hash(type)) % partitions.length].id;
      case 'round-robin':
        return partitions[this.statistics.totalEntries % partitions.length].id;
      case 'range':
        // Simple range partitioning
        return partitions[0].id;
      default:
        return partitions[0].id;
    }
  }

  private hash(str: string): number {
    let hash = 0;
    for (let i = 0; i < str.length; i++) {
      const char = str.charCodeAt(i);
      hash = ((hash << 5) - hash) + char;
      hash = hash & hash; // Convert to 32-bit integer
    }
    return hash;
  }

  private checkAccessPolicy(
    partition: MemoryPartition,
    agentId: string,
    operation: string
  ): boolean {
    const policy = partition.accessPolicy;
    
    // Check allowed agents
    if (!policy.allowedAgents.includes('*') && 
        !policy.allowedAgents.includes(agentId)) {
      return false;
    }

    // Check allowed operations
    if (!policy.allowedOperations.includes(operation as any)) {
      return false;
    }

    // Check time restrictions
    if (policy.timeRestrictions) {
      const now = new Date();
      const timeStr = now.toTimeString();
      if (timeStr < policy.timeRestrictions.startTime || 
          timeStr > policy.timeRestrictions.endTime) {
        return false;
      }
    }

    return true;
  }

  private getPartitionSize(partitionId: string): number {
    const partition = this.partitions.get(partitionId);
    if (!partition) return 0;
    
    return partition.entries.reduce((sum, entry) => sum + entry.size, 0);
  }

  private async evictOldEntries(partitionId: string): Promise<void> {
    const partition = this.partitions.get(partitionId);
    if (!partition) return;

    // Sort by last access time and cognitive weight
    partition.entries.sort((a, b) => {
      const scoreA = a.lastAccessedAt.getTime() + (a.cognitiveWeight * 1000000);
      const scoreB = b.lastAccessedAt.getTime() + (b.cognitiveWeight * 1000000);
      return scoreA - scoreB;
    });

    // Remove oldest 10% of entries
    const toRemove = Math.floor(partition.entries.length * 0.1);
    const removed = partition.entries.splice(0, toRemove);

    this.logger.debug('Evicted old entries', { 
      partitionId, 
      count: removed.length 
    });
  }

  private incrementVectorClock(nodeId: string): void {
    this.vectorClock[nodeId] = (this.vectorClock[nodeId] || 0) + 1;
  }

  private updateCache(key: string, entry: AdvancedMemoryEntry, nodeId: string): void {
    const expiry = Date.now() + this.config.cacheTtl;
    this.cache.set(key, { entry, expiry, nodeId });

    // Cleanup cache if it gets too large
    if (this.cache.size > this.config.cacheSize) {
      this.evictCacheEntries();
    }
  }

  private getCachedEntry(key: string): { entry: AdvancedMemoryEntry; expiry: number; nodeId: string } | null {
    return this.cache.get(key) || null;
  }

  private isCacheValid(cached: { entry: AdvancedMemoryEntry; expiry: number; nodeId: string }): boolean {
    return Date.now() < cached.expiry;
  }

  private evictCacheEntries(): void {
    // LRU eviction
    const entries = Array.from(this.cache.entries());
    entries.sort((a, b) => a[1].expiry - b[1].expiry);
    
    const toRemove = Math.floor(this.config.cacheSize * 0.2);
    for (let i = 0; i < toRemove; i++) {
      this.cache.delete(entries[i][0]);
    }
  }

  private extractKeywords(content: any): string[] {
    const text = typeof content === 'string' ? content : JSON.stringify(content);
    return text.toLowerCase()
      .replace(/[^\w\s]/g, ' ')
      .split(/\s+/)
      .filter(word => word.length > 3)
      .slice(0, 20); // Limit to top 20 keywords
  }

  private recordMetric(operation: string, duration: number, error: boolean): void {
    const metric = this.operationMetrics.get(operation) || { 
      count: 0, 
      totalTime: 0, 
      errors: 0 
    };
    
    metric.count++;
    metric.totalTime += duration;
    if (error) metric.errors++;
    
    this.operationMetrics.set(operation, metric);
  }

  private initializeStatistics(): MemoryStatistics {
    return {
      totalNodes: 0,
      activeNodes: 0,
      totalPartitions: 0,
      totalEntries: 0,
      totalSize: 0,
      replicationFactor: this.config.replicationFactor,
      syncOperations: {
        pending: 0,
        completed: 0,
        failed: 0
      },
      performanceMetrics: {
        averageLatency: 0,
        throughput: 0,
        errorRate: 0,
        cacheHitRate: 0
      },
      distributionMetrics: {
        loadBalance: 0,
        hotSpots: [],
        underutilizedNodes: []
      }
    };
  }

  // === PLACEHOLDER METHODS (would be implemented based on specific requirements) ===

  private async replicateEntry(entry: AdvancedMemoryEntry, partition: MemoryPartition, consistency?: ConsistencyLevel): Promise<void> {
    // Implementation for entry replication across nodes
  }

  private async ensureConsistency(entry: AdvancedMemoryEntry, partition: MemoryPartition): Promise<AdvancedMemoryEntry> {
    // Implementation for strong consistency checks
    return entry;
  }

  private async retrieveFromRemote(key: string, options: any): Promise<AdvancedMemoryEntry | null> {
    // Implementation for retrieving from remote nodes
    return null;
  }

  private async updateCrossAgentLearning(agentId: string, entry: AdvancedMemoryEntry): Promise<void> {
    // Implementation for updating cross-agent learning data
  }

  private async recordAgentAccess(agentId: string, entry: AdvancedMemoryEntry): Promise<void> {
    // Implementation for recording agent access patterns
  }

  private async handleSyncRequest(data: any): Promise<void> {
    // Implementation for handling sync requests
  }

  private async handleNodeJoined(data: any): Promise<void> {
    // Implementation for handling new nodes
  }

  private async handleNodeLeft(data: any): Promise<void> {
    // Implementation for handling node departures
  }

  private async handleConflict(data: any): Promise<void> {
    // Implementation for handling conflicts
  }

  private async handleAgentLearningUpdate(data: any): Promise<void> {
    // Implementation for handling learning updates
  }

  private async loadCrossAgentLearningData(): Promise<void> {
    // Implementation for loading learning data
  }

  private async discoverNodes(): Promise<void> {
    // Implementation for node discovery
  }

  private async syncPartitions(): Promise<void> {
    // Implementation for partition synchronization
  }

  private async updateHealthMetrics(): Promise<void> {
    // Implementation for health metric updates
  }

  private async performFullSync(operation: SyncOperation): Promise<void> {
    // Implementation for full synchronization
  }

  private async performIncrementalSync(operation: SyncOperation): Promise<void> {
    // Implementation for incremental synchronization
  }

  private async performDeltaSync(operation: SyncOperation): Promise<void> {
    // Implementation for delta synchronization
  }

  private async performConflictResolution(operation: SyncOperation): Promise<void> {
    // Implementation for conflict resolution sync
  }

  private async deleteEntry(entryId: string, partitionId: string): Promise<void> {
    // Implementation for entry deletion
  }

  private startHealthMonitoring(): void {
    this.healthMonitor = setInterval(() => {
      this.updateHealthMetrics().catch(error =>
        this.logger.error('Health monitoring failed', { error })
      );
    }, 60000); // Every minute
  }

  // === PUBLIC API ===

  async shutdown(): Promise<void> {
    this.logger.info('Shutting down Distributed Memory System');

    // Clear intervals
    if (this.syncInterval) clearInterval(this.syncInterval);
    if (this.healthMonitor) clearInterval(this.healthMonitor);

    // Save cross-agent learning data
    if (this.config.enableCrossAgentLearning) {
      await this.saveCrossAgentLearningData();
    }

    this.emit('distributed-memory:shutdown');
  }

  async getStatistics(): Promise<MemoryStatistics> {
    // Update current statistics
    this.statistics.totalNodes = this.nodes.size;
    this.statistics.activeNodes = Array.from(this.nodes.values())
      .filter(node => node.status === 'online').length;
    this.statistics.totalPartitions = this.partitions.size;
    this.statistics.totalEntries = Array.from(this.partitions.values())
      .reduce((sum, partition) => sum + partition.entries.length, 0);

    return { ...this.statistics };
  }

  async getPartitions(): Promise<MemoryPartition[]> {
    return Array.from(this.partitions.values());
  }

  async getNodes(): Promise<MemoryNode[]> {
    return Array.from(this.nodes.values());
  }

  async addNode(node: MemoryNode): Promise<void> {
    this.nodes.set(node.id, node);
    this.emit('distributed-memory:node-added', { node });
  }

  async removeNode(nodeId: string): Promise<void> {
    this.nodes.delete(nodeId);
    this.emit('distributed-memory:node-removed', { nodeId });
  }

  private async saveCrossAgentLearningData(): Promise<void> {
    // Implementation for saving learning data
  }
}