/**
 * Vector Memory - Semantic search wrapper for L4 self-evolution
 *
 * Provides vector-based semantic search over agent memories using OpenViking.
 * This enables finding conceptually similar memories rather than just keyword matches.
 *
 * Key capabilities:
 * - Semantic search: Find memories by meaning, not just keywords
 * - Relevance scoring: Get similarity scores for search results
 * - Context-aware: Search at different context levels (L0/L1/L2)
 *
 * Reference: ZCLAW_AGENT_INTELLIGENCE_EVOLUTION.md §6.4.2
 */

import { getVikingClient, type VikingHttpClient } from './viking-client';
import { getMemoryManager, type MemoryEntry, type MemoryType } from './agent-memory';

// === Types ===

export interface VectorSearchResult {
  memory: MemoryEntry;
  score: number;
  uri: string;
  highlights?: string[];
}

export interface VectorSearchOptions {
  topK?: number;           // Number of results to return (default: 10)
  minScore?: number;       // Minimum relevance score (default: 0.5)
  types?: MemoryType[];    // Filter by memory types
  agentId?: string;        // Filter by agent
  level?: 'L0' | 'L1' | 'L2';  // Context level to search
}

export interface VectorEmbedding {
  id: string;
  vector: number[];
  dimension: number;
  model: string;
}

export interface VectorMemoryConfig {
  enabled: boolean;
  defaultTopK: number;
  defaultMinScore: number;
  defaultLevel: 'L0' | 'L1' | 'L2';
  embeddingModel: string;
  cacheEmbeddings: boolean;
}

// === Default Config ===

export const DEFAULT_VECTOR_CONFIG: VectorMemoryConfig = {
  enabled: true,
  defaultTopK: 10,
  defaultMinScore: 0.3,
  defaultLevel: 'L1',
  embeddingModel: 'text-embedding-ada-002',
  cacheEmbeddings: true,
};

// === Vector Memory Service ===

export class VectorMemoryService {
  private config: VectorMemoryConfig;
  private vikingClient: VikingHttpClient | null = null;
  private embeddingCache: Map<string, VectorEmbedding> = new Map();

  constructor(config?: Partial<VectorMemoryConfig>) {
    this.config = { ...DEFAULT_VECTOR_CONFIG, ...config };
    this.initializeClient();
  }

  private async initializeClient(): Promise<void> {
    try {
      this.vikingClient = getVikingClient();
    } catch (error) {
      console.warn('[VectorMemory] Failed to initialize Viking client:', error);
    }
  }

  // === Semantic Search ===

  /**
   * Perform semantic search over memories.
   * Uses OpenViking's built-in vector search capabilities.
   */
  async semanticSearch(
    query: string,
    options?: VectorSearchOptions
  ): Promise<VectorSearchResult[]> {
    if (!this.config.enabled) {
      console.warn('[VectorMemory] Semantic search is disabled');
      return [];
    }

    if (!this.vikingClient) {
      await this.initializeClient();
      if (!this.vikingClient) {
        console.warn('[VectorMemory] Viking client not available');
        return [];
      }
    }

    try {
      const results = await this.vikingClient.find(query, {
        limit: options?.topK ?? this.config.defaultTopK,
        minScore: options?.minScore ?? this.config.defaultMinScore,
        level: options?.level ?? this.config.defaultLevel,
        scope: options?.agentId ? `memories/${options.agentId}` : undefined,
      });

      // Convert FindResult to VectorSearchResult
      const searchResults: VectorSearchResult[] = [];

      for (const result of results) {
        // Convert Viking result to MemoryEntry format
        const memory: MemoryEntry = {
          id: this.extractMemoryId(result.uri),
          agentId: options?.agentId ?? 'unknown',
          content: result.content,
          type: this.inferMemoryType(result.uri),
          importance: Math.round((1 - result.score) * 10), // Invert score to importance
          createdAt: new Date().toISOString(),
          source: 'auto',
          tags: Array.isArray((result.metadata as Record<string, unknown>)?.tags)
            ? (result.metadata as Record<string, unknown>).tags as string[]
            : [],
          lastAccessedAt: new Date().toISOString(),
          accessCount: 0,
        };

        searchResults.push({
          memory,
          score: result.score,
          uri: result.uri,
          highlights: Array.isArray((result.metadata as Record<string, unknown>)?.highlights)
            ? (result.metadata as Record<string, unknown>).highlights as string[]
            : undefined,
        });
      }

      // Apply type filter if specified
      if (options?.types && options.types.length > 0) {
        return searchResults.filter(r => options.types!.includes(r.memory.type));
      }

      return searchResults;
    } catch (error) {
      console.error('[VectorMemory] Semantic search failed:', error);
      return [];
    }
  }

  /**
   * Find similar memories to a given memory.
   */
  async findSimilar(
    memoryId: string,
    options?: Omit<VectorSearchOptions, 'types'>
  ): Promise<VectorSearchResult[]> {
    // Get the memory content first
    const memoryManager = getMemoryManager();
    const memories = await memoryManager.getAll(options?.agentId ?? 'default');
    const memory = memories.find((m: MemoryEntry) => m.id === memoryId);

    if (!memory) {
      console.warn(`[VectorMemory] Memory not found: ${memoryId}`);
      return [];
    }

    // Use the memory content as query for semantic search
    const results = await this.semanticSearch(memory.content, {
      ...options,
      topK: (options?.topK ?? 10) + 1, // +1 to account for the memory itself
    });

    // Filter out the original memory from results
    return results.filter(r => r.memory.id !== memoryId);
  }

  /**
   * Find memories related to a topic/concept.
   */
  async findByConcept(
    concept: string,
    options?: VectorSearchOptions
  ): Promise<VectorSearchResult[]> {
    return this.semanticSearch(concept, options);
  }

  /**
   * Cluster memories by semantic similarity.
   * Returns groups of related memories.
   */
  async clusterMemories(
    agentId: string,
    clusterCount: number = 5
  ): Promise<VectorSearchResult[][]> {
    const memoryManager = getMemoryManager();
    const memories = await memoryManager.getAll(agentId);

    if (memories.length === 0) {
      return [];
    }

    // Simple clustering: use each memory as a seed and find similar ones
    const clusters: VectorSearchResult[][] = [];
    const usedIds = new Set<string>();

    for (const memory of memories) {
      if (usedIds.has(memory.id)) continue;

      const similar = await this.findSimilar(memory.id, { agentId, topK: clusterCount });

      if (similar.length > 0) {
        const cluster: VectorSearchResult[] = [
          { memory, score: 1.0, uri: `memory://${memory.id}` },
          ...similar.filter(r => !usedIds.has(r.memory.id)),
        ];

        cluster.forEach(r => usedIds.add(r.memory.id));
        clusters.push(cluster);

        if (clusters.length >= clusterCount) break;
      }
    }

    return clusters;
  }

  // === Embedding Operations ===

  /**
   * Get or compute embedding for a text.
   * Note: OpenViking handles embeddings internally, this is for advanced use.
   */
  async getEmbedding(text: string): Promise<VectorEmbedding | null> {
    if (!this.config.enabled) return null;

    // Check cache first
    const cacheKey = this.hashText(text);
    if (this.config.cacheEmbeddings && this.embeddingCache.has(cacheKey)) {
      return this.embeddingCache.get(cacheKey)!;
    }

    // OpenViking handles embeddings internally via /api/find
    // This method is provided for future extensibility
    console.warn('[VectorMemory] Direct embedding computation not available - OpenViking handles this internally');
    return null;
  }

  /**
   * Compute similarity between two texts.
   */
  async computeSimilarity(text1: string, text2: string): Promise<number> {
    if (!this.config.enabled || !this.vikingClient) return 0;

    try {
      // Use OpenViking to find text1, then check if text2 is in results
      const results = await this.vikingClient.find(text1, { limit: 20 });

      // If we find text2 in results, return its score
      for (const result of results) {
        if (result.content.includes(text2) || text2.includes(result.content)) {
          return result.score;
        }
      }

      // Otherwise, return 0 (no similarity found)
      return 0;
    } catch {
      return 0;
    }
  }

  // === Utility Methods ===

  /**
   * Check if vector search is available.
   */
  async isAvailable(): Promise<boolean> {
    if (!this.config.enabled) return false;

    if (!this.vikingClient) {
      await this.initializeClient();
    }

    return this.vikingClient?.isAvailable() ?? false;
  }

  /**
   * Get current configuration.
   */
  getConfig(): VectorMemoryConfig {
    return { ...this.config };
  }

  /**
   * Update configuration.
   */
  updateConfig(updates: Partial<VectorMemoryConfig>): void {
    this.config = { ...this.config, ...updates };
  }

  /**
   * Clear embedding cache.
   */
  clearCache(): void {
    this.embeddingCache.clear();
  }

  // === Private Helpers ===

  private extractMemoryId(uri: string): string {
    // Extract memory ID from Viking URI
    // Format: memories/agent-id/memory-id or similar
    const parts = uri.split('/');
    return parts[parts.length - 1] || uri;
  }

  private inferMemoryType(uri: string): MemoryType {
    // Infer memory type from URI or metadata
    if (uri.includes('preference')) return 'preference';
    if (uri.includes('fact')) return 'fact';
    if (uri.includes('task')) return 'task';
    if (uri.includes('lesson')) return 'lesson';
    return 'fact'; // Default
  }

  private hashText(text: string): string {
    // Simple hash for cache key
    let hash = 0;
    for (let i = 0; i < text.length; i++) {
      const char = text.charCodeAt(i);
      hash = ((hash << 5) - hash) + char;
      hash = hash & hash;
    }
    return hash.toString(16);
  }
}

// === Singleton ===

let _instance: VectorMemoryService | null = null;

export function getVectorMemory(): VectorMemoryService {
  if (!_instance) {
    _instance = new VectorMemoryService();
  }
  return _instance;
}

export function resetVectorMemory(): void {
  _instance = null;
}

// === Helper Functions ===

/**
 * Quick semantic search helper.
 */
export async function semanticSearch(
  query: string,
  options?: VectorSearchOptions
): Promise<VectorSearchResult[]> {
  return getVectorMemory().semanticSearch(query, options);
}

/**
 * Find similar memories helper.
 */
export async function findSimilarMemories(
  memoryId: string,
  agentId?: string
): Promise<VectorSearchResult[]> {
  return getVectorMemory().findSimilar(memoryId, { agentId });
}

/**
 * Check if vector search is available.
 */
export async function isVectorSearchAvailable(): Promise<boolean> {
  return getVectorMemory().isAvailable();
}