D1 Database Implementation

/**
 * Constructs D1 database queries based on semantic intent rather than technical 
 * query flags, implementing intelligent query optimization and result shaping.
 * 
 * SEMANTIC QUERY PRINCIPLE: Query structure and optimization driven by business
 * intent (data scope, urgency, quality requirements) not technical parameters.
 */

export class SemanticQueryBuilder {
  private intent: DataSemanticIntent;
  private queryPlan: QueryPlan;
  
  /**
   * Creates semantic query builder for specific business intent.
   * 
   * @param intent Semantic intent driving query construction
   * @returns Builder configured for intent-driven data access
   * 
   * @example
   * ```typescript
   * // ✅ SEMANTIC QUERY BUILDING: Intent drives query structure
   * const intent = new DataSemanticIntent({
   *   dataScope: DataScope.ExecutiveSummary,
   *   urgencyContext: UrgencyContext.Urgent,
   *   userContext: UserContext.ExecutiveDecision
   * });
   * const query = SemanticQueryBuilder.forIntent(intent);
   * const results = await query.executeAsync(db);
   * 
   * // ❌ WRONG: Technical parameters driving queries
   * // const results = await db.prepare("SELECT * FROM reports WHERE level = ?")
   * //   .bind(isQuick ? 1 : 3).all(); // NO!
   * ```
   * 
   * @remarks
   * Eliminates the anti-pattern where technical query complexity drives
   * business data retrieval. Instead, uses semantic intent to determine:
   * 1. Which columns/tables to include (data scope semantics)
   * 2. Query optimization strategy (performance profile semantics) 
   * 3. Result filtering and shaping (quality requirements)
   * 4. Caching and indexing hints (urgency context semantics)
   */
  static forIntent(intent: DataSemanticIntent): SemanticQueryBuilder {
    const builder = new SemanticQueryBuilder();
    builder.intent = intent;
    builder.queryPlan = builder.deriveQueryPlan(intent);
    return builder;
  }

  /**
   * Executes semantically-driven query against D1 database with intent-based optimization.
   * 
   * @param db D1 database connection
   * @returns Results shaped according to semantic intent requirements
   * 
   * @remarks 
   * Query execution adapts based on semantic intent:
   * - ExecutiveSummary: Aggregated data with KPIs
   * - OperationalDetails: Current operational data with details
   * - ComprehensiveAnalysis: Full dataset with related tables
   * - RealTimeMonitoring: Latest data with change indicators
   * - HistoricalTrends: Time-series data with trend analysis
   */
  async executeAsync(db: D1Database): Promise> {
    const startTime = performance.now();
    
    try {
      // Generate intent-driven SQL query
      const sqlQuery = this.buildSemanticQuery();
      
      console.log(`📊 SEMANTIC QUERY: ${this.intent.dataScope} for ${this.intent.userContext}`);
      console.log(`🎯 QUERY PLAN: ${this.queryPlan.strategy} with ${this.queryPlan.optimizations.join(', ')}`);
      
      // Execute with semantic optimizations
      const rawResults = await this.executeWithOptimizations(db, sqlQuery);
      
      // Shape results according to semantic intent
      const shapedResults = this.shapeResultsForIntent(rawResults);
      
      const executionTime = performance.now() - startTime;
      
      // Validate performance profile compliance
      this.validatePerformanceCompliance(executionTime);
      
      return {
        data: shapedResults,
        metadata: {
          semanticIntent: this.intent,
          queryPlan: this.queryPlan,
          executionTime,
          recordCount: shapedResults.length,
          dataQuality: this.assessDataQuality(shapedResults),
          semanticCompliance: true
        }
      };
      
    } catch (error) {
      console.error(`🚨 SEMANTIC QUERY ERROR: ${error.message}`);
      throw new SemanticQueryException(`Query failed for ${this.intent.dataScope}: ${error.message}`);
    }
  }

  /**
   * Derives query execution plan from semantic intent, avoiding technical complexity flags.
   */
  private deriveQueryPlan(intent: DataSemanticIntent): QueryPlan {
    const strategy = this.determineQueryStrategy(intent);
    const optimizations = this.determineOptimizations(intent);
    const indexHints = this.determineIndexHints(intent);
    
    return {
      strategy,
      optimizations,
      indexHints,
      resultShaping: this.determineResultShaping(intent)
    };
  }

  /**
   * Determines query strategy based on semantic data scope and performance requirements.
   */
  private determineQueryStrategy(intent: DataSemanticIntent): QueryStrategy {
    // Executive summary needs aggregated data strategy
    if (intent.dataScope === DataScope.ExecutiveSummary) {
      return QueryStrategy.Aggregated;
    }
    
    // Real-time monitoring needs latest data strategy
    if (intent.dataScope === DataScope.RealTimeMonitoring) {
      return QueryStrategy.Latest;
    }
    
    // Historical analysis needs time-series strategy
    if (intent.dataScope === DataScope.HistoricalTrends) {
      return QueryStrategy.TimeSeries;
    }
    
    // Comprehensive analysis needs join strategy
    if (intent.dataScope === DataScope.ComprehensiveAnalysis) {
      return QueryStrategy.Comprehensive;
    }
    
    return QueryStrategy.Standard;
  }

  /**
   * Builds SQL query optimized for semantic intent rather than technical flags.
   */
  private buildSemanticQuery(): string {
    const baseQuery = this.buildBaseQuery();
    const semanticFilters = this.buildSemanticFilters();
    const performanceOptimizations = this.buildPerformanceOptimizations();
    
    return `
      ${baseQuery}
      ${semanticFilters}
      ${performanceOptimizations}
    `.trim();
  }

  /**
   * Builds base query structure based on semantic data scope.
   */
  private buildBaseQuery(): string {
    switch (this.intent.dataScope) {
      case DataScope.ExecutiveSummary:
        return `
          SELECT 
            DATE(created_at) as date,
            COUNT(*) as total_count,
            SUM(CASE WHEN status = 'completed' THEN 1 ELSE 0 END) as completed_count,
            AVG(performance_score) as avg_performance,
            SUM(revenue) as total_revenue
          FROM reports r
          LEFT JOIN performance_metrics pm ON r.id = pm.report_id
        `;
        
      case DataScope.RealTimeMonitoring:
        return `
          SELECT 
            r.*,
            pm.current_status,
            pm.last_updated,
            pm.health_score
          FROM reports r
          INNER JOIN performance_metrics pm ON r.id = pm.report_id
          WHERE r.created_at > datetime('now', '-1 hour')
        `;
        
      case DataScope.ComprehensiveAnalysis:
        return `
          SELECT 
            r.*,
            u.name as author_name,
            u.department,
            pm.*,
            t.name as category_name
          FROM reports r
          LEFT JOIN users u ON r.author_id = u.id
          LEFT JOIN performance_metrics pm ON r.id = pm.report_id  
          LEFT JOIN categories t ON r.category_id = t.id
        `;
        
      case DataScope.HistoricalTrends:
        return `
          SELECT 
            DATE(r.created_at) as date,
            r.category_id,
            COUNT(*) as daily_count,
            AVG(pm.performance_score) as avg_score,
            RANK() OVER (PARTITION BY DATE(r.created_at) ORDER BY COUNT(*) DESC) as daily_rank
          FROM reports r
          LEFT JOIN performance_metrics pm ON r.id = pm.report_id
          WHERE r.created_at >= datetime('now', '-90 days')
        `;
        
      default: // OperationalDetails
        return `
          SELECT 
            r.id,
            r.title,
            r.status,
            r.created_at,
            r.updated_at,
            u.name as author_name,
            pm.performance_score
          FROM reports r
          LEFT JOIN users u ON r.author_id = u.id
          LEFT JOIN performance_metrics pm ON r.id = pm.report_id
        `;
    }
  }

  /**
   * Adds semantic filters based on user context and quality requirements.
   */
  private buildSemanticFilters(): string {
    let filters: string[] = [];
    
    // Quality-based filtering
    if (this.intent.qualityRequirements === QualityRequirements.Authoritative) {
      filters.push("r.approval_status = 'approved'");
      filters.push("r.data_quality_score >= 95");
    }
    
    // User context filtering
    if (this.intent.userContext === UserContext.ExecutiveDecision) {
      filters.push("r.visibility_level >= 'executive'");
    }
    
    // Urgency-based filtering  
    if (this.intent.urgencyContext === UrgencyContext.Critical) {
      filters.push("r.priority = 'high'");
      filters.push("r.status != 'draft'");
    }
    
    return filters.length > 0 ? `WHERE ${filters.join(' AND ')}` : '';
  }

  /**
   * Adds performance optimizations based on semantic performance profile.
   */
  private buildPerformanceOptimizations(): string {
    let optimizations: string[] = [];
    
    // Sorting and limiting based on intent
    if (this.intent.dataScope === DataScope.ExecutiveSummary) {
      optimizations.push("GROUP BY DATE(r.created_at)");
      optimizations.push("ORDER BY date DESC");
      optimizations.push("LIMIT 30"); // Last 30 days for executives
    }
    
    if (this.intent.dataScope === DataScope.RealTimeMonitoring) {
      optimizations.push("ORDER BY r.updated_at DESC");
      optimizations.push("LIMIT 100"); // Recent monitoring data
    }
    
    if (this.intent.performanceProfile === PerformanceProfile.Interactive) {
      optimizations.push("-- HINT: USE INDEX FOR INTERACTIVE PERFORMANCE");
    }
    
    return optimizations.join('
');
  }

  /**
   * Shapes query results according to semantic intent and user context.
   */
  private shapeResultsForIntent(rawResults: any[]): T[] {
    if (!rawResults?.length) return [] as T[];
    
    switch (this.intent.dataScope) {
      case DataScope.ExecutiveSummary:
        return this.shapeForExecutive(rawResults) as T[];
        
      case DataScope.RealTimeMonitoring:  
        return this.shapeForMonitoring(rawResults) as T[];
        
      case DataScope.ComprehensiveAnalysis:
        return this.shapeForAnalysis(rawResults) as T[];
        
      default:
        return rawResults as T[];
    }
  }

  /**
   * Shapes data for executive consumption with KPIs and summaries.
   */
  private shapeForExecutive(data: any[]): ExecutiveSummary[] {
    return data.map(row => ({
      date: row.date,
      totalReports: row.total_count,
      completionRate: (row.completed_count / row.total_count * 100).toFixed(1) + '%',
      averagePerformance: row.avg_performance?.toFixed(1) || 'N/A',
      revenue: this.formatCurrency(row.total_revenue),
      trend: this.calculateTrend(row), // Semantic trend analysis
      semanticInsight: this.generateExecutiveInsight(row)
    }));
  }

  /**
   * Validates that query performance meets semantic profile requirements.
   */
  private validatePerformanceCompliance(executionTime: number): void {
    const maxTime = this.getMaxExecutionTime(this.intent.performanceProfile);
    
    if (executionTime > maxTime) {
      console.warn(`⚠️ PERFORMANCE VIOLATION: Query took ${executionTime}ms, expected < ${maxTime}ms for ${this.intent.performanceProfile} profile`);
      
      // Log semantic performance violation for analysis
      console.log(`🔍 SEMANTIC CONTEXT: ${this.intent.userContext} requesting ${this.intent.dataScope} with ${this.intent.urgencyContext} urgency`);
    }
  }

  private getMaxExecutionTime(profile: PerformanceProfile): number {
    switch (profile) {
      case PerformanceProfile.Instantaneous: return 100;
      case PerformanceProfile.Interactive: return 2000;
      case PerformanceProfile.Responsive: return 10000;
      case PerformanceProfile.Batch: return 60000;
      default: return 5000;
    }
  }
}

// Supporting types and interfaces
export enum QueryStrategy {
  Aggregated = 'aggregated',
  Latest = 'latest', 
  TimeSeries = 'timeseries',
  Comprehensive = 'comprehensive',
  Standard = 'standard'
}

export interface QueryPlan {
  strategy: QueryStrategy;
  optimizations: string[];
  indexHints: string[];
  resultShaping: string;
}

export interface SemanticQueryResult {
  data: T[];
  metadata: {
    semanticIntent: DataSemanticIntent;
    queryPlan: QueryPlan;
    executionTime: number;
    recordCount: number;
    dataQuality: string;
    semanticCompliance: boolean;
  };
}

export interface ExecutiveSummary {
  date: string;
  totalReports: number;
  completionRate: string;
  averagePerformance: string;
  revenue: string;
  trend: string;
  semanticInsight: string;
}

export class SemanticQueryException extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'SemanticQueryException';
  }
}