Technical Debt Management: Balancing Speed and Quality

// Technical debt categorization
interface TechnicalDebt {
  id: string;
  title: string;
  description: string;
  category: DebtCategory;
  severity: 'low' | 'medium' | 'high' | 'critical';
  impact: DebtImpact;
  effort: number; // days to resolve
  priority: number; // calculated priority score
  createdAt: Date;
  discoveredBy: string;
  affectedComponents: string[];
}

type DebtCategory = 
  | 'code-quality'
  | 'performance'
  | 'security'
  | 'architecture'
  | 'documentation'
  | 'testing'
  | 'dependencies'
  | 'legacy-code';

interface DebtImpact {
  developmentVelocity: number; // 0-1 impact on velocity
  bugRisk: number; // 0-1 risk of bugs
  maintenanceCost: number; // 0-1 maintenance impact
  scalability: number; // 0-1 impact on scalability
  securityRisk: number; // 0-1 security risk
}

// Debt identification examples
const technicalDebtExamples: TechnicalDebt[] = [
  {
    id: 'DEBT-001',
    title: 'Duplicate Code in User Management',
    description: 'User creation and update logic duplicated across 3 modules',
    category: 'code-quality',
    severity: 'medium',
    impact: {
      developmentVelocity: 0.3,
      bugRisk: 0.4,
      maintenanceCost: 0.5,
      scalability: 0.2,
      securityRisk: 0.1
    },
    effort: 2,
    priority: 0,
    createdAt: new Date('2024-01-15'),
    discoveredBy: 'code-review',
    affectedComponents: ['user-service', 'admin-panel', 'api-gateway']
  },
  {
    id: 'DEBT-002',
    title: 'Missing Database Indexes',
    description: 'Slow queries due to missing indexes on frequently queried columns',
    category: 'performance',
    severity: 'high',
    impact: {
      developmentVelocity: 0.1,
      bugRisk: 0.2,
      maintenanceCost: 0.3,
      scalability: 0.8,
      securityRisk: 0.0
    },
    effort: 1,
    priority: 0,
    createdAt: new Date('2024-01-10'),
    discoveredBy: 'performance-monitoring',
    affectedComponents: ['database', 'user-queries', 'reporting']
  },
  {
    id: 'DEBT-003',
    title: 'Outdated Dependencies',
    description: '15 packages with known security vulnerabilities',
    category: 'security',
    severity: 'critical',
    impact: {
      developmentVelocity: 0.1,
      bugRisk: 0.3,
      maintenanceCost: 0.2,
      scalability: 0.1,
      securityRisk: 0.9
    },
    effort: 3,
    priority: 0,
    createdAt: new Date('2024-01-05'),
    discoveredBy: 'security-scan',
    affectedComponents: ['all']
  }
];

// Priority calculation system
class DebtPriorityCalculator {
  // Calculate priority score based on multiple factors
  calculatePriority(debt: TechnicalDebt): number {
    const severityWeight = this.getSeverityWeight(debt.severity);
    const impactWeight = this.calculateImpactWeight(debt.impact);
    const effortWeight = this.calculateEffortWeight(debt.effort);
    const ageWeight = this.calculateAgeWeight(debt.createdAt);
    
    return (severityWeight * 0.4) + 
           (impactWeight * 0.3) + 
           (effortWeight * 0.2) + 
           (ageWeight * 0.1);
  }
  
  private getSeverityWeight(severity: string): number {
    const weights = {
      'low': 1,
      'medium': 2,
      'high': 3,
      'critical': 4
    };
    return weights[severity] || 1;
  }
  
  private calculateImpactWeight(impact: DebtImpact): number {
    return (impact.developmentVelocity * 0.3) +
           (impact.bugRisk * 0.25) +
           (impact.maintenanceCost * 0.2) +
           (impact.scalability * 0.15) +
           (impact.securityRisk * 0.1);
  }
  
  private calculateEffortWeight(effort: number): number {
    // Lower effort = higher priority (easier to fix)
    return Math.max(0, 5 - effort) / 5;
  }
  
  private calculateAgeWeight(createdAt: Date): number {
    const daysSinceCreation = (Date.now() - createdAt.getTime()) / (1000 * 60 * 60 * 24);
    return Math.min(daysSinceCreation / 30, 1); // Max weight after 30 days
  }
}

// Risk assessment for debt items
interface DebtRiskAssessment {
  debtId: string;
  riskLevel: 'low' | 'medium' | 'high' | 'critical';
  riskFactors: RiskFactor[];
  mitigationStrategies: string[];
  timeline: 'immediate' | 'short-term' | 'medium-term' | 'long-term';
}

interface RiskFactor {
  factor: string;
  probability: number; // 0-1
  impact: number; // 0-1
  description: string;
}

// Example risk assessment
const debtRiskAssessment: DebtRiskAssessment = {
  debtId: 'DEBT-003',
  riskLevel: 'critical',
  riskFactors: [
    {
      factor: 'Security Vulnerability',
      probability: 0.8,
      impact: 0.9,
      description: 'High probability of security breach due to outdated packages'
    },
    {
      factor: 'Compliance Issues',
      probability: 0.6,
      impact: 0.7,
      description: 'May fail security audits and compliance checks'
    }
  ],
  mitigationStrategies: [
    'Immediate package updates',
    'Security patch testing',
    'Compliance review'
  ],
  timeline: 'immediate'
};

// Debt prevention strategies
interface DebtPreventionStrategy {
  name: string;
  description: string;
  category: DebtCategory;
  implementation: string;
  effectiveness: number; // 0-1
  cost: 'low' | 'medium' | 'high';
}

const preventionStrategies: DebtPreventionStrategy[] = [
  {
    name: 'Code Review Requirements',
    description: 'Mandatory code review for all changes',
    category: 'code-quality',
    implementation: 'All pull requests require 2+ approvals',
    effectiveness: 0.8,
    cost: 'medium'
  },
  {
    name: 'Automated Testing',
    description: 'Comprehensive test coverage requirements',
    category: 'testing',
    implementation: 'Minimum 80% test coverage, automated testing on all commits',
    effectiveness: 0.7,
    cost: 'high'
  },
  {
    name: 'Dependency Monitoring',
    description: 'Automated monitoring of dependency updates',
    category: 'dependencies',
    implementation: 'Automated alerts for outdated packages and security vulnerabilities',
    effectiveness: 0.9,
    cost: 'low'
  },
  {
    name: 'Performance Monitoring',
    description: 'Continuous performance monitoring and alerting',
    category: 'performance',
    implementation: 'Real-time performance metrics with automated alerts',
    effectiveness: 0.6,
    cost: 'medium'
  },
  {
    name: 'Architecture Reviews',
    description: 'Regular architecture review sessions',
    category: 'architecture',
    implementation: 'Monthly architecture review meetings with senior developers',
    effectiveness: 0.5,
    cost: 'medium'
  }
];

// Debt prevention implementation
class DebtPreventionManager {
  private strategies: Map<DebtCategory, DebtPreventionStrategy[]>;
  
  constructor() {
    this.strategies = new Map();
    this.initializeStrategies();
  }
  
  private initializeStrategies(): void {
    preventionStrategies.forEach(strategy => {
      if (!this.strategies.has(strategy.category)) {
        this.strategies.set(strategy.category, []);
      }
      this.strategies.get(strategy.category)!.push(strategy);
    });
  }
  
  // Get prevention strategies for a category
  getStrategiesForCategory(category: DebtCategory): DebtPreventionStrategy[] {
    return this.strategies.get(category) || [];
  }
  
  // Calculate prevention effectiveness
  calculatePreventionEffectiveness(category: DebtCategory): number {
    const strategies = this.getStrategiesForCategory(category);
    if (strategies.length === 0) return 0;
    
    return strategies.reduce((sum, strategy) => sum + strategy.effectiveness, 0) / strategies.length;
  }
  
  // Implement prevention strategy
  async implementStrategy(strategy: DebtPreventionStrategy): Promise<boolean> {
    try {
      // Implementation logic would go here
      console.log(`Implementing ${strategy.name}: ${strategy.implementation}`);
      return true;
    } catch (error) {
      console.error(`Failed to implement ${strategy.name}:`, error);
      return false;
    }
  }
}

// Production debt management system
export class ProductionDebtManager {
  private debtDatabase: DebtDatabase;
  private preventionManager: DebtPreventionManager;
  private priorityCalculator: DebtPriorityCalculator;
  
  constructor() {
    this.debtDatabase = new DebtDatabase();
    this.preventionManager = new DebtPreventionManager();
    this.priorityCalculator = new DebtPriorityCalculator();
  }
  
  // Comprehensive debt audit
  async conductDebtAudit(projectId: string): Promise<TechnicalDebt[]> {
    const auditResults: TechnicalDebt[] = [];
    
    // Code quality audit
    const codeQualityDebt = await this.auditCodeQuality(projectId);
    auditResults.push(...codeQualityDebt);
    
    // Performance audit
    const performanceDebt = await this.auditPerformance(projectId);
    auditResults.push(...performanceDebt);
    
    // Security audit
    const securityDebt = await this.auditSecurity(projectId);
    auditResults.push(...securityDebt);
    
    // Architecture audit
    const architectureDebt = await this.auditArchitecture(projectId);
    auditResults.push(...architectureDebt);
    
    // Calculate priorities
    auditResults.forEach(debt => {
      debt.priority = this.priorityCalculator.calculatePriority(debt);
    });
    
    // Sort by priority
    auditResults.sort((a, b) => b.priority - a.priority);
    
    return auditResults;
  }
  
  // Generate debt resolution plan
  async generateResolutionPlan(debtItems: TechnicalDebt[]): Promise<DebtResolutionPlan> {
    const plan: DebtResolutionPlan = {
      totalDebtItems: debtItems.length,
      totalEffort: debtItems.reduce((sum, debt) => sum + debt.effort, 0),
      timeline: this.calculateTimeline(debtItems),
      phases: this.organizeIntoPhases(debtItems),
      resources: this.calculateResourceRequirements(debtItems)
    };
    
    return plan;
  }
  
  // Monitor debt resolution progress
  async monitorProgress(planId: string): Promise<DebtResolutionProgress> {
    const plan = await this.getResolutionPlan(planId);
    const completedItems = await this.getCompletedDebtItems(planId);
    
    const progress: DebtResolutionProgress = {
      planId,
      totalItems: plan.totalDebtItems,
      completedItems: completedItems.length,
      completionPercentage: (completedItems.length / plan.totalDebtItems) * 100,
      remainingEffort: plan.totalEffort - completedItems.reduce((sum, item) => sum + item.effort, 0),
      estimatedCompletionDate: this.calculateEstimatedCompletion(plan, completedItems)
    };
    
    return progress;
  }
}