Technical Debt Management: Snelheid en Kwaliteit Balanceren

// Probleem: Technical debt impact
const newFeatureTime = 3; // weken
const expectedTime = 1;   // weken
const debtMultiplier = newFeatureTime / expectedTime; // 3x langzamer

const bugCount = 15;      // bugs per sprint
const acceptableBugs = 3;  // bugs per sprint
const debtImpact = bugCount / acceptableBugs; // 5x meer bugs

// Technical debt categorisatie
interface TechnicalDebt {
  id: string;
  description: string;
  category: 'code_quality' | 'performance' | 'security' | 'maintainability' | 'architecture';
  severity: 'low' | 'medium' | 'high' | 'critical';
  impact: {
    developmentVelocity: number;  // 0-100%
    bugRisk: number;              // 0-100%
    maintenanceCost: number;      // 0-100%
  };
  effort: number;                 // story points
  dependencies: string[];         // andere debt items
}

interface DebtAudit {
  totalDebtItems: number;
  categories: Map<string, TechnicalDebt[]>;
  criticalItems: TechnicalDebt[];
  quickWins: TechnicalDebt[];
  debtScore: number;
}

class DebtAuditor {
  async conductAudit(codebase: Codebase): Promise<DebtAudit> {
    const debtItems: TechnicalDebt[] = [];
    
    // Code quality debt
    debtItems.push(...await this.identifyCodeQualityDebt(codebase));
    
    // Performance debt
    debtItems.push(...await this.identifyPerformanceDebt(codebase));
    
    // Security debt
    debtItems.push(...await this.identifySecurityDebt(codebase));
    
    // Architecture debt
    debtItems.push(...await this.identifyArchitectureDebt(codebase));

    return this.categorizeDebt(debtItems);
  }

  private async identifyCodeQualityDebt(codebase: Codebase): Promise<TechnicalDebt[]> {
    const debtItems: TechnicalDebt[] = [];
    
    // Duplicate code
    const duplicates = await this.findDuplicateCode(codebase);
    duplicates.forEach(dup => {
      debtItems.push({
        id: `dup-${dup.id}`,
        description: `Duplicate code in ${dup.files.join(', ')}`,
        category: 'code_quality',
        severity: 'medium',
        impact: {
          developmentVelocity: 20,
          bugRisk: 30,
          maintenanceCost: 40
        },
        effort: 3,
        dependencies: []
      });
    });

    // Long methods
    const longMethods = await this.findLongMethods(codebase);
    longMethods.forEach(method => {
      debtItems.push({
        id: `long-method-${method.id}`,
        description: `Long method: ${method.name} (${method.lines} lines)`,
        category: 'code_quality',
        severity: 'high',
        impact: {
          developmentVelocity: 40,
          bugRisk: 50,
          maintenanceCost: 60
        },
        effort: 5,
        dependencies: []
      });
    });

    return debtItems;
  }
}

// Risico-gebaseerde prioritering
interface DebtPriority {
  debtItem: TechnicalDebt;
  priorityScore: number;
  riskLevel: 'low' | 'medium' | 'high' | 'critical';
  businessImpact: number;
  technicalImpact: number;
  resolutionStrategy: ResolutionStrategy;
}

interface ResolutionStrategy {
  approach: 'immediate' | 'scheduled' | 'gradual' | 'preventive';
  timeline: string;
  resources: string[];
  successCriteria: string[];
}

class DebtPrioritizer {
  calculatePriority(debtItem: TechnicalDebt): DebtPriority {
    // Bereken priority score op basis van impact en effort
    const impactScore = (
      debtItem.impact.developmentVelocity +
      debtItem.impact.bugRisk +
      debtItem.impact.maintenanceCost
    ) / 3;

    const effortScore = debtItem.effort;
    const priorityScore = impactScore / effortScore; // Hoger is beter

    // Bepaal risico niveau
    let riskLevel: 'low' | 'medium' | 'high' | 'critical';
    if (priorityScore > 20) riskLevel = 'critical';
    else if (priorityScore > 15) riskLevel = 'high';
    else if (priorityScore > 10) riskLevel = 'medium';
    else riskLevel = 'low';

    // Bepaal resolution strategie
    const resolutionStrategy = this.determineResolutionStrategy(debtItem, riskLevel);

    return {
      debtItem,
      priorityScore,
      riskLevel,
      businessImpact: debtItem.impact.developmentVelocity,
      technicalImpact: debtItem.impact.bugRisk + debtItem.impact.maintenanceCost,
      resolutionStrategy
    };
  }

  private determineResolutionStrategy(
    debtItem: TechnicalDebt, 
    riskLevel: string
  ): ResolutionStrategy {
    switch (riskLevel) {
      case 'critical':
        return {
          approach: 'immediate',
          timeline: '1-2 sprints',
          resources: ['senior_developer', 'architect'],
          successCriteria: ['Zero bugs', 'Improved performance', 'Reduced complexity']
        };
      
      case 'high':
        return {
          approach: 'scheduled',
          timeline: '2-4 sprints',
          resources: ['developer', 'code_reviewer'],
          successCriteria: ['Reduced bugs', 'Better maintainability', 'Improved velocity']
        };
      
      case 'medium':
        return {
          approach: 'gradual',
          timeline: '4-8 sprints',
          resources: ['developer'],
          successCriteria: ['Incremental improvement', 'Reduced technical debt']
        };
      
      default:
        return {
          approach: 'preventive',
          timeline: 'ongoing',
          resources: ['all_developers'],
          successCriteria: ['Prevent new debt', 'Maintain quality standards']
        };
    }
  }
}

// Technical debt preventie systeem
interface PreventionStrategy {
  name: string;
  description: string;
  implementation: string;
  effectiveness: number;  // 0-100%
  cost: 'low' | 'medium' | 'high';
}

class DebtPreventionManager {
  private strategies: PreventionStrategy[] = [
    {
      name: 'Code Review Standards',
      description: 'Strikte code review criteria om debt te voorkomen',
      implementation: `
        - Minimum 2 reviewers per PR
        - Debt detection checklist
        - Automated quality gates
        - Code complexity limits
      `,
      effectiveness: 80,
      cost: 'low'
    },
    {
      name: 'Automated Quality Gates',
      description: 'CI/CD pipeline checks voor code kwaliteit',
      implementation: `
        - SonarQube quality gates
        - Test coverage requirements
        - Performance benchmarks
        - Security vulnerability scans
      `,
      effectiveness: 90,
      cost: 'medium'
    },
    {
      name: 'Refactoring Time Allocation',
      description: 'Dedicated tijd voor refactoring in elke sprint',
      implementation: `
        - 20% van sprint tijd voor refactoring
        - Technical debt backlog
        - Refactoring stories in sprint planning
        - Team education over debt impact
      `,
      effectiveness: 70,
      cost: 'low'
    },
    {
      name: 'Architecture Reviews',
      description: 'Regelmatige architectuur reviews om debt te voorkomen',
      implementation: `
        - Monthly architecture reviews
        - Design pattern guidelines
        - Technology decision framework
        - Technical debt impact assessment
      `,
      effectiveness: 85,
      cost: 'medium'
    }
  ];

  async implementPreventionStrategy(strategy: PreventionStrategy): Promise<void> {
    console.log(`Implementing prevention strategy: ${strategy.name}`);
    
    switch (strategy.name) {
      case 'Code Review Standards':
        await this.implementCodeReviewStandards();
        break;
      case 'Automated Quality Gates':
        await this.implementQualityGates();
        break;
      case 'Refactoring Time Allocation':
        await this.implementRefactoringTime();
        break;
      case 'Architecture Reviews':
        await this.implementArchitectureReviews();
        break;
    }
  }

  private async implementCodeReviewStandards(): Promise<void> {
    // Implementeer code review standards
    const standards = {
      minReviewers: 2,
      debtChecklist: [
        'No duplicate code',
        'Methods under 50 lines',
        'Classes under 500 lines',
        'No TODO comments',
        'Proper error handling',
        'Unit tests present'
      ],
      complexityLimits: {
        cyclomaticComplexity: 10,
        cognitiveComplexity: 15
      }
    };

    console.log('Code review standards implemented:', standards);
  }
}

// Probleem: Geen tracking van debt resolution
interface DebtResolutionStatus {
  totalDebt: number;
  resolvedDebt: number;
  progress: number;  // percentage
  velocity: number;  // debt resolved per sprint
}

// Technical debt tracking systeem
interface DebtResolutionTracker {
  trackResolution(debtItem: TechnicalDebt, resolution: DebtResolution): Promise<void>;
  calculateProgress(): Promise<DebtProgress>;
  generateReport(): Promise<DebtReport>;
  predictCompletion(): Promise<CompletionPrediction>;
}

interface DebtResolution {
  debtItemId: string;
  resolutionDate: Date;
  effortSpent: number;
  approach: string;
  successMetrics: SuccessMetric[];
}

interface DebtProgress {
  totalDebtItems: number;
  resolvedItems: number;
  inProgressItems: number;
  pendingItems: number;
  progressPercentage: number;
  velocity: number;  // items per sprint
  trend: 'improving' | 'stable' | 'declining';
}

class DebtTracker implements DebtResolutionTracker {
  private resolutions: DebtResolution[] = [];
  private debtItems: TechnicalDebt[] = [];

  async trackResolution(debtItem: TechnicalDebt, resolution: DebtResolution): Promise<void> {
    this.resolutions.push(resolution);
    
    // Update debt item status
    const item = this.debtItems.find(d => d.id === debtItem.id);
    if (item) {
      // Mark as resolved
      console.log(`Debt item ${debtItem.id} resolved in ${resolution.effortSpent} story points`);
    }

    // Track success metrics
    await this.trackSuccessMetrics(resolution);
  }

  async calculateProgress(): Promise<DebtProgress> {
    const totalItems = this.debtItems.length;
    const resolvedItems = this.resolutions.length;
    const inProgressItems = this.debtItems.filter(d => 
      this.resolutions.find(r => r.debtItemId === d.id) === undefined
    ).length;
    const pendingItems = totalItems - resolvedItems - inProgressItems;

    const progressPercentage = (resolvedItems / totalItems) * 100;
    
    // Bereken velocity (items per sprint)
    const velocity = this.calculateVelocity();
    
    // Bepaal trend
    const trend = this.calculateTrend();

    return {
      totalDebtItems: totalItems,
      resolvedItems,
      inProgressItems,
      pendingItems,
      progressPercentage,
      velocity,
      trend
    };
  }

  private calculateVelocity(): number {
    // Bereken gemiddelde items per sprint over laatste 4 sprints
    const recentResolutions = this.resolutions
      .filter(r => r.resolutionDate > new Date(Date.now() - 30 * 24 * 60 * 60 * 1000))
      .length;
    
    return recentResolutions / 4; // 4 sprints = 1 maand
  }

  private calculateTrend(): 'improving' | 'stable' | 'declining' {
    const lastMonth = this.resolutions
      .filter(r => r.resolutionDate > new Date(Date.now() - 30 * 24 * 60 * 60 * 1000))
      .length;
    
    const previousMonth = this.resolutions
      .filter(r => {
        const date = r.resolutionDate;
        return date > new Date(Date.now() - 60 * 24 * 60 * 60 * 1000) && 
               date <= new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
      })
      .length;

    if (lastMonth > previousMonth) return 'improving';
    if (lastMonth < previousMonth) return 'declining';
    return 'stable';
  }

  async generateReport(): Promise<DebtReport> {
    const progress = await this.calculateProgress();
    
    return {
      summary: {
        totalDebt: progress.totalDebtItems,
        resolved: progress.resolvedItems,
        progress: progress.progressPercentage,
        velocity: progress.velocity,
        trend: progress.trend
      },
      categories: await this.analyzeByCategory(),
      recommendations: await this.generateRecommendations(),
      nextSteps: await this.generateNextSteps()
    };
  }
}

// Probleem: Team onbegrip
interface TeamPerception {
  debtAwareness: 'low' | 'medium' | 'high';
  debtImpact: 'underestimated' | 'accurate' | 'overestimated';
  preventionKnowledge: 'poor' | 'fair' | 'good' | 'excellent';
}

// Team education systeem
interface EducationProgram {
  modules: EducationModule[];
  assessments: Assessment[];
  certifications: Certification[];
  continuousLearning: ContinuousLearning[];
}

interface EducationModule {
  title: string;
  content: string;
  duration: number;  // minuten
  difficulty: 'beginner' | 'intermediate' | 'advanced';
  practicalExercises: Exercise[];
}

class TeamEducator {
  private educationProgram: EducationProgram;

  constructor() {
    this.educationProgram = {
      modules: [
        {
          title: 'Technical Debt Fundamentals',
          content: 'Wat is technical debt en waarom is het belangrijk...',
          duration: 60,
          difficulty: 'beginner',
          practicalExercises: [
            {
              name: 'Debt Identification Exercise',
              description: 'Identificeer debt in sample codebase',
              duration: 30
            }
          ]
        },
        {
          title: 'Debt Impact Assessment',
          content: 'Hoe technical debt development velocity beïnvloedt...',
          duration: 90,
          difficulty: 'intermediate',
          practicalExercises: [
            {
              name: 'Impact Calculation',
              description: 'Bereken impact van verschillende debt types',
              duration: 45
            }
          ]
        },
        {
          title: 'Prevention Strategies',
          content: 'Hoe voorkom je technical debt tijdens development...',
          duration: 120,
          difficulty: 'advanced',
          practicalExercises: [
            {
              name: 'Prevention Implementation',
              description: 'Implementeer preventie strategieën',
              duration: 60
            }
          ]
        }
      ],
      assessments: [
        {
          name: 'Debt Knowledge Assessment',
          questions: 20,
          passingScore: 80
        }
      ],
      certifications: [
        {
          name: 'Technical Debt Management Certified',
          requirements: ['Complete all modules', 'Pass assessment', 'Complete practical exercises']
        }
      ],
      continuousLearning: [
        {
          name: 'Monthly Debt Review',
          frequency: 'monthly',
          content: 'Review van nieuwe debt patterns en best practices'
        }
      ]
    };
  }

  async educateTeam(team: Team): Promise<void> {
    for (const member of team.members) {
      await this.educateMember(member);
    }
  }

  private async educateMember(member: TeamMember): Promise<void> {
    console.log(`Educating team member: ${member.name}`);
    
    for (const module of this.educationProgram.modules) {
      await this.presentModule(member, module);
      await this.conductAssessment(member, module);
    }
    
    await this.issueCertification(member);
  }
}