📤 Export Types: Type-Only Exports

🎯 Introduction

Welcome to the publishing house of the TypeScript world! 📤 If import types were like subscribing to magazines for their information content only, then export types are like being the publisher who decides to distribute only the information pages, leaving out the heavy paper and glossy ads - pure content delivery with zero shipping weight!

Type-only exports are the flip side of type-only imports, allowing you to export type information without any runtime code. This creates cleaner module APIs, enables better tree-shaking, and is essential for building efficient TypeScript libraries. By carefully separating type exports from value exports, you can create modules that provide rich type information while maintaining minimal runtime footprints.

By the end of this tutorial, you’ll be a type-only export expert, capable of designing sophisticated module architectures that deliver maximum type safety with minimal bundle overhead. Let’s explore the art of efficient type distribution! 🌟

📚 Understanding Type-Only Exports

🤔 What Are Type-Only Exports?

Type-only exports allow you to export type information (interfaces, type aliases, type utilities) without exporting any runtime values. These exports are completely erased during compilation but provide full type information for consumers of your module.

// 🌟 Regular exports - include both types AND runtime values
export interface User {
  id: string;
  name: string;
}

export const createUser = (data: Partial<User>): User => {
  return { id: generateId(), name: data.name || 'Unknown', ...data };
};

export const validateUser = (user: User): boolean => {
  return user.id.length > 0 && user.name.length > 0;
};

// Bundle includes: User interface + createUser function + validateUser function

// 📤 Type-only exports - ONLY types, zero runtime code
export type { User } from './types/User';
export type { ApiResponse, ApiError } from './types/Api';

// Runtime exports separate
export { createUser, validateUser } from './services/UserService';

// Bundle includes: ONLY createUser function + validateUser function
// Types are available for TypeScript but don't add to bundle size!

// ✨ Mixed exports with clear separation
export type {
  // Type-only exports (zero runtime cost)
  User,
  UserRole,
  UserPreferences,
  CreateUserRequest,
  UpdateUserRequest
} from './types/User';

export {
  // Runtime exports (included in bundle)
  createUser,
  validateUser,
  UserService
} from './services/UserService';

// 🎯 This creates a clean API boundary between types and values

// 📦 Example: Publishing a TypeScript library
// Before type-only exports (everything bundled)
export interface LibraryConfig {
  apiKey: string;
  baseUrl?: string;
}

export interface LibraryResponse<T> {
  data: T;
  status: number;
}

export class LibraryClient {
  constructor(config: LibraryConfig) {}
  async request<T>(url: string): Promise<LibraryResponse<T>> {
    return {} as LibraryResponse<T>;
  }
}

export const DEFAULT_CONFIG: LibraryConfig = {
  apiKey: '',
  baseUrl: 'https://api.example.com'
};

// Bundle includes: LibraryClient class + DEFAULT_CONFIG object + interface metadata

// 📤 After type-only exports (optimized)
// types/index.ts
export type LibraryConfig = {
  apiKey: string;
  baseUrl?: string;
};

export type LibraryResponse<T> = {
  data: T;
  status: number;
};

// src/index.ts
export type { LibraryConfig, LibraryResponse } from './types';

export class LibraryClient {
  constructor(config: LibraryConfig) {}
  async request<T>(url: string): Promise<LibraryResponse<T>> {
    return {} as LibraryResponse<T>;
  }
}

export const DEFAULT_CONFIG: LibraryConfig = {
  apiKey: '',
  baseUrl: 'https://api.example.com'
};

// Bundle includes: ONLY LibraryClient class + DEFAULT_CONFIG object
// Types available for development but zero runtime cost!

// 🎮 Let's create a comprehensive type export management system
console.log('📤 Type-Only Export Examples');

// 🏗️ Type export analyzer and optimizer
class TypeExportAnalyzer {
  // 📊 Track export statistics
  private exportStats = {
    typeOnlyExports: 0,
    valueExports: 0,
    mixedExports: 0,
    reExports: 0,
    totalExports: 0
  };

  // 🗂️ Module export registry
  private moduleRegistry = new Map<string, {
    types: Set<string>;
    values: Set<string>;
    reExports: Set<string>;
    source: string;
  }>();

  // 🔍 Analyze export statement
  analyzeExport(
    exportStatement: string,
    modulePath: string
  ): {
    type: 'type-only' | 'value-only' | 'mixed' | 're-export';
    typeExports: string[];
    valueExports: string[];
    suggestions: string[];
    bundleImpact: number;
  } {
    console.log(`🔍 Analyzing export: ${exportStatement}`);

    const typeExports: string[] = [];
    const valueExports: string[] = [];
    const suggestions: string[] = [];
    let bundleImpact = 0;

    // 🎯 Parse export statement
    const analysis = this.parseExportStatement(exportStatement);
    
    // 📊 Classify exports
    analysis.exports.forEach(exp => {
      if (exp.isType) {
        typeExports.push(exp.name);
      } else {
        valueExports.push(exp.name);
        bundleImpact += this.estimateBundleImpact(exp.name, exp.kind);
      }
    });

    // 🏷️ Determine export type
    let exportType: 'type-only' | 'value-only' | 'mixed' | 're-export';
    
    if (analysis.isReExport) {
      exportType = 're-export';
      this.exportStats.reExports++;
    } else if (typeExports.length > 0 && valueExports.length === 0) {
      exportType = 'type-only';
      this.exportStats.typeOnlyExports++;
    } else if (valueExports.length > 0 && typeExports.length === 0) {
      exportType = 'value-only';
      this.exportStats.valueExports++;
    } else {
      exportType = 'mixed';
      this.exportStats.mixedExports++;
    }

    this.exportStats.totalExports++;

    // 💡 Generate suggestions
    if (exportType === 'mixed') {
      suggestions.push('Consider separating type and value exports for better optimization');
    }

    if (typeExports.length > 0 && !analysis.isTypeOnly) {
      suggestions.push('Use type-only exports for better tree-shaking');
    }

    if (bundleImpact > 10) {
      suggestions.push('Large bundle impact detected - consider lazy loading or code splitting');
    }

    // 🗂️ Update registry
    this.updateModuleRegistry(modulePath, typeExports, valueExports, analysis.isReExport);

    console.log(`📊 Export analysis complete: ${exportType}`);

    return {
      type: exportType,
      typeExports,
      valueExports,
      suggestions,
      bundleImpact
    };
  }

  // 🔍 Parse export statement
  private parseExportStatement(statement: string): {
    exports: Array<{
      name: string;
      isType: boolean;
      kind: 'interface' | 'type' | 'class' | 'function' | 'const' | 'enum';
    }>;
    isTypeOnly: boolean;
    isReExport: boolean;
    fromModule?: string;
  } {
    const exports: Array<any> = [];
    const isTypeOnly = statement.includes('export type');
    const isReExport = statement.includes('from ');

    // 📝 Extract from module if re-export
    let fromModule: string | undefined;
    const fromMatch = statement.match(/from\s+['"]([^'"]+)['"]/);
    if (fromMatch) {
      fromModule = fromMatch[1];
    }

    // 🔍 Extract exported names
    const exportMatch = statement.match(/export\s+(?:type\s+)?{([^}]+)}/);
    if (exportMatch) {
      const exportNames = exportMatch[1].split(',').map(name => name.trim());
      
      exportNames.forEach(name => {
        const isTypeExport = name.startsWith('type ') || isTypeOnly;
        const cleanName = name.replace('type ', '');
        
        exports.push({
          name: cleanName,
          isType: isTypeExport,
          kind: this.inferExportKind(cleanName, isTypeExport)
        });
      });
    }

    // 🔍 Handle inline exports
    const inlineExports = [
      { pattern: /export\s+interface\s+(\w+)/, kind: 'interface', isType: true },
      { pattern: /export\s+type\s+(\w+)/, kind: 'type', isType: true },
      { pattern: /export\s+class\s+(\w+)/, kind: 'class', isType: false },
      { pattern: /export\s+function\s+(\w+)/, kind: 'function', isType: false },
      { pattern: /export\s+const\s+(\w+)/, kind: 'const', isType: false },
      { pattern: /export\s+enum\s+(\w+)/, kind: 'enum', isType: false }
    ];

    inlineExports.forEach(({ pattern, kind, isType }) => {
      const match = statement.match(pattern);
      if (match) {
        exports.push({
          name: match[1],
          isType,
          kind
        });
      }
    });

    return {
      exports,
      isTypeOnly,
      isReExport,
      fromModule
    };
  }

  // 🎯 Infer export kind from name
  private inferExportKind(name: string, isType: boolean): string {
    if (isType) {
      if (name.endsWith('Interface') || /^I[A-Z]/.test(name)) {
        return 'interface';
      }
      return 'type';
    }

    // 🔍 Value export heuristics
    if (/^[A-Z]/.test(name) && !name.includes('_')) {
      return 'class';
    }
    
    if (name.includes('_') && name === name.toUpperCase()) {
      return 'const';
    }

    if (/^[a-z]/.test(name)) {
      return 'function';
    }

    return 'const';
  }

  // 📊 Estimate bundle impact
  private estimateBundleImpact(name: string, kind: string): number {
    // 🎯 Rough estimates in KB
    const impactMap: Record<string, number> = {
      'class': 5,
      'function': 2,
      'const': 0.5,
      'enum': 1,
      'interface': 0, // No runtime impact
      'type': 0      // No runtime impact
    };

    return impactMap[kind] || 1;
  }

  // 🗂️ Update module registry
  private updateModuleRegistry(
    modulePath: string,
    typeExports: string[],
    valueExports: string[],
    isReExport: boolean
  ): void {
    if (!this.moduleRegistry.has(modulePath)) {
      this.moduleRegistry.set(modulePath, {
        types: new Set(),
        values: new Set(),
        reExports: new Set(),
        source: modulePath
      });
    }

    const moduleData = this.moduleRegistry.get(modulePath)!;
    
    typeExports.forEach(exp => moduleData.types.add(exp));
    valueExports.forEach(exp => moduleData.values.add(exp));
    
    if (isReExport) {
      [...typeExports, ...valueExports].forEach(exp => 
        moduleData.reExports.add(exp)
      );
    }
  }

  // 🏗️ Generate optimized export structure
  generateOptimizedExports(modulePath: string): {
    typeOnlyExports: string[];
    valueOnlyExports: string[];
    reExports: string[];
    bundleSizeReduction: number;
  } {
    console.log(`🏗️ Generating optimized exports for: ${modulePath}`);

    const moduleData = this.moduleRegistry.get(modulePath);
    if (!moduleData) {
      return {
        typeOnlyExports: [],
        valueOnlyExports: [],
        reExports: [],
        bundleSizeReduction: 0
      };
    }

    const typeOnlyExports: string[] = [];
    const valueOnlyExports: string[] = [];
    const reExports: string[] = [];

    // 📤 Generate type-only exports
    if (moduleData.types.size > 0) {
      const typeNames = Array.from(moduleData.types).join(', ');
      typeOnlyExports.push(`export type { ${typeNames} } from './types';`);
    }

    // 📦 Generate value exports
    if (moduleData.values.size > 0) {
      const valueNames = Array.from(moduleData.values).join(', ');
      valueOnlyExports.push(`export { ${valueNames} } from './implementation';`);
    }

    // 🔄 Generate re-exports
    if (moduleData.reExports.size > 0) {
      const reExportNames = Array.from(moduleData.reExports).join(', ');
      reExports.push(`export { ${reExportNames} } from './external';`);
    }

    // 📊 Calculate bundle size reduction
    const bundleSizeReduction = moduleData.types.size * 0.1; // Estimated savings

    console.log(`✅ Generated optimized exports with ${bundleSizeReduction}KB estimated savings`);

    return {
      typeOnlyExports,
      valueOnlyExports,
      reExports,
      bundleSizeReduction
    };
  }

  // 📊 Generate comprehensive export report
  generateExportReport(): {
    summary: string;
    statistics: typeof this.exportStats;
    moduleBreakdown: Array<{
      module: string;
      typeCount: number;
      valueCount: number;
      reExportCount: number;
      totalCount: number;
    }>;
    recommendations: string[];
    potentialSavings: number;
  } {
    const recommendations: string[] = [];
    let potentialSavings = 0;

    // 📈 Analyze statistics
    const typeOnlyRatio = this.exportStats.typeOnlyExports / this.exportStats.totalExports;
    const mixedExportRatio = this.exportStats.mixedExports / this.exportStats.totalExports;

    if (typeOnlyRatio < 0.3) {
      recommendations.push('Low usage of type-only exports - consider optimization');
    }

    if (mixedExportRatio > 0.4) {
      recommendations.push('High number of mixed exports - separate types and values');
      potentialSavings += this.exportStats.mixedExports * 0.2;
    }

    // 🗂️ Module breakdown
    const moduleBreakdown: Array<any> = [];
    
    for (const [module, data] of this.moduleRegistry) {
      const breakdown = {
        module,
        typeCount: data.types.size,
        valueCount: data.values.size,
        reExportCount: data.reExports.size,
        totalCount: data.types.size + data.values.size
      };

      moduleBreakdown.push(breakdown);

      // 💡 Module-specific recommendations
      if (breakdown.typeCount > breakdown.valueCount * 2) {
        recommendations.push(`${module} exports mostly types - optimize structure`);
        potentialSavings += breakdown.typeCount * 0.05;
      }
    }

    const summary = `Analyzed ${this.exportStats.totalExports} exports across ${this.moduleRegistry.size} modules`;

    return {
      summary,
      statistics: { ...this.exportStats },
      moduleBreakdown,
      recommendations,
      potentialSavings: Math.round(potentialSavings * 100) / 100
    };
  }

  // 🧹 Reset analyzer
  reset(): void {
    this.exportStats = {
      typeOnlyExports: 0,
      valueExports: 0,
      mixedExports: 0,
      reExports: 0,
      totalExports: 0
    };
    this.moduleRegistry.clear();
    
    console.log('🧹 Export analyzer reset');
  }
}

// 🎮 Usage examples
const typeExportDemo = (): void => {
  const analyzer = new TypeExportAnalyzer();

  // 🔍 Analyze different export patterns
  const exports = [
    "export interface User { id: string; name: string; }",
    "export type { User, UserRole } from './types';",
    "export { createUser, validateUser } from './services';",
    "export { UserService, type User, type UserRole } from './module';",
    "export type UserConfig = { apiKey: string; };"
  ];

  exports.forEach((exportStatement, index) => {
    const analysis = analyzer.analyzeExport(exportStatement, `./module${index}`);
    console.log(`📊 Analysis ${index + 1}:`, analysis);
  });

  // 🏗️ Generate optimized exports
  const optimized = analyzer.generateOptimizedExports('./module0');
  console.log('🏗️ Optimized Exports:', optimized);

  // 📊 Generate comprehensive report
  const report = analyzer.generateExportReport();
  console.log('📊 Export Report:', report);
};

// 🎯 Advanced type export patterns
interface TypeExportStrategy {
  // 📂 Organization strategy
  separateTypeModules: boolean;     // Keep types in separate modules
  useBarrelExports: boolean;        // Use barrel exports for organization
  groupByFeature: boolean;          // Group exports by feature
  
  // 🔧 Export optimization
  preferTypeOnlyExports: boolean;   // Prefer type-only exports
  minimizeReExports: boolean;       // Minimize re-export chains
  optimizeForTreeShaking: boolean;  // Optimize for tree-shaking
  
  // 📊 Bundle optimization
  trackBundleImpact: boolean;       // Track bundle size impact
  generateTypeMaps: boolean;        // Generate type-only modules
  analyzeUsage: boolean;            // Analyze export usage patterns
}

// 🏗️ Smart type export manager
class SmartTypeExportManager {
  private strategy: TypeExportStrategy;
  private exportUsage = new Map<string, {
    module: string;
    exported: number;
    imported: number;
    lastUsed: Date;
  }>();

  constructor(strategy: TypeExportStrategy) {
    this.strategy = strategy;
  }

  // 🎯 Generate optimal module structure
  generateModuleStructure(
    exports: Array<{
      name: string;
      type: 'interface' | 'type' | 'class' | 'function' | 'const';
      isType: boolean;
      dependencies: string[];
      category: string;
    }>
  ): {
    typeModules: Map<string, string[]>;
    valueModules: Map<string, string[]>;
    barrelExports: string[];
    structure: string;
  } {
    console.log('🎯 Generating optimal module structure...');

    const typeModules = new Map<string, string[]>();
    const valueModules = new Map<string, string[]>();
    const barrelExports: string[] = [];

    // 📂 Group exports by category if enabled
    if (this.strategy.groupByFeature) {
      const categories = new Set(exports.map(exp => exp.category));
      
      categories.forEach(category => {
        const categoryExports = exports.filter(exp => exp.category === category);
        
        // 📝 Separate types and values
        const types = categoryExports.filter(exp => exp.isType);
        const values = categoryExports.filter(exp => !exp.isType);

        if (types.length > 0) {
          typeModules.set(`${category}/types`, types.map(t => t.name));
        }

        if (values.length > 0) {
          valueModules.set(`${category}/implementation`, values.map(v => v.name));
        }
      });
    }

    // 🏪 Generate barrel exports if enabled
    if (this.strategy.useBarrelExports) {
      // 📤 Type-only barrel
      if (typeModules.size > 0) {
        barrelExports.push('// Type-only exports');
        for (const [module, exports] of typeModules) {
          barrelExports.push(`export type { ${exports.join(', ')} } from './${module}';`);
        }
        barrelExports.push('');
      }

      // 📦 Value exports barrel
      if (valueModules.size > 0) {
        barrelExports.push('// Value exports');
        for (const [module, exports] of valueModules) {
          barrelExports.push(`export { ${exports.join(', ')} } from './${module}';`);
        }
      }
    }

    // 🏗️ Generate structure documentation
    const structure = this.generateStructureDocumentation(typeModules, valueModules);

    console.log(`✅ Generated structure with ${typeModules.size} type modules and ${valueModules.size} value modules`);

    return {
      typeModules,
      valueModules,
      barrelExports,
      structure
    };
  }

  // 📚 Generate structure documentation
  private generateStructureDocumentation(
    typeModules: Map<string, string[]>,
    valueModules: Map<string, string[]>
  ): string {
    let doc = '# 📤 Module Export Structure\n\n';
    
    doc += '## 📁 Directory Structure\n\n';
    doc += '```\n';
    doc += 'src/\n';
    doc += '├── index.ts          # Main barrel export\n';
    
    // 📝 Document type modules
    if (typeModules.size > 0) {
      doc += '├── types/\n';
      for (const [module] of typeModules) {
        doc += `│   ├── ${module.split('/').pop()}.ts\n`;
      }
    }

    // 📦 Document value modules
    if (valueModules.size > 0) {
      doc += '├── implementation/\n';
      for (const [module] of valueModules) {
        doc += `│   ├── ${module.split('/').pop()}.ts\n`;
      }
    }

    doc += '```\n\n';

    // 📊 Export statistics
    doc += '## 📊 Export Statistics\n\n';
    doc += `- Type modules: ${typeModules.size}\n`;
    doc += `- Value modules: ${valueModules.size}\n`;
    doc += `- Total exports: ${Array.from(typeModules.values()).flat().length + Array.from(valueModules.values()).flat().length}\n\n`;

    return doc;
  }

  // 🔧 Optimize export statements
  optimizeExportStatements(
    statements: string[]
  ): {
    optimized: string[];
    bundleReduction: number;
    recommendations: string[];
  } {
    console.log('🔧 Optimizing export statements...');

    const optimized: string[] = [];
    const recommendations: string[] = [];
    let bundleReduction = 0;

    statements.forEach(statement => {
      const { optimizedStatement, reduction, suggestion } = this.optimizeSingleStatement(statement);
      
      optimized.push(optimizedStatement);
      bundleReduction += reduction;
      
      if (suggestion) {
        recommendations.push(suggestion);
      }
    });

    console.log(`✅ Optimization complete with ${bundleReduction}KB estimated reduction`);

    return {
      optimized,
      bundleReduction,
      recommendations
    };
  }

  // 🔧 Optimize single export statement
  private optimizeSingleStatement(statement: string): {
    optimizedStatement: string;
    reduction: number;
    suggestion?: string;
  } {
    let optimizedStatement = statement;
    let reduction = 0;
    let suggestion: string | undefined;

    // 🎯 Convert mixed exports to separate type/value exports
    if (statement.includes('export {') && !statement.includes('export type {')) {
      const hasTypes = this.detectTypesInExport(statement);
      
      if (hasTypes.types.length > 0 && hasTypes.values.length > 0) {
        // 📝 Separate the exports
        const typeExport = `export type { ${hasTypes.types.join(', ')} } from '${hasTypes.fromModule}';`;
        const valueExport = `export { ${hasTypes.values.join(', ')} } from '${hasTypes.fromModule}';`;
        
        optimizedStatement = `${typeExport}\n${valueExport}`;
        reduction = hasTypes.types.length * 0.1; // Estimated savings
        suggestion = 'Separated type and value exports for better tree-shaking';
      }
    }

    // 🎯 Convert to type-only if all exports are types
    if (!statement.includes('export type') && this.isAllTypesExport(statement)) {
      optimizedStatement = statement.replace('export {', 'export type {');
      reduction = this.countExports(statement) * 0.05;
      suggestion = 'Converted to type-only export';
    }

    return {
      optimizedStatement,
      reduction,
      suggestion
    };
  }

  // 🔍 Detect types in export statement
  private detectTypesInExport(statement: string): {
    types: string[];
    values: string[];
    fromModule: string;
  } {
    const types: string[] = [];
    const values: string[] = [];
    let fromModule = '';

    // 📝 Extract from module
    const fromMatch = statement.match(/from\s+['"]([^'"]+)['"]/);
    if (fromMatch) {
      fromModule = fromMatch[1];
    }

    // 🔍 Extract export names
    const exportMatch = statement.match(/export\s+{([^}]+)}/);
    if (exportMatch) {
      const exportNames = exportMatch[1].split(',').map(name => name.trim());
      
      exportNames.forEach(name => {
        // 🤔 Heuristic: PascalCase names are likely types
        if (/^[A-Z]/.test(name) && !name.includes('Service') && !name.includes('Manager')) {
          types.push(name);
        } else {
          values.push(name);
        }
      });
    }

    return { types, values, fromModule };
  }

  // 🔍 Check if export contains only types
  private isAllTypesExport(statement: string): boolean {
    const { types, values } = this.detectTypesInExport(statement);
    return types.length > 0 && values.length === 0;
  }

  // 🔢 Count exports in statement
  private countExports(statement: string): number {
    const exportMatch = statement.match(/export\s+{([^}]+)}/);
    if (exportMatch) {
      return exportMatch[1].split(',').length;
    }
    return 0;
  }

  // 📊 Track export usage
  trackExportUsage(
    exportName: string,
    module: string,
    action: 'exported' | 'imported'
  ): void {
    if (!this.strategy.analyzeUsage) return;

    const key = `${module}:${exportName}`;
    const current = this.exportUsage.get(key) || {
      module,
      exported: 0,
      imported: 0,
      lastUsed: new Date()
    };

    if (action === 'exported') {
      current.exported++;
    } else {
      current.imported++;
    }

    current.lastUsed = new Date();
    this.exportUsage.set(key, current);
  }

  // 🔍 Find unused exports
  findUnusedExports(): Array<{
    module: string;
    exportName: string;
    timeSinceLastImport: number;
    exportCount: number;
  }> {
    const unused: Array<any> = [];
    const now = new Date();

    this.exportUsage.forEach((usage, key) => {
      if (usage.imported === 0 && usage.exported > 0) {
        const [module, exportName] = key.split(':');
        const timeSinceLastImport = now.getTime() - usage.lastUsed.getTime();
        
        unused.push({
          module,
          exportName,
          timeSinceLastImport: Math.floor(timeSinceLastImport / (1000 * 60 * 60 * 24)), // Days
          exportCount: usage.exported
        });
      }
    });

    return unused.sort((a, b) => b.timeSinceLastImport - a.timeSinceLastImport);
  }

  // 📊 Generate usage report
  generateUsageReport(): {
    totalExports: number;
    usedExports: number;
    unusedExports: number;
    mostUsedExports: Array<{ name: string; module: string; imports: number }>;
    recommendations: string[];
  } {
    let totalExports = 0;
    let usedExports = 0;
    let unusedExports = 0;
    const mostUsed: Array<any> = [];
    const recommendations: string[] = [];

    this.exportUsage.forEach((usage, key) => {
      totalExports++;
      
      if (usage.imported > 0) {
        usedExports++;
        const [module, name] = key.split(':');
        mostUsed.push({ name, module, imports: usage.imported });
      } else {
        unusedExports++;
      }
    });

    // 🔝 Sort most used
    mostUsed.sort((a, b) => b.imports - a.imports);

    // 💡 Generate recommendations
    if (unusedExports > totalExports * 0.2) {
      recommendations.push('High number of unused exports - consider removing them');
    }

    if (usedExports > 0) {
      recommendations.push('Focus optimization efforts on most-used exports');
    }

    return {
      totalExports,
      usedExports,
      unusedExports,
      mostUsedExports: mostUsed.slice(0, 10),
      recommendations
    };
  }
}

// 🎮 Advanced usage example
const advancedTypeExportDemo = (): void => {
  const strategy: TypeExportStrategy = {
    separateTypeModules: true,
    useBarrelExports: true,
    groupByFeature: true,
    preferTypeOnlyExports: true,
    minimizeReExports: true,
    optimizeForTreeShaking: true,
    trackBundleImpact: true,
    generateTypeMaps: true,
    analyzeUsage: true
  };

  const manager = new SmartTypeExportManager(strategy);

  // 🎯 Generate optimal structure
  const sampleExports = [
    { name: 'User', type: 'interface' as const, isType: true, dependencies: [], category: 'user' },
    { name: 'UserService', type: 'class' as const, isType: false, dependencies: ['User'], category: 'user' },
    { name: 'ApiResponse', type: 'type' as const, isType: true, dependencies: [], category: 'api' },
    { name: 'ApiClient', type: 'class' as const, isType: false, dependencies: ['ApiResponse'], category: 'api' }
  ];

  const structure = manager.generateModuleStructure(sampleExports);
  console.log('🎯 Generated Structure:', structure);

  // 🔧 Optimize export statements
  const statements = [
    "export { User, UserService, validateUser } from './user';",
    "export { ApiResponse, ApiClient, fetchData } from './api';",
    "export interface Config { apiKey: string; }"
  ];

  const optimization = manager.optimizeExportStatements(statements);
  console.log('🔧 Optimization Results:', optimization);

  // 📊 Track usage and generate report
  manager.trackExportUsage('User', './types/user', 'exported');
  manager.trackExportUsage('User', './types/user', 'imported');
  manager.trackExportUsage('UserService', './services/user', 'exported');

  const usageReport = manager.generateUsageReport();
  console.log('📊 Usage Report:', usageReport);

  // 🔍 Find unused exports
  const unusedExports = manager.findUnusedExports();
  console.log('🔍 Unused Exports:', unusedExports);
};

// 🎯 Execute demonstrations
typeExportDemo();
advancedTypeExportDemo();

💡 Common Type-Only Export Patterns

Let’s explore the most effective patterns for implementing type-only exports:

// 🌟 Pattern 1: Pure Type Module Architecture
// Organize types in dedicated modules with clean separation

// 📁 types/User.ts - Pure type module
export interface User {
  id: string;
  name: string;
  email: string;
  role: UserRole;
  preferences: UserPreferences;
}

export interface UserRole {
  id: string;
  name: string;
  permissions: Permission[];
}

export interface UserPreferences {
  theme: 'light' | 'dark' | 'auto';
  language: string;
  notifications: NotificationSettings;
}

export interface Permission {
  resource: string;
  actions: string[];
}

export interface NotificationSettings {
  email: boolean;
  push: boolean;
  inApp: boolean;
}

// Type utilities
export type CreateUserRequest = Omit<User, 'id'>;
export type UpdateUserRequest = Partial<Pick<User, 'name' | 'email' | 'preferences'>>;
export type UserWithoutSensitiveData = Omit<User, 'email' | 'role'>;

// 📁 services/UserService.ts - Implementation module
import type { 
  User, 
  UserRole, 
  CreateUserRequest, 
  UpdateUserRequest 
} from '../types/User';

export class UserService {
  async createUser(request: CreateUserRequest): Promise<User> {
    // Implementation
    return {} as User;
  }

  async updateUser(id: string, request: UpdateUserRequest): Promise<User> {
    // Implementation
    return {} as User;
  }

  async getUserRole(userId: string): Promise<UserRole> {
    // Implementation
    return {} as UserRole;
  }
}

export const validateUser = (user: User): boolean => {
  return user.id.length > 0 && user.email.includes('@');
};

// 📁 index.ts - Main export with clean separation
// Type-only exports (zero bundle impact)
export type {
  User,
  UserRole,
  UserPreferences,
  Permission,
  NotificationSettings,
  CreateUserRequest,
  UpdateUserRequest,
  UserWithoutSensitiveData
} from './types/User';

// Value exports (runtime code)
export { UserService, validateUser } from './services/UserService';

// 🌟 Pattern 2: Feature-Based Type Organization
// Group types by business domain or feature

// 📁 features/auth/types.ts
export interface AuthState {
  isAuthenticated: boolean;
  user: User | null;
  token: string | null;
  refreshToken: string | null;
}

export interface LoginCredentials {
  email: string;
  password: string;
  rememberMe?: boolean;
}

export interface RegisterData {
  name: string;
  email: string;
  password: string;
  confirmPassword: string;
}

export interface AuthConfig {
  apiUrl: string;
  tokenStorage: 'localStorage' | 'sessionStorage' | 'memory';
  autoRefresh: boolean;
  refreshThreshold: number;
}

// Auth-specific type utilities
export type AuthActionType = 
  | 'LOGIN_START'
  | 'LOGIN_SUCCESS' 
  | 'LOGIN_FAILURE'
  | 'LOGOUT'
  | 'REFRESH_TOKEN'
  | 'UPDATE_USER';

export type AuthAction<T = any> = {
  type: AuthActionType;
  payload?: T;
};

// 📁 features/auth/index.ts
// Export types separately from implementation
export type {
  AuthState,
  LoginCredentials,
  RegisterData,
  AuthConfig,
  AuthActionType,
  AuthAction
} from './types';

// Export implementation
export { AuthService } from './AuthService';
export { AuthProvider, useAuth } from './AuthProvider';
export { authReducer } from './authReducer';

// 🌟 Pattern 3: Library Type Distribution
// Efficient type distribution for TypeScript libraries

// 📁 lib/types/index.ts - Library type definitions
export interface LibraryConfig {
  apiKey: string;
  baseUrl?: string;
  timeout?: number;
  retryAttempts?: number;
  debug?: boolean;
}

export interface LibraryOptions {
  autoRetry: boolean;
  cacheResponses: boolean;
  validateResponses: boolean;
}

export interface LibraryResponse<T = any> {
  data: T;
  status: number;
  statusText: string;
  headers: Record<string, string>;
}

export interface LibraryError {
  code: string;
  message: string;
  status?: number;
  details?: Record<string, any>;
}

// Generic type utilities
export type ApiResult<T> = LibraryResponse<T> | LibraryError;
export type RequestMethod = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH';
export type RequestConfig<T = any> = {
  method: RequestMethod;
  url: string;
  data?: T;
  headers?: Record<string, string>;
  params?: Record<string, any>;
};

// 📁 lib/index.ts - Main library export
// Type-only exports (available to consumers with zero runtime cost)
export type {
  LibraryConfig,
  LibraryOptions,
  LibraryResponse,
  LibraryError,
  ApiResult,
  RequestMethod,
  RequestConfig
} from './types';

// Runtime exports (actual library functionality)
export { LibraryClient } from './LibraryClient';
export { createLibrary } from './factory';
export { isLibraryError, isLibraryResponse } from './guards';

// 📁 Usage in consumer application
import type { LibraryConfig, LibraryResponse } from 'my-library';
import { createLibrary } from 'my-library';

// Types available for development, but no runtime code imported!

// 🌟 Pattern 4: Conditional Type Exports
// Export different types based on build configuration

// 📁 types/conditional.ts
// Base types always available
export interface BaseConfig {
  apiUrl: string;
  version: string;
}

export interface ProductionConfig extends BaseConfig {
  optimizations: OptimizationSettings;
  monitoring: MonitoringConfig;
}

// Development-only types (tree-shaken in production)
export interface DevelopmentConfig extends BaseConfig {
  debugMode: boolean;
  devTools: DevToolsConfig;
  hotReload: HotReloadConfig;
}

export interface DevToolsConfig {
  enabled: boolean;
  logLevel: 'debug' | 'info' | 'warn' | 'error';
  showPerformanceMetrics: boolean;
}

export interface HotReloadConfig {
  enabled: boolean;
  watchPaths: string[];
  excludePatterns: string[];
}

// Test-only types (tree-shaken in production)
export interface TestConfig extends BaseConfig {
  testMode: boolean;
  mockData: boolean;
  testHelpers: TestHelpersConfig;
}

export interface TestHelpersConfig {
  autoMock: boolean;
  seedData: boolean;
  resetBetweenTests: boolean;
}

// Conditional type exports based on environment
export type AppConfig = 
  typeof process.env.NODE_ENV extends 'development' 
    ? DevelopmentConfig
    : typeof process.env.NODE_ENV extends 'test'
    ? TestConfig
    : ProductionConfig;

// 📁 config/index.ts
// Base exports always available
export type { BaseConfig, ProductionConfig, AppConfig } from '../types/conditional';

// Conditional exports based on environment
if (process.env.NODE_ENV === 'development') {
  export type { 
    DevelopmentConfig, 
    DevToolsConfig, 
    HotReloadConfig 
  } from '../types/conditional';
}

if (process.env.NODE_ENV === 'test') {
  export type { 
    TestConfig, 
    TestHelpersConfig 
  } from '../types/conditional';
}

// 🌟 Pattern 5: Namespace-Based Type Exports
// Organize related types under namespaces

// 📁 types/namespaced.ts
export namespace API {
  export interface Request<T = any> {
    method: string;
    url: string;
    data?: T;
    headers?: Record<string, string>;
  }

  export interface Response<T = any> {
    data: T;
    status: number;
    headers: Record<string, string>;
  }

  export interface Error {
    code: string;
    message: string;
    status: number;
  }

  export namespace Auth {
    export interface LoginRequest {
      email: string;
      password: string;
    }

    export interface LoginResponse {
      token: string;
      user: User.Profile;
    }

    export interface RefreshRequest {
      refreshToken: string;
    }
  }
}

export namespace User {
  export interface Profile {
    id: string;
    name: string;
    email: string;
    avatar?: string;
  }

  export interface Preferences {
    theme: 'light' | 'dark';
    language: string;
    timezone: string;
  }

  export interface Settings {
    notifications: NotificationSettings;
    privacy: PrivacySettings;
    security: SecuritySettings;
  }

  export interface NotificationSettings {
    email: boolean;
    push: boolean;
    sms: boolean;
  }

  export interface PrivacySettings {
    profileVisibility: 'public' | 'private' | 'friends';
    showEmail: boolean;
    showActivity: boolean;
  }

  export interface SecuritySettings {
    twoFactorEnabled: boolean;
    sessionTimeout: number;
    allowedDevices: Device[];
  }

  export interface Device {
    id: string;
    name: string;
    type: 'mobile' | 'desktop' | 'tablet';
    lastUsed: Date;
  }
}

// 📁 Export namespaces as types
export type { API, User } from './types/namespaced';

// Usage: Clean, organized type access
// import type { API, User } from 'my-library';
// const request: API.Request = { ... };
// const profile: User.Profile = { ... };

// 🌟 Pattern 6: Build-Time Type Optimization
// Optimize type exports for different build targets

// 📁 build/types-builder.ts
class TypesBuilder {
  // 🎯 Generate optimized type exports for different targets
  static generateTypeExports(
    target: 'browser' | 'node' | 'universal',
    environment: 'development' | 'production'
  ): string {
    let exports = '';

    // 🌐 Universal types (always included)
    exports += 'export type { BaseConfig, ApiResponse } from "./core";\n';

    // 🌍 Environment-specific types
    if (environment === 'development') {
      exports += 'export type { DevConfig, DebugInfo } from "./dev";\n';
    }

    // 🎯 Target-specific types
    switch (target) {
      case 'browser':
        exports += 'export type { BrowserConfig, DOMEvents } from "./browser";\n';
        break;
      
      case 'node':
        exports += 'export type { NodeConfig, ProcessEnv } from "./node";\n';
        break;
      
      case 'universal':
        exports += 'export type { UniversalConfig } from "./universal";\n';
        break;
    }

    return exports;
  }

  // 📦 Generate package-specific type exports
  static generatePackageTypes(
    packageName: string,
    version: string,
    exports: string[]
  ): string {
    let content = `// Generated types for ${packageName}@${version}\n`;
    content += `// This file contains type-only exports with zero runtime cost\n\n`;

    // 📝 Group exports by category
    const typeExports = exports.filter(exp => exp.includes('type'));
    const interfaceExports = exports.filter(exp => exp.includes('interface'));
    const utilityExports = exports.filter(exp => exp.includes('utility'));

    if (typeExports.length > 0) {
      content += '// Type aliases\n';
      typeExports.forEach(exp => content += `${exp}\n`);
      content += '\n';
    }

    if (interfaceExports.length > 0) {
      content += '// Interfaces\n';
      interfaceExports.forEach(exp => content += `${exp}\n`);
      content += '\n';
    }

    if (utilityExports.length > 0) {
      content += '// Utility types\n';
      utilityExports.forEach(exp => content += `${exp}\n`);
      content += '\n';
    }

    return content;
  }
}

// 🌟 Pattern 7: Micro-Frontend Type Sharing
// Share types across micro-frontends efficiently

// 📁 shared-types/src/index.ts
// Central type registry for micro-frontends
export type { User, UserRole, UserPreferences } from './user';
export type { Product, ProductCategory, ProductVariant } from './product';
export type { Order, OrderItem, OrderStatus } from './order';
export type { Payment, PaymentMethod, PaymentStatus } from './payment';

// Common utilities available to all micro-frontends
export type { ApiResponse, ApiError, PaginatedResponse } from './api';
export type { AppConfig, FeatureFlags, ThemeConfig } from './config';

// Event types for micro-frontend communication
export type { 
  MicroFrontendEvent, 
  UserEvent, 
  NavigationEvent, 
  DataEvent 
} from './events';

// 📁 Package configuration for optimal sharing
// package.json
{
  "name": "@company/shared-types",
  "version": "1.0.0",
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "sideEffects": false,  // Critical for tree-shaking
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/index.mjs",
      "require": "./dist/index.js"
    },
    "./user": {
      "types": "./dist/user.d.ts"
    },
    "./product": {
      "types": "./dist/product.d.ts"
    }
  }
}

// Usage in micro-frontends (zero runtime dependency!)
// Micro-frontend A
import type { User, ApiResponse } from '@company/shared-types';

// Micro-frontend B  
import type { Product, Order } from '@company/shared-types';

// 🌟 Pattern 8: Progressive Type Loading
// Load types progressively based on feature usage

// 📁 types/progressive.ts
// Core types always loaded
export interface CoreTypes {
  User: {
    id: string;
    name: string;
  };
  
  Config: {
    apiUrl: string;
  };
}

// Feature-specific types loaded on demand
export interface AdvancedUserTypes {
  UserWithAnalytics: CoreTypes['User'] & {
    analytics: UserAnalytics;
    behaviorData: BehaviorData;
  };
  
  UserAnalytics: {
    pageViews: number;
    sessionDuration: number;
    conversionRate: number;
  };

  BehaviorData: {
    clickHeatmap: ClickData[];
    scrollDepth: number;
    timeOnPage: number;
  };
}

// 📁 Progressive type loader
class ProgressiveTypeLoader {
  private static loadedTypes = new Set<string>();

  // 🎯 Load types based on feature usage
  static async loadFeatureTypes(feature: string): Promise<void> {
    if (this.loadedTypes.has(feature)) {
      return; // Already loaded
    }

    try {
      switch (feature) {
        case 'analytics':
          // Types are loaded but don't affect bundle
          await import('./advanced-analytics-types');
          break;
        
        case 'ecommerce':
          await import('./ecommerce-types');
          break;
          
        case 'admin':
          await import('./admin-types');
          break;
      }
      
      this.loadedTypes.add(feature);
      console.log(`✅ Loaded types for feature: ${feature}`);
      
    } catch (error) {
      console.error(`❌ Failed to load types for feature: ${feature}`, error);
    }
  }

  // 📊 Check if feature types are available
  static hasFeatureTypes(feature: string): boolean {
    return this.loadedTypes.has(feature);
  }
}

// Usage: Types loaded progressively as features are used
// When user enables analytics feature:
await ProgressiveTypeLoader.loadFeatureTypes('analytics');
// Now analytics types are available for development

🎉 Conclusion

Congratulations! You’ve mastered the art of type-only exports! 📤

🎯 What You’ve Learned

• 📤 Type-Only Export Syntax: Using export type for zero-cost type distribution
• 🏗️ Module Architecture: Designing clean separation between types and runtime code
• 📦 Bundle Optimization: Eliminating unnecessary type overhead from bundles
• 🔧 Advanced Patterns: Sophisticated strategies for organizing and distributing types
• 📊 Performance Analysis: Tools for measuring and optimizing export efficiency

🚀 Key Benefits

• 📉 Smaller Bundles: Zero runtime cost for type information
• 🎯 Cleaner APIs: Clear separation between types and implementation
• ⚡ Better Performance: Optimized builds with efficient tree-shaking
• 📚 Improved DX: Rich type information without runtime overhead
• 🔧 Library Optimization: Perfect for creating efficient TypeScript libraries

🔥 Best Practices Recap

1. 📤 Separate Types from Values: Use type-only exports for pure type information
2. 🏗️ Organize by Purpose: Create dedicated type modules for better structure
3. 📦 Optimize for Tree-Shaking: Ensure your exports enable optimal bundling
4. 📊 Monitor Bundle Impact: Track the effect of your export strategies
5. 🎯 Design for Consumers: Think about how your types will be used

You’re now equipped to create highly optimized TypeScript modules that provide rich type information while maintaining minimal runtime footprints - the perfect balance of developer experience and performance! 🌟

Happy coding, and may your types always be exported efficiently! 📤✨