TypeScriptのメソッドデコレーターを使った関数のアクセス制御方法

function Logging(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
  const originalMethod = descriptor.value;
  descriptor.value = function (...args: any[]) {
    console.log(`Method ${propertyKey} called with args:`, args);
    return originalMethod.apply(this, args);
  };
  return descriptor;
}

function AdminOnly(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
  const originalMethod = descriptor.value;

  descriptor.value = function (...args: any[]) {
    if (!this.isAdmin) {
      throw new Error("Access Denied: Admins only");
    }
    return originalMethod.apply(this, args);
  };

  return descriptor;
}

class UserService {
  public isAdmin: boolean;

  constructor(isAdmin: boolean) {
    this.isAdmin = isAdmin;
  }

  @AdminOnly
  deleteUser(userId: number) {
    console.log(`User with ID ${userId} has been deleted.`);
  }
}

// Usage example
const adminUser = new UserService(true);
adminUser.deleteUser(123); // 実行成功

const regularUser = new UserService(false);
regularUser.deleteUser(123); // エラー: "Access Denied: Admins only"

function RoleCheck(allowedRoles: string[]) {
  return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;

    descriptor.value = function (...args: any[]) {
      if (!allowedRoles.includes(this.role)) {
        throw new Error(`Access Denied: ${this.role} does not have permission to execute ${propertyKey}`);
      }
      return originalMethod.apply(this, args);
    };

    return descriptor;
  };
}

class DocumentService {
  public role: string;

  constructor(role: string) {
    this.role = role;
  }

  @RoleCheck(['Admin', 'Editor'])
  updateDocument(docId: number, content: string) {
    console.log(`Document ${docId} updated with content: ${content}`);
  }

  @RoleCheck(['Admin'])
  deleteDocument(docId: number) {
    console.log(`Document ${docId} has been deleted.`);
  }
}

// Usage example
const editorUser = new DocumentService('Editor');
editorUser.updateDocument(101, 'New content');  // 実行成功

const regularUser = new DocumentService('Viewer');
regularUser.updateDocument(101, 'New content');  // エラー: "Access Denied: Viewer does not have permission to execute updateDocument"

const adminUser = new DocumentService('Admin');
adminUser.deleteDocument(102);  // 実行成功

function RequireRole(roles: string[]) {
  return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;

    descriptor.value = function (...args: any[]) {
      if (!roles.includes(this.role)) {
        throw new Error(`Access Denied: ${this.role} does not have permission to access ${propertyKey}`);
      }
      return originalMethod.apply(this, args);
    };

    return descriptor;
  };
}

class FileService {
  public role: string;

  constructor(role: string) {
    this.role = role;
  }

  @RequireRole(['Admin', 'Editor'])
  uploadFile(fileName: string) {
    console.log(`File ${fileName} uploaded.`);
  }

  @RequireRole(['Admin'])
  deleteFile(fileName: string) {
    console.log(`File ${fileName} deleted.`);
  }

  @RequireRole(['Admin', 'Editor', 'Viewer'])
  viewFile(fileName: string) {
    console.log(`Viewing file: ${fileName}`);
  }
}

// Usage example
const adminUser = new FileService('Admin');
adminUser.uploadFile('report.pdf');  // 実行成功
adminUser.deleteFile('report.pdf');  // 実行成功
adminUser.viewFile('report.pdf');    // 実行成功

const editorUser = new FileService('Editor');
editorUser.uploadFile('report.pdf'); // 実行成功
editorUser.deleteFile('report.pdf'); // エラー: "Access Denied: Editor does not have permission to access deleteFile"
editorUser.viewFile('report.pdf');   // 実行成功

const viewerUser = new FileService('Viewer');
viewerUser.viewFile('report.pdf');   // 実行成功
viewerUser.uploadFile('report.pdf'); // エラー: "Access Denied: Viewer does not have permission to access uploadFile"

function LogExecution(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
  const originalMethod = descriptor.value;

  descriptor.value = function (...args: any[]) {
    console.log(`Executing ${propertyKey} with arguments: ${JSON.stringify(args)}`);
    const result = originalMethod.apply(this, args);
    console.log(`Result of ${propertyKey}: ${JSON.stringify(result)}`);
    return result;
  };

  return descriptor;
}

class UserService {
  @LogExecution
  createUser(name: string, age: number) {
    // ユーザー作成処理
    return { name, age };
  }

  @LogExecution
  deleteUser(userId: number) {
    // ユーザー削除処理
    console.log(`User with ID ${userId} deleted.`);
  }
}

// Usage example
const userService = new UserService();
userService.createUser('Alice', 30);  // ログ: "Executing createUser with arguments: [...]" 結果のログも表示
userService.deleteUser(123);  // ログ: "Executing deleteUser with arguments: [...]" 実行結果も表示

@RequireRole(['Admin'])
@LogExecution
deleteUser(userId: number) {
  console.log(`User with ID ${userId} deleted.`);
}

function RoleCheck(allowedRoles: string[]) {
  return function (target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;

    descriptor.value = function (...args: any[]) {
      if (!allowedRoles.includes(this.role)) {
        throw new Error(`Access Denied: ${this.role} does not have permission to execute ${propertyKey}`);
      }
      return originalMethod.apply(this, args);
    };

    return descriptor;
  };
}

function LogExecution(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
  const originalMethod = descriptor.value;

  descriptor.value = function (...args: any[]) {
    console.log(`Executing ${propertyKey} with arguments: ${JSON.stringify(args)}`);
    const result = originalMethod.apply(this, args);
    console.log(`Result of ${propertyKey}: ${JSON.stringify(result)}`);
    return result;
  };

  return descriptor;
}

class UserService {
  public role: string;

  constructor(role: string) {
    this.role = role;
  }

  @RoleCheck(['Admin', 'Editor'])
  @LogExecution
  createContent(title: string) {
    return `Content titled "${title}" created.`;
  }

  @RoleCheck(['Admin', 'Editor'])
  @LogExecution
  editContent(id: number, title: string) {
    return `Content with ID ${id} edited to "${title}".`;
  }

  @RoleCheck(['Admin'])
  @LogExecution
  deleteContent(id: number) {
    return `Content with ID ${id} deleted.`;
  }

  @RoleCheck(['Admin', 'Editor', 'Viewer'])
  @LogExecution
  viewContent(id: number) {
    return `Viewing content with ID ${id}.`;
  }
}

// Usage example
const adminUser = new UserService('Admin');
console.log(adminUser.createContent('New Post'));  // 実行成功
console.log(adminUser.deleteContent(123));         // 実行成功

const viewerUser = new UserService('Viewer');
console.log(viewerUser.viewContent(123));          // 実行成功
console.log(viewerUser.deleteContent(123));        // エラー: "Access Denied: Viewer does not have permission to execute deleteContent"

{
  "compilerOptions": {
    "experimentalDecorators": true
  }
}

@RequireRole(['Admin'])
@LogExecution
deleteUser(userId: number) { ... }

descriptor.value = function (...args: any[]) {
  try {
    console.log(`Executing ${propertyKey} with arguments: ${JSON.stringify(args)}`);
    const result = originalMethod.apply(this, args);
    console.log(`Result of ${propertyKey}: ${JSON.stringify(result)}`);
    return result;
  } catch (error) {
    console.error(`Error in ${propertyKey}: ${error}`);
    throw error;
  }
};

descriptor.value = function (...args: any[]) {
  return originalMethod.apply(this, args);
}.bind(this);