Initialize NestJS project with basic structure and configurations

- Added .gitignore to exclude build artifacts and environment files.
- Created .prettierrc for code formatting preferences.
- Set up ESLint configuration for TypeScript with Prettier integration.
- Configured Nest CLI with nest-cli.json.
- Established package.json and package-lock.json for project dependencies.
- Created initial README.md for project documentation.
- Defined TypeScript configurations in tsconfig.json and tsconfig.build.json.
- Implemented basic application structure with AppModule, AppController, and AppService.
- Developed Book, Visitor, and Worker modules with respective controllers and services.
- Added DTOs for data validation and Swagger setup for API documentation.
- Implemented utility functions for file management, encryption, and date handling.
- Created initial data files for books, visitors, and workers.
- Added exception filters and response interceptors for error handling and response formatting.

.gitignore

@@ -0,0 +1,56 @@
+# compiled output
+/dist
+/node_modules
+/build
+
+# Logs
+logs
+*.log
+npm-debug.log*
+pnpm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# OS
+.DS_Store
+
+# Tests
+/coverage
+/.nyc_output
+
+# IDEs and editors
+/.idea
+.project
+.classpath
+.c9/
+*.launch
+.settings/
+*.sublime-workspace
+
+# IDE - VSCode
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# temp directory
+.temp
+.tmp
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json

.prettierrc

@@ -0,0 +1,4 @@
+{
+  "singleQuote": true,
+  "trailingComma": "all"
+}

README.md

@@ -0,0 +1,98 @@
+<p align="center">
+  <a href="http://nestjs.com/" target="blank"><img src="https://nestjs.com/img/logo-small.svg" width="120" alt="Nest Logo" /></a>
+</p>
+
+[circleci-image]: https://img.shields.io/circleci/build/github/nestjs/nest/master?token=abc123def456
+[circleci-url]: https://circleci.com/gh/nestjs/nest
+
+  <p align="center">A progressive <a href="http://nodejs.org" target="_blank">Node.js</a> framework for building efficient and scalable server-side applications.</p>
+    <p align="center">
+<a href="https://www.npmjs.com/~nestjscore" target="_blank"><img src="https://img.shields.io/npm/v/@nestjs/core.svg" alt="NPM Version" /></a>
+<a href="https://www.npmjs.com/~nestjscore" target="_blank"><img src="https://img.shields.io/npm/l/@nestjs/core.svg" alt="Package License" /></a>
+<a href="https://www.npmjs.com/~nestjscore" target="_blank"><img src="https://img.shields.io/npm/dm/@nestjs/common.svg" alt="NPM Downloads" /></a>
+<a href="https://circleci.com/gh/nestjs/nest" target="_blank"><img src="https://img.shields.io/circleci/build/github/nestjs/nest/master" alt="CircleCI" /></a>
+<a href="https://discord.gg/G7Qnnhy" target="_blank"><img src="https://img.shields.io/badge/discord-online-brightgreen.svg" alt="Discord"/></a>
+<a href="https://opencollective.com/nest#backer" target="_blank"><img src="https://opencollective.com/nest/backers/badge.svg" alt="Backers on Open Collective" /></a>
+<a href="https://opencollective.com/nest#sponsor" target="_blank"><img src="https://opencollective.com/nest/sponsors/badge.svg" alt="Sponsors on Open Collective" /></a>
+  <a href="https://paypal.me/kamilmysliwiec" target="_blank"><img src="https://img.shields.io/badge/Donate-PayPal-ff3f59.svg" alt="Donate us"/></a>
+    <a href="https://opencollective.com/nest#sponsor"  target="_blank"><img src="https://img.shields.io/badge/Support%20us-Open%20Collective-41B883.svg" alt="Support us"></a>
+  <a href="https://twitter.com/nestframework" target="_blank"><img src="https://img.shields.io/twitter/follow/nestframework.svg?style=social&label=Follow" alt="Follow us on Twitter"></a>
+</p>
+  <!--[![Backers on Open Collective](https://opencollective.com/nest/backers/badge.svg)](https://opencollective.com/nest#backer)
+  [![Sponsors on Open Collective](https://opencollective.com/nest/sponsors/badge.svg)](https://opencollective.com/nest#sponsor)-->
+
+## Description
+
+[Nest](https://github.com/nestjs/nest) framework TypeScript starter repository.
+
+## Project setup
+
+```bash
+$ npm install
+```
+
+## Compile and run the project
+
+```bash
+# development
+$ npm run start
+
+# watch mode
+$ npm run start:dev
+
+# production mode
+$ npm run start:prod
+```
+
+## Run tests
+
+```bash
+# unit tests
+$ npm run test
+
+# e2e tests
+$ npm run test:e2e
+
+# test coverage
+$ npm run test:cov
+```
+
+## Deployment
+
+When you're ready to deploy your NestJS application to production, there are some key steps you can take to ensure it runs as efficiently as possible. Check out the [deployment documentation](https://docs.nestjs.com/deployment) for more information.
+
+If you are looking for a cloud-based platform to deploy your NestJS application, check out [Mau](https://mau.nestjs.com), our official platform for deploying NestJS applications on AWS. Mau makes deployment straightforward and fast, requiring just a few simple steps:
+
+```bash
+$ npm install -g @nestjs/mau
+$ mau deploy
+```
+
+With Mau, you can deploy your application in just a few clicks, allowing you to focus on building features rather than managing infrastructure.
+
+## Resources
+
+Check out a few resources that may come in handy when working with NestJS:
+
+- Visit the [NestJS Documentation](https://docs.nestjs.com) to learn more about the framework.
+- For questions and support, please visit our [Discord channel](https://discord.gg/G7Qnnhy).
+- To dive deeper and get more hands-on experience, check out our official video [courses](https://courses.nestjs.com/).
+- Deploy your application to AWS with the help of [NestJS Mau](https://mau.nestjs.com) in just a few clicks.
+- Visualize your application graph and interact with the NestJS application in real-time using [NestJS Devtools](https://devtools.nestjs.com).
+- Need help with your project (part-time to full-time)? Check out our official [enterprise support](https://enterprise.nestjs.com).
+- To stay in the loop and get updates, follow us on [X](https://x.com/nestframework) and [LinkedIn](https://linkedin.com/company/nestjs).
+- Looking for a job, or have a job to offer? Check out our official [Jobs board](https://jobs.nestjs.com).
+
+## Support
+
+Nest is an MIT-licensed open source project. It can grow thanks to the sponsors and support by the amazing backers. If you'd like to join them, please [read more here](https://docs.nestjs.com/support).
+
+## Stay in touch
+
+- Author - [Kamil Myśliwiec](https://twitter.com/kammysliwiec)
+- Website - [https://nestjs.com](https://nestjs.com/)
+- Twitter - [@nestframework](https://twitter.com/nestframework)
+
+## License
+
+Nest is [MIT licensed](https://github.com/nestjs/nest/blob/master/LICENSE).

eslint.config.mjs

@@ -0,0 +1,35 @@
+// @ts-check
+import eslint from '@eslint/js';
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
+import globals from 'globals';
+import tseslint from 'typescript-eslint';
+
+export default tseslint.config(
+  {
+    ignores: ['eslint.config.mjs'],
+  },
+  eslint.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked,
+  eslintPluginPrettierRecommended,
+  {
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        ...globals.jest,
+      },
+      sourceType: 'commonjs',
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+  },
+  {
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off',
+      '@typescript-eslint/no-floating-promises': 'warn',
+      '@typescript-eslint/no-unsafe-argument': 'warn',
+      "prettier/prettier": ["error", { endOfLine: "auto" }],
+    },
+  },
+);

nest-cli.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://json.schemastore.org/nest-cli",
+  "collection": "@nestjs/schematics",
+  "sourceRoot": "src",
+  "compilerOptions": {
+    "deleteOutDir": true
+  }
+}

package.json

@@ -0,0 +1,75 @@
+{
+  "name": "lab4",
+  "version": "0.0.1",
+  "description": "",
+  "author": "",
+  "private": true,
+  "license": "UNLICENSED",
+  "scripts": {
+    "build": "nest build",
+    "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
+    "start": "nest start",
+    "start:dev": "nest start --watch",
+    "start:debug": "nest start --debug --watch",
+    "start:prod": "node dist/main",
+    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
+    "test": "jest",
+    "test:watch": "jest --watch",
+    "test:cov": "jest --coverage",
+    "test:debug": "node --inspect-brk -r tsconfig-paths/register -r ts-node/register node_modules/.bin/jest --runInBand",
+    "test:e2e": "jest --config ./test/jest-e2e.json"
+  },
+  "dependencies": {
+    "@nestjs/common": "^11.0.1",
+    "@nestjs/core": "^11.0.1",
+    "@nestjs/mapped-types": "*",
+    "@nestjs/platform-express": "^11.0.1",
+    "@nestjs/swagger": "^11.2.3",
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.14.3",
+    "reflect-metadata": "^0.2.2",
+    "rxjs": "^7.8.1"
+  },
+  "devDependencies": {
+    "@eslint/eslintrc": "^3.2.0",
+    "@eslint/js": "^9.18.0",
+    "@nestjs/cli": "^11.0.0",
+    "@nestjs/schematics": "^11.0.0",
+    "@nestjs/testing": "^11.0.1",
+    "@types/express": "^5.0.0",
+    "@types/jest": "^30.0.0",
+    "@types/node": "^22.10.7",
+    "@types/supertest": "^6.0.2",
+    "eslint": "^9.18.0",
+    "eslint-config-prettier": "^10.0.1",
+    "eslint-plugin-prettier": "^5.2.2",
+    "globals": "^16.0.0",
+    "jest": "^30.0.0",
+    "prettier": "^3.4.2",
+    "source-map-support": "^0.5.21",
+    "supertest": "^7.0.0",
+    "ts-jest": "^29.2.5",
+    "ts-loader": "^9.5.2",
+    "ts-node": "^10.9.2",
+    "tsconfig-paths": "^4.2.0",
+    "typescript": "^5.7.3",
+    "typescript-eslint": "^8.20.0"
+  },
+  "jest": {
+    "moduleFileExtensions": [
+      "js",
+      "json",
+      "ts"
+    ],
+    "rootDir": "src",
+    "testRegex": ".*\\.spec\\.ts$",
+    "transform": {
+      "^.+\\.(t|j)s$": "ts-jest"
+    },
+    "collectCoverageFrom": [
+      "**/*.(t|j)s"
+    ],
+    "coverageDirectory": "../coverage",
+    "testEnvironment": "node"
+  }
+}

src/app.controller.spec.ts

@@ -0,0 +1,22 @@
+import { Test, TestingModule } from '@nestjs/testing';
+import { AppController } from './app.controller';
+import { AppService } from './app.service';
+
+describe('AppController', () => {
+  let appController: AppController;
+
+  beforeEach(async () => {
+    const app: TestingModule = await Test.createTestingModule({
+      controllers: [AppController],
+      providers: [AppService],
+    }).compile();
+
+    appController = app.get<AppController>(AppController);
+  });
+
+  describe('root', () => {
+    it('should return "Hello World!"', () => {
+      expect(appController.getHello()).toBe('Hello World!');
+    });
+  });
+});

src/app.controller.ts

@@ -0,0 +1,7 @@
+import { Controller } from '@nestjs/common';
+import { AppService } from './app.service';
+
+@Controller()
+export class AppController {
+  constructor(private readonly appService: AppService) {}
+}

src/app.module.ts

@@ -0,0 +1,13 @@
+import { Module } from '@nestjs/common';
+import { AppController } from './app.controller';
+import { AppService } from './app.service';
+import { BookModule } from './book/book.module';
+import { WorkerModule } from './worker/worker.module';
+import { VisitorModule } from './visitor/visitor.module';
+
+@Module({
+  imports: [BookModule, WorkerModule, VisitorModule],
+  controllers: [AppController],
+  providers: [AppService],
+})
+export class AppModule {}

src/app.service.ts

@@ -0,0 +1,4 @@
+import { Injectable } from '@nestjs/common';
+
+@Injectable()
+export class AppService {}

src/book/book.controller.ts

@@ -0,0 +1,110 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Patch,
+  Delete,
+  Param,
+  Body,
+  NotFoundException,
+  BadRequestException,
+} from '@nestjs/common';
+import { BookService } from './book.service';
+import { VisitorService } from '../visitor/visitor.service';
+import { CreateBookDto } from './dto/create-book.dto';
+import { BorrowBookDto } from './dto/borrow-book.dto';
+import { ReturnBookDto } from './dto/return-book.dto';
+import { DateUtils } from 'src/utils/date.utils';
+import { WorkerService } from 'src/worker/worker.service';
+import { UpdateBookDto } from './dto/update-book.dto';
+import { buildDownloadFile } from 'src/utils/download.utils';
+
+@Controller('books')
+export class BookController {
+  constructor(
+    private readonly bookService: BookService,
+    private readonly visitorService: VisitorService,
+    private readonly workerService: WorkerService,
+  ) {}
+
+  @Get('all')
+  async getAll() {
+    return await this.bookService.getAll();
+  }
+
+  @Get(':id/download')
+  async download(@Param('id') id: string) {
+    const book = await this.bookService.getById(id);
+    if (!book) throw new NotFoundException(`Book with id ${id} not found`);
+    return buildDownloadFile('books', id, book);
+  }
+
+  @Post('create')
+  async create(@Body() dto: CreateBookDto) {
+    return await this.bookService.add(dto);
+  }
+
+  @Get(':id')
+  async getById(@Param('id') id: string) {
+    const book = await this.bookService.getById(id);
+    if (!book) throw new NotFoundException(`Book with id ${id} not found`);
+    return book;
+  }
+
+  @Patch(':id')
+  async update(@Param('id') id: string, @Body() dto: UpdateBookDto) {
+    const updated = await this.bookService.update(id, dto);
+    if (!updated) throw new NotFoundException(`Book with id ${id} not found`);
+    return updated;
+  }
+
+  @Delete(':id')
+  async remove(@Param('id') id: string) {
+    const deleted = await this.bookService.delete(id);
+    if (!deleted) throw new NotFoundException(`Book with id ${id} not found`);
+    return { message: `Book with id ${id} deleted successfully` };
+  }
+
+  @Post('borrow')
+  async borrow(@Body() dto: BorrowBookDto) {
+    const visitor = await this.visitorService.getById(dto.visitorId);
+    if (!visitor) throw new NotFoundException(`Visitor not found`);
+
+    const worker = await this.workerService.getById(dto.workerId);
+    if (!worker) throw new NotFoundException(`Worker not found`);
+
+    if (!DateUtils.isWorkingDay(dto.borrowDate, worker.workDays)) {
+      throw new BadRequestException('Library is closed on this day');
+    }
+
+    const borrowedBooks = await this.bookService.borrowBooks(
+      dto.bookIds,
+      visitor,
+    );
+    await this.visitorService.addCurrentBooks(visitor.id, borrowedBooks);
+    await this.workerService.addIssuedBooks(worker.id, borrowedBooks);
+
+    return { message: `Successfully borrowed ${borrowedBooks.length} book(s)` };
+  }
+
+  @Post('return')
+  async return(@Body() dto: ReturnBookDto) {
+    const visitor = await this.visitorService.getById(dto.visitorId);
+    if (!visitor) throw new NotFoundException(`Visitor not found`);
+
+    const worker = await this.workerService.getById(dto.workerId);
+    if (!worker) throw new NotFoundException(`Worker not found`);
+
+    if (!DateUtils.isWorkingDay(dto.returnDate, worker.workDays)) {
+      throw new BadRequestException('Library is closed on this day');
+    }
+
+    const returnedBooks = await this.bookService.returnBooks(
+      dto.bookIds,
+      visitor,
+    );
+    await this.visitorService.moveToHistory(visitor.id, returnedBooks);
+
+    return { message: `Successfully returned ${returnedBooks.length} book(s)` };
+  }
+}

src/book/book.module.ts

@@ -0,0 +1,14 @@
+import { Module } from '@nestjs/common';
+import { BookController } from './book.controller';
+import { BookService } from './book.service';
+import { BookLinkManager } from 'src/common/book-link-manager';
+import { VisitorModule } from '../visitor/visitor.module';
+import { WorkerModule } from '../worker/worker.module';
+
+@Module({
+  imports: [VisitorModule, WorkerModule],
+  controllers: [BookController],
+  providers: [BookService, BookLinkManager],
+  exports: [BookService, BookLinkManager],
+})
+export class BookModule {}

src/book/book.service.ts

@@ -0,0 +1,123 @@
+import {
+  Injectable,
+  NotFoundException,
+  BadRequestException,
+} from '@nestjs/common';
+import { Book } from './dto/book.dto';
+import { FileManager } from '../utils/file-manager';
+import { parseTxtRow, serializeTxtRow } from '../utils/file.utils';
+import { randomUUID } from 'crypto';
+import { BookStatus } from 'src/types/book.types';
+import { CreateBookDto } from './dto/create-book.dto';
+import { UpdateBookDto } from './dto/update-book.dto';
+import { Visitor } from '../visitor/dto/visitor.dto';
+import { bookLinkManager } from 'src/common/book-link-manager';
+
+@Injectable()
+export class BookService {
+  private file = new FileManager('src/data/books.txt');
+
+  async getAll(): Promise<Book[]> {
+    const lines = await this.file.readLines();
+    return lines.map(parseTxtRow) as unknown as Book[];
+  }
+
+  async getById(id: string): Promise<Book | null> {
+    const books = await this.getAll();
+    return books.find((b) => b.id === id) || null;
+  }
+
+  async add(dto: CreateBookDto): Promise<Book> {
+    const newBook: Book = {
+      id: randomUUID(),
+      ...dto,
+      status: BookStatus.AVAILABLE,
+    };
+    const lines = await this.file.readLines();
+    lines.push(await serializeTxtRow(newBook));
+    await this.file.writeLines(lines);
+    return newBook;
+  }
+
+  async update(id: string, dto: UpdateBookDto): Promise<Book | null> {
+    const books = await this.getAll();
+    const index = books.findIndex((b) => b.id === id);
+    if (index === -1) return null;
+    books[index] = { ...books[index], ...dto };
+    await this.file.writeLines(
+      await Promise.all(books.map((book) => serializeTxtRow(book))),
+    );
+    return books[index];
+  }
+
+  async delete(id: string): Promise<boolean> {
+    const books = await this.getAll();
+    const index = books.findIndex((b) => b.id === id);
+    if (index === -1) return false;
+    books.splice(index, 1);
+    await this.file.writeLines(
+      await Promise.all(books.map((book) => serializeTxtRow(book))),
+    );
+    return true;
+  }
+
+  async borrowBooks(bookIds: string[], visitor: Visitor): Promise<Book[]> {
+    const books = await this.getAll();
+    const borrowed: Book[] = [];
+
+    for (const bookId of bookIds) {
+      const book = books.find((b) => b.id === bookId);
+      if (!book)
+        throw new NotFoundException(`Book with id ${bookId} not found`);
+      if (book.status === BookStatus.BORROWED) {
+        throw new BadRequestException(
+          `Book "${book.title}" is already borrowed`,
+        );
+      }
+
+      book.status = BookStatus.BORROWED;
+      visitor.currentBooks.push(bookLinkManager.toLink(bookId));
+
+      borrowed.push(book);
+    }
+
+    await this.file.writeLines(
+      await Promise.all(books.map((book) => serializeTxtRow(book))),
+    );
+    return borrowed;
+  }
+
+  async returnBooks(bookIds: string[], visitor: Visitor): Promise<Book[]> {
+    const books = await this.getAll();
+    const returned: Book[] = [];
+
+    for (const bookId of bookIds) {
+      const book = books.find((b) => b.id === bookId);
+      if (!book)
+        throw new NotFoundException(`Book with id ${bookId} not found`);
+      if (book.status === BookStatus.AVAILABLE) {
+        throw new BadRequestException(`Book "${book.title}" is not borrowed`);
+      }
+
+      const currentBookIndex = visitor.currentBooks.findIndex(
+        (link) => link.id === bookId,
+      );
+
+      if (currentBookIndex === -1) {
+        throw new BadRequestException(
+          `Visitor does not have book "${book.title}"`,
+        );
+      }
+
+      book.status = BookStatus.AVAILABLE;
+      const returnedLink = visitor.currentBooks.splice(currentBookIndex, 1)[0];
+      visitor.history.push(returnedLink);
+      returned.push(book);
+    }
+
+    await this.file.writeLines(
+      await Promise.all(books.map((book) => serializeTxtRow(book))),
+    );
+    return returned;
+  }
+}

src/book/dto/book.dto.ts

@@ -0,0 +1,77 @@
+import { ApiProperty } from '@nestjs/swagger';
+import {
+  IsString,
+  IsInt,
+  MinLength,
+  MaxLength,
+  Min,
+  Max,
+  IsNotEmpty,
+  IsEnum,
+} from 'class-validator';
+import { BookStatus, Genre } from 'src/types/book.types';
+
+export class Book {
+  @ApiProperty({
+    description: 'Уникальный идентификатор книги',
+    example: 'b1f3c2e7-9bd1-4f41-82b3-fc4c938f4a1d',
+  })
+  @IsString()
+  id: string;
+
+  @ApiProperty({
+    description: 'Название книги',
+    example: 'Pride and Prejudice',
+  })
+  @IsString()
+  @IsNotEmpty({ message: 'Title is required' })
+  @MinLength(2, { message: 'Title must be at least 2 characters' })
+  @MaxLength(100, { message: 'Title must be at most 100 characters' })
+  title: string;
+
+  @ApiProperty({
+    description: 'Автор книги',
+    example: 'Jane Austen',
+  })
+  @IsString()
+  @IsNotEmpty({ message: 'Author is required' })
+  @MinLength(2, { message: 'Author must be at least 2 characters' })
+  @MaxLength(100, { message: 'Author must be at most 100 characters' })
+  author: string;
+
+  @ApiProperty({
+    description: 'Количество страниц',
+    example: 279,
+  })
+  @IsInt({ message: 'Pages must be an integer' })
+  @Min(1, { message: 'Pages must be at least 1' })
+  @Max(10000, { message: 'Pages must be at most 10000' })
+  pages: number;
+
+  @ApiProperty({
+    description: 'Год публикации',
+    example: 1813,
+  })
+  @IsInt({ message: 'Year must be an integer' })
+  @Min(1000, { message: 'Year must be at least 1000' })
+  @Max(new Date().getFullYear(), {
+    message: `Year cannot be greater than ${new Date().getFullYear()}`,
+  })
+  year: number;
+
+  @ApiProperty({
+    description: 'Жанр книги',
+    enum: Genre,
+    example: Genre.Romance,
+  })
+  @IsEnum(Genre, { message: 'Invalid genre' })
+  genre: Genre;
+
+  @ApiProperty({
+    description: 'Статус книги',
+    enum: BookStatus,
+    example: BookStatus.AVAILABLE,
+  })
+  @IsEnum(BookStatus, { message: 'Invalid book status' })
+  status: BookStatus;
+}

src/book/dto/borrow-book.dto.ts

@@ -0,0 +1,39 @@
+import { ApiProperty } from '@nestjs/swagger';
+import {
+  IsArray,
+  IsString,
+  IsDateString,
+  ArrayNotEmpty,
+} from 'class-validator';
+
+export class BorrowBookDto {
+  @ApiProperty({
+    description: 'Список ID книг, которые выдаются',
+    example: ['book1', 'book2'],
+  })
+  @IsArray()
+  @ArrayNotEmpty({ message: 'bookIds cannot be empty' })
+  @IsString({ each: true })
+  bookIds: string[];
+
+  @ApiProperty({
+    description: 'ID посетителя',
+    example: 'visitor123',
+  })
+  @IsString()
+  visitorId: string;
+
+  @ApiProperty({
+    description: 'ID сотрудника, который выдает книги',
+    example: 'employee456',
+  })
+  @IsString()
+  workerId: string;
+
+  @ApiProperty({
+    description: 'Дата выдачи (ISO)',
+    example: '2025-11-25',
+  })
+  @IsDateString()
+  borrowDate: string;
+}

src/book/dto/create-book.dto.ts

@@ -0,0 +1,68 @@
+import { ApiProperty } from '@nestjs/swagger';
+import {
+  IsString,
+  IsInt,
+  MinLength,
+  MaxLength,
+  Min,
+  Max,
+  IsNotEmpty,
+  IsEnum,
+} from 'class-validator';
+import { BookStatus, Genre } from 'src/types/book.types';
+
+export class CreateBookDto {
+  @ApiProperty({
+    description: 'Название книги',
+    example: 'Pride and Prejudice',
+  })
+  @IsString()
+  @IsNotEmpty({ message: 'Title is required' })
+  @MinLength(2)
+  @MaxLength(100)
+  title: string;
+
+  @ApiProperty({
+    description: 'Автор книги',
+    example: 'Jane Austen',
+  })
+  @IsString()
+  @IsNotEmpty({ message: 'Author is required' })
+  @MinLength(2)
+  @MaxLength(100)
+  author: string;
+
+  @ApiProperty({
+    description: 'Количество страниц',
+    example: 279,
+  })
+  @IsInt()
+  @Min(1)
+  @Max(10000)
+  pages: number;
+
+  @ApiProperty({
+    description: 'Год публикации',
+    example: 1813,
+  })
+  @IsInt()
+  @Min(1000)
+  @Max(new Date().getFullYear())
+  year: number;
+
+  @ApiProperty({
+    description: 'Жанр книги',
+    enum: Genre,
+    example: Genre.Romance,
+  })
+  @IsEnum(Genre)
+  genre: Genre;
+
+  @ApiProperty({
+    description: 'Статус книги',
+    enum: BookStatus,
+    example: BookStatus.AVAILABLE,
+  })
+  @IsEnum(BookStatus, { message: 'Invalid book status' })
+  status: BookStatus;
+}

src/book/dto/return-book.dto.ts

@@ -0,0 +1,39 @@
+import { ApiProperty } from '@nestjs/swagger';
+import {
+  IsArray,
+  IsString,
+  IsDateString,
+  ArrayNotEmpty,
+} from 'class-validator';
+
+export class ReturnBookDto {
+  @ApiProperty({
+    description: 'Список ID книг, которые возвращаются',
+    example: ['book1', 'book2'],
+  })
+  @IsArray()
+  @ArrayNotEmpty({ message: 'bookIds cannot be empty' })
+  @IsString({ each: true })
+  bookIds: string[];
+
+  @ApiProperty({
+    description: 'ID посетителя',
+    example: 'visitor123',
+  })
+  @IsString()
+  visitorId: string;
+
+  @ApiProperty({
+    description: 'ID сотрудника, который принимает книги',
+    example: 'employee456',
+  })
+  @IsString()
+  workerId: string;
+
+  @ApiProperty({
+    description: 'Дата возврата (ISO)',
+    example: '2025-11-25',
+  })
+  @IsDateString()
+  returnDate: string;
+}

src/book/dto/update-book.dto.ts

@@ -0,0 +1,4 @@
+import { PartialType } from '@nestjs/swagger';
+import { CreateBookDto } from './create-book.dto';
+
+export class UpdateBookDto extends PartialType(CreateBookDto) {}

src/common/Link.ts

@@ -0,0 +1,15 @@
+export class Link {
+  constructor(
+    public table: string,
+    public id: string,
+  ) {}
+
+  static fromString(str: string): Link {
+    const [table, id] = str.split(':');
+    return new Link(table, id);
+  }
+
+  toString(): string {
+    return `${this.table}:${this.id}`;
+  }
+}

src/common/LinkManager.ts

@@ -0,0 +1,33 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+import { FileManager } from '../utils/file-manager';
+import { parseTxtRow } from '../utils/file.utils';
+import { Link } from './Link';
+
+export abstract class LinkManager<T> {
+  protected abstract fileName: string;
+  protected abstract tableName: string;
+
+  private getFile() {
+    return new FileManager(`src/data/${this.fileName}`);
+  }
+
+  toLink(id: string): Link {
+    return new Link(this.tableName, id);
+  }
+
+  async resolve(link: Link): Promise<T | null> {
+    if (link.table !== this.tableName)
+      throw new Error(`Expected link to ${this.tableName}, got ${link.table}`);
+
+    const file = this.getFile();
+    const rows = await file.readLines();
+    const items = rows.map(parseTxtRow) as T[];
+
+    return items.find((i: any) => i.id === link.id) || null;
+  }
+
+  async resolveMany(links: Link[]): Promise<T[]> {
+    const resolved = await Promise.all(links.map((l) => this.resolve(l)));
+    return resolved.filter((i) => i !== null) as T[];
+  }
+}

src/common/book-link-manager.ts

@@ -0,0 +1,9 @@
+import { LinkManager } from './LinkManager';
+import { Book } from '../book/dto/book.dto';
+
+export class BookLinkManager extends LinkManager<Book> {
+  protected fileName = 'books.txt';
+  protected tableName = 'books';
+}
+
+export const bookLinkManager = new BookLinkManager();

src/common/key-manager.ts

@@ -0,0 +1,51 @@
+import { promises as fs } from 'fs';
+import path from 'path';
+import {
+  decryptWithAlphabet,
+  encryptWithAlphabet,
+} from 'src/utils/offset-encryption.util';
+
+const dataDir = path.join(process.cwd(), 'src/data/encrypted/');
+const keyFile = path.join(dataDir, '.encryption_key');
+
+const MASTER_KEY = process.env.MASTER_KEY || 'RSIOT_SECRET_KEY_VARIAHT1';
+
+export async function ensureDataDir(): Promise<void> {
+  try {
+    await fs.access(dataDir);
+  } catch {
+    await fs.mkdir(dataDir, { recursive: true });
+  }
+}
+
+export async function getOrCreateKey(): Promise<string> {
+  await ensureDataDir();
+
+  try {
+    const encryptedKey = await fs.readFile(keyFile, 'utf-8');
+    return decryptWithAlphabet(encryptedKey, MASTER_KEY);
+  } catch (err: unknown) {
+    if (err instanceof Error && err.message.includes('ENOENT')) {
+      const newKey = generateRandomKey(16);
+      await saveKey(newKey);
+      return newKey;
+    }
+    throw err;
+  }
+}
+
+export async function saveKey(key: string): Promise<void> {
+  await ensureDataDir();
+  const encryptedKey = encryptWithAlphabet(key, MASTER_KEY);
+  await fs.writeFile(keyFile, encryptedKey, 'utf-8');
+}
+
+export function generateRandomKey(length: number): string {
+  const chars =
+    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*';
+  let key = '';
+  for (let i = 0; i < length; i++) {
+    key += chars.charAt(Math.floor(Math.random() * chars.length));
+  }
+  return key;
+}

src/common/visitor-link-manager.ts

@@ -0,0 +1,33 @@
+import { LinkManager } from './LinkManager';
+import { Visitor } from '../visitor/dto/visitor.dto';
+import { bookLinkManager } from './book-link-manager';
+import { Link } from './Link';
+
+export interface VisitorWithBooks
+  extends Omit<Visitor, 'currentBooks' | 'history'> {
+  currentBooks: any[];
+  history: any[];
+}
+
+export class VisitorLinkManager extends LinkManager<Visitor> {
+  protected fileName = 'visitors.txt';
+  protected tableName = 'visitors';
+
+  async enrich(visitor: Visitor): Promise<VisitorWithBooks> {
+    const currentBooks = await bookLinkManager.resolveMany(
+      visitor.currentBooks as unknown as Link[],
+    );
+
+    const history = await bookLinkManager.resolveMany(
+      visitor.history as unknown as Link[],
+    );
+
+    return {
+      ...visitor,
+      currentBooks,
+      history,
+    };
+  }
+}
+
+export const visitorLinkManager = new VisitorLinkManager();

src/common/worker-link-manager.ts

@@ -0,0 +1,27 @@
+import { Worker } from 'src/worker/dto/worker.dto';
+import { bookLinkManager } from './book-link-manager';
+import { LinkManager } from './LinkManager';
+import { Link } from './Link';
+import { Book } from 'src/book/dto/book.dto';
+
+export interface WorkerWithBooks extends Omit<Worker, 'issuedBooks'> {
+  issuedBooks: Book[];
+}
+
+export class WorkerLinkManager extends LinkManager<Worker> {
+  protected fileName = 'workers.txt';
+  protected tableName = 'workers';
+
+  async enrich(worker: Worker): Promise<WorkerWithBooks> {
+    const issuedBooks = await bookLinkManager.resolveMany(
+      worker.issuedBooks as unknown as Link[],
+    );
+
+    return {
+      ...worker,
+      issuedBooks,
+    };
+  }
+}
+
+export const workerLinkManager = new WorkerLinkManager();

src/config/swagger.config.ts

@@ -0,0 +1,9 @@
+import { DocumentBuilder } from '@nestjs/swagger';
+
+export function getSwaggerConfig() {
+  return new DocumentBuilder()
+    .setTitle('Library API')
+    .setDescription('Library API Documentation')
+    .addBearerAuth()
+    .build();
+}

src/data/books.txt

@@ -0,0 +1,8 @@
+id=ccb1b578-8343-45de-a465-007af8af7c28;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Borrowed
+id=9ac18f0d-8bf7-4dfd-aa20-cc9b1b66e610;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Borrowed
+id=84d1af3f-db4e-4331-b94d-e846b0adeb06;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Available
+id=088e4a3d-cb61-4894-a9f0-b62ed9bd4cc1;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Available
+id=aba6d1d3-2c1e-4b14-948d-a370f0699da7;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Available
+id=583f1c35-2f17-4006-9919-ce292cf6803a;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Available
+id=25d250e9-c6ad-44e0-894a-bb5507da6971;title=Pride and Prejudice;author=Jane Austen;pages=279;year=1813;genre=Romance;status=Available
+7p*&qcw[2X?e1,u^7q*&qcw[2X!e2.u&6p &qcw[2X!d1,v&7p *qcw[2X!d1.v&6q *rcw[2X!d1.u&7p *rdw[2X!d1.u&7p*&qdx[2X!d1.u^7q*&qcx]2X!d1.u^6q &qdx[3X!d1.u^6p**rcw[2Y!d1.u^6p*&rdw[2X?d1.u^6p*&rdw[2Y?e1.u^6p*&qcx[3Y!e2.u^6p*&qcw]3X?e2,u^6p*&qcw[3Y!d2,v^6p*&qcw[2Y?d2,u&6p*&qcw[2Y?d1,u&7p*&qcw[2X!e1,v^7q*&qcw[2X!d2,u&6p &qcw[2X!d2,u^7p**qcw[2X!d1.v&7p*&rcw[2X!d1.u&7p**qdw[2X!d1.u^7p *qdx[2X!d1.u^7q*&qdw]2X!d1.u^6p *qdw]3X!d1.u^6p**rcx[2Y!d1.u^6p**rcw]3X?d1.u^6p*&qdw]3X?e1.u^6p*&qcx]2X!e2.u^6p*&qcw]3X!d2,u^6p*&qcw[3Y!e1,v^6p*&qcw[2Y?d2.v&6p*&qcw[2X?e1.v^7p*&qcw[2X!e2,u^6q*&qcw[2X!d2,u&6q &qcw[2X!d1,v^6p *qcw[2X!d1,v^6p**rcw[2X!d1.u&7q*&rdw[2X!d1.u^7q*&rdx[2X!d1.u^6q &qcw]2X!d1.u^6p *rcx]3X!d1.u^6p *rcx[2Y!d1.u^6p**rcx[2Y?d1.u^6p*&rdx[3X!e1.u^6p*&qdx[3Y!d2.u^6p*&qcx]2X?d2,u^6p*&qcw[3Y?e1,v^6p*&qcw[3X?d1.u&6p*&qcw[2Y?e1.v^7p*&qcw[2X?e1,u^7q*&qcw[2X!e2.u&6p &qcw[2X!d2,u^7p *qcw[2X!d1.v^6p*&rcw[2X!d1.v&6p*&rdw[2X!d1.u&7p *rcx[2X!d1.u^7q*&rcw]2X!d1.u^6p &qcw[3X!d1.u^6p &rcw[2Y!d1.u^6p**rdw[3X?d1.u^6p*&rdw[3X?e1.u^6p*&qdx[3X?d2.u^6p*&qcx]3X?d2,u^6p*&qcw]3X!e1.v^6p*&qcw[3Y!e1.v&6p*&qcw[2Y?d1.v&7p*&qcw[2X?e1.v^7q*&qcw[2X!d2,v^7q &qcw[2X!d2,u^6p *qcw[2X!d1,v&6q**rcw[2X!d1.v&7p &qdw[2X!d1.u&7p &qcx[2X!d1.u^7q**rdx]2X!d1.u^6q *qcx[3X!d1.u^6p**rdx[3Y!d1.u^6p**qcx[3X?d1.u^6p*&rdw[2X?e1.u^6p*&qdx[3Y?d2.u^6p*&qcx]2X?d2,u^6p*&qcw[3X!d1.v^6p*&qcw[3X!d1.v&6p*&qcw[2Y?e1,u&7p*&qcw[2X?e2.u&7q*&qcw[2X!e2,u&6p &qcw[2X!d2,u^7p *qcw[2X!d1,v^7q &rcw[2X!d1.u&7q**rdw[2X!d1.u&7q*&qcx[2X!d1.u^7q*&qcx]2X!d1.u^6q &qdx]3X!d1.u^6p *qcx[3Y!d1.u^6p**rdw[3Y?d1.u^6p*&qdx]3X?e1.u^6p*&qcx]2X?d2.u^6p*&qcw]3X?e2,u^6p*&qcw[3Y?d1,v^6p*&qcw[2Y?e1,v&6p*&qcw[2Y?e2.u&7p*&qcw[2X?e1.v^7q*&qcw[2X!e2.u^6q &qcw[2X!d2,v^6q**qcw[2X!d1.v&7q**rcw[2X!d1.u&7p*&rdw[2X!d1.u^7q &qcx[2X!d1.u^6q &qcx]2X!d1.u^6p *qcx]3X!d1.u^6p**rdw]3Y!d1.u^6p**rcw]3Y?d1.u^6p*&rdw[3X?e1.u^6p*&qdx[3Y?d2.u^6p*&qcx]3X!e1,u^6p*&qcw]3X!e1,v^6p*&qcw[2Y?e2.v&6p*&qcw[2Y!e1.v^7p*&qcw[2X?e1,v&7q*&qcw[2X!e2.v&6q &qcw[2X!d2,u^6p *qcw[2X!d1,v^7q &qcw[2X!e2.v^7p*&qcw]2X!d1.u^6q *qcx]3X!d1.u^6p *rcx[2Y!d1.u^6p**rcw[2Y?d1.u^6p*&rdx[3X!e1.u^6p*&qdx]2Y!e2.u^6p*&qcx]3X!e2,u^6p*&qcw[3Y?e1,v^6p*&qcw[3X!d1.v&6p*&qcw[2Y?e1,v^7p*&qcw[2X?e1.u^7q*&qcw[2X!e2.v^6q &qcw[2X!d2,u&7p**qcw[2X!d1,v^6p**rcw[2X!d1.v&6p**qdw[2X!d1.u&7p *qcx[2X!d1.u^7q*&rcx

src/data/encrypted/.encryption_key

@@ -0,0 +1 @@
+Xh(}jDoYEOU^/U*$

src/data/visitors.txt

@@ -0,0 +1 @@
+id=10441103-8fc4-4975-8b6b-c26f87dcbc7c;name=John;surname=Doe;registrationDate="2025-12-15T11:50:53.837Z";currentBooks=["books:ccb1b578-8343-45de-a465-007af8af7c28","books:9ac18f0d-8bf7-4dfd-aa20-cc9b1b66e610"];history=[]

src/data/workers.txt

@@ -0,0 +1 @@
+id=77c37ac4-101c-47a5-a064-b4927e21fc8c;name=John;surname=Doe;experience=5;workDays=["Monday","Wednesday","Friday"];issuedBooks=["books:ccb1b578-8343-45de-a465-007af8af7c28","books:9ac18f0d-8bf7-4dfd-aa20-cc9b1b66e610"]

src/filters/http-exception.filter.ts

@@ -0,0 +1,58 @@
+import {
+  ExceptionFilter,
+  Catch,
+  ArgumentsHost,
+  HttpException,
+  HttpStatus,
+} from '@nestjs/common';
+import { Response } from 'express';
+import { ApiResponse, ErrorResponse } from 'src/utils/response-wrapper.utils';
+
+@Catch()
+export class HttpExceptionFilter implements ExceptionFilter {
+  catch(exception: unknown, host: ArgumentsHost) {
+    const ctx = host.switchToHttp();
+    const response = ctx.getResponse<Response>();
+
+    let status = HttpStatus.INTERNAL_SERVER_ERROR;
+    let message = 'Internal server error';
+    let code: string | undefined;
+
+    // Обработка HttpException (NotFoundException, BadRequestException и т.д.)
+    if (exception instanceof HttpException) {
+      status = exception.getStatus();
+      const exceptionResponse = exception.getResponse();
+
+      if (typeof exceptionResponse === 'string') {
+        message = exceptionResponse;
+      } else if (
+        typeof exceptionResponse === 'object' &&
+        exceptionResponse !== null
+      ) {
+        const response = exceptionResponse as ErrorResponse;
+
+        if (Array.isArray(response.message)) {
+          message = response.message.join(', ');
+        } else {
+          message = response.message || message;
+        }
+
+        code = response.code;
+      }
+    } else if (exception instanceof Error) {
+      message = exception.message;
+    }
+
+    const errorResponse: ApiResponse<void> = {
+      data: null,
+      successful: false,
+      error: {
+        message,
+        statusCode: status,
+        code,
+      },
+    };
+
+    response.status(status).json(errorResponse);
+  }
+}

src/interceptors/response.interceptor.ts

@@ -0,0 +1,33 @@
+import {
+  Injectable,
+  NestInterceptor,
+  ExecutionContext,
+  CallHandler,
+  StreamableFile,
+} from '@nestjs/common';
+import { Response } from 'express';
+import { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+import { ApiResponse } from '../utils/response-wrapper.utils';
+
+@Injectable()
+export class ResponseInterceptor<T>
+  implements NestInterceptor<T, ApiResponse<T> | T>
+{
+  intercept(
+    context: ExecutionContext,
+    next: CallHandler,
+  ): Observable<ApiResponse<T> | T> {
+    const response = context.switchToHttp().getResponse<Response>();
+    return next.handle().pipe(
+      map((data: T) => {
+        if (data instanceof StreamableFile) return data;
+        if (response.headersSent) return data;
+        return {
+          data,
+          successful: true,
+        };
+      }),
+    );
+  }
+}

src/main.ts

@@ -0,0 +1,26 @@
+import { NestFactory } from '@nestjs/core';
+import { AppModule } from './app.module';
+import { setupSwagger } from './utils/swagger.utils';
+import { ValidationPipe } from '@nestjs/common';
+import { ResponseInterceptor } from './interceptors/response.interceptor';
+import { HttpExceptionFilter } from './filters/http-exception.filter';
+
+async function bootstrap() {
+  const app = await NestFactory.create(AppModule);
+  setupSwagger(app);
+  app.useGlobalPipes(
+    new ValidationPipe({
+      whitelist: true,
+      forbidNonWhitelisted: true,
+      transform: true,
+    }),
+  );
+  app.enableCors({
+    origin: 'http://localhost:5173',
+    credentials: true,
+  });
+  app.useGlobalInterceptors(new ResponseInterceptor());
+  app.useGlobalFilters(new HttpExceptionFilter());
+  await app.listen(process.env.PORT ?? 3000);
+}
+bootstrap();

src/types/book.types.ts

@@ -0,0 +1,53 @@
+export enum Genre {
+  Fiction = 'Fiction',
+  NonFiction = 'Non-Fiction',
+  Mystery = 'Mystery',
+  SciFi = 'Sci-Fi',
+  Fantasy = 'Fantasy',
+  Biography = 'Biography',
+  History = 'History',
+  Romance = 'Romance',
+  Thriller = 'Thriller',
+  Horror = 'Horror',
+  Poetry = 'Poetry',
+  Drama = 'Drama',
+  Comics = 'Comics',
+  Other = 'Other',
+}
+
+export enum BookStatus {
+  AVAILABLE = 'Available',
+  BORROWED = 'Borrowed',
+}
+
+export interface Book {
+  id: string;
+  title: string;
+  author: string;
+  pages: number;
+  year: number;
+  genre: Genre;
+  status: BookStatus;
+}
+
+export interface CreateBookRequest {
+  title: string;
+  author: string;
+  pages: number;
+  year: number;
+  genre: Genre;
+}
+
+export interface BorrowBookRequest {
+  bookIds: string[];
+  visitorId: string;
+  employeeId: string;
+  borrowDate: string;
+}
+
+export interface ReturnBookRequest {
+  bookIds: string[];
+  visitorId: string;
+  employeeId: string;
+  returnDate: string;
+}

src/types/worker.types.ts

@@ -0,0 +1,25 @@
+export enum DayOfWeek {
+  MONDAY = 'Monday',
+  TUESDAY = 'Tuesday',
+  WEDNESDAY = 'Wednesday',
+  THURSDAY = 'Thursday',
+  FRIDAY = 'Friday',
+  SATURDAY = 'Saturday',
+  SUNDAY = 'Sunday',
+}
+
+export interface Employee {
+  id: string;
+  name: string;
+  surname: string;
+  experience: number;
+  workDays: DayOfWeek[];
+  issuedBooks?: string[];
+}
+
+export interface CreateEmployeeRequest {
+  name: string;
+  surname: string;
+  experience: number;
+  workDays: DayOfWeek[];
+}

src/utils/crypto.utils.ts

@@ -0,0 +1,23 @@
+import { lzssEncode, lzssDecode } from './lzss.util';
+import {
+  encryptWithAlphabet,
+  decryptWithAlphabet,
+} from './offset-encryption.util';
+import { getOrCreateKey } from 'src/common/key-manager';
+
+export async function encryptData(data: string): Promise<string> {
+  const compressed = lzssEncode(data);
+  const key = await getOrCreateKey();
+  const encrypted = encryptWithAlphabet(compressed, key);
+
+  return encrypted;
+}
+
+export async function decryptData(encrypted: string): Promise<string> {
+  const key = await getOrCreateKey();
+  const decrypted = decryptWithAlphabet(encrypted, key);
+  const decompressed = lzssDecode(decrypted);
+  console.log('decompressed', decompressed);
+
+  return decompressed;
+}

src/utils/date.utils.ts

@@ -0,0 +1,26 @@
+export class DateUtils {
+  private static readonly DAY_NAMES = [
+    'Sunday',
+    'Monday',
+    'Tuesday',
+    'Wednesday',
+    'Thursday',
+    'Friday',
+    'Saturday',
+  ] as const;
+
+  private static readonly DAY_MAP = Object.fromEntries(
+    DateUtils.DAY_NAMES.map((day, index) => [index, day]),
+  );
+
+  public static getDayName(date: Date | string): string {
+    const dateObj = typeof date === 'string' ? new Date(date) : date;
+    const dayOfWeek = dateObj.getDay();
+    return this.DAY_MAP[dayOfWeek];
+  }
+
+  public static isWorkingDay(date: Date | string, workDays: string[]): boolean {
+    const dayName = this.getDayName(date);
+    return workDays.includes(dayName);
+  }
+}

src/utils/download.utils.ts

@@ -0,0 +1,16 @@
+import { StreamableFile } from '@nestjs/common';
+
+export function buildDownloadFile(
+  table: string,
+  id: string,
+  payload: unknown,
+): StreamableFile {
+  const content = JSON.stringify(payload, null, 2);
+  const buffer = Buffer.from(content, 'utf-8');
+  const safeTable = table.replace(/[^a-z0-9_-]/gi, '') || 'item';
+  const safeId = id.replace(/[^a-z0-9_-]/gi, '') || 'data';
+  return new StreamableFile(buffer, {
+    type: 'text/plain',
+    disposition: `attachment; filename="${safeTable}-${safeId}.txt"`,
+  });
+}

src/utils/file-manager.ts

@@ -0,0 +1,53 @@
+import * as fs from 'fs/promises';
+import * as path from 'path';
+// import { CryptoProvider } from './crypto.utils';
+
+export class FileManager {
+  constructor(
+    private readonly filePath: string,
+    // private readonly crypto = new CryptoProvider(),
+  ) {}
+
+  private async ensureFile(): Promise<void> {
+    const dir = path.dirname(this.filePath);
+
+    try {
+      await fs.stat(dir);
+    } catch {
+      await fs.mkdir(dir, { recursive: true });
+    }
+
+    try {
+      await fs.stat(this.filePath);
+    } catch {
+      await fs.writeFile(this.filePath, '', 'utf-8');
+    }
+  }
+
+  async readLines(): Promise<string[]> {
+    await this.ensureFile();
+    const data = await fs.readFile(this.filePath, 'utf-8');
+
+    if (!data) return [];
+
+    try {
+      // const decrypted = await this.crypto.decrypt(data);
+      return data
+        .split(/\r?\n/)
+        .map((line: string) => line.trim())
+        .filter(Boolean);
+    } catch {
+      return data
+        .split(/\r?\n/)
+        .map((line: string) => line.trim())
+        .filter(Boolean);
+    }
+  }
+
+  async writeLines(lines: string[]): Promise<void> {
+    await this.ensureFile();
+    const plain = lines.join('\n');
+    // const encrypted = await this.crypto.encrypt(plain);
+    await fs.writeFile(this.filePath, plain, 'utf-8');
+  }
+}

src/utils/file.utils.ts

@@ -0,0 +1,88 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+import { Link } from '../common/Link';
+import { decryptData, encryptData } from './crypto.utils';
+
+function isLinkString(value: string | undefined) {
+  if (!value) return false;
+  return /^[a-zA-Z]+:[^:]+$/.test(value);
+}
+
+function parseTxtRowInternal(row: string): any {
+  if (typeof row !== 'string') {
+    throw new Error('parseTxtRow: row is not string: ' + JSON.stringify(row));
+  }
+
+  const parts = row.split(';');
+  const obj: any = {};
+
+  for (const part of parts) {
+    const [key, rawValue] = part.split('=');
+    const value = rawValue?.trim();
+
+    if (!key) continue;
+
+    if (value?.startsWith('[') && value.includes(':')) {
+      const arr = JSON.parse(value) as string[];
+      obj[key] = arr.map((s: string) =>
+        isLinkString(s) ? Link.fromString(s) : s,
+      );
+      continue;
+    }
+    if (isLinkString(value)) {
+      obj[key] = Link.fromString(value);
+      continue;
+    }
+
+    if (value === '[]') {
+      obj[key] = [];
+      continue;
+    }
+
+    if (value?.startsWith('[') || value?.startsWith('{')) {
+      try {
+        obj[key] = JSON.parse(value) as unknown;
+        continue;
+      } catch {
+        obj[key] = value;
+      }
+    }
+
+    obj[key] = value;
+  }
+
+  return obj;
+}
+
+function serializeTxtRowInternal(obj: any): string {
+  return Object.entries(obj)
+    .map(([key, value]) => {
+      if (value instanceof Link) {
+        return `${key}=${value.toString()}`;
+      }
+
+      if (Array.isArray(value) && value.every((v) => v instanceof Link)) {
+        return `${key}=${JSON.stringify(value.map((v) => v.toString()))}`;
+      }
+
+      if (Array.isArray(value) && value.length === 0) {
+        return `${key}=[]`;
+      }
+
+      if (typeof value === 'object') {
+        return `${key}=${JSON.stringify(value)}`;
+      }
+
+      return `${key}=${value as string}`;
+    })
+    .join(';');
+}
+
+export async function parseTxtRow(encryptedRow: string): Promise<any> {
+  const decrypted = await decryptData(encryptedRow);
+  return parseTxtRowInternal(decrypted);
+}
+
+export async function serializeTxtRow(obj: any): Promise<string> {
+  const serialized = serializeTxtRowInternal(obj);
+  return await encryptData(serialized);
+}

src/utils/lzss.util.ts

@@ -0,0 +1,165 @@
+export interface LZSSMatch {
+  offset: number;
+  length: number;
+}
+
+export interface LZSSToken {
+  type: 'literal' | 'match';
+  value: string | LZSSMatch;
+}
+
+// Параметры LZSS
+const WINDOW_SIZE = 4096; // Размер окна поиска (12 бит)
+const LOOKAHEAD_SIZE = 18; // Размер буфера упреждения
+const MIN_MATCH_LENGTH = 3; // Минимальная длина совпадения
+
+export function lzssEncode(text: string): string {
+  if (!text) return '';
+
+  const tokens: LZSSToken[] = [];
+  let pos = 0;
+
+  while (pos < text.length) {
+    let bestMatch: LZSSMatch | null = null;
+    let bestLength = 0;
+
+    // Определяем начало окна поиска
+    const windowStart = Math.max(0, pos - WINDOW_SIZE);
+    const lookaheadEnd = Math.min(text.length, pos + LOOKAHEAD_SIZE);
+
+    // Ищем самое длинное совпадение в окне
+    for (let i = windowStart; i < pos; i++) {
+      let matchLength = 0;
+
+      // Считаем длину совпадения
+      while (
+        pos + matchLength < lookaheadEnd &&
+        text[i + matchLength] === text[pos + matchLength]
+      ) {
+        matchLength++;
+      }
+
+      // Если найдено лучшее совпадение
+      if (matchLength >= MIN_MATCH_LENGTH && matchLength > bestLength) {
+        bestLength = matchLength;
+        bestMatch = {
+          offset: pos - i,
+          length: matchLength,
+        };
+      }
+    }
+
+    if (bestMatch) {
+      tokens.push({
+        type: 'match',
+        value: bestMatch,
+      });
+      pos += bestMatch.length;
+    } else {
+      tokens.push({
+        type: 'literal',
+        value: text[pos],
+      });
+      pos++;
+    }
+  }
+
+  // Кодируем токены в бинарную строку
+  return encodeTokens(tokens);
+}
+
+function encodeTokens(tokens: LZSSToken[]): string {
+  let result = '';
+
+  for (const token of tokens) {
+    if (token.type === 'literal') {
+      // Флаг 1 означает литерал, затем 8 бит символа
+      result += '1';
+      const char = token.value as string;
+      const charCode = char.charCodeAt(0);
+      result += charCode.toString(2).padStart(16, '0'); // 16 бит для Unicode
+    } else {
+      // Флаг 0 означает совпадение
+      result += '0';
+      const match = token.value as LZSSMatch;
+      // 12 бит для смещения, 6 бит для длины (максимум 18+3=21)
+      result += match.offset.toString(2).padStart(12, '0');
+      result += (match.length - MIN_MATCH_LENGTH).toString(2).padStart(6, '0');
+    }
+  }
+
+  return result;
+}
+
+export function lzssDecode(encoded: string): string {
+  if (!encoded) return '';
+
+  let result = '';
+  let pos = 0;
+
+  while (pos < encoded.length) {
+    const flag = encoded[pos];
+    pos++;
+
+    if (flag === '1') {
+      // Литерал: читаем 16 бит
+      if (pos + 16 > encoded.length) {
+        console.error('Неполный литерал на позиции', pos);
+        break;
+      }
+      const charCode = parseInt(encoded.substring(pos, pos + 16), 2);
+      result += String.fromCharCode(charCode);
+      pos += 16;
+    } else if (flag === '0') {
+      // Совпадение: читаем 12 бит смещения и 6 бит длины
+      if (pos + 18 > encoded.length) {
+        console.error('Неполное совпадение на позиции', pos);
+        break;
+      }
+
+      const offset = parseInt(encoded.substring(pos, pos + 12), 2);
+      pos += 12;
+      const length =
+        parseInt(encoded.substring(pos, pos + 6), 2) + MIN_MATCH_LENGTH;
+      pos += 6;
+
+      // Копируем из уже декодированной части
+      const startPos = result.length - offset;
+
+      if (startPos < 0) {
+        console.error(
+          `Некорректное смещение: ${offset} на позиции результата ${result.length}`,
+        );
+        break;
+      }
+
+      for (let i = 0; i < length; i++) {
+        result += result[startPos + i];
+      }
+    } else {
+      console.error('Неизвестный флаг:', flag);
+      break;
+    }
+  }
+
+  return result;
+}
+
+// Функция для статистики сжатия
+export function getLZSSStats(
+  original: string,
+  encoded: string,
+): {
+  originalSize: number;
+  compressedSize: number;
+  compressionRatio: number;
+} {
+  const originalSize = original.length * 16; // 16 бит на символ (UTF-16)
+  const compressedSize = encoded.length;
+
+  return {
+    originalSize,
+    compressedSize,
+    compressionRatio: compressedSize / originalSize,
+  };
+}

src/utils/offset-encryption.util.ts

@@ -0,0 +1,55 @@
+export const CUSTOM_ALPHABET =
+  'abcdefghijklmnopqrstuvwxyz' +
+  'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
+  '0123456789' +
+  '.,;:=|!?()[]{}"\'-_/\\@#$%^&* ';
+
+const alphabetMap = new Map<string, number>();
+
+for (let i = 0; i < CUSTOM_ALPHABET.length; i++) {
+  alphabetMap.set(CUSTOM_ALPHABET[i], i + 1);
+}
+
+function getPos(char: string): number {
+  const pos = alphabetMap.get(char);
+  if (!pos) throw new Error(`Character "${char}" is missing in the alphabet`);
+  return pos;
+}
+
+function getChar(pos: number): string {
+  return CUSTOM_ALPHABET[pos - 1];
+}
+
+export function encryptWithAlphabet(text: string, key: string): string {
+  let result = '';
+  const N = CUSTOM_ALPHABET.length;
+
+  for (let i = 0; i < text.length; i++) {
+    const tPos = getPos(text[i]);
+    const kPos = getPos(key[i % key.length]);
+
+    let encPos = tPos + kPos;
+    if (encPos > N) encPos -= N;
+
+    result += getChar(encPos);
+  }
+
+  return result;
+}
+
+export function decryptWithAlphabet(encrypted: string, key: string): string {
+  let result = '';
+  const N = CUSTOM_ALPHABET.length;
+
+  for (let i = 0; i < encrypted.length; i++) {
+    const ePos = getPos(encrypted[i]);
+    const kPos = getPos(key[i % key.length]);
+
+    let decPos = ePos - kPos;
+    if (decPos <= 0) decPos += N;
+
+    result += getChar(decPos);
+  }
+
+  return result;
+}

src/utils/response-wrapper.utils.ts

@@ -0,0 +1,11 @@
+export interface ErrorResponse {
+  message: string;
+  code?: string;
+  statusCode?: number;
+}
+
+export interface ApiResponse<T> {
+  data?: T | null;
+  successful: boolean;
+  error?: ErrorResponse | null;
+}

src/utils/swagger.utils.ts

@@ -0,0 +1,10 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+import type { INestApplication } from '@nestjs/common';
+import { SwaggerModule } from '@nestjs/swagger';
+import { getSwaggerConfig } from 'src/config/swagger.config';
+
+export function setupSwagger(app: INestApplication) {
+  const config = getSwaggerConfig();
+  const document = SwaggerModule.createDocument(app, config);
+  SwaggerModule.setup('/api/docs', app, document);
+}

src/visitor/dto/create-visitor.dto.ts

@@ -0,0 +1,20 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { IsNotEmpty, IsString, Length } from 'class-validator';
+
+export class CreateVisitorDto {
+  @ApiProperty({ description: 'Visitor first name', example: 'John' })
+  @IsString()
+  @IsNotEmpty()
+  @Length(2, 50)
+  name: string;
+
+  @ApiProperty({ description: 'Visitor surname', example: 'Doe' })
+  @IsString()
+  @IsNotEmpty()
+  @Length(2, 50)
+  surname: string;
+
+  // @ApiProperty({ description: 'Registration date', example: '2025-11-26' })
+  // @IsDateString()
+  // registrationDate: string;
+}

src/visitor/dto/update-visitor.dto.ts

@@ -0,0 +1,20 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { IsString, Length } from 'class-validator';
+
+export class UpdateVisitorDto {
+  @ApiProperty({
+    description: 'Visitor first name',
+    example: 'John',
+  })
+  @IsString()
+  @Length(2, 50)
+  name?: string;
+
+  @ApiProperty({
+    description: 'Visitor surname',
+    example: 'Doe',
+  })
+  @IsString()
+  @Length(2, 50)
+  surname?: string;
+}

src/visitor/dto/visitor.dto.ts

@@ -0,0 +1,48 @@
+import { ApiProperty } from '@nestjs/swagger';
+import {
+  IsString,
+  IsNotEmpty,
+  Length,
+  IsDateString,
+  IsArray,
+  ValidateNested,
+} from 'class-validator';
+import { Type } from 'class-transformer';
+import { Link } from 'src/common/Link';
+
+export class Visitor {
+  @ApiProperty({
+    description: 'Visitor ID',
+    example: '123e4567-e89b-12d3-a456-426614174000',
+  })
+  @IsString()
+  id: string;
+
+  @ApiProperty({ description: 'Visitor first name', example: 'John' })
+  @IsString()
+  @IsNotEmpty()
+  @Length(2, 50)
+  name: string;
+
+  @ApiProperty({ description: 'Visitor surname', example: 'Doe' })
+  @IsString()
+  @IsNotEmpty()
+  @Length(2, 50)
+  surname: string;
+
+  @ApiProperty({ description: 'Registration date', example: '2025-11-26' })
+  @IsDateString()
+  registrationDate: Date;
+
+  @ApiProperty({ description: 'Currently borrowed books', type: [Link] })
+  @IsArray()
+  @ValidateNested({ each: true })
+  @Type(() => Link)
+  currentBooks: Link[];
+
+  @ApiProperty({ description: 'History of returned books', type: [Link] })
+  @IsArray()
+  @ValidateNested({ each: true })
+  @Type(() => Link)
+  history: Link[];
+}

src/visitor/visitor.controller.ts

@@ -0,0 +1,52 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Patch,
+  Delete,
+  Body,
+  Param,
+} from '@nestjs/common';
+import { VisitorService } from './visitor.service';
+import { Visitor } from './dto/visitor.dto';
+import { CreateVisitorDto } from './dto/create-visitor.dto';
+import { UpdateVisitorDto } from './dto/update-visitor.dto';
+import { buildDownloadFile } from 'src/utils/download.utils';
+
+@Controller('visitors')
+export class VisitorController {
+  constructor(private readonly visitorService: VisitorService) {}
+
+  @Get('all')
+  async getAll(): Promise<Visitor[]> {
+    return this.visitorService.getAll();
+  }
+
+  @Get(':id/download')
+  async download(@Param('id') id: string) {
+    const visitor = await this.visitorService.getById(id);
+    return buildDownloadFile('visitors', id, visitor);
+  }
+
+  @Post('create')
+  async create(@Body() dto: CreateVisitorDto): Promise<Visitor> {
+    return this.visitorService.add(dto);
+  }
+  @Get(':id')
+  async getById(@Param('id') id: string): Promise<Visitor> {
+    return this.visitorService.getById(id);
+  }
+
+  @Patch(':id')
+  async update(
+    @Param('id') id: string,
+    @Body() dto: UpdateVisitorDto,
+  ): Promise<Visitor> {
+    return this.visitorService.update(id, dto);
+  }
+
+  @Delete('delete/:id')
+  async remove(@Param('id') id: string): Promise<void> {
+    return this.visitorService.delete(id);
+  }
+}

src/visitor/visitor.module.ts

@@ -0,0 +1,13 @@
+import { Module, forwardRef } from '@nestjs/common';
+import { VisitorController } from './visitor.controller';
+import { VisitorService } from './visitor.service';
+import { VisitorLinkManager } from 'src/common/visitor-link-manager';
+import { BookModule } from '../book/book.module';
+
+@Module({
+  imports: [forwardRef(() => BookModule)],
+  controllers: [VisitorController],
+  providers: [VisitorService, VisitorLinkManager],
+  exports: [VisitorService, VisitorLinkManager],
+})
+export class VisitorModule {}

src/visitor/visitor.service.ts

@@ -0,0 +1,138 @@
+/* eslint-disable prettier/prettier */
+import {
+  Injectable,
+  NotFoundException,
+  BadRequestException,
+} from '@nestjs/common';
+import { FileManager } from 'src/utils/file-manager';
+import { parseTxtRow, serializeTxtRow } from 'src/utils/file.utils';
+import { Visitor } from './dto/visitor.dto';
+import { randomUUID } from 'crypto';
+import { CreateVisitorDto } from './dto/create-visitor.dto';
+import { UpdateVisitorDto } from './dto/update-visitor.dto';
+import { Book } from 'src/book/dto/book.dto';
+import { bookLinkManager } from 'src/common/book-link-manager';
+import { VisitorLinkManager } from 'src/common/visitor-link-manager';
+import { Link } from 'src/common/Link';
+
+@Injectable()
+export class VisitorService {
+  private file = new FileManager('src/data/visitors.txt');
+  private visitorLinkManager: VisitorLinkManager = new VisitorLinkManager();
+
+  async getAll(): Promise<Visitor[]> {
+    const lines = await this.file.readLines();
+    return lines.map(parseTxtRow) as unknown as Visitor[];
+  }
+
+  async getById(id: string): Promise<Visitor> {
+    const allVisitors = await this.getAll();
+    const visitor = allVisitors.find((v) => v.id === id);
+    if (!visitor) {
+      throw new NotFoundException(`Visitor with id ${id} not found`);
+    }
+
+    return this.visitorLinkManager.enrich(visitor);
+  }
+
+  async add(dto: CreateVisitorDto): Promise<Visitor> {
+    const newVisitor: Visitor = {
+      id: randomUUID(),
+      name: dto.name.trim(),
+      surname: dto.surname.trim(),
+      registrationDate: new Date(),
+      currentBooks: [],
+      history: [],
+    };
+
+    const lines = await this.file.readLines();
+    lines.push(await serializeTxtRow(newVisitor));
+    await this.file.writeLines(lines);
+
+    return newVisitor;
+  }
+
+  async update(id: string, dto: UpdateVisitorDto): Promise<Visitor> {
+    const visitors = await this.getAll();
+    const index = visitors.findIndex((v) => v.id === id);
+    if (index === -1)
+      throw new NotFoundException(`Visitor with id ${id} not found`);
+
+    visitors[index] = { ...visitors[index], ...dto };
+    await this.file.writeLines(
+      await Promise.all(visitors.map((visitor) => serializeTxtRow(visitor))),
+    );
+    return visitors[index];
+  }
+
+  async delete(id: string): Promise<void> {
+    const visitors = await this.getAll();
+    const index = visitors.findIndex((v) => v.id === id);
+    if (index === -1)
+      throw new NotFoundException(`Visitor with id ${id} not found`);
+
+    if (visitors[index].currentBooks.length > 0) {
+      throw new BadRequestException(
+        'Cannot delete visitor with unreturned books',
+      );
+    }
+
+    visitors.splice(index, 1);
+    await this.file.writeLines(
+      await Promise.all(visitors.map((visitor) => serializeTxtRow(visitor))),
+    );
+  }
+
+  async addCurrentBooks(visitorId: string, books: Book[]): Promise<void> {
+    const visitors = await this.getAll();
+    const visitorIndex = visitors.findIndex((v) => v.id === visitorId);
+
+    if (visitorIndex === -1) {
+      throw new BadRequestException(`Visitor with id ${visitorId} not found`);
+    }
+
+    visitors[visitorIndex].currentBooks.push(
+      ...books.map((b) => bookLinkManager.toLink(b.id)),
+    );
+    await this.file.writeLines(
+      await Promise.all(visitors.map((visitor) => serializeTxtRow(visitor))),
+    );
+  }
+
+  async moveToHistory(visitorId: string, books: Book[]): Promise<void> {
+    const visitors = await this.getAll();
+    const visitorIndex = visitors.findIndex((v) => v.id === visitorId);
+
+    if (visitorIndex === -1) {
+      throw new BadRequestException(`Visitor with id ${visitorId} not found`);
+    }
+
+    const visitor = visitors[visitorIndex];
+
+    for (const book of books) {
+      const currentBookIndex = visitor.currentBooks.findIndex(
+        (b) => b.id === book.id,
+      );
+
+      if (currentBookIndex === -1) {
+        throw new BadRequestException(
+          `Visitor does not have book "${book.title}"`,
+        );
+      }
+
+      const [removedBook] = visitor.currentBooks.splice(currentBookIndex, 1);
+      visitor.history.push(removedBook);
+    }
+
+    await this.file.writeLines(
+      await Promise.all(visitors.map((visitor) => serializeTxtRow(visitor))),
+    );
+  }
+
+  async hasBook(visitorId: string, bookId: string): Promise<boolean> {
+    const visitor = await this.getById(visitorId);
+    if (!visitor) return false;
+
+    return visitor.currentBooks.some((b: Link) => b.id === bookId);
+  }
+}