library/api/src/app/services/book.service.ts

/**
 * @copyright 2026 NHCarrigan
 * @license Naomi's Public License
 * @author Naomi Carrigan
 */

import { Book, BookStatus, CreateBookDto, UpdateBookDto } from "@library/shared-types";
import { prisma } from "../lib/prisma";
import {
  validateUrl,
  validateRating,
  validateStringLength,
  validateDataUrl,
  MAX_LENGTHS,
} from "../utils/validation";

export class BookService {
  private prisma = prisma;

  constructor() {}

  /**
   * Validate book data for security.
   */
  private validateBookData(data: CreateBookDto | UpdateBookDto): void {
    // Validate string lengths
    if (!validateStringLength(data.title, MAX_LENGTHS.TITLE)) {
      throw new Error(`Title must be ${MAX_LENGTHS.TITLE} characters or less.`);
    }
    if (!validateStringLength(data.author, MAX_LENGTHS.AUTHOR)) {
      throw new Error(`Author must be ${MAX_LENGTHS.AUTHOR} characters or less.`);
    }
    if (!validateStringLength(data.isbn, MAX_LENGTHS.ISBN)) {
      throw new Error(`ISBN must be ${MAX_LENGTHS.ISBN} characters or less.`);
    }
    if (!validateStringLength(data.notes, MAX_LENGTHS.NOTES)) {
      throw new Error(`Notes must be ${MAX_LENGTHS.NOTES} characters or less.`);
    }
    // Validate rating
    if (!validateRating(data.rating)) {
      throw new Error("Rating must be an integer between 0 and 10.");
    }

    if (data.coverImage) {
      if (data.coverImage.startsWith("data:")) {
        const base64Data = data.coverImage.split(",")[1];
        if (!base64Data) {
          throw new Error("Invalid image data URL format.");
        }
        const sizeInBytes = base64Data.length * 0.75;
        if (sizeInBytes > MAX_LENGTHS.DATA_URL) {
          throw new Error("Cover image must be under 5MB.");
        }
        if (!validateDataUrl(data.coverImage)) {
          throw new Error("Invalid image data URL.");
        }
      } else {
        if (!validateStringLength(data.coverImage, MAX_LENGTHS.URL)) {
          throw new Error(`Cover image URL must be ${MAX_LENGTHS.URL} characters or less.`);
        }
        if (!validateUrl(data.coverImage)) {
          throw new Error("Invalid cover image URL. Only http and https URLs are allowed.");
        }
      }
    }

    // Validate tags
    if (data.tags) {
      for (const tag of data.tags) {
        if (!validateStringLength(tag, MAX_LENGTHS.TAGS)) {
          throw new Error(`Each tag must be ${MAX_LENGTHS.TAGS} characters or less.`);
        }
      }
    }

    // Validate link URLs
    if (data.links) {
      for (const link of data.links) {
        if (!validateUrl(link.url)) {
          throw new Error(`Invalid link URL: ${link.title}. Only http and https URLs are allowed.`);
        }
        if (!validateStringLength(link.title, MAX_LENGTHS.TITLE)) {
          throw new Error(`Link title must be ${MAX_LENGTHS.TITLE} characters or less.`);
        }
        if (!validateStringLength(link.url, MAX_LENGTHS.URL)) {
          throw new Error(`Link URL must be ${MAX_LENGTHS.URL} characters or less.`);
        }
      }
    }
  }

  /**
   * Get all books.
   */
  async getAllBooks(): Promise<Book[]> {
    const books = await this.prisma.book.findMany({
      orderBy: { updatedAt: "desc" },
    });

    return books.map((book) => ({
      ...book,
      status: book.status as unknown as BookStatus,
      dateAdded: book.dateAdded,
      dateStarted: book.dateStarted || undefined,
      dateFinished: book.dateFinished || undefined,
      tags: book.tags ?? [],
      links: book.links ?? [],
      createdAt: book.createdAt,
      updatedAt: book.updatedAt,
    }));
  }

  /**
   * Get book by ID.
   */
  async getBookById(id: string): Promise<Book | null> {
    const book = await this.prisma.book.findUnique({
      where: { id },
    });

    if (!book) return null;

    return {
      ...book,
      status: book.status as unknown as BookStatus,
      dateAdded: book.dateAdded,
      dateStarted: book.dateStarted || undefined,
      dateFinished: book.dateFinished || undefined,
      tags: book.tags ?? [],
      links: book.links ?? [],
      createdAt: book.createdAt,
      updatedAt: book.updatedAt,
    };
  }

  /**
   * Get all books in a series, ordered by seriesOrder.
   */
  async getBooksBySeries(seriesName: string): Promise<Book[]> {
    const books = await this.prisma.book.findMany({
      where: { series: seriesName },
      orderBy: { seriesOrder: "asc" },
    });

    return books.map((book) => ({
      ...book,
      status: book.status as unknown as BookStatus,
      dateAdded: book.dateAdded,
      dateStarted: book.dateStarted || undefined,
      dateFinished: book.dateFinished || undefined,
      tags: book.tags ?? [],
      links: book.links ?? [],
      createdAt: book.createdAt,
      updatedAt: book.updatedAt,
    }));
  }

  /**
   * Create new book.
   */
  async createBook(data: CreateBookDto): Promise<Book> {
    // Validate input
    this.validateBookData(data);

    const book = await this.prisma.book.create({
      data: {
        ...data,
        status: data.status.toUpperCase() as any,
      },
    });

    return {
      ...book,
      status: book.status as unknown as BookStatus,
      dateAdded: book.dateAdded,
      dateStarted: book.dateStarted || undefined,
      dateFinished: book.dateFinished || undefined,
      tags: book.tags ?? [],
      links: book.links ?? [],
      createdAt: book.createdAt,
      updatedAt: book.updatedAt,
    };
  }

  /**
   * Update book by ID.
   */
  async updateBook(id: string, data: UpdateBookDto): Promise<Book> {
    // Validate input
    this.validateBookData(data);

    const updateData = { ...data };
    if (updateData.status) {
      updateData.status = updateData.status.toUpperCase() as any;
    }

    const book = await this.prisma.book.update({
      where: { id },
      data: updateData,
    });

    return {
      ...book,
      status: book.status as unknown as BookStatus,
      dateAdded: book.dateAdded,
      dateStarted: book.dateStarted || undefined,
      dateFinished: book.dateFinished || undefined,
      tags: book.tags ?? [],
      links: book.links ?? [],
      createdAt: book.createdAt,
      updatedAt: book.updatedAt,
    };
  }

  /**
   * Delete book by ID.
   */
  async deleteBook(id: string): Promise<void> {
    await this.prisma.book.delete({
      where: { id },
    });
  }
}