Untitled

class Book {
    constructor(title, author, year) {
        this.title = title;
        this.author = author;
        this.year = year;
    }

    toString() {
        return `Title: ${this.title}, Author: ${this.author}, Year: ${this.year}`;
    }
}

class BookLibrary {

    constructor() {
        this.books = new Map();
    }

    addBook(title, author, year) {
        const key = this.generateKey(title, author);

        if (this.books.has(key)) {
            throw new Error('Book already exists in library.');
        }

        this.books.set(key, new Book(title, author, year))
    }

    findBooks({ title, author }) {
        return this.toArray().filter(book => {
            const titleMatches = !title
                || book.title.toLowerCase().includes(title.toLowerCase());

            const authorMatches = !author
                || book.author.toLowerCase().includes(author.toLowerCase());
                
            return titleMatches && authorMatches;
        });
    }

    findByTitle(title) {
        return this.findBooks({ title });
    }

    findByAuthor(author) {
        return this.findBooks({ author });
    }

    listAllBooks() {
        const array = this.toArray();

        if (!array.length) {
            console.log('No books available.');
        } else {
            array.forEach(book => console.log(book.toString()));
        }
    }

    toArray() {
        return Array.from(this.books.values());
    }

    generateKey(title, author) {
        return `${author.toLowerCase()}-${title.toLowerCase()}`;
    }
}