main.js

function counter() {
    let count = 0;
    function increment() {
        count += 1;
        return count;
    }
    return increment;
}

const generateId = counter();

function Book(title, author, category = "General", year = new Date().getFullYear()) {
    this.id = generateId();
    this.title = title;
    this.author = author;
    this.category = category;
    this.year = year;
    this.location = {shelf: "", floor: 1};
}

function createBook(title, author, category = "General", year = new Date().getFullYear()) {
    return {
        id: generateId(),
        title,
        author,
        category,
        year,
        location : {
            shelf: "",
            floor: 1
        }
    };
}

const library = [];
// ...books: rest argument that accepts any number of book objects
function addBooks(...books) {
    books.forEach(book => library.push(book));
}

// ...args: rest argument that accepts any number of arguments
function randomPicker(...args) {
    // Generate a random index based on the length of the args array
    return args[Math.floor(Math.random() * args.length)];
}

const logBook = function(book) {
    console.log(`
        --------------------------
        ID: ${book.id}
        Title: ${book.title}
        Author: ${book.author}
        Category: ${book.category}
        Year: ${book.year}
        Location : Floor ${book.location.floor}, Shelf ${book.location.shelf}
        --------------------------`);
};

const getBookById = (id => library.find(book => book.id === id));

const getBooksOlderThan10Years = () => {
    const currentYear = new Date().getFullYear();
    return library.filter(book => currentYear - book.year > 10);
};

function getTitles() {
    return library.map(book => book.title);
};

function filterByCategory(category) {
    return library.filter(book => book.category.toLowerCase() === category.toLowerCase());   
}

function countBooksByAuthor() {
    return library.reduce((accumulator, book) => {
        accumulator[book.author] = (accumulator[book.author] || 0) + 1; 
        return accumulator;
    }, {});
}

function printAllBooks() {
    console.log(`All Books in the Library`);
    console.log(`=========================`);
    library.forEach(book => logBook(book));
    console.log(`=========================`);
}

function searchBooks(keyword) {
    const loweredKeyword = keyword.toLowerCase();
    return library.filter(book => book.title.toLowerCase().includes(loweredKeyword) || 
                                    book.author.toLowerCase().includes(loweredKeyword)
);
}

function libraryStats() {
    const totalBooks = library.length;

    function getDetails() {
        const authors = [...new Set(library.map(book => book.author))].join(", ");
        const categories = [...new Set(library.map(book => book.category))].join(", ");

        function printDetails() {
            console.log(`Total Books: ${totalBooks}`);
            console.log(`Authors: ${authors}`);
            console.log(`Categories: ${categories}`);
        }
        printDetails();
    }
    getDetails();
}

const LibraryManagerPrototype = {
    info() {
        console.log(`Library Manager: ${this.name}, Managed Since: ${this.since}`);
    }
};

const LibraryManager = Object.create(LibraryManagerPrototype);
LibraryManager.name = "Ahmed Ali";
LibraryManager.since = 2010;

const defaultSettings = {
    maxBooksPerUser: 3,
    loanDurationDays: 14,
    theme: "light",
    language: "English"
}

function applySettings(userSettings = {}) {
    return Object.assign({}, defaultSettings, userSettings);
}

console.log("================   Library Management System   ================");

console.log("Create Book using createBook() function:");
const book1 = createBook("Romeo and Juliet", "Shakespeare", "Drama",1597);
// access properties using Dot Notation
book1.location.shelf = "B2";
book1.location.floor = 2;

console.log("Create Book using new with Book() Constructor:");
const book2 = new Book("Harry Potter", "J.K. Rowling", "Fantasy", 1997);
// access properties using Bracket Notation
book2["location"]["shelf"] = "A1";

console.log("Create Book using Object Literal Notation");
const book3 = {
    id: generateId(),
    title: "Math For Beginners",
    author: "John Smith",
    category: "Education",
    year: 2010,
    location: {shelf: "C1", floor: 3}
};

console.log("Create Book using Object.create()");
const book4 = Object.create(book3);
book4.id = generateId();
book4.title = "Learn JavaScript";
book4.year = 2015;
book4.location = {shelf: "C2", floor: 3};

console.log("Create Book using Object.assign()");
const book5 = Object.assign({}, book1, {
    id : generateId(),
    title: "Hamlet",
    year: 1603,
    location: {shelf: "B1", floor: 2}
});

const book6 = createBook("The Lion King", "Walt Disney", "Fantasy");
book6.location.shelf = "A1";

console.log("Adding all books to Library object");
addBooks(book1, book2, book3, book4, book5, book6);

// Print All Books;
printAllBooks();

console.log("Library Statistics");
libraryStats();

const randomBook = randomPicker(book1, book2, book3, book4, book5, book6);
console.log("Random Book Picked:");
logBook(randomBook);

// prompt user to enter book id, and search for a book with this id
let validatedId;
while(true) {
    const rowId = prompt("Enter Book ID: ");
    const cleanedId = (rowId ?? "").trim();

    if(cleanedId === "") {
        alert("Book ID cannot be empty. Re enter a valid value.");
        continue;
    }

    const parsedId = Number(cleanedId);
    if(isNaN(parsedId)) {
        alert("Book ID must be a number. Re enter a valid value");
        continue;
    }

    if(!Number.isInteger(parsedId)) {
        alert("Book ID must be an integer value. Re enter a valid value");
        continue;
    }
    validatedId = parsedId;
    break;
}

console.log(`Search Result for Book ID ${validatedId}`);
const foundBook = getBookById(validatedId);
foundBook ? logBook(foundBook) : console.log(`Book is not found`);

console.log("Books Older than 10 years:");
const booksOlderThan10Years = getBooksOlderThan10Years();
booksOlderThan10Years.forEach(book => logBook(book));

console.log("All Books Titles:");
console.log(getTitles().join(", "));

console.log(`Books in "Education" Category:`);
filterByCategory("Education").forEach(book => logBook(book));

console.log("Book Count by Author:");
console.log(countBooksByAuthor());

console.log("Search Results for Author: John smith");
searchBooks("John smith").forEach(book => logBook(book));

// Print Library Manager Information;
LibraryManager.info();

const activeSettings = applySettings({maxBooksPerUser: 4, language: "Arabic"});
console.log("Active Library Settings: ");
console.log(activeSettings);