02. Library Collection

class LibraryCollection {
    constructor(capacity) {
        this.capacity = capacity;
        this.books = [];
    }

    addBook(bookName, bookAuthor) {
        if (this.books.length == this.capacity) {
            throw new Error("Not enough space in the collection.");
        } else {
            this.books.push({
                bookName,
                bookAuthor,
                payed: false,
            });

            return `The ${bookName}, with an author ${bookAuthor}, collect.`;
        }
    }

    payBook(bookName) {
        let book = this.books.find((b) => b.bookName == bookName);

        if (!book) {
            throw new Error(`${bookName} is not in the collection.`);
        }

        // check if book is alredy paid
        if (book.payed) {
            throw new Error(`${bookName} has already been paid.`);
        }

        book.payed = true;
        return `${bookName} has been successfully paid.`;
    }

    removeBook(bookName) {
        let book = this.books.find((b) => b.bookName == bookName);
        if (!book) {
            throw new Error("The book, you're looking for, is not found.");
        }

        if (book.payed == false) {
            throw new Error(
                `${bookName} need to be paid before removing from the collection.`
            );
        } else {
            for (const b of this.books) {
                delete book.bookName;
                return `${bookName} remove from the collection.`;
            }
        }
    }

    getStatistics(bookAuthor) {
        let isPayed;

        if (bookAuthor) {
            if (!this.books.find(b => b.bookAuthor == bookAuthor)) {
                throw new Error(`${bookAuthor} is not in the collection.`);
            }

            // you need to return array of all books by given author
            const booksByAuthor = [];

            this.books.map(b => b.bookAuthor == bookAuthor);

            for (const book of this.books) {
                if (book.payed) {
                    isPayed = "Has Paid";
                } else {
                    isPayed = "Not Paid";
                }

                booksByAuthor.push(
                    `${book.bookName} == ${book.bookAuthor} - ${isPayed}.`
                );
            }

            return booksByAuthor.join("\n");
        } else {
            let resultArr = [
                `The book collection has ${this.capacity - this.books.length
                } empty spots left.`,
            ];
            let sortedNames = this.books.sort((a, b) =>
                a.bookName.localeCompare(b.bookName)
            );
            for (const sortedBook of sortedNames) {
                if (sortedBook.payed) {
                    isPayed = "Has Paid";
                } else {
                    isPayed = "Not Paid";
                }
                resultArr.push(
                    `${sortedBook.bookName} == ${sortedBook.bookAuthor} - ${isPayed}.`
                );
            }
            return resultArr.join("\n");
        }
    }
}