class LibraryCollection{
    constructor(capacity){
        this.capacity=capacity;
        this.books=[];
    }
    addBook (bookName, bookAuthor){
        if(this.books.length > this.capacity){
            throw Error('Not enough space in the collection.');
        }else{

            let book={
                bookName:bookName,
                bookAuthor:bookAuthor,
                payed: false,
            }

            this.books.push(book)

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

    payBook( bookName ) {
        if(!this.books.some(x => x.bookName == bookName)){
            throw new Error(`${bookName} is not in the collection.`)
        }
        if (this.books.some(x => x.payed == true)) {
         throw new Error(`${bookName} has already been paid.`)
        }else{

            let book = this.books.some(x => x.bookName == bookName);
            this.book.payed = true;
            return `${bookName} has been successfully paid.`;
        }
    }

    removeBook(bookName) {
        if(!this.books.some(x => x.bookName == bookName)){
            throw new Error(`The book, you're looking for, is not found.`);
        }
        if (this.books.some(x => x.payed == false)) {
            throw new Error(`${bookName} need to be paid before removing from the collection.`);
        }else{
            this.books=this.books.filter(x => x.bookName != bookName);
            return `${bookName} remove from the collection.`;
        }
    }
}