03. School Library

function library(arr) {
    let library = arr.shift().split("&");
    let indexOfBook;
    let indexOfSecondBook;

    for (let token of arr) {
        if (token === "Done" || "") {
            // do nothing
        }

        token = token.split(" | ");
        let action = token.shift();
        let book = token.shift();

        if (action === "Add Book" && !check(book)) {
            library.unshift(book)

        } else if (action === "Take Book" && check(book)) {
            let indexOfBook = library.indexOf(book);
            library.splice(indexOfBook, 1);

        } else if (action === "Swap Books" && check(book) && check(token[0])) {
            let secondBook = token.shift();
            indexOfBook = library.indexOf(book);
            indexOfSecondBook = library.indexOf(secondBook);
            library.splice(indexOfBook, 1, secondBook);
            library.splice(indexOfSecondBook, 1, book);

        } else if (action === "Insert Book" && !check(book)) {
            library.push(book);

        } else if (action === "Check Book" && 0 <= book && book < library.length) {
            console.log(library[book]);

        }
    }
    return library.join(", ")
    function check(checkedItem) {
        if (library.includes(checkedItem)) {
            return true;
        } else {
            return false;
        }
    }
}

// console.log(library([
//     'Don Quixote&The Great Gatsby&Moby Dick&Hamlet',
//     'Add Book | The Odyssey',
//     'Take Book | Don Quixote',
//     "Insert Book | Alice's Adventures in Wonderland",
//     'Check Book | 3',
//     'Done',
//     '',
//     '',
//     ''
//   ]));
// console.log(library([
//     'Anna Karenina&Heart of Darkness&Catch-22& The Stranger',
//     'Add Book | David Copperfield',
//     'Add Book | One Thousand and One Nights',
//     'Swap Books | One Thousand and One Nights | Catch-22',
//     'Take Book | David Copperfield',
//     'Insert Book | The Stories of Anton Chekhov',
//     'Check Book | 17',
//     'Done',
//     ''
//   ]));