public List<Book> getBooks(Set<Integer> isbnSet) throws BookStoreException {
if (isbnSet == null) {
throw new BookStoreException(BookStoreConstants.NULL_INPUT);
}
List<Book> listBooks = new ArrayList<Book>();
try {
bsLock.readLock().lock();
// Check that all ISBNs that we rate are there first.
for (Integer ISBN : isbnSet) {
if (BookStoreUtility.isInvalidISBN(ISBN))
throw new BookStoreException(BookStoreConstants.ISBN + ISBN + BookStoreConstants.INVALID);
if (!bookMap.containsKey(ISBN))
throw new BookStoreException(
BookStoreConstants.ISBN + ISBN + BookStoreConstants.NOT_AVAILABLE);
}
// Get the books
for (Integer ISBN : isbnSet) {
listBooks.add(bookMap.get(ISBN).immutableBook());
}
} finally {
bsLock.readLock().unlock();
}
return listBooks;
}
public List<StockBook> getBooks() {
List<StockBook> listBooks = new ArrayList<StockBook>();
try {
bsLock.readLock().lock();
Collection<BookStoreBook> bookMapValues = bookMap.values();
for (BookStoreBook book : bookMapValues) {
listBooks.add(book.immutableStockBook());
}
} finally {
bsLock.readLock().unlock();
}
return listBooks;
}
@Override
public List<Book> getTopRatedBooks(int numBooks) throws BookStoreException {
// TODO Auto-generated method stub
// No negative number
if (numBooks <= 0) {
throw new BookStoreException("numBooks = " + numBooks + ", but it must be positive");
}
Collection<BookStoreBook> books = bookMap.values();
if (books.isEmpty()) {
throw new BookStoreException("No books in the bookstore");
}
List<BookStoreBook> listRatedBooks = new ArrayList<BookStoreBook>();
List<Book> listTopRatedBooks = new ArrayList<Book>();
try {
bsLock.readLock().lock(); // block other from writing data
// we only count the book has a rating
for (BookStoreBook book : books) {
if (book.getAverageRating() > 0) listRatedBooks.add(book);
}
Comparator<BookStoreBook> comparator =
new Comparator<BookStoreBook>() {
public int compare(BookStoreBook book1, BookStoreBook book2) {
return Float.compare(
book2.getAverageRating(), book1.getAverageRating()); // get right order of books
}
};
Collections.sort(listRatedBooks, comparator);
for (BookStoreBook book : listRatedBooks) {
listTopRatedBooks.add(book.immutableStockBook());
if (listTopRatedBooks.size() == numBooks) break;
}
} finally {
bsLock.readLock().unlock();
}
// return the certain amount of books by its rating
return listTopRatedBooks;
}
public List<Book> getEditorPicks(int numBooks) throws BookStoreException {
if (numBooks < 0) {
throw new BookStoreException("numBooks = " + numBooks + ", but it must be positive");
}
List<BookStoreBook> listAllEditorPicks = new ArrayList<BookStoreBook>();
List<Book> listEditorPicks = new ArrayList<Book>();
try {
bsLock.readLock().lock();
Iterator<Entry<Integer, BookStoreBook>> it = bookMap.entrySet().iterator();
BookStoreBook book;
// Get all books that are editor picks
while (it.hasNext()) {
Entry<Integer, BookStoreBook> pair = (Entry<Integer, BookStoreBook>) it.next();
book = (BookStoreBook) pair.getValue();
if (book.isEditorPick()) {
listAllEditorPicks.add(book);
}
}
// Find numBooks random indices of books that will be picked
Random rand = new Random();
Set<Integer> tobePicked = new HashSet<Integer>();
int rangePicks = listAllEditorPicks.size();
if (rangePicks < numBooks) {
throw new BookStoreException("Only " + rangePicks + " editor picks are available.");
}
int randNum;
while (tobePicked.size() < numBooks) {
randNum = rand.nextInt(rangePicks);
tobePicked.add(randNum);
}
// Get the numBooks random books
for (Integer index : tobePicked) {
book = listAllEditorPicks.get(index);
listEditorPicks.add(book.immutableBook());
}
} finally {
bsLock.readLock().unlock();
}
return listEditorPicks;
}
