<?php
/**
* BookStore has single coopies of books
*/
class BookStore {
	private $books = array();

	/**
	* @param Book book, book to be added
	* @return boolean true if book was added, false if book was in store...
	*/
	public function addBook(Book $book) {
		if ($this->isBookInStore($book))
			return false;

		//Add book to the end of the array
		$this->books[] = $book;

		return true;
	}

	/**
	* @param Book book, book to be compared to Store
	* @return boolean true if book exists in store
	*/
	private function isBookInStore(Book $book) {
		//isBookin store
		foreach ($this->books as $inStoreBook) {
			if ($inStoreBook->isSame($book)) {
				return true;
			}
		}
		return false;
	}
}

//Testcase
$store = new BookStore();
$bookUnlimited = new Book("Daniel", "PHP Unlimited", "123456");

$bookWasInStore = $store->AddBook($bookUnlimited);
assert($bookWasInStore);

//Add the same book again
$bookWasInStore = $store->AddBook($bookUnlimited);
assert(!$bookWasInStore);