package flyweight;
import java.util.HashMap;

public class Data {
	private Data() {}
	private static HashMap<Integer,Video> hashmap = new HashMap<Integer,Video>();

	private static int hash3 (Object key1, Object key2, Object key3) {
		return key1.hashCode () + 5 * key2.hashCode () + 13 * key3.hashCode ();
	}

	/**
	 * Creates and manages flyweight objects. Ensures that flyweights
	 * are shared properly.  When a client requests a flyweight, the
	 * Flyweight Factory object supplies an existing instance or
	 * creates one, if none exists.
	 */
	static public Video getVideo(String title, int year, String director) {
		if (  (title == null)
				|| (director == null)
				|| (year <= 1800)
				|| (year >= 5000)) {
			throw new IllegalArgumentException();
		}
		title = title.trim();
		director = director.trim();
		if (  ("".equals(title))
				|| ("".equals(director))) {
			throw new IllegalArgumentException();
		}
		Integer key = hash3(title, year, director);
		Video v = hashmap.get(key);
		if (   (v == null)
				|| !(v.title().equals(title))
				|| (v.year() != year)
				|| !(v.title().equals(title))) {
			v = new VideoObj(title, year, director);
			hashmap.put(key, v);
		}
		return v;
	}
}