package reentrantrwlock;

import java.util.Map;
import java.util.List;
import java.util.Random;
import java.util.TreeMap;
import java.util.ArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.Iterator;

public class MovieCatalog {

	private final Map<String, Movie> movies;
	private final ReentrantReadWriteLock rwlock;
	private final Lock rLock, wLock;
	private static final Random generator = new Random();

	public MovieCatalog() {
		movies = new TreeMap<>();
		rwlock = new ReentrantReadWriteLock();
		rLock = rwlock.readLock();
		wLock = rwlock.writeLock();
	}

	/**
	 * Returns the current size of this catalog
	 * @return the size of this catalog
	 */
	public int getSize() {
		int length;
		rLock.lock();
		length = movies.size();
		rLock.unlock();
		return length;
	}

	/**
	 * Returns a movie from this catalog
	 * @param the title of movie to be obtained
	 * @return the movie with the title provided or
	 * null if the movie is not in the catalog
	 */
	public Movie getMovie(String title) {
		Movie m;
		rLock.lock();
		m = movies.get(title);
		rLock.unlock();
		return m;
	}

	/**
	 * Returns the list of all movie titles in this catalog
	 * @return a list of the movie titles in this catalog
	 */
	public List<String> getTitles() {
		List<String> titles;
		rLock.lock();
		titles = new ArrayList<>(movies.keySet());
		rLock.unlock();
		return titles;
	}

	/**
	 * Returns a random movie from this catalog
	 * @return a randomly selected movie from this catalog
	 */
	public Movie getRandomMovie() {
		Movie m;
		rLock.lock();
		final int r = generator.nextInt(movies.size()) - 1;
		final Iterator<Movie> it = movies.values().iterator();
		for (int i = 0; i < r; i++) {
			it.next();
		}
		m = it.next();
		rLock.unlock();
		return m;
	}

	/**
	 * Adds a movie to the catalog
	 * @param the movie to be added to the catalog
	 */
	public void addMovie(Movie movie) {
		wLock.lock();
		movies.put(movie.getTitle(), movie);
		wLock.unlock();
	}
}