package envoy.client.data;

import java.io.Serializable;
import java.util.*;

/**
 * Stores a heterogeneous map of {@link Cache} objects with different type
 * parameters.
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-beta
 */
public final class CacheMap implements Serializable {

	private final Map<Class<?>, Cache<?>> map = new HashMap<>();

	private static final long serialVersionUID = 1L;

	/**
	 * Adds a cache to the map.
	 *
	 * @param <T>   the type accepted by the cache
	 * @param key   the class that maps to the cache
	 * @param cache the cache to store
	 * @since Envoy Client v0.1-beta
	 */
	public <T> void put(Class<T> key, Cache<T> cache) { map.put(key, cache); }

	/**
	 * Returns a cache mapped by a class.
	 *
	 * @param <T> the type accepted by the cache
	 * @param key the class that maps to the cache
	 * @return the cache
	 * @since Envoy Client v0.1-beta
	 */
	public <T> Cache<T> get(Class<T> key) { return (Cache<T>) map.get(key); }

	/**
	 * Returns a cache mapped by a class or any of its subclasses.
	 *
	 * @param <T> the type accepted by the cache
	 * @param key the class that maps to the cache
	 * @return the cache
	 * @since Envoy Client v0.1-beta
	 */
	public <T> Cache<? super T> getApplicable(Class<T> key) {
		Cache<? super T> cache = get(key);
		if (cache == null)
			for (final var e : map.entrySet())
				if (e.getKey().isAssignableFrom(key))
					cache = (Cache<? super T>) e.getValue();
		return cache;
	}

	/**
	 * @return the map in which the caches are stored
	 * @since Envoy Client v0.1-beta
	 */
	public Map<Class<?>, Cache<?>> getMap() { return map; }

	/**
	 * Clears the caches of this map of any values.
	 *
	 * @since Envoy Client v0.2-beta
	 */
	public void clear() { map.values().forEach(Cache::clear); }
}