package org.apidesign.anagram.app.registergeneral;

import java.util.LinkedHashMap;

import java.util.Map;

public final class Registry {

    private static Map<Class<?>,Object[]> instances = new LinkedHashMap<Class<?>,Object[]>();

    private Registry() {

    }

    public static void registerClass(Class<?> impl) {

        instances.put(impl, new Object[1]);

    }

    public static <T> T find(Class<T> whatType) {

        for (Map.Entry<Class<?>, Object[]> entry : instances.entrySet()) {

            if (whatType.isAssignableFrom(entry.getKey())) {

                if (entry.getValue()[0] == null) {

                    try {

                        entry.getValue()[0] = entry.getKey().newInstance();

                    } catch (Exception ex) {

                        throw new IllegalStateException(ex);

                    }

                }

                return whatType.cast(entry.getValue()[0]);

            }

        }

        return null;

    }

}