/*
 * Copyright (c) 2018. Developed by Hedgecode.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.hedgecode.chess.service;

import java.util.Iterator;
import java.util.ServiceLoader;

import org.hedgecode.chess.domain.Adapter;
import org.hedgecode.chess.domain.EtudeAdapter;
import org.hedgecode.chess.dto.EtudeDTO;
import org.hedgecode.chess.persistence.PersistenceManager;

/**
 * Service Provider Interface (SPI) Registry.
 *
 * @author Dmitry Samoshin aka gotty
 */
public final class ServiceRegistry {

    private ServiceRegistry() {
    }

    public static <ServiceType> Iterator<ServiceType> providers(Class<ServiceType> serviceClass) {
        final Iterator<ServiceType> providers = ServiceLoader.load(serviceClass).iterator();

        if (!providers.hasNext()) {
            throw new ServiceRegistryException("service.provider.not.found", serviceClass.getName());
        }

        return providers;
    }

    public static <ServiceType> ServiceType singleProvider(Class<ServiceType> serviceClass) {
        final Iterator<ServiceType> providers = providers(serviceClass);

        ServiceType provider = providers.next();
        if (providers.hasNext()) {
            throw new ServiceRegistryException("service.too.many.providers", serviceClass.getName());
        }

        return provider;
    }

    public static <AdapterType extends Adapter, TargetType> AdapterType singleAdapter(
            Class<AdapterType> adapterClass,
            Class<TargetType> targetClass)
    {
        AdapterType targetAdapter = null;

        final Iterator<AdapterType> providers = providers(adapterClass);

        while (providers.hasNext()) {
            AdapterType adapter = providers.next();
            if (adapter.getTargetClass().equals(targetClass)) {
                if (targetAdapter != null)
                    throw new ServiceRegistryException(
                            "service.too.many.adapters", adapterClass.getName(), targetClass.getName()
                    );
                targetAdapter = adapter;
            }
        }
        if (targetAdapter == null)
            throw new ServiceRegistryException(
                    "service.adapter.not.found", adapterClass.getName(), targetClass.getName()
            );

        return targetAdapter;
    }


    public static void main(String... args) {

        AuthorService as = ServiceRegistry.singleProvider(AuthorService.class);
        System.out.println(as);
        PersistenceManager pm = ServiceRegistry.singleProvider(PersistenceManager.class);
        System.out.println(pm);
        EtudeAdapter ea = ServiceRegistry.singleAdapter(EtudeAdapter.class, EtudeDTO.class);
        System.out.println(ea);

    }

}