package com.foo;

import javax.servlet.ServletContext;
import javax.ws.rs.Path;

import java.util.HashSet;
import java.util.Set;

import org.glassfish.hk2.api.DynamicConfiguration;
import org.glassfish.hk2.api.Factory;
import org.glassfish.hk2.api.ServiceLocator;
import org.glassfish.hk2.utilities.binding.ServiceBindingBuilder;
import org.glassfish.jersey.internal.inject.Injections;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

/**
 * implement the spring integration ourselves since jersey's spring3 module
 * requires integration with hk2's injection system and is quite slow
 *
 * @author mhauck
 */
public class JerseySpringBridge {

    public static ApplicationContext getApplicationContext(ServiceLocator locator) {
        return WebApplicationContextUtils.getWebApplicationContext(
            locator.getService(ServletContext.class)
        );
    }


    /**
     * Integrate spring w/ jersey/hk2
     */
    public static void integrate(ApplicationContext ctx, ServiceLocator locator) {
        DynamicConfiguration config = Injections.getConfiguration(locator);

        for (ResourceBean bean : resourceBeans(ctx)) {
            ServiceBindingBuilder<Object> binding = Injections.newFactoryBinder(
                new SpringLookup(ctx, bean)
            );
            binding.to(bean.type);
            Injections.addBinding(binding, config);
        }

        config.commit();
    }

    private static Set<ResourceBean> resourceBeans(ApplicationContext ctx) {
        Set<ResourceBean> resources = new HashSet<>();
        for (String beanName : ctx.getBeanDefinitionNames()) {
            Class<?> beanType = ctx.getType(beanName);
            if (isResource(beanType)) {
                resources.add(new ResourceBean(beanName, beanType));
            }
        }

        return resources;
    }

    protected static boolean isResource(Class<?> type) {
        return type.isAnnotationPresent(Path.class);
    }

    private static class ResourceBean {

        final String name;
        final Class<?> type;

        public ResourceBean(String name, Class<?> type) {
            this.name = name;
            this.type = type;
        }
    }

    private static class SpringLookup implements Factory<Object> {

        private ResourceBean resource;
        private ApplicationContext ctx;

        SpringLookup(ApplicationContext ctx, ResourceBean resource) {
            this.ctx = ctx;
            this.resource = resource;
        }

        @Override
        public Object provide() {
            return ctx.getBean(resource.name, resource.type);
        }

        @Override
        public void dispose(Object instance) {

        }

    }

}