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package io.graceland.inject;

import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.codahale.metrics.health.HealthCheck;
import com.google.common.base.Preconditions;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.inject.ConfigurationException;
import com.google.inject.Injector;
import com.google.inject.Key;

import io.dropwizard.Bundle;
import io.dropwizard.cli.Command;
import io.dropwizard.lifecycle.Managed;
import io.dropwizard.servlets.tasks.Task;
import io.graceland.dropwizard.Configurator;
import io.graceland.dropwizard.Initializer;
import io.graceland.filter.FilterSpec;

/**
 * Wraps a Guice {@link com.google.inject.Injector} and provides helper functions to help deal with bindings coming
 * from a {@link com.google.inject.multibindings.Multibinder}.
 */
public class InjectorWrapper {

    private static final Logger LOGGER = LoggerFactory.getLogger(InjectorWrapper.class);
    private final Injector injector;

    InjectorWrapper(Injector injector) {
        this.injector = Preconditions.checkNotNull(injector, "Injector cannot be null.");
    }

    /**
     * Returns a wrapper around the {@link com.google.inject.Injector}.
     *
     * @param injector The injector to wrap.
     * @return A wrapper.
     */
    public static InjectorWrapper wrap(Injector injector) {
        Preconditions.checkNotNull(injector, "Injector cannot be null.");
        return new InjectorWrapper(injector);
    }

    // =====================
    // KISS Helper Functions
    // =====================

    private  Set getSetSafely(Key> key) {
        try {
            return injector.getInstance(key);

        } catch (ConfigurationException e) {
            LOGGER.debug("No bindings found for key: {}", key, e);
            return ImmutableSet.of();
        }
    }

    private  ImmutableSet getAndBuildInstances(Key> concreteKey, Key>> classKey) {
        Set instances = getSetSafely(concreteKey);
        Set> classes = getSetSafely(classKey);

        ImmutableSet.Builder allInstances = ImmutableSet.builder();
        allInstances.addAll(instances);

        for (Class klass : classes) {
            T instance = injector.getInstance(klass);
            allInstances.add(instance);
        }

        return allInstances.build();
    }

    // =============================
    // Injector Multibinder Wrappers
    // =============================

    /**
     * Returns a Set of Jersey components, including Providers and Resources. These objects are usually fed into the
     * {@link io.dropwizard.jersey.setup.JerseyEnvironment#register(Class)} method.
     *
     * @return An immutable set of Jersey components.
     */
    @SuppressWarnings("unchecked")
    public ImmutableSet