/*
 * Copyright (c) 2012, 2023 Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2018 Payara Foundation and/or its affiliates.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.jersey.client;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ScheduledExecutorService;

import jakarta.ws.rs.RuntimeType;
import jakarta.ws.rs.core.Configurable;
import jakarta.ws.rs.core.Configuration;
import jakarta.ws.rs.core.Feature;

import org.glassfish.jersey.CommonProperties;
import org.glassfish.jersey.ExtendedConfig;
import org.glassfish.jersey.client.internal.LocalizationMessages;
import org.glassfish.jersey.client.innate.inject.NonInjectionManager;
import org.glassfish.jersey.client.internal.inject.ParameterUpdaterConfigurator;
import org.glassfish.jersey.client.spi.Connector;
import org.glassfish.jersey.client.spi.ConnectorProvider;
import org.glassfish.jersey.internal.AutoDiscoverableConfigurator;
import org.glassfish.jersey.internal.BootstrapBag;
import org.glassfish.jersey.internal.BootstrapConfigurator;
import org.glassfish.jersey.internal.ContextResolverFactory;
import org.glassfish.jersey.internal.ExceptionMapperFactory;
import org.glassfish.jersey.internal.FeatureConfigurator;
import org.glassfish.jersey.internal.JaxrsProviders;
import org.glassfish.jersey.internal.ServiceFinder;
import org.glassfish.jersey.internal.inject.Bindings;
import org.glassfish.jersey.internal.inject.InjectionManager;
import org.glassfish.jersey.internal.inject.Injections;
import org.glassfish.jersey.internal.inject.ProviderBinder;
import org.glassfish.jersey.internal.spi.AutoDiscoverable;
import org.glassfish.jersey.internal.util.collection.LazyValue;
import org.glassfish.jersey.internal.util.collection.Value;
import org.glassfish.jersey.internal.util.collection.Values;
import org.glassfish.jersey.model.internal.CommonConfig;
import org.glassfish.jersey.model.internal.ComponentBag;
import org.glassfish.jersey.model.internal.ManagedObjectsFinalizer;
import org.glassfish.jersey.process.internal.RequestScope;
import org.glassfish.jersey.internal.inject.ParamConverterConfigurator;
import org.glassfish.jersey.spi.ComponentProvider;

/**
 * Jersey externalized implementation of client-side JAX-RS {@link jakarta.ws.rs.core.Configurable
 * configurable} contract.
 *
 * @author Marek Potociar
 * @author Martin Matula
 * @author Libor Kramolis
 * @author Gaurav Gupta (gaurav.gupta@payara.fish)
 */
public class ClientConfig implements Configurable<ClientConfig>, ExtendedConfig {
    /**
     * Internal configuration state.
     */
    private State state;

    private static class RuntimeConfigConfigurator implements BootstrapConfigurator {

        private final State runtimeConfig;

        private RuntimeConfigConfigurator(State runtimeConfig) {
            this.runtimeConfig = runtimeConfig;
        }

        @Override
        public void init(InjectionManager injectionManager, BootstrapBag bootstrapBag) {
            bootstrapBag.setConfiguration(runtimeConfig);
            injectionManager.register(Bindings.service(runtimeConfig).to(Configuration.class));
        }
    }

    /**
     * Default encapsulation of the internal configuration state.
     */
    private static class State implements Configurable<State>, ExtendedConfig {

        /**
         * Strategy that returns the same state instance.
         */
        private static final StateChangeStrategy IDENTITY = state -> state;
        /**
         * Strategy that returns a copy of the state instance.
         */
        private static final StateChangeStrategy COPY_ON_CHANGE = State::copy;

        private volatile StateChangeStrategy strategy;
        private final CommonConfig commonConfig;
        private final JerseyClient client;
        private volatile ConnectorProvider connectorProvider;
        private volatile ExecutorService executorService;
        private volatile ScheduledExecutorService scheduledExecutorService;

        private final LazyValue<ClientRuntime> runtime = Values.lazy((Value<ClientRuntime>) this::initRuntime);

        /**
         * Configuration state change strategy.
         */
        private interface StateChangeStrategy {

            /**
             * Invoked whenever a mutator method is called in the given configuration
             * state.
             *
             * @param state configuration state to be mutated.
             * @return state instance that will be mutated and returned from the
             * invoked configuration state mutator method.
             */
            State onChange(final State state);
        }

        /**
         * Default configuration state constructor with {@link StateChangeStrategy "identity"}
         * state change strategy.
         *
         * @param client bound parent Jersey client.
         */
        State(final JerseyClient client) {
            this.strategy = IDENTITY;
            this.commonConfig = new CommonConfig(RuntimeType.CLIENT, ComponentBag.EXCLUDE_EMPTY);
            this.client = client;
            final Iterator<ConnectorProvider> iterator = ServiceFinder.find(ConnectorProvider.class).iterator();
            if (iterator.hasNext()) {
                this.connectorProvider = iterator.next();
            } else {
                this.connectorProvider = new HttpUrlConnectorProvider();
            }
        }

        /**
         * Copy the original configuration state while using the default state change
         * strategy.
         *
         * @param client   new Jersey client parent for the state.
         * @param original configuration strategy to be copied.
         */
        private State(final JerseyClient client, final State original) {
            this.strategy = IDENTITY;
            this.client = client;
            this.commonConfig = new CommonConfig(original.commonConfig);
            this.connectorProvider = original.connectorProvider;
            this.executorService = original.executorService;
            this.scheduledExecutorService = original.scheduledExecutorService;
        }

        /**
         * Create a copy of the configuration state within the same parent Jersey
         * client instance scope.
         *
         * @return configuration state copy.
         */
        State copy() {
            return new State(this.client, this);
        }

        /**
         * Create a copy of the configuration state in a scope of the given
         * parent Jersey client instance.
         *
         * @param client parent Jersey client instance.
         * @return configuration state copy.
         */
        State copy(final JerseyClient client) {
            return new State(client, this);
        }

        void markAsShared() {
            strategy = COPY_ON_CHANGE;
        }

        State preInitialize() {
            final State state = strategy.onChange(this);
            state.strategy = COPY_ON_CHANGE;
            state.runtime.get().preInitialize();
            return state;

        }

        @Override
        public State property(final String name, final Object value) {
            final State state = strategy.onChange(this);
            state.commonConfig.property(name, value);
            return state;
        }

        public State loadFrom(final Configuration config) {
            final State state = strategy.onChange(this);
            state.commonConfig.loadFrom(config);
            return state;
        }

        @Override
        public State register(final Class<?> providerClass) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(providerClass);
            return state;
        }

        @Override
        public State register(final Object provider) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(provider);
            return state;
        }

        @Override
        public State register(final Class<?> providerClass, final int bindingPriority) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(providerClass, bindingPriority);
            return state;
        }

        @Override
        public State register(final Class<?> providerClass, final Class<?>... contracts) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(providerClass, contracts);
            return state;
        }

        @Override
        public State register(final Class<?> providerClass, final Map<Class<?>, Integer> contracts) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(providerClass, contracts);
            return state;
        }

        @Override
        public State register(final Object provider, final int bindingPriority) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(provider, bindingPriority);
            return state;
        }

        @Override
        public State register(final Object provider, final Class<?>... contracts) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(provider, contracts);
            return state;
        }

        @Override
        public State register(final Object provider, final Map<Class<?>, Integer> contracts) {
            final State state = strategy.onChange(this);
            state.commonConfig.register(provider, contracts);
            return state;
        }

        State connectorProvider(final ConnectorProvider provider) {
            if (provider == null) {
                throw new NullPointerException(LocalizationMessages.NULL_CONNECTOR_PROVIDER());
            }
            final State state = strategy.onChange(this);
            state.connectorProvider = provider;
            return state;
        }

        State executorService(final ExecutorService executorService) {
            if (executorService == null) {
                throw new NullPointerException(LocalizationMessages.NULL_EXECUTOR_SERVICE());
            }
            final State state = strategy.onChange(this);
            state.executorService = executorService;
            return state;
        }

        State scheduledExecutorService(final ScheduledExecutorService scheduledExecutorService) {
            if (scheduledExecutorService == null) {
                throw new NullPointerException(LocalizationMessages.NULL_SCHEDULED_EXECUTOR_SERVICE());
            }
            final State state = strategy.onChange(this);
            state.scheduledExecutorService = scheduledExecutorService;
            return state;
        }

        Connector getConnector() {
            // Get the connector only if the runtime has been initialized.
            return (runtime.isInitialized()) ? runtime.get().getConnector() : null;
        }

        ConnectorProvider getConnectorProvider() {
            return connectorProvider;
        }

        ExecutorService getExecutorService() {
            return executorService;
        }

        ScheduledExecutorService getScheduledExecutorService() {
            return scheduledExecutorService;
        }

        JerseyClient getClient() {
            return client;
        }

        @Override
        public State getConfiguration() {
            return this;
        }

        @Override
        public RuntimeType getRuntimeType() {
            return commonConfig.getConfiguration().getRuntimeType();
        }

        @Override
        public Map<String, Object> getProperties() {
            return commonConfig.getConfiguration().getProperties();
        }

        @Override
        public Object getProperty(final String name) {
            return commonConfig.getConfiguration().getProperty(name);
        }

        @Override
        public Collection<String> getPropertyNames() {
            return commonConfig.getConfiguration().getPropertyNames();
        }

        @Override
        public boolean isProperty(final String name) {
            return commonConfig.getConfiguration().isProperty(name);
        }

        @Override
        public boolean isEnabled(final Feature feature) {
            return commonConfig.getConfiguration().isEnabled(feature);
        }

        @Override
        public boolean isEnabled(final Class<? extends Feature> featureClass) {
            return commonConfig.getConfiguration().isEnabled(featureClass);
        }

        @Override
        public boolean isRegistered(final Object component) {
            return commonConfig.getConfiguration().isRegistered(component);
        }

        @Override
        public boolean isRegistered(final Class<?> componentClass) {
            return commonConfig.getConfiguration().isRegistered(componentClass);
        }

        @Override
        public Map<Class<?>, Integer> getContracts(final Class<?> componentClass) {
            return commonConfig.getConfiguration().getContracts(componentClass);
        }

        @Override
        public Set<Class<?>> getClasses() {
            return commonConfig.getConfiguration().getClasses();
        }

        @Override
        public Set<Object> getInstances() {
            return commonConfig.getConfiguration().getInstances();
        }

        public void configureAutoDiscoverableProviders(InjectionManager injectionManager,
                                                       List<AutoDiscoverable> autoDiscoverables) {
            commonConfig.configureAutoDiscoverableProviders(injectionManager, autoDiscoverables, false);
        }

        public void configureForcedAutoDiscoverableProviders(InjectionManager injectionManager) {
            commonConfig.configureAutoDiscoverableProviders(injectionManager, Collections.emptyList(), true);
        }

        public void configureMetaProviders(InjectionManager injectionManager, ManagedObjectsFinalizer finalizer) {
            commonConfig.configureMetaProviders(injectionManager, finalizer);
        }

        public ComponentBag getComponentBag() {
            return commonConfig.getComponentBag();
        }

        /**
         * Initialize the newly constructed client instance.
         */
        @SuppressWarnings("MethodOnlyUsedFromInnerClass")
        private ClientRuntime initRuntime() {
            /*
             * Ensure that any attempt to add a new provider, feature, binder or modify the connector
             * will cause a copy of the current state.
             */
            markAsShared();

            final State runtimeCfgState = this.copy();
            runtimeCfgState.markAsShared();

            final InjectionManager injectionManager = findInjectionManager();
            injectionManager.register(new ClientBinder(runtimeCfgState.getProperties()));

            final ClientBootstrapBag bootstrapBag = new ClientBootstrapBag();
            bootstrapBag.setManagedObjectsFinalizer(new ManagedObjectsFinalizer(injectionManager));

            final ClientMessageBodyFactory.MessageBodyWorkersConfigurator messageBodyWorkersConfigurator =
                    new ClientMessageBodyFactory.MessageBodyWorkersConfigurator();

            List<BootstrapConfigurator> bootstrapConfigurators = Arrays.asList(
                    new RequestScope.RequestScopeConfigurator(),
                    new ParamConverterConfigurator(),
                    new ParameterUpdaterConfigurator(),
                    new RuntimeConfigConfigurator(runtimeCfgState),
                    new ContextResolverFactory.ContextResolversConfigurator(),
                    messageBodyWorkersConfigurator,
                    new ExceptionMapperFactory.ExceptionMappersConfigurator(),
                    new JaxrsProviders.ProvidersConfigurator(),
                    new AutoDiscoverableConfigurator(RuntimeType.CLIENT),
                    new ClientComponentConfigurator(),
                    new FeatureConfigurator(RuntimeType.CLIENT));
            bootstrapConfigurators.forEach(configurator -> configurator.init(injectionManager, bootstrapBag));

            // AutoDiscoverable.
            if (!CommonProperties.getValue(runtimeCfgState.getProperties(), RuntimeType.CLIENT,
                    CommonProperties.FEATURE_AUTO_DISCOVERY_DISABLE, Boolean.FALSE, Boolean.class)) {
                runtimeCfgState.configureAutoDiscoverableProviders(injectionManager, bootstrapBag.getAutoDiscoverables());
            } else {
                runtimeCfgState.configureForcedAutoDiscoverableProviders(injectionManager);
            }

            // Configure binders and features.
            runtimeCfgState.configureMetaProviders(injectionManager, bootstrapBag.getManagedObjectsFinalizer());

            // Bind providers.
            final Collection<ComponentProvider> componentProviders = bootstrapBag.getComponentProviders().get();
            ProviderBinder.bindProviders(
                    runtimeCfgState.getComponentBag(), RuntimeType.CLIENT, null, injectionManager, componentProviders
            );

            ClientExecutorProvidersConfigurator executorProvidersConfigurator =
                    new ClientExecutorProvidersConfigurator(runtimeCfgState.getComponentBag(),
                            runtimeCfgState.client,
                            this.executorService,
                            this.scheduledExecutorService);
            executorProvidersConfigurator.init(injectionManager, bootstrapBag);

            injectionManager.completeRegistration();

            bootstrapConfigurators.forEach(configurator -> configurator.postInit(injectionManager, bootstrapBag));

            final ClientConfig configuration = new ClientConfig(runtimeCfgState);
            final Connector connector = connectorProvider.getConnector(client, configuration);
            final ClientRuntime crt = new ClientRuntime(configuration, connector, injectionManager, bootstrapBag);

            client.registerShutdownHook(crt);
            messageBodyWorkersConfigurator.setClientRuntime(crt);

            return crt;
        }

        private final InjectionManager findInjectionManager() {
            try {
                return Injections.createInjectionManager(RuntimeType.CLIENT);
            } catch (IllegalStateException ise) {
                return new NonInjectionManager(true);
            }
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            final State state = (State) o;

            if (client != null ? !client.equals(state.client) : state.client != null) {
                return false;
            }
            if (!commonConfig.equals(state.commonConfig)) {
                return false;
            }
            return connectorProvider == null ? state.connectorProvider == null
                    : connectorProvider.equals(state.connectorProvider);
        }

        @Override
        public int hashCode() {
            int result = commonConfig.hashCode();
            result = 31 * result + (client != null ? client.hashCode() : 0);
            result = 31 * result + (connectorProvider != null ? connectorProvider.hashCode() : 0);
            return result;
        }
    }

    /**
     * Construct a new Jersey configuration instance with the default features
     * and property values.
     */
    public ClientConfig() {
        this.state = new State(null);
    }

    /**
     * Construct a new Jersey configuration instance and register the provided list of provider classes.
     *
     * @param providerClasses provider classes to be registered with this client configuration.
     */
    public ClientConfig(final Class<?>... providerClasses) {
        this();
        for (final Class<?> providerClass : providerClasses) {
            state.register(providerClass);
        }
    }

    /**
     * Construct a new Jersey configuration instance and register the provided list of provider instances.
     *
     * @param providers provider instances to be registered with this client configuration.
     */
    public ClientConfig(final Object... providers) {
        this();
        for (final Object provider : providers) {
            state.register(provider);
        }
    }

    /**
     * Construct a new Jersey configuration instance with the features as well as
     * property values copied from the supplied JAX-RS configuration instance.
     *
     * @param parent parent Jersey client instance.
     */
    ClientConfig(final JerseyClient parent) {
        this.state = new State(parent);
    }

    /**
     * Construct a new Jersey configuration instance with the features as well as
     * property values copied from the supplied JAX-RS configuration instance.
     *
     * @param parent parent Jersey client instance.
     * @param that   original {@link jakarta.ws.rs.core.Configuration}.
     */
    ClientConfig(final JerseyClient parent, final Configuration that) {
        if (that instanceof ClientConfig) {
            state = ((ClientConfig) that).state.copy(parent);
        } else {
            state = new State(parent);
            state.loadFrom(that);
        }
    }

    /**
     * Construct a new Jersey configuration instance using the supplied state.
     *
     * @param state to be referenced from the new configuration instance.
     */
    private ClientConfig(final State state) {
        this.state = state;
    }

    /**
     * Take a snapshot of the current configuration and its internal state.
     * <p/>
     * The returned configuration object is an new instance different from the
     * original one, however the cloning of the internal configuration state is
     * lazily deferred until either original or the snapshot configuration is
     * modified for the first time since the snapshot was taken.
     *
     * @return snapshot of the current configuration.
     */
    ClientConfig snapshot() {
        state.markAsShared();
        return new ClientConfig(state);
    }

    /**
     * Load the internal configuration state from an externally provided configuration state.
     * <p>
     * Calling this method effectively replaces existing configuration state of the instance
     * with the state represented by the externally provided configuration.
     *
     * @param config external configuration state to replace the configuration of this configurable
     *               instance.
     * @return the updated client configuration instance.
     */
    public ClientConfig loadFrom(final Configuration config) {
        if (config instanceof ClientConfig) {
            state = ((ClientConfig) config).state.copy();
        } else {
            state.loadFrom(config);
        }
        return this;
    }

    @Override
    public ClientConfig register(final Class<?> providerClass) {
        state = state.register(providerClass);
        return this;
    }

    @Override
    public ClientConfig register(final Object provider) {
        state = state.register(provider);
        return this;
    }

    @Override
    public ClientConfig register(final Class<?> providerClass, final int bindingPriority) {
        state = state.register(providerClass, bindingPriority);
        return this;
    }

    @Override
    public ClientConfig register(final Class<?> providerClass, final Class<?>... contracts) {
        state = state.register(providerClass, contracts);
        return this;
    }

    @Override
    public ClientConfig register(final Class<?> providerClass, final Map<Class<?>, Integer> contracts) {
        state = state.register(providerClass, contracts);
        return this;
    }

    @Override
    public ClientConfig register(final Object provider, final int bindingPriority) {
        state = state.register(provider, bindingPriority);
        return this;
    }

    @Override
    public ClientConfig register(final Object provider, final Class<?>... contracts) {
        state = state.register(provider, contracts);
        return this;
    }

    @Override
    public ClientConfig register(final Object provider, final Map<Class<?>, Integer> contracts) {
        state = state.register(provider, contracts);
        return this;
    }

    @Override
    public ClientConfig property(final String name, final Object value) {
        state = state.property(name, value);
        return this;
    }

    @Override
    public ClientConfig getConfiguration() {
        return this;
    }

    @Override
    public RuntimeType getRuntimeType() {
        return state.getRuntimeType();
    }

    @Override
    public Map<String, Object> getProperties() {
        return state.getProperties();
    }

    @Override
    public Object getProperty(final String name) {
        return state.getProperty(name);
    }

    @Override
    public Collection<String> getPropertyNames() {
        return state.getPropertyNames();
    }

    @Override
    public boolean isProperty(final String name) {
        return state.isProperty(name);
    }

    @Override
    public boolean isEnabled(final Feature feature) {
        return state.isEnabled(feature);
    }

    @Override
    public boolean isEnabled(final Class<? extends Feature> featureClass) {
        return state.isEnabled(featureClass);
    }

    @Override
    public boolean isRegistered(final Object component) {
        return state.isRegistered(component);
    }

    @Override
    public Map<Class<?>, Integer> getContracts(final Class<?> componentClass) {
        return state.getContracts(componentClass);
    }

    @Override
    public boolean isRegistered(final Class<?> componentClass) {
        return state.isRegistered(componentClass);
    }

    @Override
    public Set<Class<?>> getClasses() {
        return state.getClasses();
    }

    @Override
    public Set<Object> getInstances() {
        return state.getInstances();
    }

    /**
     * Register a custom Jersey client connector provider.
     * <p>
     * The registered {@code ConnectorProvider} instance will provide a
     * Jersey client {@link org.glassfish.jersey.client.spi.Connector}
     * for the {@link org.glassfish.jersey.client.JerseyClient} instance
     * created with this client configuration.
     * </p>
     *
     * @param connectorProvider custom connector provider. Must not be {@code null}.
     * @return this client config instance.
     * @throws java.lang.NullPointerException in case the {@code connectorProvider} is {@code null}.
     * @since 2.5
     */
    public ClientConfig connectorProvider(final ConnectorProvider connectorProvider) {
        state = state.connectorProvider(connectorProvider);
        return this;
    }

    /**
     * Register custom Jersey client async executor.
     *
     * @param executorService custom executor service instance
     * @return this client config instance
     */
    public ClientConfig executorService(final ExecutorService executorService) {
        state = state.executorService(executorService);
        return this;
    }

    /**
     * Register custom Jersey client scheduler.
     *
     * @param scheduledExecutorService custom scheduled executor service instance
     * @return this client config instance
     */
    public ClientConfig scheduledExecutorService(final ScheduledExecutorService scheduledExecutorService) {
        state = state.scheduledExecutorService(scheduledExecutorService);
        return this;
    }

    /**
     * Get the client transport connector.
     * <p>
     * May return {@code null} if no connector has been set.
     *
     * @return client transport connector or {code null} if not set.
     */
    public Connector getConnector() {
        return state.getConnector();
    }

    /**
     * Get the client transport connector provider.
     * <p>
     * If no custom connector provider has been set,
     * {@link org.glassfish.jersey.client.HttpUrlConnectorProvider default connector provider}
     * instance is returned.
     *
     * @return configured client transport connector provider.
     * @since 2.5
     */
    public ConnectorProvider getConnectorProvider() {
        return state.getConnectorProvider();
    }

    /**
     * Get custom client executor service.
     * <p>
     * May return null if no custom executor service has been set.
     *
     * @return custom executor service instance or {@code null} if not set.
     * @since 2.26
     */
    public ExecutorService getExecutorService() {
        return state.getExecutorService();
    }

    /**
     * Get custom client scheduled executor service.
     * <p>
     * May return null if no custom scheduled executor service has been set.
     *
     * @return custom executor service instance or {@code null} if not set.
     * @since 2.26
     */
    public ScheduledExecutorService getScheduledExecutorService() {
        return state.getScheduledExecutorService();
    }

    /**
     * Get the configured runtime.
     *
     * @return configured runtime.
     */
    ClientRuntime getRuntime() {
        return state.runtime.get();
    }

    public ClientExecutor getClientExecutor() {
        return state.runtime.get();
    }

    /**
     * Get the parent Jersey client this configuration is bound to.
     * <p>
     * May return {@code null} if no parent client has been bound.
     *
     * @return bound parent Jersey client or {@code null} if not bound.
     */
    public JerseyClient getClient() {
        return state.getClient();
    }


    /**
     * Pre initializes this configuration by initializing {@link ClientRuntime client runtime}
     * including {@link org.glassfish.jersey.message.MessageBodyWorkers message body workers}.
     * Once this method is called no other method implementing {@link Configurable} should be called
     * on this pre initialized configuration otherwise configuration will change back to uninitialized.
     * <p/>
     * Note that this method must be called only when configuration is attached to the client.
     *
     * @return Client configuration.
     */
    ClientConfig preInitialize() {
        state = state.preInitialize();
        return this;
    }

    /**
     * Check that the configuration instance has a parent client set.
     *
     * @throws IllegalStateException in case no parent Jersey client has been
     *                               bound to the configuration instance yet.
     */
    void checkClient() throws IllegalStateException {
        if (getClient() == null) {
            throw new IllegalStateException("Client configuration does not contain a parent client instance.");
        }
    }

    @Override
    public boolean equals(final Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final ClientConfig other = (ClientConfig) obj;
        return this.state == other.state || (this.state != null && this.state.equals(other.state));
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 47 * hash + (this.state != null ? this.state.hashCode() : 0);
        return hash;
    }
}
