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package org.glassfish.jersey.client;

import java.util.Arrays;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;

import javax.ws.rs.ProcessingException;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MultivaluedMap;

import org.glassfish.jersey.ExtendedConfig;
import org.glassfish.jersey.client.spi.AsyncConnectorCallback;
import org.glassfish.jersey.client.spi.Connector;
import org.glassfish.jersey.internal.Version;
import org.glassfish.jersey.internal.util.PropertiesHelper;
import org.glassfish.jersey.message.MessageBodyWorkers;
import org.glassfish.jersey.process.internal.ChainableStage;
import org.glassfish.jersey.process.internal.RequestScope;
import org.glassfish.jersey.process.internal.Stage;
import org.glassfish.jersey.process.internal.Stages;

import org.glassfish.hk2.api.ServiceLocator;

import com.google.common.util.concurrent.SettableFuture;

/**
 * Client-side request processing runtime.
 *
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
class ClientRuntime {
    private final Stage<ClientRequest> requestProcessingRoot;
    private final Stage<ClientResponse> responseProcessingRoot;

    private final Connector connector;
    private final ExtendedConfig config;

    private final RequestScope requestScope;
    private final ClientAsyncExecutorFactory asyncExecutorsFactory;

    private final ServiceLocator locator;

    /**
     * Create new client request processing runtime.
     *
     * @param config    client runtime configuration.
     * @param connector client transport connector.
     * @param locator   HK2 service locator.
     */
    public ClientRuntime(final ExtendedConfig config, final Connector connector, final ServiceLocator locator) {
        final Stage.Builder<ClientRequest> requestingChainBuilder = Stages
                .chain(locator.createAndInitialize(RequestProcessingInitializationStage.class));
        final ChainableStage<ClientRequest> requestFilteringStage = ClientFilteringStages.createRequestFilteringStage(locator);
        this.requestProcessingRoot = requestFilteringStage != null ?
                requestingChainBuilder.build(requestFilteringStage) : requestingChainBuilder.build();

        final ChainableStage<ClientResponse> responseFilteringStage = ClientFilteringStages.createResponseFilteringStage(locator);
        this.responseProcessingRoot = responseFilteringStage != null ?
                responseFilteringStage : Stages.<ClientResponse>identity();

        this.config = config;
        this.connector = connector;

        this.requestScope = locator.getService(RequestScope.class);

        int asyncThreadPoolSize = PropertiesHelper.getValue(config.getProperties(), ClientProperties.ASYNC_THREADPOOL_SIZE, 0);
        asyncThreadPoolSize = (asyncThreadPoolSize < 0) ? 0 : asyncThreadPoolSize;
        this.asyncExecutorsFactory = new ClientAsyncExecutorFactory(locator, asyncThreadPoolSize);

        this.locator = locator;
    }

    /**
     * Submit a {@link ClientRequest client request} for asynchronous processing.
     * <p>
     * Both, the request processing as well as response callback invocation will be executed
     * in a context of an active {@link RequestScope.Instance request scope instance}.
     * </p>
     *
     * @param request  client request to be sent.
     * @param callback asynchronous response callback.
     */
    public void submit(final ClientRequest request, final ResponseCallback callback) {
        submit(asyncExecutorsFactory.getExecutor(), new Runnable() {

            @Override
            public void run() {
                ClientRequest processedRequest;
                try {
                    processedRequest = Stages.process(request, requestProcessingRoot);
                    processedRequest = addUserAgent(processedRequest, connector.getName());
                } catch (AbortException aborted) {
                    processResponse(aborted.getAbortResponse(), callback);
                    return;
                }

                try {
                    final SettableFuture<ClientResponse> responseFuture = SettableFuture.create();
                    final AsyncConnectorCallback connectorCallback = new AsyncConnectorCallback() {

                        @Override
                        public void response(final ClientResponse response) {
                            responseFuture.set(response);
                        }

                        @Override
                        public void failure(Throwable failure) {
                            responseFuture.setException(failure);
                        }
                    };
                    connector.apply(processedRequest, connectorCallback);

                    processResponse(responseFuture.get(), callback);
                } catch (ExecutionException e) {
                    processFailure(e.getCause(), callback);
                } catch (Throwable throwable) {
                    processFailure(throwable, callback);
                }
            }
        });
    }

    private void processResponse(final ClientResponse response, final ResponseCallback callback) {
        final ClientResponse processedResponse;
        try {
            processedResponse = Stages.process(response, responseProcessingRoot);
        } catch (Throwable throwable) {
            processFailure(throwable, callback);
            return;
        }
        callback.completed(processedResponse, requestScope);
    }

    private void processFailure(Throwable failure, final ResponseCallback callback) {
        callback.failed(failure instanceof ProcessingException ?
                (ProcessingException) failure : new ProcessingException(failure));
    }

    private Future<?> submit(final ExecutorService executor, final Runnable task) {
        return executor.submit(new Runnable() {
            @Override
            public void run() {
                requestScope.runInScope(task);
            }
        });
    }

    private ClientRequest addUserAgent(ClientRequest clientRequest, String connectorName) {
        final MultivaluedMap<String, Object> headers = clientRequest.getHeaders();
        if (headers.containsKey(HttpHeaders.USER_AGENT)) {
            // Check for explicitly set null value and if set, then remove the header - see JERSEY-2189
            if (clientRequest.getHeaderString(HttpHeaders.USER_AGENT) == null) {
                headers.remove(HttpHeaders.USER_AGENT);
            }
        } else {
            if (connectorName != null && !connectorName.isEmpty()) {
                headers.put(HttpHeaders.USER_AGENT,
                        Arrays.<Object>asList(String.format("Jersey/%s (%s)", Version.getVersion(), connectorName)));
            } else {
                headers.put(HttpHeaders.USER_AGENT,
                        Arrays.<Object>asList(String.format("Jersey/%s", Version.getVersion())));
            }
        }

        return clientRequest;
    }

    /**
     * Invoke a request processing synchronously in the context of the caller's thread.
     * <p>
     * NOTE: the method does not explicitly start a new request scope context. Instead
     * it is assumed that the method is invoked from within a context of a proper, running
     * {@link RequestScope.Instance request scope instance}. A caller may use the
     * {@link #getRequestScope()} method to retrieve the request scope instance and use it to
     * initialize the proper request scope context prior the method invocation.
     * </p>
     *
     * @param request client request to be invoked.
     * @return client response.
     * @throws javax.ws.rs.ProcessingException in case of an invocation failure.
     */
    public ClientResponse invoke(final ClientRequest request) {
        ClientResponse response;
        try {
            try {
                response = connector.apply(addUserAgent(Stages.process(request, requestProcessingRoot), connector.getName()));
            } catch (AbortException aborted) {
                response = aborted.getAbortResponse();
            }

            return Stages.process(response, responseProcessingRoot);
        } catch (ProcessingException ex) {
            throw ex;
        } catch (Throwable t) {
            throw new ProcessingException(t.getMessage(), t);
        }
    }

    /**
     * Get the request scope instance configured for the runtime.
     *
     * @return request scope instance.
     */
    public RequestScope getRequestScope() {
        return requestScope;
    }

    /**
     * Get runtime configuration.
     *
     * @return runtime configuration.
     */
    public ExtendedConfig getConfig() {
        return config;
    }

    /**
     * Close the client runtime and release the underlying transport connector.
     */
    public void close() {
        try {
            connector.close();
        } finally {
            asyncExecutorsFactory.close();
        }
    }

    /**
     * Pre-initialize the client runtime.
     */
    public void preInitialize() {
        // pre-initialize MessageBodyWorkers
        locator.getService(MessageBodyWorkers.class);
    }

    /**
     * Runtime connector.
     *
     * @return runtime connector.
     */
    public Connector getConnector() {
        return connector;
    }
}
