/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.client;

import java.io.Closeable;
import java.io.IOException;
import java.net.URI;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.annotation.Contract;
import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Args;
import org.apache.http.util.EntityUtils;

Base implementation of HttpClient that also implements Closeable. 
Since:
4.3/**
 * Base implementation of {@link HttpClient} that also implements {@link Closeable}.
 *
 * @since 4.3
 */
@Contract(threading = ThreadingBehavior.SAFE)
public abstract class CloseableHttpClient implements HttpClient, Closeable {

    private final Log log = LogFactory.getLog(getClass());

    protected abstract CloseableHttpResponse doExecute(HttpHost target, HttpRequest request,
            HttpContext context) throws IOException, ClientProtocolException;

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public CloseableHttpResponse execute(
            final HttpHost target,
            final HttpRequest request,
            final HttpContext context) throws IOException, ClientProtocolException {
        return doExecute(target, request, context);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public CloseableHttpResponse execute(
            final HttpUriRequest request,
            final HttpContext context) throws IOException, ClientProtocolException {
        Args.notNull(request, "HTTP request");
        return doExecute(determineTarget(request), request, context);
    }

    private static HttpHost determineTarget(final HttpUriRequest request) throws ClientProtocolException {
        // A null target may be acceptable if there is a default target.
        // Otherwise, the null target is detected in the director.
        HttpHost target = null;

        final URI requestURI = request.getURI();
        if (requestURI.isAbsolute()) {
            target = URIUtils.extractHost(requestURI);
            if (target == null) {
                throw new ClientProtocolException("URI does not specify a valid host name: "
                        + requestURI);
            }
        }
        return target;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public CloseableHttpResponse execute(
            final HttpUriRequest request) throws IOException, ClientProtocolException {
        return execute(request, (HttpContext) null);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public CloseableHttpResponse execute(
            final HttpHost target,
            final HttpRequest request) throws IOException, ClientProtocolException {
        return doExecute(target, request, null);
    }

    
Executes a request using the default context and processes the response using the given response handler. The content entity associated with the response is fully consumed and the underlying connection is released back to the connection manager automatically in all cases relieving individual ResponseHandlers from having to manage resource deallocation internally. 
Params:
request –   the request to execute
responseHandler – the response handler
Throws:
IOException – in case of a problem or the connection was aborted
ClientProtocolException – in case of an http protocol error
Returns:
 the response object as generated by the response handler./**
     * Executes a request using the default context and processes the
     * response using the given response handler. The content entity associated
     * with the response is fully consumed and the underlying connection is
     * released back to the connection manager automatically in all cases
     * relieving individual {@link ResponseHandler}s from having to manage
     * resource deallocation internally.
     *
     * @param request   the request to execute
     * @param responseHandler the response handler
     *
     * @return  the response object as generated by the response handler.
     * @throws IOException in case of a problem or the connection was aborted
     * @throws ClientProtocolException in case of an http protocol error
     */
    @Override
    public <T> T execute(final HttpUriRequest request,
            final ResponseHandler<? extends T> responseHandler) throws IOException,
            ClientProtocolException {
        return execute(request, responseHandler, null);
    }

    
Executes a request using the default context and processes the response using the given response handler. The content entity associated with the response is fully consumed and the underlying connection is released back to the connection manager automatically in all cases relieving individual ResponseHandlers from having to manage resource deallocation internally. 
Params:
request –   the request to execute
responseHandler – the response handler
context –  the context to use for the execution, or null to use the default context
Throws:
IOException – in case of a problem or the connection was aborted
ClientProtocolException – in case of an http protocol error
Returns:
 the response object as generated by the response handler./**
     * Executes a request using the default context and processes the
     * response using the given response handler. The content entity associated
     * with the response is fully consumed and the underlying connection is
     * released back to the connection manager automatically in all cases
     * relieving individual {@link ResponseHandler}s from having to manage
     * resource deallocation internally.
     *
     * @param request   the request to execute
     * @param responseHandler the response handler
     * @param context   the context to use for the execution, or
     *                  {@code null} to use the default context
     *
     * @return  the response object as generated by the response handler.
     * @throws IOException in case of a problem or the connection was aborted
     * @throws ClientProtocolException in case of an http protocol error
     */
    @Override
    public <T> T execute(final HttpUriRequest request,
            final ResponseHandler<? extends T> responseHandler, final HttpContext context)
            throws IOException, ClientProtocolException {
        final HttpHost target = determineTarget(request);
        return execute(target, request, responseHandler, context);
    }

    
Executes a request using the default context and processes the response using the given response handler. The content entity associated with the response is fully consumed and the underlying connection is released back to the connection manager automatically in all cases relieving individual ResponseHandlers from having to manage resource deallocation internally. 
Params:
target –  the target host for the request. Implementations may accept null if they can still determine a route, for example to a default target or by inspecting the request.
request –   the request to execute
responseHandler – the response handler
Throws:
IOException – in case of a problem or the connection was aborted
ClientProtocolException – in case of an http protocol error
Returns:
 the response object as generated by the response handler./**
     * Executes a request using the default context and processes the
     * response using the given response handler. The content entity associated
     * with the response is fully consumed and the underlying connection is
     * released back to the connection manager automatically in all cases
     * relieving individual {@link ResponseHandler}s from having to manage
     * resource deallocation internally.
     *
     * @param target    the target host for the request.
     *                  Implementations may accept {@code null}
     *                  if they can still determine a route, for example
     *                  to a default target or by inspecting the request.
     * @param request   the request to execute
     * @param responseHandler the response handler
     *
     * @return  the response object as generated by the response handler.
     * @throws IOException in case of a problem or the connection was aborted
     * @throws ClientProtocolException in case of an http protocol error
     */
    @Override
    public <T> T execute(final HttpHost target, final HttpRequest request,
            final ResponseHandler<? extends T> responseHandler) throws IOException,
            ClientProtocolException {
        return execute(target, request, responseHandler, null);
    }

    
Executes a request using the default context and processes the response using the given response handler. The content entity associated with the response is fully consumed and the underlying connection is released back to the connection manager automatically in all cases relieving individual ResponseHandlers from having to manage resource deallocation internally. 
Params:
target –  the target host for the request. Implementations may accept null if they can still determine a route, for example to a default target or by inspecting the request.
request –   the request to execute
responseHandler – the response handler
context –  the context to use for the execution, or null to use the default context
Throws:
IOException – in case of a problem or the connection was aborted
ClientProtocolException – in case of an http protocol error
Returns:
 the response object as generated by the response handler./**
     * Executes a request using the default context and processes the
     * response using the given response handler. The content entity associated
     * with the response is fully consumed and the underlying connection is
     * released back to the connection manager automatically in all cases
     * relieving individual {@link ResponseHandler}s from having to manage
     * resource deallocation internally.
     *
     * @param target    the target host for the request.
     *                  Implementations may accept {@code null}
     *                  if they can still determine a route, for example
     *                  to a default target or by inspecting the request.
     * @param request   the request to execute
     * @param responseHandler the response handler
     * @param context   the context to use for the execution, or
     *                  {@code null} to use the default context
     *
     * @return  the response object as generated by the response handler.
     * @throws IOException in case of a problem or the connection was aborted
     * @throws ClientProtocolException in case of an http protocol error
     */
    @Override
    public <T> T execute(final HttpHost target, final HttpRequest request,
            final ResponseHandler<? extends T> responseHandler, final HttpContext context)
            throws IOException, ClientProtocolException {
        Args.notNull(responseHandler, "Response handler");

        final CloseableHttpResponse response = execute(target, request, context);
        try {
            final T result = responseHandler.handleResponse(response);
            final HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);
            return result;
        } catch (final ClientProtocolException t) {
            // Try to salvage the underlying connection in case of a protocol exception
            final HttpEntity entity = response.getEntity();
            try {
                EntityUtils.consume(entity);
            } catch (final Exception t2) {
                // Log this exception. The original exception is more
                // important and will be thrown to the caller.
                this.log.warn("Error consuming content after an exception.", t2);
            }
            throw t;
        } finally {
            response.close();
        }
    }

}