001/*
002 * Copyright (c) 2011-2017 Nexmo Inc
003 *
004 * Permission is hereby granted, free of charge, to any person obtaining a copy
005 * of this software and associated documentation files (the "Software"), to deal
006 * in the Software without restriction, including without limitation the rights
007 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
008 * copies of the Software, and to permit persons to whom the Software is
009 * furnished to do so, subject to the following conditions:
010 *
011 * The above copyright notice and this permission notice shall be included in
012 * all copies or substantial portions of the Software.
013 *
014 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
015 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
016 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
017 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
018 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
019 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
020 * THE SOFTWARE.
021 */
022package com.nexmo.client.voice.endpoints;
023
024import com.nexmo.client.HttpWrapper;
025import com.nexmo.client.NexmoClientException;
026import com.nexmo.client.NexmoMethodFailedException;
027import com.nexmo.client.NexmoUnexpectedException;
028import com.nexmo.client.auth.AuthMethod;
029import org.apache.commons.logging.Log;
030import org.apache.commons.logging.LogFactory;
031import org.apache.http.HttpEntity;
032import org.apache.http.HttpEntityEnclosingRequest;
033import org.apache.http.HttpResponse;
034import org.apache.http.client.HttpClient;
035import org.apache.http.client.entity.UrlEncodedFormEntity;
036import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
037import org.apache.http.client.methods.HttpUriRequest;
038import org.apache.http.client.methods.RequestBuilder;
039import org.apache.http.util.EntityUtils;
040
041import java.io.IOException;
042import java.io.UnsupportedEncodingException;
043import java.nio.charset.Charset;
044import java.util.HashSet;
045import java.util.Set;
046
047/**
048 * Abstract class to assist in implementing a call against a REST endpoint.
049 * <p>
050 * Concrete implementations must implement {@link #makeRequest(Object)} to construct a {@link RequestBuilder} from the
051 * provided parameterized request object, and {@link #parseResponse(HttpResponse)} to construct the parameterized
052 * {@link HttpResponse} object.
053 * <p>
054 * The REST call is executed by calling {@link #execute(Object)}.
055 *
056 * @param <RequestT> The type of the method-specific request object that will be used to construct an HTTP request
057 * @param <ResultT>  The type of method-specific response object which will be constructed from the returned
058 *                   HTTP response
059 */
060public abstract class AbstractMethod<RequestT, ResultT> implements Method<RequestT, ResultT> {
061    private static final Log LOG = LogFactory.getLog(AbstractMethod.class);
062
063    private final HttpWrapper httpWrapper;
064    private Set<Class> acceptable;
065
066    public AbstractMethod(HttpWrapper httpWrapper) {
067        this.httpWrapper = httpWrapper;
068    }
069
070    /**
071     * Execute the REST call represented by this method object.
072     *
073     * @param request A RequestT representing input to the REST call to be made
074     * @return A ResultT representing the response from the executed REST call
075     * @throws IOException          if an exception occurs making the REST call
076     * @throws NexmoClientException if there is a problem parsing the HTTP response
077     */
078    // TODO: Consider wrapping IOException in a nexmo-specific transport exception.
079    public ResultT execute(RequestT request) throws IOException, NexmoClientException {
080        try {
081            RequestBuilder requestBuilder = applyAuth(makeRequest(request));
082            HttpUriRequest httpRequest = requestBuilder.build();
083
084            // If we have a URL Encoded form entity, we may need to regenerate it as UTF-8
085            // due to a bug (or two!) in RequestBuilder:
086            //
087            // This fix can be removed when HttpClient is upgraded to 4.5, although 4.5 also
088            // has a bug where RequestBuilder.put(uri) and RequestBuilder.post(uri) use the
089            // wrong encoding, whereas RequestBuilder.put().setUri(uri) uses UTF-8.
090            // - MS 2017-04-12
091            if (httpRequest instanceof HttpEntityEnclosingRequest) {
092                HttpEntityEnclosingRequest entityRequest =
093                        (HttpEntityEnclosingRequest) httpRequest;
094                HttpEntity entity = entityRequest.getEntity();
095                if (entity != null && entity instanceof UrlEncodedFormEntity) {
096                    entityRequest.setEntity(new UrlEncodedFormEntity(
097                            requestBuilder.getParameters(),
098                            Charset.forName("UTF-8")));
099                }
100            }
101            LOG.debug("Request: " + httpRequest);
102            if (LOG.isDebugEnabled() && httpRequest instanceof HttpEntityEnclosingRequestBase) {
103                HttpEntityEnclosingRequestBase enclosingRequest = (HttpEntityEnclosingRequestBase) httpRequest;
104                LOG.debug(EntityUtils.toString(enclosingRequest.getEntity()));
105            }
106            HttpResponse response = this.httpWrapper.getHttpClient().execute(httpRequest);
107            return parseResponse(response);
108        } catch (UnsupportedEncodingException uee) {
109            throw new NexmoUnexpectedException("UTF-8 encoding is not supported by this JVM.", uee);
110        }
111    }
112
113    /**
114     * Apply an appropriate authentication method (specified by {@link #getAcceptableAuthMethods()} to the provided
115     * {@link RequestBuilder}, and return the result.
116     *
117     * @param request A RequestBuilder which has not yet had authentication information applied
118     * @return A RequestBuilder with appropriate authentication information applied (may or not be the same instance as
119     * <pre>request</pre>)
120     * @throws NexmoClientException If no appropriate {@link AuthMethod} is available
121     */
122    protected RequestBuilder applyAuth(RequestBuilder request) throws NexmoClientException {
123        return getAuthMethod(getAcceptableAuthMethods()).apply(request);
124    }
125
126    /**
127     * Utility method for obtaining an appropriate {@link AuthMethod} for this call.
128     *
129     * @param acceptableAuthMethods an array of classes, representing authentication methods that are acceptable for
130     *                              this endpoint
131     * @return An AuthMethod created from one of the provided acceptableAuthMethods.
132     * @throws NexmoClientException If no AuthMethod is available from the provided array of acceptableAuthMethods.
133     */
134    protected AuthMethod getAuthMethod(Class[] acceptableAuthMethods) throws NexmoClientException {
135        if (acceptable == null) {
136            this.acceptable = new HashSet<>();
137            for (Class c : acceptableAuthMethods) {
138                acceptable.add(c);
139            }
140        }
141
142        return this.httpWrapper.getAuthCollection().getAcceptableAuthMethod(acceptable);
143    }
144
145    public void setHttpClient(HttpClient client) {
146        this.httpWrapper.setHttpClient(client);
147    }
148
149    protected abstract Class[] getAcceptableAuthMethods();
150
151    /**
152     * Construct and return a RequestBuilder instance from the provided request.
153     *
154     * @param request A RequestT representing input to the REST call to be made
155     * @return A ResultT representing the response from the executed REST call
156     * @throws NexmoClientException         if a problem is encountered constructing the request or response.
157     * @throws UnsupportedEncodingException if UTF-8 encoding is not supported by the JVM
158     */
159    public abstract RequestBuilder makeRequest(RequestT request)
160            throws NexmoClientException, UnsupportedEncodingException;
161
162    /**
163     * Construct a ResultT representing the contents of the HTTP response returned from the Nexmo Voice API.
164     *
165     * @param response An HttpResponse returned from the Nexmo Voice API
166     * @return A ResultT type representing the result of the REST call
167     * @throws IOException if a problem occurs parsing the response
168     */
169    public abstract ResultT parseResponse(HttpResponse response) throws IOException, NexmoClientException;
170}