[ECR-2906] LC: Implemented System API endpoints support

exonum-light-client/src/main/java/com/exonum/client/ExonumClient.java

@@ -40,6 +40,29 @@ public interface ExonumClient {
    */
   HashCode submitTransaction(TransactionMessage tx);
 
+  /**
+   * Returns a number of unconfirmed transactions those are currently located in
+   * the memory pool and are waiting for acceptance to a block.
+   * @throws RuntimeException if the client is unable to complete a request
+   *        (e.g., in case of connectivity problems)
+   */
+  int getUnconfirmedTransactions();
+
+  /**
+   * Returns <b>true</b> if the node is connected to the other peers.
+   * And <b>false</b> otherwise.
+   * @throws RuntimeException if the client is unable to complete a request
+   *        (e.g., in case of connectivity problems)
+   */
+  boolean healthCheck();
+
+  /**
+   * Returns string containing information about Exonum, Rust and OS version.
+   * @throws RuntimeException if the client is unable to complete a request
+   *        (e.g., in case of connectivity problems)
+   */
+  String getUserAgentInfo();
+
   /**
    * Returns Exonum client builder.
    */

exonum-light-client/src/main/java/com/exonum/client/ExonumHttpClient.java

@@ -18,7 +18,10 @@
 package com.exonum.client;
 
 import static com.exonum.binding.common.serialization.json.JsonSerializer.json;
+import static com.exonum.client.ExonumUrls.HEALTH_CHECK;
+import static com.exonum.client.ExonumUrls.MEMORY_POOL;
 import static com.exonum.client.ExonumUrls.SUBMIT_TRANSACTION;
+import static com.exonum.client.ExonumUrls.USER_AGENT;
 
 import com.exonum.binding.common.hash.HashCode;
 import com.exonum.binding.common.message.TransactionMessage;
@@ -54,17 +57,50 @@ class ExonumHttpClient implements ExonumClient {
   public HashCode submitTransaction(TransactionMessage transactionMessage) {
     String msg = toHex(transactionMessage.toBytes());
 
-    Request request = createRequest(toFullUrl(SUBMIT_TRANSACTION), new SubmitTxRequest(msg));
+    Request request = postRequest(toFullUrl(SUBMIT_TRANSACTION), new SubmitTxRequest(msg));
     SubmitTxResponse result = blockingExecuteWithResponse(request, SubmitTxResponse.class);
 
     return result.hash;
   }
 
+  @Override
+  public int getUnconfirmedTransactions() {
+    Request request = getRequest(toFullUrl(MEMORY_POOL));
+    MemoryPoolResponse result = blockingExecuteWithResponse(request,
+        MemoryPoolResponse.class);
+
+    return result.size;
+  }
+
+  @Override
+  public boolean healthCheck() {
+    Request request = getRequest(toFullUrl(HEALTH_CHECK));
+    HealthCheckResponse result = blockingExecuteWithResponse(request,
+        HealthCheckResponse.class);
+
+    return result.connectivity;
+  }
+
+  @Override
+  public String getUserAgentInfo() {
+    Request request = getRequest(toFullUrl(USER_AGENT));
+    String result = blockingExecutePlainText(request);
+
+    return result;
+  }
+
   private static String toHex(byte[] array) {
     return HEX_ENCODER.encode(array);
   }
 
-  private static Request createRequest(URL url, Object requestBody) {
+  private static Request getRequest(URL url) {
+    return new Request.Builder()
+        .url(url)
+        .get()
+        .build();
+  }
+
+  private static Request postRequest(URL url, Object requestBody) {
     String jsonBody = json().toJson(requestBody);
 
     return new Request.Builder()
@@ -81,17 +117,20 @@ private URL toFullUrl(String relativeUrl) {
     }
   }
 
-  private <T> T blockingExecuteWithResponse(Request request, Class<T> responseObject) {
+  private String blockingExecutePlainText(Request request) {
     try (Response response = httpClient.newCall(request).execute()) {
       if (!response.isSuccessful()) {
         throw new RuntimeException("Execution wasn't success: " + response.toString());
       }
-      String responseJson = response.body().string();
-
-      return json().fromJson(responseJson, responseObject);
+      return response.body().string();
     } catch (IOException e) {
       throw new RuntimeException(e);
     }
   }
 
+  private <T> T blockingExecuteWithResponse(Request request, Class<T> type) {
+    String response = blockingExecutePlainText(request);
+    return json().fromJson(response, type);
+  }
+
 }

exonum-light-client/src/main/java/com/exonum/client/ExonumUrls.java

@@ -21,5 +21,11 @@
  * Contains Exonum API URLs.
  */
 final class ExonumUrls {
-  static final String SUBMIT_TRANSACTION = "/api/explorer/v1/transactions";
+  private static final String EXPLORER_PATHS_PREFIX = "/api/explorer/v1";
+  private static final String SYS_PATHS_PREFIX = "/api/system/v1";
+  static final String SUBMIT_TRANSACTION = EXPLORER_PATHS_PREFIX + "/transactions";
+  static final String MEMORY_POOL = SYS_PATHS_PREFIX + "/mempool";
+  static final String HEALTH_CHECK = SYS_PATHS_PREFIX + "/healthcheck";
+  static final String USER_AGENT = SYS_PATHS_PREFIX + "/user_agent";
+
 }

exonum-light-client/src/main/java/com/exonum/client/HealthCheckResponse.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * Licensed 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.
+ *
+ */
+
+package com.exonum.client;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Json object wrapper for health check response.
+ */
+class HealthCheckResponse {
+  boolean connectivity;
+
+  @Override
+  public String toString() {
+    return MoreObjects.toStringHelper(this)
+        .add("connectivity", connectivity)
+        .toString();
+  }
+
+}

exonum-light-client/src/main/java/com/exonum/client/MemoryPoolResponse.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019 The Exonum Team
+ *
+ * Licensed 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.
+ *
+ */
+
+package com.exonum.client;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Json object wrapper for memory pool response.
+ */
+class MemoryPoolResponse {
+  int size;
+
+  @Override
+  public String toString() {
+    return MoreObjects.toStringHelper(this)
+        .add("size", size)
+        .toString();
+  }
+
+}

exonum-light-client/src/test/java/com/exonum/client/ExonumHttpClientIntegrationTest.java

@@ -20,7 +20,10 @@
 import static com.exonum.binding.common.crypto.CryptoFunctions.ed25519;
 import static com.exonum.binding.common.serialization.json.JsonSerializer.json;
 import static com.exonum.client.ExonumHttpClient.HEX_ENCODER;
+import static com.exonum.client.ExonumUrls.HEALTH_CHECK;
+import static com.exonum.client.ExonumUrls.MEMORY_POOL;
 import static com.exonum.client.ExonumUrls.SUBMIT_TRANSACTION;
+import static com.exonum.client.ExonumUrls.USER_AGENT;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 
@@ -89,4 +92,59 @@ void submitTransactionTest() throws InterruptedException {
     assertThat(actualTxMessage, is(txMessage));
   }
 
+  @Test
+  void getUnconfirmedTransactions() throws InterruptedException {
+    // Mock response
+    int mockCount = 10;
+    String mockResponse = "{\"size\": " + mockCount + " }";
+    server.enqueue(new MockResponse().setBody(mockResponse));
+
+    // Call
+    int actualCount = exonumClient.getUnconfirmedTransactions();
+
+    // Assert response
+    assertThat(actualCount, is(mockCount));
+
+    // Assert request params
+    RecordedRequest recordedRequest = server.takeRequest();
+    assertThat(recordedRequest.getMethod(), is("GET"));
+    assertThat(recordedRequest.getPath(), is(MEMORY_POOL));
+  }
+
+  @Test
+  void healthCheck() throws InterruptedException {
+    // Mock response
+    boolean mockConnectivity = true;
+    String mockResponse = "{\"connectivity\": " + mockConnectivity + " }";
+    server.enqueue(new MockResponse().setBody(mockResponse));
+
+    // Call
+    boolean actualConnectivity = exonumClient.healthCheck();
+
+    // Assert response
+    assertThat(actualConnectivity, is(mockConnectivity));
+
+    // Assert request params
+    RecordedRequest recordedRequest = server.takeRequest();
+    assertThat(recordedRequest.getMethod(), is("GET"));
+    assertThat(recordedRequest.getPath(), is(HEALTH_CHECK));
+  }
+
+  @Test
+  void getUserAgentInfo() throws InterruptedException {
+    // Mock response
+    String mockResponse = "exonum 0.6.0/rustc 1.26.0 (2789b067d 2018-03-06)\n\n/Mac OS10.13.3";
+    server.enqueue(new MockResponse().setBody(mockResponse));
+
+    // Call
+    String actualResponse = exonumClient.getUserAgentInfo();
+
+    // Assert response
+    assertThat(actualResponse, is(mockResponse));
+
+    // Assert request params
+    RecordedRequest recordedRequest = server.takeRequest();
+    assertThat(recordedRequest.getMethod(), is("GET"));
+    assertThat(recordedRequest.getPath(), is(USER_AGENT));
+  }
 }