Support for JSON based LogResponse (#1000)

* Support for JSON logResponse

Author: rlazo

transport/transport-backend-cct/src/main/java/com/google/android/datatransport/cct/internal/LogResponse.java

@@ -0,0 +1,65 @@
+// Copyright 2019 Google LLC
+//
+// 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.google.android.datatransport.cct.internal;
+
+import android.util.JsonReader;
+import android.util.JsonToken;
+import android.util.MalformedJsonException;
+import androidx.annotation.Nullable;
+import com.google.android.datatransport.runtime.logging.Logging;
+import com.google.auto.value.AutoValue;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.Reader;
+
+@AutoValue
+public abstract class LogResponse {
+  private static final String LOG_TAG = "LogResponseInternal";
+
+  /** Client should wait for next_request_wait_millis before sending the next log request. */
+  public abstract long getNextRequestWaitMillis();
+
+  static LogResponse create(long nextRequestWaitMillis) {
+    return new AutoValue_LogResponse(nextRequestWaitMillis);
+  }
+
+  @Nullable
+  public static LogResponse fromJson(@Nullable Reader reader) throws IOException {
+    if (reader == null) {
+      return null;
+    }
+
+    JsonReader jsonReader = new JsonReader(reader);
+    try {
+      jsonReader.beginObject();
+      while (jsonReader.hasNext()) {
+        String name = jsonReader.nextName();
+        if (name.equals("nextRequestWaitMillis")) {
+          if (jsonReader.peek() == JsonToken.STRING) {
+            return LogResponse.create(Long.parseLong(jsonReader.nextString()));
+          } else {
+            return LogResponse.create(jsonReader.nextLong());
+          }
+        }
+      }
+      return null;
+    } catch (MalformedJsonException | EOFException e) {
+      Logging.e(LOG_TAG, "Couldn't parse json response from backend.", e);
+      return null;
+    } finally {
+      jsonReader.close();
+    }
+  }
+}

transport/transport-backend-cct/src/test/java/com/google/android/datatransport/cct/internal/LogResponseTest.java

@@ -0,0 +1,63 @@
+// Copyright 2019 Google LLC
+//
+// 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.google.android.datatransport.cct.internal;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.io.IOException;
+import java.io.StringReader;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+@RunWith(RobolectricTestRunner.class)
+public class LogResponseTest {
+
+  @Test
+  public void testLogRequestParsing_null() throws IOException {
+    assertThat(LogResponse.fromJson(null)).isNull();
+  }
+
+  @Test
+  public void testLogRequestParsing_emptyJson() throws IOException {
+    assertThat(LogResponse.fromJson(new StringReader(""))).isNull();
+  }
+
+  @Test
+  public void testLogRequestParsing_onlyAwaitMillis() throws IOException {
+    String jsonInput = "{\"nextRequestWaitMillis\":1000}";
+    assertThat(LogResponse.fromJson(new StringReader(jsonInput)).getNextRequestWaitMillis())
+        .isEqualTo(1000);
+  }
+
+  @Test
+  public void testLogRequestParsing_stringAwaitMillis() throws IOException {
+    String jsonInput = "{\"nextRequestWaitMillis\":\"1000\"}";
+    assertThat(LogResponse.fromJson(new StringReader(jsonInput)).getNextRequestWaitMillis())
+        .isEqualTo(1000);
+  }
+
+  @Test
+  public void testLogRequestParsing_invalidJsonIncomplete() throws IOException {
+    String jsonInput = "{\"nextRequestWaitMillis\":";
+    assertThat(LogResponse.fromJson(new StringReader(jsonInput))).isNull();
+  }
+
+  @Test
+  public void testLogRequestParsing_invalidJsonInvalid() throws IOException {
+    String jsonInput = "{\"nextRequestWaitMillis\":}";
+    assertThat(LogResponse.fromJson(new StringReader(jsonInput))).isNull();
+  }
+}