[android] #5536 - Building GzipRequestInterceptor

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/telemetry/GzipRequestInterceptor.java

@@ -0,0 +1,54 @@
+package com.mapbox.mapboxsdk.telemetry;
+
+import android.util.Log;
+import java.io.IOException;
+import okhttp3.Interceptor;
+import okhttp3.MediaType;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+import okio.BufferedSink;
+import okio.GzipSink;
+import okio.Okio;
+
+/**
+ * OkHttp Interceptor for Gzipping Telemetry Data requests to the server.
+ * Based on: https://github.com/square/okhttp/wiki/Interceptors
+ */
+public final class GzipRequestInterceptor implements Interceptor {
+
+    private static final String TAG = "GzipRequestInterceptor";
+
+    @Override public Response intercept(Interceptor.Chain chain) throws IOException {
+        Request originalRequest = chain.request();
+        if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
+            Log.d(TAG, "Not compressing");
+            return chain.proceed(originalRequest);
+        }
+
+        Log.d(TAG, "Compressing");
+        Request compressedRequest = originalRequest.newBuilder()
+                .header("Content-Encoding", "gzip")
+                .method(originalRequest.method(), gzip(originalRequest.body()))
+                .build();
+        return chain.proceed(compressedRequest);
+    }
+
+    private RequestBody gzip(final RequestBody body) {
+        return new RequestBody() {
+            @Override public MediaType contentType() {
+                return body.contentType();
+            }
+
+            @Override public long contentLength() {
+                return -1; // We don't know the compressed length in advance!
+            }
+
+            @Override public void writeTo(BufferedSink sink) throws IOException {
+                BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
+                body.writeTo(gzipSink);
+                gzipSink.close();
+            }
+        };
+    }
+}