Add custom upload progress RequestBody.

Author: Sam1301

app/src/main/java/com/zulip/android/networking/UploadProgressResponse.java

@@ -0,0 +1,66 @@
+package com.zulip.android.networking;
+
+import java.io.IOException;
+
+import okhttp3.MediaType;
+import okhttp3.ResponseBody;
+import okio.Buffer;
+import okio.BufferedSource;
+import okio.ForwardingSource;
+import okio.Okio;
+import okio.Source;
+
+/**
+ * TODO: add description
+ */
+
+public class UploadProgressResponse extends ResponseBody {
+    private final ResponseBody responseBody;
+    private final ProgressListener progressListener;
+    private BufferedSource bufferedSource;
+    private int mNotificationId;
+
+    public UploadProgressResponse(ResponseBody responseBody, ProgressListener progressListener,
+                                  int notificationId) {
+        this.responseBody = responseBody;
+        this.progressListener = progressListener;
+        this.mNotificationId = notificationId;
+    }
+
+    @Override
+    public MediaType contentType() {
+        return responseBody.contentType();
+    }
+
+    @Override
+    public long contentLength() {
+        return responseBody.contentLength();
+    }
+
+    @Override
+    public BufferedSource source() {
+        if (bufferedSource == null) {
+            bufferedSource = Okio.buffer(source(responseBody.source()));
+        }
+        return bufferedSource;
+    }
+
+    private Source source(Source source) {
+        return new ForwardingSource(source) {
+            long totalBytesRead = 0L;
+
+            @Override
+            public long read(Buffer sink, long byteCount) throws IOException {
+                long bytesRead = super.read(sink, byteCount);
+                // read() returns the number of bytes read, or -1 if this source is exhausted.
+                totalBytesRead += bytesRead != -1 ? bytesRead : 0;
+                progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1, mNotificationId);
+                return bytesRead;
+            }
+        };
+    }
+
+    public interface ProgressListener {
+        void update(long bytesRead, long contentLength, boolean done, int notificationId);
+    }
+}