Polling and Converter.Factory customization support (#10)

* Allow customization of converter factories in RetrofitServices

* Polling mechanisms

* Remove unnecesary Manifest stuff

* Remove unnecesary string

* Add comment as to why Timer is fine

* Update Wolmo version to v1.3.1

networking/build.gradle

@@ -24,7 +24,7 @@ android {
 }
 
 buildscript {
-    ext.wolmo_version = 'v1.2.0'
+    ext.wolmo_version = 'v1.3.1'
     ext.retrofit_version = '2.3.0'
     ext.okhttp3_version = '3.9.0'
 }

networking/src/main/AndroidManifest.xml

@@ -1,10 +1,9 @@
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-          package="ar.com.wolox.wolmo.networking">
+<manifest
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    package="ar.com.wolox.wolmo.networking">
 
     <application
         android:allowBackup="true"
-        android:label="@string/app_name"
-        android:supportsRtl="true"
-        android:theme="@style/AppTheme"/>
+        android:supportsRtl="true"/>
 
 </manifest>

networking/src/main/java/ar/com/wolox/wolmo/networking/exception/PollRunOutOfTriesException.java

@@ -0,0 +1,17 @@
+package ar.com.wolox.wolmo.networking.exception;
+
+import android.support.annotation.NonNull;
+
+import retrofit2.Call;
+
+/**
+ * {@link Exception} raised when polling an endpoint, for a maximum amount of tries, consumes all
+ * of its tries available (ie: reaches 0).
+ */
+public final class PollRunOutOfTriesException extends RuntimeException {
+
+    public PollRunOutOfTriesException(@NonNull Call call) {
+        super("Polling to " + call.request().url().toString() + " failed after running out of tries");
+    }
+
+}

networking/src/main/java/ar/com/wolox/wolmo/networking/retrofit/RetrofitServices.java

@@ -26,12 +26,15 @@
 
 import com.google.gson.Gson;
 
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import ar.com.wolox.wolmo.networking.retrofit.serializer.BaseGsonBuilder;
 import okhttp3.OkHttpClient;
 import okhttp3.logging.HttpLoggingInterceptor;
+import retrofit2.Converter;
 import retrofit2.Retrofit;
 import retrofit2.converter.gson.GsonConverterFactory;
 
@@ -52,11 +55,19 @@ public abstract class RetrofitServices {
      */
     public void init() {
         mServices = new HashMap<>();
-        mRetrofit = new Retrofit.Builder()
+        mRetrofit = buildRetrofitInstance();
+    }
+
+    private Retrofit buildRetrofitInstance() {
+        Retrofit.Builder retrofitBuilder = new Retrofit.Builder()
                 .baseUrl(getApiEndpoint())
-                .addConverterFactory(GsonConverterFactory.create(getGson()))
-                .client(getOkHttpClient())
-                .build();
+                .client(getOkHttpClient());
+
+        for (Converter.Factory converterFactory : getConverterFactories()) {
+            retrofitBuilder.addConverterFactory(converterFactory);
+        }
+
+        return retrofitBuilder.build();
     }
 
     /**
@@ -67,6 +78,24 @@ public void init() {
     @NonNull
     public abstract String getApiEndpoint();
 
+    /**
+     * Allows configuration of the {@link Converter.Factory} to be used by {@link Retrofit}.
+     * The default implementation returns a list with a single {@link GsonConverterFactory}
+     * instance. The {@link} must not contain a {@code null} {@link Converter.Factory}.
+     * <p/>
+     * An important implicit aspect of what is returned in this method is that {@link Retrofit}
+     * iterates through the list <bold>in order</bold> to match a {@link okhttp3.ResponseBody}
+     * with a {@link Converter}.
+     * <p/>
+     * Implementations should pay attention to these because, for example,
+     * {@link GsonConverterFactory} <bold>always</bold> matches, thus preventing the fall-through.
+     *
+     * @return the {@link List} of {@link GsonConverterFactory} to use.
+     */
+    protected List<Converter.Factory> getConverterFactories() {
+        return Collections.singletonList(GsonConverterFactory.create(getGson()));
+    }
+
     /**
      * Returns an instance of Gson to use for conversion.
      * This method calls <i>initGson(builder)</i> to configure the Gson Builder.
@@ -138,7 +167,7 @@ private boolean isInitialized() {
      * @param <T>   Service class
      * @return service
      */
-    public <T> T getService(@NonNull Class<T> clazz) {
+    public final <T> T getService(@NonNull Class<T> clazz) {
         if (!isInitialized()) throw new RuntimeException("RetrofitServices is not initialized! " +
                 "Must call init() at least once before calling getService(clazz)");
 

networking/src/main/java/ar/com/wolox/wolmo/networking/utils/CallUtils.java

@@ -0,0 +1,81 @@
+package ar.com.wolox.wolmo.networking.utils;
+
+import android.support.annotation.IntRange;
+import android.support.annotation.NonNull;
+
+import com.android.internal.util.Predicate;
+
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.TimeUnit;
+
+import ar.com.wolox.wolmo.networking.exception.PollRunOutOfTriesException;
+import retrofit2.Call;
+import retrofit2.Callback;
+import retrofit2.Response;
+
+/**
+ * Common uses of Retrofit's {@link Call}, {@link Callback} and their interactions.
+ */
+public class CallUtils {
+
+    private CallUtils() {}
+
+    /**
+     * Polls with a delay in-between calls.
+     *
+     * @param tries amount of tries
+     * @param call to poll
+     * @param pollingCondition that dictates whether to keep polling
+     * @param callback to be notified when polling ends
+     * @param delay to apply in-between calls
+     * @param timeoutUnit to convert delay
+
+     * @return a {@link Timer} which is controlling the polling
+     */
+    public static <T> Timer pollWithDelay(@IntRange(from = 1) final int tries,
+                                          @NonNull final Call<T> call,
+                                          @NonNull final Predicate<Response<T>> pollingCondition,
+                                          @NonNull final Callback<T> callback,
+                                          @IntRange(from = 0) long delay,
+                                          @NonNull TimeUnit timeoutUnit) {
+        // Timer can be used safely since Retrofit callback is called on UiThread
+        Timer pollingTimer = new Timer();
+        pollWithDelay(tries, call, pollingCondition, callback,
+                timeoutUnit.toMillis(delay), pollingTimer);
+        return pollingTimer;
+    }
+
+    private static <T> void pollWithDelay(@IntRange(from = 1) final int triesRemaining,
+                                           @NonNull final Call<T> call,
+                                           @NonNull final Predicate<Response<T>> pollingCondition,
+                                           @NonNull final Callback<T> callback,
+                                           @IntRange(from = 0) long delayInMillis,
+                                           @NonNull final Timer pollingTimer) {
+        if (triesRemaining <= 0) callback.onFailure(call, new PollRunOutOfTriesException(call));
+
+        call.enqueue(new Callback<T>() {
+            @Override
+            public void onResponse(Call<T> call, Response<T> response) {
+                if (!pollingCondition.apply(response)) {
+                    callback.onResponse(call, response);
+                    return;
+                }
+
+                pollingTimer.schedule(new TimerTask() {
+                    @Override
+                    public void run() {
+                        pollWithDelay(triesRemaining - 1, call.clone(),
+                                pollingCondition, callback, delayInMillis, pollingTimer);
+                    }
+                }, delayInMillis);
+            }
+
+            @Override
+            public void onFailure(Call<T> call, Throwable t) {
+                callback.onFailure(call, t);
+            }
+        });
+    }
+
+}

networking/src/main/res/values/strings.xml

@@ -1,5 +1,4 @@
 <resources>
-    <string name="app_name">Networking</string>
 
     <!-- General -->
     <string name="unknown_error">Whoops! Something went wrong</string>