3 files changed, 95 insertions, 0 deletions
diff --git a/android/app/src/fcm/java/io/coinos/app/CoinosApp.java b/android/app/src/fcm/java/io/coinos/app/CoinosApp.java
new file mode 100644
index 0000000..855db91
--- /dev/null
+++ b/android/app/src/fcm/java/io/coinos/app/CoinosApp.java
@@ -0,0 +1,12 @@
+package io.coinos.app;
+
+import android.app.Application;
+
+/** Sets Firebase up before anything in the process (a push included) needs it. */
+public class CoinosApp extends Application {
+  @Override
+  public void onCreate() {
+    super.onCreate();
+    Fcm.init(this);
+  }
+}
diff --git a/android/app/src/fcm/java/io/coinos/app/Fcm.java b/android/app/src/fcm/java/io/coinos/app/Fcm.java
new file mode 100644
index 0000000..02ce12c
--- /dev/null
+++ b/android/app/src/fcm/java/io/coinos/app/Fcm.java
@@ -0,0 +1,64 @@
+package io.coinos.app;
+
+import android.content.Context;
+
+import com.google.firebase.FirebaseApp;
+import com.google.firebase.FirebaseOptions;
+import com.google.firebase.messaging.FirebaseMessaging;
+
+/**
+ * Firebase Cloud Messaging, for a phone with Google Play Services: the same
+ * channel web push rides in Chrome, so the wallet is reached with no
+ * distributor app to install. Its token goes to the web app as the push
+ * endpoint "fcm:<token>", down the road a UnifiedPush endpoint takes (?up=,
+ * or straight into the page's storage), and the notifier sends an fcm:
+ * endpoint through Firebase. A phone without Play Services, or a build made
+ * without android/app/google-services.json, falls back to UnifiedPush.
+ *
+ * <p>Firebase is set up here from the values build.gradle read out of that
+ * file, rather than by Google's Gradle plugin.
+ */
+final class Fcm {
+  private Fcm() {}
+  static final String PREFIX = "fcm:";
+
+  static boolean configured() { return !BuildConfig.FCM_APP_ID.isEmpty(); }
+
+  static boolean available(Context c) {
+    if (!configured()) return false;
+    return Push.playServices(c);
+  }
+
+  /** Called from CoinosApp, before anything (FcmService included) asks for Firebase. */
+  static void init(Context c) {
+    if (!configured()) return;
+    try {
+      if (!FirebaseApp.getApps(c).isEmpty()) return;
+      FirebaseApp.initializeApp(c, new FirebaseOptions.Builder()
+          .setApplicationId(BuildConfig.FCM_APP_ID)
+          .setApiKey(BuildConfig.FCM_API_KEY)
+          .setProjectId(BuildConfig.FCM_PROJECT_ID)
+          .setGcmSenderId(BuildConfig.FCM_SENDER_ID)
+          .build());
+    } catch (Throwable ignored) {}
+  }
+
+  /**
+   * Ask for the token. It arrives later; onEndpoint runs (on any thread) once
+   * it's stored as this app's push endpoint.
+   * @return whether Firebase will deliver this app's pushes
+   */
+  static boolean register(Context c, Runnable onEndpoint) {
+    if (!available(c)) return false;
+    init(c);
+    try {
+      FirebaseMessaging.getInstance().getToken().addOnSuccessListener((token) -> {
+        if (token == null || token.isEmpty()) return;
+        String ep = PREFIX + token;
+        if (!ep.equals(Push.endpoint(c))) Push.setEndpoint(c, ep);
+        if (onEndpoint != null) onEndpoint.run();
+      });
+      return true;
+    } catch (Throwable t) { return false; }
+  }
+}
diff --git a/android/app/src/fcm/java/io/coinos/app/FcmService.java b/android/app/src/fcm/java/io/coinos/app/FcmService.java
new file mode 100644
index 0000000..24d4aca
--- /dev/null
+++ b/android/app/src/fcm/java/io/coinos/app/FcmService.java
@@ -0,0 +1,19 @@
+package io.coinos.app;
+
+import com.google.firebase.messaging.FirebaseMessagingService;
+import com.google.firebase.messaging.RemoteMessage;
+
+/** Firebase's half of PushReceiver: the notifier's JSON arrives as data "body". */
+public class FcmService extends FirebaseMessagingService {
+  @Override
+  public void onNewToken(String token) {
+    // a rotated token is a new endpoint; the page gets it on its next load
+    if (token != null && !token.isEmpty()) Push.setEndpoint(this, Fcm.PREFIX + token);
+  }
+
+  @Override
+  public void onMessageReceived(RemoteMessage msg) {
+    String body = msg.getData() == null ? null : msg.getData().get("body");
+    if (body != null) PushReceiver.onPush(this, body);
+  }
+}