Connection Status: Added Network Broadcast Receiver

Fixes #312

Author: nitish1211

Diff for: app/src/main/java/com/zulip/android/activities/ZulipActivity.java

@@ -28,6 +28,7 @@
 import android.graphics.Bitmap;
 import android.graphics.PorterDuff;
 import android.graphics.drawable.Drawable;
+import android.net.ConnectivityManager;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
@@ -553,6 +554,7 @@ public Cursor runQuery(CharSequence charSequence) {
         handleOnFragmentChange();
         calendar = Calendar.getInstance();
         setupSnackBar();
+        setupNetworkBroadcastReceiver();
     }
 
     /**
@@ -2141,4 +2143,32 @@ public void onClick(View view) {
     public enum Flag {
         RESET_DATABASE,
     }
+    public void setupNetworkBroadcastReceiver()
+    {
+        BroadcastReceiver networkStateReceiver = new BroadcastReceiver() {
+            final CoordinatorLayout coordinatorLayout = (CoordinatorLayout) findViewById(R.id.coordinatorLayout);
+            @Override
+            public void onReceive(Context context, Intent intent) {
+                Log.d("Network Listener", "Network Type Changed");
+                boolean isConnected = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
+                if(isConnected){
+                    //Disable fab when there is no connectivity
+                    fab.setEnabled(false);
+                    fab.setVisibility(View.INVISIBLE);
+                    Snackbar.make(coordinatorLayout,"No Connection!",Snackbar.LENGTH_INDEFINITE).show();
+                    Log.d("Network Listener", "No Internet");
+                }
+                else{
+                    //Enabling fab when connection is reestablished
+                    fab.setEnabled(true);
+                    fab.setVisibility(View.VISIBLE);
+                    Snackbar.make(coordinatorLayout,"Connection Established",Snackbar.LENGTH_SHORT).show();
+                    Log.d("Network Listener", "Internet");
+                }
+            }
+        };
+
+        IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
+        registerReceiver(networkStateReceiver, filter);
+    }
 }