1 files changed, 227 insertions, 0 deletions
diff --git a/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/AccountLoader.java b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/AccountLoader.java
new file mode 100644
index 000000000..8a31c1ce0
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+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/AccountLoader.java
@@ -0,0 +1,227 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.fxa;
+
+import org.mozilla.gecko.fxa.authenticator.AndroidFxAccount;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.os.Handler;
+import android.os.Looper;
+import android.content.AsyncTaskLoader;
+import android.support.v4.content.LocalBroadcastManager;
+
+import java.lang.ref.WeakReference;
+
+/**
+ * A Loader that queries and updates based on the existence of Firefox and
+ * legacy Sync Android Accounts.
+ *
+ * The loader returns an Android Account (of either Account type) if an account
+ * exists, and null to indicate no Account is present.
+ *
+ * The loader listens for Accounts added and deleted, and also Accounts being
+ * updated by Sync or another Activity, via the use of
+ * {@link AndroidFxAccount#setState(org.mozilla.gecko.fxa.login.State)}.
+ * Be careful of message loops if you update the account state from an activity
+ * that uses this loader.
+ *
+ * This implementation is based on
+ * <a href="http://www.androiddesignpatterns.com/2012/08/implementing-loaders.html">http://www.androiddesignpatterns.com/2012/08/implementing-loaders.html</a>.
+ */
+public class AccountLoader extends AsyncTaskLoader<Account> {
+  protected Account account = null;
+  protected BroadcastReceiver broadcastReceiver = null;
+
+  // Hold a weak reference to AccountLoader instance in this Runnable to avoid potentially leaking it
+  // after posting to a Handler in the BroadcastReceiver returned from makeNewObserver.
+  private final BroadcastReceiverRunnable broadcastReceiverRunnable = new BroadcastReceiverRunnable(this);
+
+  public AccountLoader(final Context context) {
+    super(context);
+  }
+
+  // Task that performs the asynchronous load.
+  @Override
+  public Account loadInBackground() {
+    return FirefoxAccounts.getFirefoxAccount(getContext());
+  }
+
+  // Deliver the results to the registered listener.
+  @Override
+  public void deliverResult(Account data) {
+    if (isReset()) {
+      // The Loader has been reset; ignore the result and invalidate the data.
+      releaseResources(data);
+      return;
+    }
+
+    // Hold a reference to the old data so it doesn't get garbage collected.
+    // We must protect it until the new data has been delivered.
+    Account oldData = account;
+    account = data;
+
+    if (isStarted()) {
+      // If the Loader is in a started state, deliver the results to the
+      // client. The superclass method does this for us.
+      super.deliverResult(data);
+    }
+
+    // Invalidate the old data as we don't need it any more.
+    if (oldData != null && oldData != data) {
+      releaseResources(oldData);
+    }
+  }
+
+  // The Loader’s state-dependent behavior.
+  @Override
+  protected void onStartLoading() {
+    if (account != null) {
+      // Deliver any previously loaded data immediately.
+      deliverResult(account);
+    }
+
+    // Begin monitoring the underlying data source.
+    if (broadcastReceiver == null) {
+      broadcastReceiver = makeNewObserver();
+      registerLocalObserver(getContext(), broadcastReceiver);
+      registerSystemObserver(getContext(), broadcastReceiver);
+    }
+
+    if (takeContentChanged() || account == null) {
+      // When the observer detects a change, it should call onContentChanged()
+      // on the Loader, which will cause the next call to takeContentChanged()
+      // to return true. If this is ever the case (or if the current data is
+      // null), we force a new load.
+      forceLoad();
+    }
+  }
+
+  @Override
+  protected void onStopLoading() {
+    // The Loader is in a stopped state, so we should attempt to cancel the
+    // current load (if there is one).
+    cancelLoad();
+
+    // Note that we leave the observer as is. Loaders in a stopped state
+    // should still monitor the data source for changes so that the Loader
+    // will know to force a new load if it is ever started again.
+  }
+
+  @Override
+  protected void onReset() {
+    // Ensure the loader has been stopped.  In CursorLoader and the template
+    // this code follows (see the class comment), this is onStopLoading, which
+    // appears to not set the started flag (see Loader itself).
+    stopLoading();
+
+    // At this point we can release the resources associated with 'mData'.
+    if (account != null) {
+      releaseResources(account);
+      account = null;
+    }
+
+    // The Loader is being reset, so we should stop monitoring for changes.
+    if (broadcastReceiver != null) {
+      final BroadcastReceiver observer = broadcastReceiver;
+      broadcastReceiver = null;
+      unregisterObserver(getContext(), observer);
+    }
+  }
+
+  @Override
+  public void onCanceled(final Account data) {
+    // Attempt to cancel the current asynchronous load.
+    super.onCanceled(data);
+
+    // The load has been canceled, so we should release the resources
+    // associated with 'data'.
+    releaseResources(data);
+  }
+
+  // Observer which receives notifications when the data changes.
+  protected BroadcastReceiver makeNewObserver() {
+    return new BroadcastReceiver() {
+      @Override
+      public void onReceive(Context context, Intent intent) {
+        // onContentChanged must be called on the main thread.
+        // If we're already on the main thread, call it directly.
+        if (Looper.myLooper() == Looper.getMainLooper()) {
+          onContentChanged();
+          return;
+        }
+
+        // Otherwise, post a Runnable to a Handler bound to the main thread's message loop.
+        final Handler mainHandler = new Handler(Looper.getMainLooper());
+        mainHandler.post(broadcastReceiverRunnable);
+      }
+    };
+  }
+
+  private static class BroadcastReceiverRunnable implements Runnable {
+    private final WeakReference<AccountLoader> accountLoaderWeakReference;
+
+    public BroadcastReceiverRunnable(final AccountLoader accountLoader) {
+      accountLoaderWeakReference = new WeakReference<>(accountLoader);
+    }
+
+    @Override
+    public void run() {
+      final AccountLoader accountLoader = accountLoaderWeakReference.get();
+      if (accountLoader != null) {
+        accountLoader.onContentChanged();
+      }
+    }
+  }
+
+  private void releaseResources(Account data) {
+    // For a simple List, there is nothing to do. For something like a Cursor, we
+    // would close it in this method. All resources associated with the Loader
+    // should be released here.
+  }
+
+  /**
+   * Register provided observer with the LocalBroadcastManager to listen for internal events.
+   *
+   * @param context <code>Context</code> to use for obtaining LocalBroadcastManager instance.
+   * @param observer <code>BroadcastReceiver</code> which will handle local events.
+   */
+  protected static void registerLocalObserver(final Context context, final BroadcastReceiver observer) {
+    final IntentFilter intentFilter = new IntentFilter();
+    // Firefox Account internal state changed.
+    intentFilter.addAction(FxAccountConstants.ACCOUNT_STATE_CHANGED_ACTION);
+    // Firefox Account profile state changed.
+    intentFilter.addAction(FxAccountConstants.ACCOUNT_PROFILE_JSON_UPDATED_ACTION);
+
+    LocalBroadcastManager.getInstance(context).registerReceiver(observer, intentFilter);
+  }
+
+  /**
+   * Register provided observer for handling system-wide broadcasts.
+   *
+   * @param context <code>Context</code> to use for registering a receiver.
+   * @param observer <code>BroadcastReceiver</code> which will handle system events.
+   */
+  protected static void registerSystemObserver(final Context context, final BroadcastReceiver observer) {
+    context.registerReceiver(observer,
+            // Android Account added or removed.
+            new IntentFilter(AccountManager.LOGIN_ACCOUNTS_CHANGED_ACTION),
+            // No broadcast permissions required.
+            null,
+            // Null handler ensures that broadcasts will be handled on the main thread.
+            null
+    );
+  }
+
+  protected static void unregisterObserver(final Context context, final BroadcastReceiver observer) {
+    LocalBroadcastManager.getInstance(context).unregisterReceiver(observer);
+    context.unregisterReceiver(observer);
+  }
+}
+