Add page listing multiple mobile networks

When a device supports simultaneous connection to multiple mobile
networks, we want the "Mobile network" entry on the Network & internet
page to list the number of active SIMs and when clicked, go to a page
that lists them all.

Bug: 116349402
Test: make RunSettingsRoboTests
Change-Id: Ie642d7801cda07dcbbe74d42c234db6605566be4

src/com/android/settings/network/MobileNetworkSummaryController.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.network;
+
+import static androidx.lifecycle.Lifecycle.Event.ON_PAUSE;
+import static androidx.lifecycle.Lifecycle.Event.ON_RESUME;
+
+import android.content.Context;
+import android.content.Intent;
+import android.telephony.SubscriptionInfo;
+import android.telephony.SubscriptionManager;
+
+import com.android.settings.R;
+import com.android.settings.network.telephony.MobileNetworkActivity;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import java.util.List;
+
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleObserver;
+import androidx.lifecycle.OnLifecycleEvent;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+public class MobileNetworkSummaryController extends AbstractPreferenceController implements
+        SubscriptionsChangeListener.SubscriptionsChangeListenerClient, LifecycleObserver {
+    private static final String TAG = "MobileNetSummaryCtlr";
+
+    private static final String KEY = "mobile_network_list";
+
+    private SubscriptionManager mSubscriptionManager;
+    private SubscriptionsChangeListener mChangeListener;
+    private PreferenceScreen mScreen;
+
+    /**
+     * This controls the summary text and click behavior of the "Mobile network" item on the
+     * Network & internet page. There are 3 separate cases depending on the number of mobile network
+     * subscriptions:
+     * <ul>
+     * <li>No subscription: click action begins a UI flow to add a network subscription, and
+     * the summary text indicates this</li>
+     *
+     * <li>One subscription: click action takes you to details for that one network, and
+     * the summary text is the network name</li>
+     *
+     * <li>More than one subscription: click action takes you to a page listing the subscriptions,
+     * and the summary text gives the count of SIMs</li>
+     * </ul>
+     */
+    public MobileNetworkSummaryController(Context context, Lifecycle lifecycle) {
+        super(context);
+        mSubscriptionManager = context.getSystemService(SubscriptionManager.class);
+        mChangeListener = new SubscriptionsChangeListener(context, this);
+        lifecycle.addObserver(this);
+    }
+
+    @OnLifecycleEvent(ON_RESUME)
+    public void onResume() {
+        mChangeListener.start();
+        update();
+    }
+
+    @OnLifecycleEvent(ON_PAUSE)
+    public void onPause() {
+        mChangeListener.stop();
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mScreen = screen;
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        final List<SubscriptionInfo> subs = SubscriptionUtil.getAvailableSubscriptions(
+                mSubscriptionManager);
+        if (subs.isEmpty()) {
+            return mContext.getResources().getString(R.string.mobile_network_summary_add_a_network);
+        } else if (subs.size() == 1) {
+            return subs.get(0).getDisplayName();
+        } else {
+            final int count = subs.size();
+            return mContext.getResources().getQuantityString(R.plurals.mobile_network_summary_count,
+                    count, count);
+        }
+    }
+
+    private void update() {
+        if (mScreen != null) {
+            final Preference preference = mScreen.findPreference(getPreferenceKey());
+            refreshSummary(preference);
+            final List<SubscriptionInfo> subs = SubscriptionUtil.getAvailableSubscriptions(
+                    mSubscriptionManager);
+
+            preference.setOnPreferenceClickListener(null);
+            preference.setFragment(null);
+            if (subs.size() == 0) {
+                preference.setOnPreferenceClickListener((Preference pref) -> {
+                    // TODO(asargent) - need to get correct intent to fire here
+                    return true;
+                });
+            } else if (subs.size() == 1) {
+                preference.setOnPreferenceClickListener((Preference pref) -> {
+                    final Intent intent = new Intent(mContext, MobileNetworkActivity.class);
+                    mContext.startActivity(intent);
+                    return true;
+                });
+            } else {
+                preference.setFragment(MobileNetworkListFragment.class.getCanonicalName());
+            }
+        }
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY;
+    }
+
+    @Override
+    public void onAirplaneModeChanged(boolean airplaneModeEnabled) {
+    }
+
+    @Override
+    public void onSubscriptionsChanged() {
+        update();
+    }
+}