[Provider Model] Add Learn more in the WFC footer

UX deck: https://screenshot.googleplex.com/4DxGCxgEsujhEpy.png
Implementation: https://screenshot.googleplex.com/5yZhQMQwwRZQkge.png

Bug: 178898044
Test: make
Change-Id: Icfde927e6781303b6016b0ec13201fd7052191d3

res/xml/network_provider_calls_sms.xml

@@ -56,6 +56,7 @@
         android:key="provider_model_calls_sms_footer"
         android:title="@string/calls_sms_footnote"
         android:selectable="false"
+        settings:allowDividerAbove="true"
         settings:searchable="false"
-        />
+        settings:controller="com.android.settings.network.telephony.NetworkProviderWfcFooterPreferenceController"/>
 </PreferenceScreen>

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

@@ -27,6 +27,7 @@ import com.android.settings.Utils;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settings.network.telephony.CallsDefaultSubscriptionController;
 import com.android.settings.network.telephony.NetworkProviderBackupCallingPreferenceController;
+import com.android.settings.network.telephony.NetworkProviderWfcFooterPreferenceController;
 import com.android.settings.network.telephony.NetworkProviderWifiCallingPreferenceController;
 import com.android.settings.network.telephony.SmsDefaultSubscriptionController;
 import com.android.settings.search.BaseSearchIndexProvider;
@@ -45,6 +46,9 @@ public class NetworkProviderCallsSmsFragment extends DashboardFragment {
     @VisibleForTesting
     static final String KEY_PREFERENCE_CATEGORY_BACKUP_CALLING =
             "provider_model_backup_calling_category";
+    static final String KEY_PREFERENCE_CATEGORY_WFC_FOOTER =
+            "provider_model_calls_sms_footer";
+
     @VisibleForTesting
     static final String KEY_PREFERENCE_CALLS= "provider_model_calls_preference";
     @VisibleForTesting
@@ -70,6 +74,12 @@ public class NetworkProviderCallsSmsFragment extends DashboardFragment {
         backupCallingPrefCtrl.init(getSettingsLifecycle());
         controllers.add(backupCallingPrefCtrl);
 
+        NetworkProviderWfcFooterPreferenceController wfcFooterPreferenceController =
+                new NetworkProviderWfcFooterPreferenceController(context,
+                        KEY_PREFERENCE_CATEGORY_WFC_FOOTER);
+        wfcFooterPreferenceController.init(getSettingsLifecycle());
+        controllers.add(wfcFooterPreferenceController);
+
         return controllers;
     }
 

src/com/android/settings/network/telephony/NetworkProviderWfcFooterPreferenceController.java

@@ -0,0 +1,77 @@
+package com.android.settings.network.telephony;
+
+import android.content.Context;
+import android.content.Intent;
+import android.telephony.SubscriptionInfo;
+import android.telephony.SubscriptionManager;
+
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.network.SubscriptionUtil;
+import com.android.settings.utils.AnnotationSpan;
+import com.android.settingslib.HelpUtils;
+import com.android.settingslib.core.lifecycle.Lifecycle;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+
+import java.util.List;
+
+public class NetworkProviderWfcFooterPreferenceController extends BasePreferenceController
+        implements LifecycleObserver {
+
+    /**
+     * Constructor.
+     */
+    public NetworkProviderWfcFooterPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    /**
+     * Initialize the binding with Lifecycle
+     *
+     * @param lifecycle Lifecycle of UI which owns this Preference
+     */
+    public void init(Lifecycle lifecycle) {
+        lifecycle.addObserver(this);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+
+        if (preference != null) {
+            // This is necessary to ensure that setting the title to the spannable string returned
+            // by getFooterText will be accepted.  Internally, setTitle does an equality check on
+            // the spannable string being set to the text already set on the preference.  That
+            // equality check apparently only takes into account the raw text and not and spannables
+            // that are part of the text.  So we clear the title before applying the spannable
+            // footer to ensure it is accepted.
+            preference.setTitle("");
+            preference.setTitle(getFooterText());
+        }
+    }
+
+    private CharSequence getFooterText() {
+        final Intent helpIntent = HelpUtils.getHelpIntent(mContext,
+                mContext.getString(R.string.help_uri_wifi_calling),
+                mContext.getClass().getName());
+        final AnnotationSpan.LinkInfo linkInfo = new AnnotationSpan.LinkInfo(mContext,
+                "url", helpIntent);
+
+        return AnnotationSpan.linkify(mContext.getText(R.string.calls_sms_footnote), linkInfo);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        final SubscriptionManager subscriptionManager =
+                mContext.getSystemService(SubscriptionManager.class);
+        final List<SubscriptionInfo> subscriptions = SubscriptionUtil.getActiveSubscriptions(
+                subscriptionManager);
+        if (subscriptions.size() >= 1) {
+            return AVAILABLE;
+        } else {
+            return CONDITIONALLY_UNAVAILABLE;
+        }
+    }
+}

src/com/android/settings/network/telephony/NetworkProviderWifiCallingPreferenceController.java

@@ -17,7 +17,6 @@
 package com.android.settings.network.telephony;
 
 import android.content.Context;
-import android.telephony.CarrierConfigManager;
 
 import androidx.annotation.VisibleForTesting;
 import androidx.preference.Preference;