[Settings] Refactor Wifi Calling description text

Refactor the display of description text when no wifi calling options available.
Enhancement:
1. These text need to align the style with the summary part of the wifi
calling options.
2. These text need to be scrollable in order to see full description.
3. The link within text need to be clickable.

Bug: 204844012
Test: local
Change-Id: Ie89a5b65e75cdd61fab68c6e1bf7c40bfcc68b6b
diff --git a/res/layout/wifi_calling_settings_preferences.xml b/res/layout/wifi_calling_settings_preferences.xml
index 98acd95..9a6cbe6 100644
--- a/res/layout/wifi_calling_settings_preferences.xml
+++ b/res/layout/wifi_calling_settings_preferences.xml
@@ -29,16 +29,11 @@
 
     <FrameLayout
         android:id="@android:id/tabcontent"
-        android:layout_width="0dip"
-        android:layout_height="0dip" />
-
-    <FrameLayout
-        android:id="@+id/prefs_container"
         android:layout_width="match_parent"
         android:layout_height="0dip"
         android:layout_weight="1"
-        android:clipChildren="false"
-        android:clipToPadding="false"
+        android:clipChildren="true"
+        android:clipToPadding="true"
         android:smoothScrollbar="false" />
 
 </LinearLayout>
diff --git a/res/xml/wifi_calling_settings.xml b/res/xml/wifi_calling_settings.xml
index 0276bdb..902ff1a 100644
--- a/res/xml/wifi_calling_settings.xml
+++ b/res/xml/wifi_calling_settings.xml
@@ -21,6 +21,7 @@
 
     <com.android.settings.wifi.calling.ListWithEntrySummaryPreference
             android:key="wifi_calling_mode"
+            isPreferenceVisible="false"
             android:title="@string/wifi_calling_mode_title"
             android:summary="@string/wifi_calling_mode_title"
             android:entries="@array/wifi_calling_mode_choices"
@@ -30,6 +31,7 @@
 
     <com.android.settings.wifi.calling.ListWithEntrySummaryPreference
             android:key="wifi_calling_roaming_mode"
+            isPreferenceVisible="false"
             android:title="@string/wifi_calling_roaming_mode_title"
             android:summary="@string/wifi_calling_roaming_mode_summary"
             android:entries="@array/wifi_calling_mode_choices_v2"
@@ -39,7 +41,12 @@
 
     <Preference
             android:key="emergency_address_key"
+            isPreferenceVisible="false"
             android:title="@string/emergency_address_title"
             android:summary="@string/emergency_address_summary" />
 
+    <com.android.settings.wifi.calling.LinkifyDescriptionPreference
+            android:key="no_options_description"
+            isPreferenceVisible="false" />
+
 </PreferenceScreen>
diff --git a/src/com/android/settings/wifi/calling/LinkifyDescriptionPreference.java b/src/com/android/settings/wifi/calling/LinkifyDescriptionPreference.java
new file mode 100644
index 0000000..60400b0
--- /dev/null
+++ b/src/com/android/settings/wifi/calling/LinkifyDescriptionPreference.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2021 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.wifi.calling;
+
+import android.content.Context;
+import android.text.SpannableString;
+import android.text.TextUtils;
+import android.text.method.LinkMovementMethod;
+import android.text.style.ClickableSpan;
+import android.text.util.Linkify;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.TextView;
+
+import androidx.core.text.util.LinkifyCompat;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceViewHolder;
+
+import com.android.settings.R;
+
+/** A preference which supports linkify text as a description in the summary **/
+public class LinkifyDescriptionPreference extends Preference {
+
+    public LinkifyDescriptionPreference(Context context) {
+        this(context, null);
+    }
+
+    public LinkifyDescriptionPreference(Context context, AttributeSet attrs) {
+      super(context, attrs);
+    }
+
+    @Override
+    public void onBindViewHolder(PreferenceViewHolder holder) {
+        super.onBindViewHolder(holder);
+
+        final TextView summaryView = (TextView) holder.findViewById(android.R.id.summary);
+        if (summaryView == null || summaryView.getVisibility() != View.VISIBLE) {
+            return;
+        }
+
+        final CharSequence summary = getSummary();
+        if (TextUtils.isEmpty(summary)) {
+            return;
+        }
+
+        summaryView.setMaxLines(Integer.MAX_VALUE);
+
+        final SpannableString spannableSummary = new SpannableString(summary);
+        if (spannableSummary.getSpans(0, spannableSummary.length(), ClickableSpan.class)
+                .length > 0) {
+            summaryView.setMovementMethod(LinkMovementMethod.getInstance());
+        }
+        LinkifyCompat.addLinks(summaryView,
+                Linkify.WEB_URLS | Linkify.EMAIL_ADDRESSES | Linkify.PHONE_NUMBERS);
+    }
+}
diff --git a/src/com/android/settings/wifi/calling/WifiCallingSettingsForSub.java b/src/com/android/settings/wifi/calling/WifiCallingSettingsForSub.java
index 18583f1..19664be 100644
--- a/src/com/android/settings/wifi/calling/WifiCallingSettingsForSub.java
+++ b/src/com/android/settings/wifi/calling/WifiCallingSettingsForSub.java
@@ -35,7 +35,6 @@
 import android.telephony.ims.ImsMmTelManager;
 import android.telephony.ims.ProvisioningManager;
 import android.text.TextUtils;
-import android.text.util.Linkify;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -58,8 +57,11 @@
 import com.android.settings.core.SubSettingLauncher;
 import com.android.settings.network.ims.WifiCallingQueryImsState;
 import com.android.settings.widget.SettingsMainSwitchBar;
+import com.android.settings.wifi.calling.LinkifyDescriptionPreference;
 import com.android.settingslib.widget.OnMainSwitchChangeListener;
 
+import java.util.List;
+
 /**
  * This is the inner class of {@link WifiCallingSettings} fragment.
  * The preference screen lets you enable/disable Wi-Fi Calling and change Wi-Fi Calling mode.
@@ -73,6 +75,7 @@
     private static final String BUTTON_WFC_MODE = "wifi_calling_mode";
     private static final String BUTTON_WFC_ROAMING_MODE = "wifi_calling_roaming_mode";
     private static final String PREFERENCE_EMERGENCY_ADDRESS = "emergency_address_key";
+    private static final String PREFERENCE_NO_OPTIONS_DESC = "no_options_description";
 
     @VisibleForTesting
     static final int REQUEST_CHECK_WFC_EMERGENCY_ADDRESS = 1;
@@ -92,7 +95,6 @@
     private ListWithEntrySummaryPreference mButtonWfcMode;
     private ListWithEntrySummaryPreference mButtonWfcRoamingMode;
     private Preference mUpdateAddress;
-    private TextView mEmptyView;
 
     private boolean mValidListener = false;
     private boolean mEditableWfcMode = true;
@@ -157,7 +159,7 @@
     }
 
     /*
-     * Launch carrier emergency address managemnent activity
+     * Launch carrier emergency address management activity
      */
     private final OnPreferenceClickListener mUpdateAddressListener =
             preference -> {
@@ -186,14 +188,6 @@
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
 
-        mEmptyView = getView().findViewById(android.R.id.empty);
-        setEmptyView(mEmptyView);
-        mEmptyView.setAutoLinkMask(Linkify.WEB_URLS);
-        final Resources res = getResourcesForSubId();
-        final String emptyViewText = res.getString(R.string.wifi_calling_off_explanation,
-                res.getString(R.string.wifi_calling_off_explanation_2));
-        mEmptyView.setText(emptyViewText);
-
         mSwitchBar = getView().findViewById(R.id.switch_bar);
         mSwitchBar.show();
     }
@@ -309,6 +303,9 @@
 
         mIntentFilter = new IntentFilter();
         mIntentFilter.addAction(ImsManager.ACTION_WFC_IMS_REGISTRATION_ERROR);
+
+        updateDescriptionForOptions(
+                List.of(mButtonWfcMode, mButtonWfcRoamingMode, mUpdateAddress));
     }
 
     @Override
@@ -324,7 +321,7 @@
         final View view = inflater.inflate(
                 R.layout.wifi_calling_settings_preferences, container, false);
 
-        final ViewGroup prefs_container = view.findViewById(R.id.prefs_container);
+        final ViewGroup prefs_container = view.findViewById(android.R.id.tabcontent);
         Utils.prepareCustomPreferencesList(container, view, prefs_container, false);
         final View prefs = super.onCreateView(inflater, prefs_container, savedInstanceState);
         prefs_container.addView(prefs);
@@ -573,28 +570,35 @@
         final PreferenceScreen preferenceScreen = getPreferenceScreen();
         final boolean updateAddressEnabled = (getCarrierActivityIntent() != null);
         if (wfcEnabled) {
-            if (mEditableWfcMode) {
-                preferenceScreen.addPreference(mButtonWfcMode);
-            } else {
-                // Don't show WFC (home) preference if it's not editable.
-                preferenceScreen.removePreference(mButtonWfcMode);
-            }
-            if (mEditableWfcRoamingMode && !mUseWfcHomeModeForRoaming) {
-                preferenceScreen.addPreference(mButtonWfcRoamingMode);
-            } else {
-                // Don't show WFC roaming preference if it's not editable.
-                preferenceScreen.removePreference(mButtonWfcRoamingMode);
-            }
-            if (updateAddressEnabled) {
-                preferenceScreen.addPreference(mUpdateAddress);
-            } else {
-                preferenceScreen.removePreference(mUpdateAddress);
-            }
+            // Don't show WFC (home) preference if it's not editable.
+            mButtonWfcMode.setVisible(mEditableWfcMode);
+            // Don't show WFC roaming preference if it's not editable.
+            mButtonWfcRoamingMode.setVisible(
+                    mEditableWfcRoamingMode && !mUseWfcHomeModeForRoaming);
+            mUpdateAddress.setVisible(updateAddressEnabled);
         } else {
-            preferenceScreen.removePreference(mButtonWfcMode);
-            preferenceScreen.removePreference(mButtonWfcRoamingMode);
-            preferenceScreen.removePreference(mUpdateAddress);
+            mButtonWfcMode.setVisible(false);
+            mButtonWfcRoamingMode.setVisible(false);
+            mUpdateAddress.setVisible(false);
         }
+        updateDescriptionForOptions(
+                List.of(mButtonWfcMode, mButtonWfcRoamingMode, mUpdateAddress));
+    }
+
+    private void updateDescriptionForOptions(List<Preference> visibleOptions) {
+        LinkifyDescriptionPreference pref = findPreference(PREFERENCE_NO_OPTIONS_DESC);
+        if (pref == null) {
+            return;
+        }
+
+        boolean optionsAvailable = visibleOptions.stream().anyMatch(Preference::isVisible);
+        if (!optionsAvailable) {
+            final Resources res = getResourcesForSubId();
+            String emptyViewText = res.getString(R.string.wifi_calling_off_explanation,
+                    res.getString(R.string.wifi_calling_off_explanation_2));
+            pref.setSummary(emptyViewText);
+        }
+        pref.setVisible(!optionsAvailable);
     }
 
     @Override