PreferenceControllers are the way of the future.

Migrates Notification settings (app level, group level, and channel
level) into PreferenceControllers (and most importantly:
PreferenceControllerTest)

Note: this removes the 'Advanced' preference group, but does
not yet use the standard system 'Advanced' grouping as it does
not currently support our use case (where we don't know how many
fields to show outside of 'Advanced' until onResume() and also
where we need fields to show below the 'Advanced' group).

Test: make RunSettingsRoboTests
Change-Id: Iddd1b4771922db322e5f73562e9d63ed077c5396

src/com/android/settings/notification/NotificationPreferenceController.java

@@ -0,0 +1,188 @@
+/*
+ * Copyright (C) 2017 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.notification;
+
+import static android.app.NotificationManager.IMPORTANCE_NONE;
+
+import android.annotation.Nullable;
+import android.app.NotificationChannel;
+import android.app.NotificationChannelGroup;
+import android.app.NotificationManager;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.os.UserManager;
+import android.support.annotation.VisibleForTesting;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceGroup;
+import android.support.v7.preference.PreferenceScreen;
+import android.util.Log;
+
+import com.android.settings.wrapper.NotificationChannelGroupWrapper;
+import com.android.settingslib.RestrictedLockUtils;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import java.util.Objects;
+
+/**
+ * Parent class for preferences appearing on notification setting pages at the app,
+ * notification channel group, or notification channel level.
+ */
+public abstract class NotificationPreferenceController extends AbstractPreferenceController
+{
+    private static final String TAG = "ChannelPrefContr";
+    @Nullable protected NotificationChannel mChannel;
+    @Nullable protected NotificationChannelGroupWrapper mChannelGroup;
+    protected RestrictedLockUtils.EnforcedAdmin mAdmin;
+    protected NotificationBackend.AppRow mAppRow;
+    protected final NotificationManager mNm;
+    protected final NotificationBackend mBackend;
+    protected final Context mContext;
+    protected final UserManager mUm;
+    protected final PackageManager mPm;
+    protected Preference mPreference;
+
+    public NotificationPreferenceController(Context context, NotificationBackend backend) {
+        super(context);
+        mContext = context;
+        mNm = (NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);
+        mBackend = backend;
+        mUm = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
+        mPm = mContext.getPackageManager();
+    }
+
+    /**
+     * Returns true if field's parent object is not blocked.
+     */
+    @Override
+    public boolean isAvailable() {
+        if (mAppRow == null) {
+            return false;
+        }
+        if (mAppRow.banned) {
+            return false;
+        }
+        if (mChannel != null) {
+            return mChannel.getImportance() != IMPORTANCE_NONE;
+        }
+        if (mChannelGroup != null && mChannelGroup.getGroup() == null) {
+            return !mChannelGroup.isBlocked();
+        }
+        return true;
+    }
+
+    /**
+     * Displays or removes preference in this controller.
+     */
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        if (isAvailable()) {
+            final Preference preference = screen.findPreference(getPreferenceKey());
+            if (mPreference != null && preference == null) {
+                screen.addPreference(mPreference);
+            }
+            if (preference != null) {
+                mPreference = preference;
+            }
+            if (this instanceof Preference.OnPreferenceChangeListener) {
+                mPreference.setOnPreferenceChangeListener(
+                        (Preference.OnPreferenceChangeListener) this);
+            }
+        } else {
+            findAndRemovePreference(screen, getPreferenceKey());
+        }
+    }
+
+    // finds the preference recursively and removes it from its parent
+    private void findAndRemovePreference(PreferenceGroup prefGroup, String key) {
+        final int preferenceCount = prefGroup.getPreferenceCount();
+        for (int i = preferenceCount - 1; i >= 0; i--) {
+            final Preference preference = prefGroup.getPreference(i);
+            final String curKey = preference.getKey();
+
+            if (curKey != null && curKey.equals(key)) {
+                mPreference = preference;
+                prefGroup.removePreference(preference);
+            }
+
+            if (preference instanceof PreferenceGroup) {
+                findAndRemovePreference((PreferenceGroup) preference, key);
+            }
+        }
+    }
+
+    protected void onResume(NotificationBackend.AppRow appRow,
+            @Nullable NotificationChannel channel, @Nullable NotificationChannelGroupWrapper group,
+            RestrictedLockUtils.EnforcedAdmin admin) {
+        mAppRow = appRow;
+        mChannel = channel;
+        mChannelGroup = group;
+        mAdmin = admin;
+    }
+
+    protected boolean checkCanBeVisible(int minImportanceVisible) {
+        if (mChannel == null) {
+            Log.w(TAG, "No channel");
+            return false;
+        }
+
+        int importance = mChannel.getImportance();
+        if (importance == NotificationManager.IMPORTANCE_UNSPECIFIED) {
+            return true;
+        }
+        return importance >= minImportanceVisible;
+    }
+
+    protected void saveChannel() {
+        if (mChannel != null && mAppRow != null) {
+            mBackend.updateChannel(mAppRow.pkg, mAppRow.uid, mChannel);
+        }
+    }
+
+    protected boolean isChannelConfigurable() {
+        if (mChannel != null && mAppRow != null) {
+            return !Objects.equals(mChannel.getId(), mAppRow.lockedChannelId);
+        }
+        return false;
+    }
+
+    protected boolean isChannelBlockable() {
+        if (mChannel != null && mAppRow != null) {
+            if (!mAppRow.systemApp) {
+                return true;
+            }
+
+            return mChannel.isBlockableSystem()
+                    || mChannel.getImportance() == IMPORTANCE_NONE;
+        }
+        return false;
+    }
+
+    protected boolean isChannelGroupBlockable() {
+        if (mChannelGroup != null && mChannelGroup.getGroup() == null && mAppRow != null) {
+            if (!mAppRow.systemApp) {
+                return true;
+            }
+
+            return mChannelGroup.isBlocked();
+        }
+        return false;
+    }
+
+    protected boolean hasValidGroup() {
+        return mChannelGroup != null && mChannelGroup.getGroup() != null;
+    }
+}