Add device name to About Phone page.

The device name is reflected in three places: A Settings.Global flag
which can be read by third party apps, the Bluetooth device name, and
the Wi-Fi tethering hotspot name.

The Bluetooth and Wi-Fi names can be changed independently of the device
name, but if the user sets the device name, they are all changed in
parallel.

Due to the naming restrictions of Bluetooth devices and SSIDs, the SSID
naming restrictions apply to the device name.

Bug: 63819909
Test: Robotest
Change-Id: I3a81535fc07d183557a6fa5d54baef3c7868499c

src/com/android/settings/deviceinfo/DeviceNamePreferenceController.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2018 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.deviceinfo;
+
+import android.annotation.Nullable;
+import android.content.Context;
+import android.net.wifi.WifiConfiguration;
+import android.net.wifi.WifiManager;
+import android.os.Build;
+import android.provider.Settings;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+import android.text.SpannedString;
+
+import com.android.settings.bluetooth.BluetoothLengthDeviceNameFilter;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.widget.ValidatedEditTextPreference;
+import com.android.settings.wifi.tether.WifiDeviceNameTextValidator;
+import com.android.settingslib.bluetooth.LocalBluetoothAdapter;
+import com.android.settingslib.bluetooth.LocalBluetoothManager;
+
+public class DeviceNamePreferenceController extends BasePreferenceController
+        implements ValidatedEditTextPreference.Validator, Preference.OnPreferenceChangeListener {
+    private static final String PREF_KEY = "device_name";
+    private String mDeviceName;
+    protected WifiManager mWifiManager;
+    private final WifiDeviceNameTextValidator mWifiDeviceNameTextValidator;
+    private ValidatedEditTextPreference mPreference;
+    @Nullable
+    private LocalBluetoothManager mBluetoothManager;
+
+    public DeviceNamePreferenceController(Context context) {
+        super(context, PREF_KEY);
+        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+        mWifiDeviceNameTextValidator = new WifiDeviceNameTextValidator();
+        initializeDeviceName();
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = (ValidatedEditTextPreference) screen.findPreference(PREF_KEY);
+        mPreference.setSummary(getSummary());
+        mPreference.setValidator(this);
+    }
+
+    private void initializeDeviceName() {
+        mDeviceName = Settings.Global.getString(mContext.getContentResolver(),
+                Settings.Global.DEVICE_NAME);
+        if (mDeviceName == null) {
+            mDeviceName = Build.MODEL;
+        }
+    }
+
+    @Override
+    public String getSummary() {
+        return mDeviceName;
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return PREF_KEY;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        mDeviceName = (String) newValue;
+        setDeviceName(mDeviceName);
+        preference.setSummary(getSummary());
+        return true;
+    }
+
+    @Override
+    public boolean isTextValid(String deviceName) {
+        // BluetoothNameDialogFragment describes BT name filter as a 248 bytes long cap.
+        // Given the restrictions presented by the SSID name filter (32 char), I don't believe it is
+        // possible to construct an SSID that is not a valid Bluetooth name.
+        return mWifiDeviceNameTextValidator.isTextValid(deviceName);
+    }
+
+    public void setLocalBluetoothManager(LocalBluetoothManager localBluetoothManager) {
+        mBluetoothManager = localBluetoothManager;
+    }
+
+    /**
+     * This method presumes that security/validity checks have already been passed.
+     */
+    private void setDeviceName(String deviceName) {
+        setSettingsGlobalDeviceName(deviceName);
+        setBluetoothDeviceName(deviceName);
+        setTetherSsidName(deviceName);
+    }
+
+    private void setSettingsGlobalDeviceName(String deviceName) {
+        Settings.Global.putString(mContext.getContentResolver(), Settings.Global.DEVICE_NAME,
+                deviceName);
+    }
+
+    private void setBluetoothDeviceName(String deviceName) {
+        // Bluetooth manager doesn't exist for certain devices.
+        if (mBluetoothManager == null) {
+            return;
+        }
+
+        final LocalBluetoothAdapter localBluetoothAdapter = mBluetoothManager.getBluetoothAdapter();
+        if (localBluetoothAdapter != null) {
+            localBluetoothAdapter.setName(getFilteredBluetoothString(deviceName));
+        }
+    }
+
+    /**
+     * Using a UTF8ByteLengthFilter, we can filter a string to be compliant with the Bluetooth spec.
+     * For more information, see {@link com.android.settings.bluetooth.BluetoothNameDialogFragment}.
+     */
+    private static final String getFilteredBluetoothString(final String deviceName) {
+        CharSequence filteredSequence = new BluetoothLengthDeviceNameFilter().filter(deviceName, 0, deviceName.length(),
+                new SpannedString(""),
+                0, 0);
+        // null -> use the original
+        if (filteredSequence == null) {
+            return deviceName;
+        }
+        return filteredSequence.toString();
+    }
+
+    private void setTetherSsidName(String deviceName) {
+        final WifiConfiguration config = mWifiManager.getWifiApConfiguration();
+        config.SSID = deviceName;
+        // TODO: If tether is running, turn off the AP and restart it after setting config.
+        mWifiManager.setWifiApConfiguration(config);
+    }
+}