Enable Bluetooth stack logging from Developer Options UI Element

The goal is to be able to enable different log levels for Bluetooth
stack logging from Developer Options in Settings. This is done by
creating a Bluetooth property which houses the current state of the log
level, adding the required UI elements and linking the two together.

Tag: #feature
Bug: 307330446
Test: atest BluetoothStackLogPreferenceControllerTest
Change-Id: I8665b17622218743aa00250118b718d5cabdb9fc

src/com/android/settings/development/bluetooth/BluetoothStackLogPreferenceController.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2023 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.development.bluetooth;
+
+import android.content.Context;
+import android.os.SystemProperties;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.ListPreference;
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+public class BluetoothStackLogPreferenceController extends DeveloperOptionsPreferenceController
+        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+
+    /* Ensure that the indexes match with bt_stack_log_values and bt_stack_log_entries ordering */
+    private static final String PREFERENCE_KEY = "bt_stack_log_level";
+    @VisibleForTesting static final int BTSTACK_LOG_MODE_VERBOSE_INDEX = 0;
+    @VisibleForTesting static final int BTSTACK_LOG_MODE_DEBUG_INDEX = 1;
+    @VisibleForTesting static final int BTSTACK_LOG_MODE_INFO_INDEX = 2;
+    @VisibleForTesting static final int BTSTACK_LOG_MODE_WARN_INDEX = 3;
+    @VisibleForTesting static final int BTSTACK_LOG_MODE_ERROR_INDEX = 4;
+
+    @VisibleForTesting
+    static final String BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY_PERSIST = "persist.log.tag.bluetooth";
+    static final String BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY = "log.tag.bluetooth";
+    static final String BLUETOOTH_STRING_NAME = "bluetooth";
+    static final int DEFAULT_MODE = BTSTACK_LOG_MODE_INFO_INDEX;
+
+    private final String[] mListValues;
+    private final String[] mListEntries;
+
+
+    public BluetoothStackLogPreferenceController(@NonNull Context context) {
+        super(context);
+        mListValues = context.getResources().getStringArray(R.array.bt_stack_log_level_values);
+        mListEntries = context.getResources().getStringArray(R.array.bt_stack_log_level_entries);
+    }
+
+    /** returns default log level index of INFO */
+    public int getDefaultModeIndex() {
+        return DEFAULT_MODE;
+    }
+
+    @Override
+    @Nullable
+    public String getPreferenceKey() {
+        return PREFERENCE_KEY;
+    }
+
+    @Override
+    public boolean onPreferenceChange(@NonNull Preference preference, @NonNull Object newValue) {
+        SystemProperties.set(BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY_PERSIST, newValue.toString());
+        SystemProperties.set(BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY, newValue.toString());
+        updateState(mPreference);
+        return true;
+    }
+
+    @Override
+    public void updateState(@NonNull Preference preference) {
+        final ListPreference listPreference = (ListPreference) preference;
+        int index = getBluetoothLogLevelIndex();
+        listPreference.setValue(mListValues[index]);
+        listPreference.setSummary(mListEntries[index]);
+    }
+
+    /**
+     *  Returns the current log level from Log.isLoggable().
+     */
+    @VisibleForTesting
+    public int getBluetoothLogLevelIndex() {
+        if (Log.isLoggable(BLUETOOTH_STRING_NAME, Log.VERBOSE)) {
+            return BTSTACK_LOG_MODE_VERBOSE_INDEX;
+        } else if (Log.isLoggable(BLUETOOTH_STRING_NAME, Log.DEBUG)) {
+            return BTSTACK_LOG_MODE_DEBUG_INDEX;
+        } else if (Log.isLoggable(BLUETOOTH_STRING_NAME, Log.INFO)) {
+            return BTSTACK_LOG_MODE_INFO_INDEX;
+        } else if (Log.isLoggable(BLUETOOTH_STRING_NAME, Log.WARN)) {
+            return BTSTACK_LOG_MODE_WARN_INDEX;
+        } else if (Log.isLoggable(BLUETOOTH_STRING_NAME, Log.ERROR)) {
+            return BTSTACK_LOG_MODE_ERROR_INDEX;
+        }
+        return BTSTACK_LOG_MODE_INFO_INDEX;
+    }
+
+    @Override
+    protected void onDeveloperOptionsSwitchDisabled() {
+        super.onDeveloperOptionsSwitchDisabled();
+        SystemProperties.set(BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY_PERSIST, null);
+        SystemProperties.set(BLUETOOTH_BTSTACK_LOG_MODE_PROPERTY, null);
+        ((ListPreference) mPreference).setValue(mListValues[getDefaultModeIndex()]);
+        ((ListPreference) mPreference).setSummary(mListEntries[getDefaultModeIndex()]);
+    }
+}