/*
 * 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.car;

import android.app.ActivityManager;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothProfile;
import android.car.ICarBluetooth;
import android.car.ICarBluetoothUserService;
import android.car.ICarUserService;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import android.util.SparseArray;

import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * CarBluetoothService - Maintains the current user's Bluetooth devices and profile connections.
 *
 * For each user, creates:
 *   1) Set of {@link BluetoothProfileDeviceManager} objects, responsible for maintaining a list of
 *      the user's known devices. These provide an interface to auto-connect devices for the given
 *      profile.
 *   2) A {@link BluetoothProfileInhibitManager} object that will maintain a set of inhibited
 *      profiles for each device, keeping a device from connecting on those profiles. This provides
 *      an interface to request and release inhibits.
 *   3) A {@link BluetoothDeviceConnectionPolicy} object, representing a default implementation of
 *      a policy based method of determining and requesting times to auto-connect devices. This
 *      default is controllable through a resource overlay if one chooses to implement their own.
 *
 * Provides an interface for other programs to request auto connections.
 */
public class CarBluetoothService extends ICarBluetooth.Stub implements CarServiceBase {
    private static final String TAG = "CarBluetoothService";
    private static final boolean DBG = Log.isLoggable(TAG, Log.DEBUG);
    private final Context mContext;

    // The list of profiles we wish to manage
    private static final List<Integer> sManagedProfiles = Arrays.asList(
            BluetoothProfile.HEADSET_CLIENT,
            BluetoothProfile.PBAP_CLIENT,
            BluetoothProfile.A2DP_SINK,
            BluetoothProfile.MAP_CLIENT,
            BluetoothProfile.PAN
    );

    // Set of Bluetooth Profile Device Managers, own the priority connection lists, updated on user
    // switch
    private SparseArray<BluetoothProfileDeviceManager> mProfileDeviceManagers = new SparseArray<>();

    // Profile-Inhibit Manager that will temporarily inhibit connections on profiles, per user
    private BluetoothProfileInhibitManager mInhibitManager = null;

    // Default Bluetooth device connection policy, per user, enabled with an overlay
    private final boolean mUseDefaultPolicy;
    private BluetoothDeviceConnectionPolicy mBluetoothDeviceConnectionPolicy = null;

    // Listen for user switch events from the PerUserCarService
    private int mUserId;
    private ICarUserService mCarUserService;
    private ICarBluetoothUserService mCarBluetoothUserService;
    private final PerUserCarServiceHelper mUserServiceHelper;
    private final PerUserCarServiceHelper.ServiceCallback mUserServiceCallback =
            new PerUserCarServiceHelper.ServiceCallback() {
        @Override
        public void onServiceConnected(ICarUserService carUserService) {
            logd("Connected to PerUserCarService");
            synchronized (this) {
                mCarUserService = carUserService;
                initializeUser();
            }
        }

        @Override
        public void onPreUnbind() {
            logd("Before Unbinding from PerCarUserService");
            destroyUser();
        }

        @Override
        public void onServiceDisconnected() {
            logd("Disconnected from PerUserCarService");
            synchronized (this) {
                mCarUserService = null;
            }
        }
    };

    /**
     * Create an instance of CarBluetoothService
     *
     * @param context - A Context object representing the context you want this service to run
     * @param userSwitchService - An instance of PerUserCarServiceHelper that we can bind a listener
     *                            to in order to receive user switch events
     */
    public CarBluetoothService(Context context, PerUserCarServiceHelper userSwitchService) {
        mUserId = -1;
        mContext = context;
        mUserServiceHelper = userSwitchService;
        mUseDefaultPolicy = mContext.getResources().getBoolean(
                R.bool.useDefaultBluetoothConnectionPolicy);
    }

    /**
     * Complete all necessary initialization keeping this service from being running.
     *
     * Wait for the user service helper to report a user before initializing a user.
     */
    @Override
    public synchronized void init() {
        logd("init()");
        mUserServiceHelper.registerServiceCallback(mUserServiceCallback);
    }

    /**
     * Release all resources required to run this service and stop running.
     *
     * Clean up the user context once we've detached from the user service helper, if any.
     */
    @Override
    public synchronized void release() {
        logd("release()");
        mUserServiceHelper.unregisterServiceCallback(mUserServiceCallback);
        destroyUser();
        mCarUserService = null;
    }

    /**
     * Returns the list of profiles that the Autoconnection policy attempts to connect on
     *
     * @return The list of managed Bluetooth profiles
     */
    public static List<Integer> getManagedProfiles() {
        return sManagedProfiles;
    }

    /**
     * Initialize the user context using the current active user.
     *
     * Only call this following a known user switch once we've connected to the user service helper.
     */
    private synchronized void initializeUser() {
        logd("Initializing new user");
        mUserId = ActivityManager.getCurrentUser();
        createBluetoothUserService();
        createBluetoothProfileDeviceManagers();
        createBluetoothProfileInhibitManager();

        // Determine if we need to begin the default policy
        mBluetoothDeviceConnectionPolicy = null;
        if (mUseDefaultPolicy) {
            createBluetoothDeviceConnectionPolicy();
        }
        logd("Switched to user " + mUserId);
    }

    /**
     * Destroy the current user context, defined by the set of profile proxies, profile device
     * managers, inhibit manager and the policy.
     */
    private synchronized void destroyUser() {
        logd("Destroying user " + mUserId);
        destroyBluetoothDeviceConnectionPolicy();
        destroyBluetoothProfileInhibitManager();
        destroyBluetoothProfileDeviceManagers();
        destroyBluetoothUserService();
        mUserId = -1;
    }

    /**
     * Sets the Per User Car Bluetooth Service (ICarBluetoothService) from the PerUserCarService
     * which acts as a top level Service running in the current user context.
     * Also sets up the connection proxy objects required to communicate with the Bluetooth
     * Profile Services.
     */
    private synchronized void createBluetoothUserService() {
        if (mCarUserService != null) {
            try {
                mCarBluetoothUserService = mCarUserService.getBluetoothUserService();
                mCarBluetoothUserService.setupBluetoothConnectionProxies();
            } catch (RemoteException e) {
                Log.e(TAG, "Remote Service Exception on ServiceConnection Callback: "
                        + e.getMessage());
            }
        } else {
            logd("PerUserCarService not connected. Cannot get bluetooth user proxy objects");
        }
    }

    /**
     * Close out the Per User Car Bluetooth profile proxy connections and destroys the Car Bluetooth
     * User Service object.
     */
    private synchronized void destroyBluetoothUserService() {
        if (mCarBluetoothUserService == null) return;
        try {
            mCarBluetoothUserService.closeBluetoothConnectionProxies();
        } catch (RemoteException e) {
            Log.e(TAG, "Remote Service Exception on ServiceConnection Callback: "
                    + e.getMessage());
        }
        mCarBluetoothUserService = null;
    }

    /**
     * Clears out Profile Device Managers and re-creates them for the current user.
     */
    private synchronized void createBluetoothProfileDeviceManagers() {
        mProfileDeviceManagers.clear();
        if (mUserId == -1) {
            logd("No foreground user, cannot create profile device managers");
            return;
        }
        for (int profileId : sManagedProfiles) {
            BluetoothProfileDeviceManager deviceManager = BluetoothProfileDeviceManager.create(
                    mContext, mUserId, mCarBluetoothUserService, profileId);
            if (deviceManager == null) {
                logd("Failed to create profile device manager for "
                        + Utils.getProfileName(profileId));
                continue;
            }
            mProfileDeviceManagers.put(profileId, deviceManager);
            logd("Created profile device manager for " + Utils.getProfileName(profileId));
        }

        for (int i = 0; i < mProfileDeviceManagers.size(); i++) {
            int key = mProfileDeviceManagers.keyAt(i);
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(key);
            deviceManager.start();
        }
    }

    /**
     * Stops and clears the entire set of Profile Device Managers.
     */
    private synchronized void destroyBluetoothProfileDeviceManagers() {
        for (int i = 0; i < mProfileDeviceManagers.size(); i++) {
            int key = mProfileDeviceManagers.keyAt(i);
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(key);
            deviceManager.stop();
        }
        mProfileDeviceManagers.clear();
    }

    /**
     * Creates an instance of a BluetoothProfileInhibitManager under the current user
     */
    private synchronized void createBluetoothProfileInhibitManager() {
        logd("Creating inhibit manager");
        if (mUserId == -1) {
            logd("No foreground user, cannot create profile inhibit manager");
            return;
        }
        mInhibitManager = new BluetoothProfileInhibitManager(mContext, mUserId,
                mCarBluetoothUserService);
        mInhibitManager.start();
    }

    /**
     * Destroys the current instance of a BluetoothProfileInhibitManager, if one exists
     */
    private synchronized void destroyBluetoothProfileInhibitManager() {
        logd("Destroying inhibit manager");
        if (mInhibitManager == null) return;
        mInhibitManager.stop();
        mInhibitManager = null;
    }

    /**
     * Creates an instance of a BluetoothDeviceConnectionPolicy under the current user
     */
    private synchronized void createBluetoothDeviceConnectionPolicy() {
        logd("Creating device connection policy");
        if (mUserId == -1) {
            logd("No foreground user, cannot create device connection policy");
            return;
        }
        mBluetoothDeviceConnectionPolicy = BluetoothDeviceConnectionPolicy.create(mContext, mUserId,
                this);
        if (mBluetoothDeviceConnectionPolicy == null) {
            logd("Failed to create default Bluetooth device connection policy.");
            return;
        }
        mBluetoothDeviceConnectionPolicy.init();
    }

    /**
     * Destroys the current instance of a BluetoothDeviceConnectionPolicy, if one exists
     */
    private synchronized void destroyBluetoothDeviceConnectionPolicy() {
        logd("Destroying device connection policy");
        if (mBluetoothDeviceConnectionPolicy != null) {
            mBluetoothDeviceConnectionPolicy.release();
            mBluetoothDeviceConnectionPolicy = null;
        }
    }

     /**
     * Determine if we are using the default device connection policy or not
     *
     * @return true if the default policy is active, false otherwise
     */
    public boolean isUsingDefaultConnectionPolicy() {
        return mBluetoothDeviceConnectionPolicy != null;
    }

   /**
     * Initiate automatated connecting of devices based on the prioritized device lists for each
     * profile.
     */
    public void connectDevices() {
        enforceBluetoothAdminPermission();
        logd("Connect devices for each profile");
        synchronized (this) {
            for (int i = 0; i < mProfileDeviceManagers.size(); i++) {
                int key = mProfileDeviceManagers.keyAt(i);
                BluetoothProfileDeviceManager deviceManager =
                        (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(key);
                deviceManager.beginAutoConnecting();
            }
        }
    }

    /**
     * Get the Auto Connect priority for a paired Bluetooth Device.
     *
     * @param profile  - BluetoothProfile to get priority list for
     * @return A list of BluetoothDevice objects, ordered by highest priority first
     */
    public List<BluetoothDevice> getProfileDevicePriorityList(int profile) {
        enforceBluetoothAdminPermission();
        synchronized (this) {
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(profile);
            if (deviceManager != null) {
                return deviceManager.getDeviceListSnapshot();
            }
        }
        return new ArrayList<BluetoothDevice>();
    }

    /**
     * Get the Auto Connect priority for a paired Bluetooth Device.
     *
     * @param profile  - BluetoothProfile to get priority for
     * @param device   - Device to get priority for
     * @return integer priority value, or -1 if no priority available.
     */
    public int getDeviceConnectionPriority(int profile, BluetoothDevice device) {
        enforceBluetoothAdminPermission();
        synchronized (this) {
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(profile);
            if (deviceManager != null) {
                return deviceManager.getDeviceConnectionPriority(device);
            }
        }
        return -1;
    }

    /**
     * Set the Auto Connect priority for a paired Bluetooth Device.
     *
     * @param profile  - BluetoothProfile to set priority for
     * @param device   - Device to set priority (Tag)
     * @param priority - What priority level to set to
     */
    public void setDeviceConnectionPriority(int profile, BluetoothDevice device, int priority) {
        enforceBluetoothAdminPermission();
        synchronized (this) {
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(profile);
            if (deviceManager != null) {
                deviceManager.setDeviceConnectionPriority(device, priority);
            }
        }
        return;
    }

    /**
     * Request to disconnect the given profile on the given device, and prevent it from reconnecting
     * until either the request is released, or the process owning the given token dies.
     *
     * @param device  The device on which to inhibit a profile.
     * @param profile The {@link android.bluetooth.BluetoothProfile} to inhibit.
     * @param token   A {@link IBinder} to be used as an identity for the request. If the process
     *                owning the token dies, the request will automatically be released
     * @return True if the profile was successfully inhibited, false if an error occurred.
     */
    synchronized boolean requestProfileInhibit(BluetoothDevice device, int profile, IBinder token) {
        logd("Request profile inhibit: profile " + Utils.getProfileName(profile)
                + ", device " + device.getAddress());
        if (mInhibitManager == null) return false;
        return mInhibitManager.requestProfileInhibit(device, profile, token);
    }

    /**
     * Undo a previous call to {@link #requestProfileInhibit} with the same parameters,
     * and reconnect the profile if no other requests are active.
     *
     * @param device  The device on which to release the inhibit request.
     * @param profile The profile on which to release the inhibit request.
     * @param token   The token provided in the original call to
     *                {@link #requestBluetoothProfileInhibit}.
     * @return True if the request was released, false if an error occurred.
     */
    synchronized boolean releaseProfileInhibit(BluetoothDevice device, int profile, IBinder token) {
        logd("Release profile inhibit: profile " + Utils.getProfileName(profile)
                + ", device " + device.getAddress());
        if (mInhibitManager == null) return false;
        return mInhibitManager.releaseProfileInhibit(device, profile, token);
    }

    /**
     * Make sure the caller has the Bluetooth permissions that are required to execute any function
     */
    private void enforceBluetoothAdminPermission() {
        if (mContext != null
                && PackageManager.PERMISSION_GRANTED == mContext.checkCallingOrSelfPermission(
                android.Manifest.permission.BLUETOOTH_ADMIN)) {
            return;
        }
        if (mContext == null) {
            Log.e(TAG, "CarBluetoothPrioritySettings does not have a Context");
        }
        throw new SecurityException("requires permission "
                + android.Manifest.permission.BLUETOOTH_ADMIN);
    }

    /**
     * Print out the verbose debug status of this object
     */
    @Override
    public synchronized void dump(PrintWriter writer) {
        writer.println("*" + TAG + "*");
        writer.println("\tUser ID: " + mUserId);
        writer.println("\tUser Proxies: " + (mCarBluetoothUserService != null ? "Yes" : "No"));

        // Profile Device Manager statuses
        for (int i = 0; i < mProfileDeviceManagers.size(); i++) {
            int key = mProfileDeviceManagers.keyAt(i);
            BluetoothProfileDeviceManager deviceManager =
                    (BluetoothProfileDeviceManager) mProfileDeviceManagers.get(key);
            deviceManager.dump(writer, "\t");
        }

        // Profile Inhibits
        if (mInhibitManager != null) mInhibitManager.dump(writer, "\t");
        else writer.println("\tBluetoothProfileInhibitManager: null");

        // Device Connection Policy
        writer.println("\tUsing default policy? " + (mUseDefaultPolicy ? "Yes" : "No"));
        if (mBluetoothDeviceConnectionPolicy == null) {
            writer.println("\tBluetoothDeviceConnectionPolicy: null");
        } else {
            mBluetoothDeviceConnectionPolicy.dump(writer, "\t");
        }
    }

    /**
     * Log to debug if debug output is enabled
     */
    private static void logd(String msg) {
        if (DBG) {
            Log.d(TAG, msg);
        }
    }
}