/*
 * Copyright (C) Stichting Akvo (Akvo Foundation)
 *
 * This file is part of Akvo Caddisfly.
 *
 * Akvo Caddisfly is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Akvo Caddisfly is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Akvo Caddisfly. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Copyright (C) 2013 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 org.akvo.caddisfly.sensor.bluetooth;

import android.app.Service;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattDescriptor;
import android.bluetooth.BluetoothGattService;
import android.bluetooth.BluetoothManager;
import android.bluetooth.BluetoothProfile;
import android.content.Context;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

import java.util.List;
import java.util.UUID;

import timber.log.Timber;

/**
 * Service for managing connection and data communication with a GATT server hosted on a
 * given Bluetooth LE device.
 */
public class BluetoothLeService extends Service {
    public static final String ACTION_GATT_CONNECTED =
            "com.example.bluetooth.le.ACTION_GATT_CONNECTED";
    public static final String ACTION_GATT_DISCONNECTED =
            "com.example.bluetooth.le.ACTION_GATT_DISCONNECTED";
    public static final String ACTION_GATT_SERVICES_DISCOVERED =
            "com.example.bluetooth.le.ACTION_GATT_SERVICES_DISCOVERED";
    public static final String ACTION_DATA_AVAILABLE =
            "com.example.bluetooth.le.ACTION_DATA_AVAILABLE";
    public static final String EXTRA_DATA =
            "com.example.bluetooth.le.EXTRA_DATA";
    private static final UUID UUID_LOVIBOND_DATA =
            UUID.fromString(GattAttributes.LOVIBOND_DATA_CHARACTERISTIC);
    private final IBinder mBinder = new LocalBinder();
    private BluetoothManager mBluetoothManager;
    private BluetoothAdapter mBluetoothAdapter;
    private String mBluetoothDeviceAddress;
    private BluetoothGatt mBluetoothGatt;

    // Implements callback methods for GATT events that the app cares about.  For example,
    // connection change and services discovered.
    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            String intentAction;
            if (newState == BluetoothProfile.STATE_CONNECTED) {
                intentAction = ACTION_GATT_CONNECTED;
                broadcastUpdate(intentAction);
                Timber.i("Connected to GATT server.");
                // Attempts to discover services after successful connection.
                Timber.i("Attempting to start service discovery:%s", mBluetoothGatt.discoverServices());

            } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
                intentAction = ACTION_GATT_DISCONNECTED;
                Timber.i("Disconnected from GATT server.");
                broadcastUpdate(intentAction);
            }
        }

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
            } else {
                Timber.w("onServicesDiscovered received: %s", status);
            }
        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt,
                                         BluetoothGattCharacteristic characteristic,
                                         int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
            }
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt,
                                            BluetoothGattCharacteristic characteristic) {
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
        }
    };

    private void broadcastUpdate(final String action) {
        final Intent intent = new Intent(action);
        sendBroadcast(intent);
    }

    private void broadcastUpdate(@SuppressWarnings("SameParameterValue") final String action,
                                 final BluetoothGattCharacteristic characteristic) {
        final Intent intent = new Intent(action);

        final byte[] data = characteristic.getValue();
        if (data != null && data.length > 0) {
            intent.putExtra(EXTRA_DATA, new String(data));
        }
        sendBroadcast(intent);
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    @Override
    public boolean onUnbind(Intent intent) {
        // After using a given device, you should make sure that BluetoothGatt.close() is called
        // such that resources are cleaned up properly.  In this particular example, close() is
        // invoked when the UI is disconnected from the Service.
        close();
        return super.onUnbind(intent);
    }

    /**
     * Initializes a reference to the local Bluetooth adapter.
     *
     * @return Return true if the initialization is successful.
     */
    @SuppressWarnings("BooleanMethodIsAlwaysInverted")
    public boolean initialize() {
        // For API level 18 and above, get a reference to BluetoothAdapter through
        // BluetoothManager.
        if (mBluetoothManager == null) {
            mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
            if (mBluetoothManager == null) {
                Timber.e("Unable to initialize BluetoothManager.");
                return false;
            }
        }

        mBluetoothAdapter = mBluetoothManager.getAdapter();
        if (mBluetoothAdapter == null) {
            Timber.e("Unable to obtain a BluetoothAdapter.");
            return false;
        }

        return true;
    }

    /**
     * Connects to the GATT server hosted on the Bluetooth LE device.
     *
     * @param address The device address of the destination device.
     * @return Return true if the connection is initiated successfully. The connection result
     * is reported asynchronously through the
     * {@code BluetoothGattCallback#onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)}
     * callback.
     */
    public boolean connect(final String address) {
        if (mBluetoothAdapter == null || address == null) {
            Timber.w("BluetoothAdapter not initialized or unspecified address.");
            return false;
        }

        // Previously connected device.  Try to reconnect.
        if (mBluetoothDeviceAddress != null && mBluetoothDeviceAddress.equals(address)
                && mBluetoothGatt != null) {
            Timber.d("Trying to use an existing mBluetoothGatt for connection.");
            //mConnectionState = STATE_CONNECTING;
            return mBluetoothGatt.connect();
        }

        final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
        if (device == null) {
            Timber.w("Device not found.  Unable to connect.");
            return false;
        }
        // We want to directly connect to the device, so we are setting the autoConnect
        // parameter to false.
        mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
        Timber.d("Trying to create a new connection.");
        mBluetoothDeviceAddress = address;
        return true;
    }

    /**
     * After using a given BLE device, the app must call this method to ensure resources are
     * released properly.
     */
    private void close() {
        if (mBluetoothGatt == null) {
            return;
        }
        mBluetoothGatt.close();
        mBluetoothGatt = null;
    }

    /**
     * Enables or disables notification on a give characteristic.
     *
     * @param characteristic Characteristic to act on.
     * @param enabled        If true, enable notification.  False otherwise.
     */
    public void setCharacteristicIndication(BluetoothGattCharacteristic characteristic,
                                            boolean enabled) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Timber.w("BluetoothAdapter not initialized");
            return;
        }
        mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);

        if (UUID_LOVIBOND_DATA.equals(characteristic.getUuid())) {
            BluetoothGattDescriptor descriptor = characteristic.getDescriptor(
                    UUID.fromString(GattAttributes.CLIENT_CHARACTERISTIC_CONFIG));
            if (descriptor != null) {
                descriptor.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE);
                mBluetoothGatt.writeDescriptor(descriptor);
            }
        }
    }

    /**
     * Retrieves a list of supported GATT services on the connected device. This should be
     * invoked only after {@code BluetoothGatt#discoverServices()} completes successfully.
     *
     * @return A {@code List} of supported services.
     */
    public List<BluetoothGattService> getSupportedGattServices() {
        if (mBluetoothGatt == null) {
            return null;
        }

        return mBluetoothGatt.getServices();
    }

    class LocalBinder extends Binder {
        BluetoothLeService getService() {
            return BluetoothLeService.this;
        }
    }
}
