/*
 * 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 android.telephony;

import static com.android.internal.util.Preconditions.checkNotNull;

import android.content.Context;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.os.Messenger;
import android.os.Parcelable;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.util.Log;
import android.util.SparseArray;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.Executor;

import com.android.internal.telephony.ITelephony;

Manages the radio access network scan requests and callbacks.
/**
 * Manages the radio access network scan requests and callbacks.
 */
public final class TelephonyScanManager {

    private static final String TAG = "TelephonyScanManager";

    
@hide
/** @hide */
    public static final String SCAN_RESULT_KEY = "scanResult";

    
@hide
/** @hide */
    public static final int CALLBACK_SCAN_RESULTS = 1;
    
@hide
/** @hide */
    public static final int CALLBACK_SCAN_ERROR = 2;
    
@hide
/** @hide */
    public static final int CALLBACK_SCAN_COMPLETE = 3;

    
The caller of TelephonyManager.requestNetworkScan(NetworkScanRequest, Executor, NetworkScanCallback) should implement and provide this callback so that the scan results or errors can be returned. /**
     * The caller of
     * {@link
     * TelephonyManager#requestNetworkScan(NetworkScanRequest, Executor, NetworkScanCallback)}
     * should implement and provide this callback so that the scan results or errors can be
     * returned.
     */
    public static abstract class NetworkScanCallback {
        
Returns the scan results to the user, this callback will be called multiple times. /** Returns the scan results to the user, this callback will be called multiple times. */
        public void onResults(List<CellInfo> results) {}

        
Informs the user that the scan has stopped.
This callback will be called when the scan is finished or cancelled by the user.
The related NetworkScanRequest will be deleted after this callback.
/**
         * Informs the user that the scan has stopped.
         *
         * This callback will be called when the scan is finished or cancelled by the user.
         * The related NetworkScanRequest will be deleted after this callback.
         */
        public void onComplete() {}

        
Informs the user that there is some error about the scan.
This callback will be called whenever there is any error about the scan, and the scan
will be terminated. onComplete() will NOT be called.
Params:
error – Error code when the scan is failed, as defined in NetworkScan./**
         * Informs the user that there is some error about the scan.
         *
         * This callback will be called whenever there is any error about the scan, and the scan
         * will be terminated. onComplete() will NOT be called.
         *
         * @param error Error code when the scan is failed, as defined in {@link NetworkScan}.
         */
        public void onError(@NetworkScan.ScanErrorCode int error) {}
    }

    private static class NetworkScanInfo {
        private final NetworkScanRequest mRequest;
        private final Executor mExecutor;
        private final NetworkScanCallback mCallback;

        NetworkScanInfo(
                NetworkScanRequest request, Executor executor, NetworkScanCallback callback) {
            mRequest = request;
            mExecutor = executor;
            mCallback = callback;
        }
    }

    private final Looper mLooper;
    private final Messenger mMessenger;
    private SparseArray<NetworkScanInfo> mScanInfo = new SparseArray<NetworkScanInfo>();

    public TelephonyScanManager() {
        HandlerThread thread = new HandlerThread(TAG);
        thread.start();
        mLooper = thread.getLooper();
        mMessenger = new Messenger(new Handler(mLooper) {
            @Override
            public void handleMessage(Message message) {
                checkNotNull(message, "message cannot be null");
                NetworkScanInfo nsi;
                synchronized (mScanInfo) {
                    nsi = mScanInfo.get(message.arg2);
                }
                if (nsi == null) {
                    throw new RuntimeException(
                        "Failed to find NetworkScanInfo with id " + message.arg2);
                }
                NetworkScanCallback callback = nsi.mCallback;
                Executor executor = nsi.mExecutor;
                if (callback == null) {
                    throw new RuntimeException(
                        "Failed to find NetworkScanCallback with id " + message.arg2);
                }
                if (executor == null) {
                    throw new RuntimeException(
                        "Failed to find Executor with id " + message.arg2);
                }

                switch (message.what) {
                    case CALLBACK_SCAN_RESULTS:
                        try {
                            final Bundle b = message.getData();
                            final Parcelable[] parcelables = b.getParcelableArray(SCAN_RESULT_KEY);
                            CellInfo[] ci = new CellInfo[parcelables.length];
                            for (int i = 0; i < parcelables.length; i++) {
                                ci[i] = (CellInfo) parcelables[i];
                            }
                            executor.execute(() ->{
                                Rlog.d(TAG, "onResults: " + ci.toString());
                                callback.onResults((List<CellInfo>) Arrays.asList(ci));
                            });
                        } catch (Exception e) {
                            Rlog.e(TAG, "Exception in networkscan callback onResults", e);
                        }
                        break;
                    case CALLBACK_SCAN_ERROR:
                        try {
                            final int errorCode = message.arg1;
                            executor.execute(() -> {
                                Rlog.d(TAG, "onError: " + errorCode);
                                callback.onError(errorCode);
                            });
                        } catch (Exception e) {
                            Rlog.e(TAG, "Exception in networkscan callback onError", e);
                        }
                        break;
                    case CALLBACK_SCAN_COMPLETE:
                        try {
                            executor.execute(() -> {
                                Rlog.d(TAG, "onComplete");
                                callback.onComplete();
                            });
                            mScanInfo.remove(message.arg2);
                        } catch (Exception e) {
                            Rlog.e(TAG, "Exception in networkscan callback onComplete", e);
                        }
                        break;
                    default:
                        Rlog.e(TAG, "Unhandled message " + Integer.toHexString(message.what));
                        break;
                }
            }
        });
    }

    
Request a network scan.
This method is asynchronous, so the network scan results will be returned by callback.
The returned NetworkScan will contain a callback method which can be used to stop the scan.
 Requires Permission: MODIFY_PHONE_STATE Or the calling app has carrier privileges. @see #hasCarrierPrivileges 
Params:
request – Contains all the RAT with bands/channels that need to be scanned.
callback – Returns network scan results or errors.
Returns:
A NetworkScan obj which contains a callback which can stop the scan.
@hide
/**
     * Request a network scan.
     *
     * This method is asynchronous, so the network scan results will be returned by callback.
     * The returned NetworkScan will contain a callback method which can be used to stop the scan.
     *
     * <p>
     * Requires Permission:
     *   {@link android.Manifest.permission#MODIFY_PHONE_STATE MODIFY_PHONE_STATE}
     * Or the calling app has carrier privileges. @see #hasCarrierPrivileges
     *
     * @param request Contains all the RAT with bands/channels that need to be scanned.
     * @param callback Returns network scan results or errors.
     * @return A NetworkScan obj which contains a callback which can stop the scan.
     * @hide
     */
    public NetworkScan requestNetworkScan(int subId,
            NetworkScanRequest request, Executor executor, NetworkScanCallback callback) {
        try {
            ITelephony telephony = getITelephony();
            if (telephony != null) {
                int scanId = telephony.requestNetworkScan(subId, request, mMessenger, new Binder());
                saveScanInfo(scanId, request, executor, callback);
                return new NetworkScan(scanId, subId);
            }
        } catch (RemoteException ex) {
            Rlog.e(TAG, "requestNetworkScan RemoteException", ex);
        } catch (NullPointerException ex) {
            Rlog.e(TAG, "requestNetworkScan NPE", ex);
        }
        return null;
    }

    private void saveScanInfo(
            int id, NetworkScanRequest request, Executor executor, NetworkScanCallback callback) {
        synchronized (mScanInfo) {
            mScanInfo.put(id, new NetworkScanInfo(request, executor, callback));
        }
    }

    private ITelephony getITelephony() {
        return ITelephony.Stub.asInterface(
            ServiceManager.getService(Context.TELEPHONY_SERVICE));
    }
}