/*
 * Copyright (C) 2014 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.server.location;

import android.content.Context;
import android.location.GnssMeasurementsEvent;
import android.location.IGnssMeasurementsListener;
import android.os.Handler;
import android.os.RemoteException;
import android.provider.Settings;
import android.util.Log;

import com.android.internal.annotations.VisibleForTesting;

/**
 * An base implementation for GPS measurements provider.
 * It abstracts out the responsibility of handling listeners, while still allowing technology
 * specific implementations to be built.
 *
 * @hide
 */
public abstract class GnssMeasurementsProvider extends
        RemoteListenerHelper<IGnssMeasurementsListener> {
    private static final String TAG = "GnssMeasurementsProvider";
    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);

    private final Context mContext;
    private final GnssMeasurementProviderNative mNative;

    private boolean mIsCollectionStarted;
    private boolean mEnableFullTracking;

    protected GnssMeasurementsProvider(Context context, Handler handler) {
        this(context, handler, new GnssMeasurementProviderNative());
    }

    @VisibleForTesting
    GnssMeasurementsProvider(Context context, Handler handler,
            GnssMeasurementProviderNative aNative) {
        super(handler, TAG);
        mContext = context;
        mNative = aNative;
    }

    // TODO(b/37460011): Use this with death recovery logic.
    void resumeIfStarted() {
        if (DEBUG) {
            Log.d(TAG, "resumeIfStarted");
        }
        if (mIsCollectionStarted) {
            mNative.startMeasurementCollection(mEnableFullTracking);
        }
    }

    @Override
    public boolean isAvailableInPlatform() {
        return mNative.isMeasurementSupported();
    }

    @Override
    protected int registerWithService() {
        int devOptions = Settings.Secure.getInt(mContext.getContentResolver(),
                Settings.Global.DEVELOPMENT_SETTINGS_ENABLED, 0);
        int fullTrackingToggled = Settings.Global.getInt(mContext.getContentResolver(),
                Settings.Global.ENABLE_GNSS_RAW_MEAS_FULL_TRACKING, 0);
        boolean enableFullTracking = (devOptions == 1 /* Developer Mode enabled */)
                && (fullTrackingToggled == 1 /* Raw Measurements Full Tracking enabled */);
        boolean result = mNative.startMeasurementCollection(enableFullTracking);
        if (result) {
            mIsCollectionStarted = true;
            mEnableFullTracking = enableFullTracking;
            return RemoteListenerHelper.RESULT_SUCCESS;
        } else {
            return RemoteListenerHelper.RESULT_INTERNAL_ERROR;
        }
    }

    @Override
    protected void unregisterFromService() {
        boolean stopped = mNative.stopMeasurementCollection();
        if (stopped) {
            mIsCollectionStarted = false;
        }
    }

    public void onMeasurementsAvailable(final GnssMeasurementsEvent event) {
        ListenerOperation<IGnssMeasurementsListener> operation =
                listener -> listener.onGnssMeasurementsReceived(event);
        foreach(operation);
    }

    public void onCapabilitiesUpdated(boolean isGnssMeasurementsSupported) {
        setSupported(isGnssMeasurementsSupported);
        updateResult();
    }

    public void onGpsEnabledChanged() {
        tryUpdateRegistrationWithService();
        updateResult();
    }

    @Override
    protected ListenerOperation<IGnssMeasurementsListener> getHandlerOperation(int result) {
        int status;
        switch (result) {
            case RESULT_SUCCESS:
                status = GnssMeasurementsEvent.Callback.STATUS_READY;
                break;
            case RESULT_NOT_AVAILABLE:
            case RESULT_NOT_SUPPORTED:
            case RESULT_INTERNAL_ERROR:
                status = GnssMeasurementsEvent.Callback.STATUS_NOT_SUPPORTED;
                break;
            case RESULT_NOT_ALLOWED:
                status = GnssMeasurementsEvent.Callback.STATUS_NOT_ALLOWED;
                break;
            case RESULT_GPS_LOCATION_DISABLED:
                status = GnssMeasurementsEvent.Callback.STATUS_LOCATION_DISABLED;
                break;
            case RESULT_UNKNOWN:
                return null;
            default:
                Log.v(TAG, "Unhandled addListener result: " + result);
                return null;
        }
        return new StatusChangedOperation(status);
    }

    private static class StatusChangedOperation
            implements ListenerOperation<IGnssMeasurementsListener> {
        private final int mStatus;

        public StatusChangedOperation(int status) {
            mStatus = status;
        }

        @Override
        public void execute(IGnssMeasurementsListener listener) throws RemoteException {
            listener.onStatusChanged(mStatus);
        }
    }

    @VisibleForTesting
    static class GnssMeasurementProviderNative {
        public boolean isMeasurementSupported() {
            return native_is_measurement_supported();
        }

        public boolean startMeasurementCollection(boolean enableFullTracking) {
            return native_start_measurement_collection(enableFullTracking);
        }

        public boolean stopMeasurementCollection() {
            return native_stop_measurement_collection();
        }
    }

    private static native boolean native_is_measurement_supported();

    private static native boolean native_start_measurement_collection(boolean enableFullTracking);

    private static native boolean native_stop_measurement_collection();
}