/*
 * Copyright (C) 2009 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.incallui;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;
import android.os.Message;
import com.android.dialer.common.LogUtil;

/**
 * This class is used to listen to the accelerometer to monitor the orientation of the phone. The
 * client of this class is notified when the orientation changes between horizontal and vertical.
 */
public class AccelerometerListener {

  // Device orientation
  public static final int ORIENTATION_UNKNOWN = 0;
  public static final int ORIENTATION_VERTICAL = 1;
  public static final int ORIENTATION_HORIZONTAL = 2;
  private static final String TAG = "AccelerometerListener";
  private static final boolean DEBUG = true;
  private static final boolean VDEBUG = false;
  private static final int ORIENTATION_CHANGED = 1234;
  private static final int VERTICAL_DEBOUNCE = 100;
  private static final int HORIZONTAL_DEBOUNCE = 500;
  private static final double VERTICAL_ANGLE = 50.0;
  private SensorManager sensorManager;
  private Sensor sensor;
  // mOrientation is the orientation value most recently reported to the client.
  private int orientation;
  // mPendingOrientation is the latest orientation computed based on the sensor value.
  // This is sent to the client after a rebounce delay, at which point it is copied to
  // mOrientation.
  private int pendingOrientation;
  private OrientationListener listener;
  Handler handler =
      new Handler() {
        @Override
        public void handleMessage(Message msg) {
          switch (msg.what) {
            case ORIENTATION_CHANGED:
              synchronized (this) {
                orientation = pendingOrientation;
                if (DEBUG) {
                  LogUtil.d(
                      TAG,
                      "orientation: "
                          + (orientation == ORIENTATION_HORIZONTAL
                              ? "horizontal"
                              : (orientation == ORIENTATION_VERTICAL ? "vertical" : "unknown")));
                }
                if (listener != null) {
                  listener.orientationChanged(orientation);
                }
              }
              break;
          }
        }
      };
  SensorEventListener sensorListener =
      new SensorEventListener() {
        @Override
        public void onSensorChanged(SensorEvent event) {
          onSensorEvent(event.values[0], event.values[1], event.values[2]);
        }

        @Override
        public void onAccuracyChanged(Sensor sensor, int accuracy) {
          // ignore
        }
      };

  public AccelerometerListener(Context context) {
    sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
    sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  }

  public void setListener(OrientationListener listener) {
    this.listener = listener;
  }

  public void enable(boolean enable) {
    if (DEBUG) {
      LogUtil.d(TAG, "enable(" + enable + ")");
    }
    synchronized (this) {
      if (enable) {
        orientation = ORIENTATION_UNKNOWN;
        pendingOrientation = ORIENTATION_UNKNOWN;
        sensorManager.registerListener(sensorListener, sensor, SensorManager.SENSOR_DELAY_NORMAL);
      } else {
        sensorManager.unregisterListener(sensorListener);
        handler.removeMessages(ORIENTATION_CHANGED);
      }
    }
  }

  private void setOrientation(int orientation) {
    synchronized (this) {
      if (pendingOrientation == orientation) {
        // Pending orientation has not changed, so do nothing.
        return;
      }

      // Cancel any pending messages.
      // We will either start a new timer or cancel alltogether
      // if the orientation has not changed.
      handler.removeMessages(ORIENTATION_CHANGED);

      if (this.orientation != orientation) {
        // Set timer to send an event if the orientation has changed since its
        // previously reported value.
        pendingOrientation = orientation;
        final Message m = handler.obtainMessage(ORIENTATION_CHANGED);
        // set delay to our debounce timeout
        int delay = (orientation == ORIENTATION_VERTICAL ? VERTICAL_DEBOUNCE : HORIZONTAL_DEBOUNCE);
        handler.sendMessageDelayed(m, delay);
      } else {
        // no message is pending
        pendingOrientation = ORIENTATION_UNKNOWN;
      }
    }
  }

  private void onSensorEvent(double x, double y, double z) {
    if (VDEBUG) {
      LogUtil.d(TAG, "onSensorEvent(" + x + ", " + y + ", " + z + ")");
    }

    // If some values are exactly zero, then likely the sensor is not powered up yet.
    // ignore these events to avoid false horizontal positives.
    if (x == 0.0 || y == 0.0 || z == 0.0) {
      return;
    }

    // magnitude of the acceleration vector projected onto XY plane
    final double xy = Math.hypot(x, y);
    // compute the vertical angle
    double angle = Math.atan2(xy, z);
    // convert to degrees
    angle = angle * 180.0 / Math.PI;
    final int orientation =
        (angle > VERTICAL_ANGLE ? ORIENTATION_VERTICAL : ORIENTATION_HORIZONTAL);
    if (VDEBUG) {
      LogUtil.d(TAG, "angle: " + angle + " orientation: " + orientation);
    }
    setOrientation(orientation);
  }

  public interface OrientationListener {

    void orientationChanged(int orientation);
  }
}