content: /*
   * Copyright 2018 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.hardware.display;
  
  import android.annotation.NonNull;
  import android.annotation.SystemApi;
  import android.annotation.TestApi;
  import android.os.Parcel;
  import android.os.Parcelable;
  
  import com.android.internal.util.Preconditions;
  
  import java.time.LocalDate;
  import java.util.Arrays;
  
  /**
   * AmbientBrightnessDayStats stores and manipulates brightness stats over a single day.
   * {@see DisplayManager.getAmbientBrightnessStats()}
   *
   * @hide
   */
  @SystemApi
  @TestApi
  public final class AmbientBrightnessDayStats implements Parcelable {
  
      /** The localdate for which brightness stats are being tracked */
      private final LocalDate mLocalDate;
  
      /** Ambient brightness values for creating bucket boundaries from */
      private final float[] mBucketBoundaries;
  
      /** Stats of how much time (in seconds) was spent in each of the buckets */
      private final float[] mStats;
  
      /**
       * Initialize day stats from the given state. The time spent in each of the bucket is
       * initialized to 0.
       *
       * @param localDate        The date for which stats are being tracked
       * @param bucketBoundaries Bucket boundaries used from creating the buckets from
       * @hide
       */
      public AmbientBrightnessDayStats(@NonNull LocalDate localDate,
              @NonNull float[] bucketBoundaries) {
          this(localDate, bucketBoundaries, null);
      }
  
      /**
       * Initialize day stats from the given state
       *
       * @param localDate        The date for which stats are being tracked
       * @param bucketBoundaries Bucket boundaries used from creating the buckets from
       * @param stats            Time spent in each of the buckets (in seconds)
       * @hide
       */
      public AmbientBrightnessDayStats(@NonNull LocalDate localDate,
              @NonNull float[] bucketBoundaries, float[] stats) {
          Preconditions.checkNotNull(localDate);
          Preconditions.checkNotNull(bucketBoundaries);
          Preconditions.checkArrayElementsInRange(bucketBoundaries, 0, Float.MAX_VALUE,
                  "bucketBoundaries");
          if (bucketBoundaries.length < 1) {
              throw new IllegalArgumentException("Bucket boundaries must contain at least 1 value");
          }
          checkSorted(bucketBoundaries);
          if (stats == null) {
              stats = new float[bucketBoundaries.length];
          } else {
              Preconditions.checkArrayElementsInRange(stats, 0, Float.MAX_VALUE, "stats");
              if (bucketBoundaries.length != stats.length) {
                  throw new IllegalArgumentException(
                          "Bucket boundaries and stats must be of same size.");
              }
          }
          mLocalDate = localDate;
          mBucketBoundaries = bucketBoundaries;
          mStats = stats;
      }
  
      /**
       * @return The {@link LocalDate} for which brightness stats are being tracked.
       */
      public LocalDate getLocalDate() {
          return mLocalDate;
      }
  
      /**
       * @return Aggregated stats of time spent (in seconds) in various buckets.
       */
      public float[] getStats() {
          return mStats;
      }
  
      /**
       * Returns the bucket boundaries (in lux) used for creating buckets. For eg., if the bucket
       * boundaries array is {b1, b2, b3}, the buckets will be [b1, b2), [b2, b3), [b3, inf).
       *
       * @return The list of bucket boundaries.
       */
      public float[] getBucketBoundaries() {
          return mBucketBoundaries;
      }
  
      private AmbientBrightnessDayStats(Parcel source) {
          mLocalDate = LocalDate.parse(source.readString());
          mBucketBoundaries = source.createFloatArray();
          mStats = source.createFloatArray();
      }
  
      public static final @android.annotation.NonNull Creator<AmbientBrightnessDayStats> CREATOR =
              new Creator<AmbientBrightnessDayStats>() {
  
                  @Override
                  public AmbientBrightnessDayStats createFromParcel(Parcel source) {
                      return new AmbientBrightnessDayStats(source);
                  }
  
                  @Override
                  public AmbientBrightnessDayStats[] newArray(int size) {
                      return new AmbientBrightnessDayStats[size];
                  }
              };
  
      @Override
      public boolean equals(Object obj) {
          if (this == obj) {
              return true;
          }
          if (obj == null) {
              return false;
          }
          if (getClass() != obj.getClass()) {
              return false;
          }
          AmbientBrightnessDayStats other = (AmbientBrightnessDayStats) obj;
          return mLocalDate.equals(other.mLocalDate) && Arrays.equals(mBucketBoundaries,
                  other.mBucketBoundaries) && Arrays.equals(mStats, other.mStats);
      }
  
      @Override
      public int hashCode() {
          final int prime = 31;
          int result = 1;
          result = result * prime + mLocalDate.hashCode();
          result = result * prime + Arrays.hashCode(mBucketBoundaries);
          result = result * prime + Arrays.hashCode(mStats);
          return result;
      }
  
      @Override
      public String toString() {
          StringBuilder bucketBoundariesString = new StringBuilder();
          StringBuilder statsString = new StringBuilder();
          for (int i = 0; i < mBucketBoundaries.length; i++) {
              if (i != 0) {
                  bucketBoundariesString.append(", ");
                  statsString.append(", ");
              }
              bucketBoundariesString.append(mBucketBoundaries[i]);
              statsString.append(mStats[i]);
          }
          return new StringBuilder()
                  .append(mLocalDate).append(" ")
                  .append("{").append(bucketBoundariesString).append("} ")
                  .append("{").append(statsString).append("}").toString();
      }
  
      @Override
      public int describeContents() {
          return 0;
      }
  
      @Override
      public void writeToParcel(Parcel dest, int flags) {
          dest.writeString(mLocalDate.toString());
          dest.writeFloatArray(mBucketBoundaries);
          dest.writeFloatArray(mStats);
      }
  
      /**
       * Updates the stats by incrementing the time spent for the appropriate bucket based on ambient
       * brightness reading.
       *
       * @param ambientBrightness Ambient brightness reading (in lux)
       * @param durationSec       Time spent with the given reading (in seconds)
       * @hide
       */
      public void log(float ambientBrightness, float durationSec) {
          int bucketIndex = getBucketIndex(ambientBrightness);
          if (bucketIndex >= 0) {
              mStats[bucketIndex] += durationSec;
          }
      }
  
      private int getBucketIndex(float ambientBrightness) {
          if (ambientBrightness < mBucketBoundaries[0]) {
              return -1;
          }
          int low = 0;
          int high = mBucketBoundaries.length - 1;
          while (low < high) {
              int mid = (low + high) / 2;
              if (mBucketBoundaries[mid] <= ambientBrightness
                      && ambientBrightness < mBucketBoundaries[mid + 1]) {
                  return mid;
              } else if (mBucketBoundaries[mid] < ambientBrightness) {
                  low = mid + 1;
              } else if (mBucketBoundaries[mid] > ambientBrightness) {
                  high = mid - 1;
              }
          }
          return low;
      }
  
      private static void checkSorted(float[] values) {
          if (values.length <= 1) {
              return;
          }
          float prevValue = values[0];
          for (int i = 1; i < values.length; i++) {
              Preconditions.checkState(prevValue < values[i]);
              prevValue = values[i];
          }
          return;
      }
  }
  