/*
 *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.webrtc;

import java.util.HashMap;
import java.util.Map;
import org.jni_zero.NativeMethods;

// Java-side of androidmetrics.cc
//
// Rtc histograms can be queried through the API, getAndReset().
// The returned map holds the name of a histogram and its samples.
//
// Example of `map` with one histogram:
// `name`: "WebRTC.Video.InputFramesPerSecond"
//     `min`: 1
//     `max`: 100
//     `bucketCount`: 50
//     `samples`: [30]:1
//
// Most histograms are not updated frequently (e.g. most video metrics are an
// average over the call and recorded when a stream is removed).
// The metrics can for example be retrieved when a peer connection is closed.
public class Metrics {
  private static final String TAG = "Metrics";

  public final Map<String, HistogramInfo> map =
      new HashMap<String, HistogramInfo>(); // <name, HistogramInfo>

  @CalledByNative
  Metrics() {}

  /**
   * Class holding histogram information.
   */
  public static class HistogramInfo {
    public final int min;
    public final int max;
    public final int bucketCount;
    public final Map<Integer, Integer> samples =
        new HashMap<Integer, Integer>(); // <value, # of events>

    @CalledByNative
    public HistogramInfo(int min, int max, int bucketCount) {
      this.min = min;
      this.max = max;
      this.bucketCount = bucketCount;
    }

    @CalledByNative
    public void addSample(int value, int numEvents) {
      samples.put(value, numEvents);
    }
  }

  @CalledByNative
  private void add(String name, HistogramInfo info) {
    map.put(name, info);
  }

  // Enables gathering of metrics (which can be fetched with getAndReset()).
  // Must be called before PeerConnectionFactory is created.
  public static void enable() {
    MetricsJni.get().enable();
  }

  // Gets and clears native histograms.
  public static Metrics getAndReset() {
    return MetricsJni.get().getAndReset();
  }

  @NativeMethods
  interface Natives {
    void enable();

    Metrics getAndReset();
  }
}