using System;
using System.Diagnostics;

namespace SemiColinGames {
  public class Timer {

    private readonly Stopwatch stopwatch = new Stopwatch();
    private readonly double targetTime;
    private readonly string name;
    private readonly int[] histogram = new int[21];
    private double startTime = 0.0;
    private int totalFrames = 0;

    public Timer(double targetTime, string name) {
      this.targetTime = targetTime;
      this.name = name;
    }

    public void Start() {
      startTime = stopwatch.Elapsed.TotalSeconds;
      stopwatch.Start();
    }

    public void Stop() {
      stopwatch.Stop();
      totalFrames++;
      double frameTime = stopwatch.Elapsed.TotalSeconds - startTime;
      int bucket = FMath.Clamp((int) (10.0f * frameTime / targetTime), 0, 20);
      histogram[bucket]++;
    }

    [Conditional("DEBUG")]
    public void DumpStats() {
      Debug.WriteLine(name + ".DumpStats():");
      for (int i = 0; i < histogram.Length; i++) {
        int value = histogram[i];
        if (value == 0) {
          continue;
        }
        // Every star is one percent.
        int numStars = FMath.Clamp(100 * value / totalFrames, 1, 100);
        string prefix;
        if (i == histogram.Length - 1) {
          prefix = "   200+%: ";
        } else {
          prefix = String.Format("{0,3}-{1,3}%: ", i * 10, (i + 1) * 10);
        }
        string stars = new string('*', numStars);
        Debug.WriteLine(String.Format("{0}{1,-100} {2}", prefix, stars, value));
      }
    }
  }
}