using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace HeuristicLab.Services.Optimization.Scaler {
  public static class PerformanceCounterHelper {
    public const string HiveCounterCategory = "Hive";
    public const string HiveCounterGlobalUsageName = "% Global Usage";
    public const string HiveCounterGlobalUsage = @"\" + HiveCounterCategory + @"\" + HiveCounterGlobalUsageName;   

    public class PerformanceCounterEntry {
      public string Name { get; set; }
      public string HelpText { get; set; }
      public PerformanceCounterType Type { get; set; }
    }

    private static void InitializePerformanceCounters(string category, string categoryHelpText, params PerformanceCounterEntry[] entries) {
      
      if (PerformanceCounterCategory.Exists(category))
        PerformanceCounterCategory.Delete(category);

      var counterCollection = new CounterCreationDataCollection();
      foreach (var entry in entries) {
        var creationData = new CounterCreationData() {
          CounterName = entry.Name,
          CounterHelp = entry.HelpText,
          CounterType = entry.Type
        };
        counterCollection.Add(creationData);
      }
      PerformanceCounterCategory.Create(
        category,
        categoryHelpText,
        PerformanceCounterCategoryType.SingleInstance,
        counterCollection);

      Trace.WriteLine(string.Format("Category {0} created.", category));      
    }

    public static void InitializePerformanceCounters() {
      InitializePerformanceCounters(HiveCounterCategory, "Hive performance counters",
        new PerformanceCounterEntry() {
          Name = HiveCounterGlobalUsageName,
          Type = PerformanceCounterType.NumberOfItems32,
          HelpText = "The current usage in % over all hive slaves in the system"
        }
      );
    }

    private static PerformanceCounter hiveGlovalUsage;
    public static PerformanceCounter HiveGlobalUsage {
      get {
        if (hiveGlovalUsage == null) {
          hiveGlovalUsage = new PerformanceCounter(
            PerformanceCounterHelper.HiveCounterCategory,
            PerformanceCounterHelper.HiveCounterGlobalUsageName,
            string.Empty,
            false);
        }
        return hiveGlovalUsage;
      }
    }
  }
}