using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using HeuristicLab.Optimization;

namespace HeuristicLab.Analysis {
  public static class ExpectedRuntimeHelper {
    public static ErtCalculationResult CalculateErt(List<IRun> runs, string indexedDataTableName, double target, bool maximization) {
      var successful = new List<double>();
      var unsuccessful = new List<double>();
      foreach (var r in runs) {
        var targetAchieved = false;
        var row = ((IndexedDataTable<double>)r.Results[indexedDataTableName]).Rows.First();
        foreach (var v in row.Values) {
          if (maximization && v.Item2 >= target || !maximization && v.Item2 <= target) {
            successful.Add(v.Item1);
            targetAchieved = true;
            break;
          }
        }
        if (!targetAchieved) unsuccessful.Add(row.Values.Last().Item1);
      }

      var ert = double.NaN;

      if (successful.Count > 0) {
        if (unsuccessful.Count == 0) ert = successful.Average();
        else {
          var ps = successful.Count / (double)(successful.Count + unsuccessful.Count);
          ert = successful.Average() + ((1.0 - ps) / ps) * unsuccessful.Average();
        }
      }
      return new ErtCalculationResult(successful.Count, (successful.Count + unsuccessful.Count), ert);
    }
  }

  public struct ErtCalculationResult {
    public int SuccessfulRuns;
    public int TotalRuns;
    public double ExpectedRuntime;

    public ErtCalculationResult(int successful, int total, double ert) {
      SuccessfulRuns = successful;
      TotalRuns = total;
      ExpectedRuntime = ert;
    }

    public override string ToString() {
      return SuccessfulRuns == 0 ? "\u221e"
                                 : ExpectedRuntime.ToString("##,0.0", CultureInfo.CurrentCulture.NumberFormat);
    }
  }
}