#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Analysis;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using Irony.Interpreter;
using Irony.Parsing;

namespace HeuristicLab.BenchmarkGenerator {
  [Item("Benchmark Generator", "Utility class to generate artificial datasets based on custom user-defined formulas.")]
  public class BenchmarkGenerator : Item {
    private readonly ExpressionEvaluator evaluator;
    private Parser Parser { get { return evaluator.Parser; } }
    private ParseTree Tree { get { return Parser.Context.CurrentParseTree; } }
    private IDictionary<string, object> Globals { get { return evaluator.Globals; } }
    private DataTable table;

    [StorableConstructor]
    private BenchmarkGenerator(bool deserializing)
      : base(deserializing) {
    }

    protected BenchmarkGenerator(BenchmarkGenerator original, Cloner cloner)
      : base(original, cloner) {
      evaluator = original.evaluator;
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new BenchmarkGenerator(this, cloner);
    }

    private void AddCustomFunctions() {
      var runtime = (CustomLanguageRuntime)evaluator.Runtime;
      runtime.BuiltIns.Clear();
      runtime.BuiltIns.AddMethod(Functions.NormalDouble, "normal");
      runtime.BuiltIns.AddMethod(Functions.UniformDouble, "uniform");
      runtime.BuiltIns.AddMethod(Functions.NormalDistribution, "dnormal");
      runtime.BuiltIns.AddMethod(Functions.UniformDistribution, "duniform");
      runtime.BuiltIns.AddMethod(Functions.Steps, "steps");
      runtime.BuiltIns.AddMethod(Functions.Repeat, "repeat");
      runtime.BuiltIns.AddMethod(Functions.Sin, "sin");
      runtime.BuiltIns.AddMethod(Functions.Cos, "cos");
      runtime.BuiltIns.AddMethod(Functions.Length, "length");
      runtime.BuiltIns.AddMethod(Functions.Abs, "abs");
      runtime.BuiltIns.AddMethod(Functions.DotProduct, "dot");
    }

    public BenchmarkGenerator() {
      evaluator = new ExpressionEvaluator();
      AddCustomFunctions();
      table = new DataTable("Data");
    }

    public DataTable GenerateDataset(string formula, int nSamples) {
      Globals.Clear();
      Parser.Parse(formula);
      if (Tree.Status == ParseTreeStatus.Error) {
        throw new Exception("Invalid formula.");
      }
      evaluator.Evaluate(Tree);
      // after the tree is parsed the variables are saved in the global dictionary
      // because the Globals only grow but never shrink, the values for unused keys are set to null
      // we check that below in order to remove unused keys from our table
      foreach (var pair in Globals) {
        var key = pair.Key;
        if (pair.Value == null) {
          table.Rows.Remove(key);
          continue;
        }
        var values = ((object[])Globals[key]).Cast<double>().ToArray();
        if (!table.Rows.ContainsKey(key)) {
          table.Rows.Add(new DataRow(key) { VisualProperties = { StartIndexZero = true } });
        }
        table.Rows[key].Values.Clear();
        table.Rows[key].Values.AddRange(values);
      }
      return table;
    }
  }
}