#region License Information
/* HeuristicLab
 * Copyright (C) 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.Globalization;
using System.Text;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic {

  [Item("Smalltalk String Formatter", "String formatter for string representations of symbolic expression trees in Smalltalk syntax.")]
  public class SymbolicDataAnalysisExpressionSmalltalkFormatter : NamedItem, ISymbolicExpressionTreeStringFormatter {

    protected SymbolicDataAnalysisExpressionSmalltalkFormatter(SymbolicDataAnalysisExpressionSmalltalkFormatter original, Cloner cloner) : base(original, cloner) { }
    public SymbolicDataAnalysisExpressionSmalltalkFormatter()
      : base() {
      Name = ItemName;
      Description = ItemDescription;
    }

    public string Format(ISymbolicExpressionTree symbolicExpressionTree) {
      return FormatRecursively(symbolicExpressionTree.Root);
    }

    // returns the smalltalk expression corresponding to the node 
    // smalltalk expressions are always surrounded by parantheses "(<expr>)"
    private string FormatRecursively(ISymbolicExpressionTreeNode node) {

      ISymbol symbol = node.Symbol;

      if (symbol is ProgramRootSymbol || symbol is StartSymbol)
        return FormatRecursively(node.GetSubtree(0));

      StringBuilder stringBuilder = new StringBuilder(20);

      stringBuilder.Append("(");

      if (symbol is Addition) {
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append("+");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
        }
      } else if (symbol is And) {
        stringBuilder.Append("(");
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append("&");
          stringBuilder.Append("(");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
          stringBuilder.Append(" > 0)");
        }
        stringBuilder.Append(") ifTrue:[1] ifFalse:[-1]");
      } else if (symbol is Absolute) {
        stringBuilder.Append($"({FormatRecursively(node.GetSubtree(0))}) abs");
      } else if (symbol is AnalyticQuotient) {
        stringBuilder.Append($"({FormatRecursively(node.GetSubtree(0))}) / (1 + ({FormatPower(node.GetSubtree(1), "2")})) sqrt");
      } else if (symbol is Average) {
        stringBuilder.Append("(1/");
        stringBuilder.Append(node.SubtreeCount);
        stringBuilder.Append(")*(");
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append("+");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
        }
        stringBuilder.Append(")");
      } else if (symbol is Constant) {
        ConstantTreeNode constantTreeNode = node as ConstantTreeNode;
        stringBuilder.Append(constantTreeNode.Value.ToString(CultureInfo.InvariantCulture));
      } else if (symbol is Cosine) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" cos");
      } else if (symbol is Cube) {
        stringBuilder.Append(FormatPower(node.GetSubtree(0), "3"));
      } else if (symbol is CubeRoot) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" cbrt");
      } else if (symbol is Division) {
        if (node.SubtreeCount == 1) {
          stringBuilder.Append("1/");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        } else {
          stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
          stringBuilder.Append("/(");
          for (int i = 1; i < node.SubtreeCount; i++) {
            if (i > 1) stringBuilder.Append("*");
            stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
          }
          stringBuilder.Append(")");
        }
      } else if (symbol is Exponential) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" exp");
      } else if (symbol is GreaterThan) {
        stringBuilder.Append("(");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" > ");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(1)));
        stringBuilder.Append(") ifTrue: [1] ifFalse: [-1]");
      } else if (symbol is IfThenElse) {
        stringBuilder.Append("(");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" > 0) ifTrue: [");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(1)));
        stringBuilder.Append("] ifFalse: [");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(2)));
        stringBuilder.Append("]");
      } else if (symbol is LaggedVariable) {
        stringBuilder.Append("lagged variables are not supported");
      } else if (symbol is LessThan) {
        stringBuilder.Append("(");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" < ");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(1)));
        stringBuilder.Append(") ifTrue: [1] ifFalse: [-1]");
      } else if (symbol is Logarithm) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append("ln");
      } else if (symbol is Multiplication) {
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append("*");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
        }
      } else if (symbol is Not) {
        stringBuilder.Append("(");
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(">0) ifTrue: [-1] ifFalse: [1.0]");
      } else if (symbol is Or) {
        stringBuilder.Append("(");
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append("|");
          stringBuilder.Append("(");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
          stringBuilder.Append(">0)");
        }
        stringBuilder.Append(") ifTrue:[1] ifFalse:[-1]");
      } else if (symbol is Sine) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" sin");
      } else if (symbol is Square) {
        stringBuilder.Append(FormatPower(node.GetSubtree(0), "2"));
      } else if (symbol is SquareRoot) {
        stringBuilder.Append(FormatPower(node.GetSubtree(0), "(1/2)"));
      } else if (symbol is Subtraction) {
        if (node.SubtreeCount == 1) {
          stringBuilder.Append("-1*");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        } else {
          stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
          for (int i = 1; i < node.SubtreeCount; i++) {
            stringBuilder.Append(" - ");
            stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
          }
        }
      } else if (symbol is Tangent) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" tan");
      } else if (symbol is HyperbolicTangent) {
        stringBuilder.Append(FormatRecursively(node.GetSubtree(0)));
        stringBuilder.Append(" tanh");
      } else if (symbol is Variable) {
        VariableTreeNode variableTreeNode = node as VariableTreeNode;
        stringBuilder.Append(variableTreeNode.Weight.ToString(CultureInfo.InvariantCulture));
        stringBuilder.Append("*");
        stringBuilder.Append(variableTreeNode.VariableName);
      } else if (symbol is BinaryFactorVariable || symbol is FactorVariable) {
        stringBuilder.Append("factor variables are not supported");
      } else {
        stringBuilder.Append("(");
        for (int i = 0; i < node.SubtreeCount; i++) {
          if (i > 0) stringBuilder.Append(", ");
          stringBuilder.Append(FormatRecursively(node.GetSubtree(i)));
        }
        stringBuilder.AppendFormat(" {0} [Not Supported] )", node.Symbol.Name);
      }

      stringBuilder.Append(")");

      return stringBuilder.ToString();
    }

    private string FormatPower(ISymbolicExpressionTreeNode node, string exponent) {
      return $"(({FormatRecursively(node)}) log * {exponent}) exp ";
    }

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