using System;
using System.IO;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
  public static class SymbolicDataAnalysisSolutionTextRenderer {
    public static void TextRender(this ISymbolicExpressionTree tree) {
      RenderTree(Console.Out, tree);
    }

    private static void RenderTree(TextWriter writer, ISymbolicExpressionTree tree) {
      RenderNode(writer, tree.Root, string.Empty);
    }

    public static void RenderNode(TextWriter writer, ISymbolicExpressionTreeNode node, string prefix) {
      string label;
      if (node is VariableTreeNode) {
        var variable = node as VariableTreeNode;
        label = string.Concat(string.Format("{0:0.000}", variable.Weight), '·', variable.VariableName);
      } else if (node is ConstantTreeNode) {
        var constant = node as ConstantTreeNode;
        label = string.Format("{0:0.000}", constant.Value);
      } else {
        label = node.Symbol.ToString();
      }

      writer.Write(label);
      if (node.SubtreeCount > 0) {
        var padding = prefix + new string(' ', label.Length);
        for (int i = 0; i != node.SubtreeCount; ++i) {
          char connector, extender = ' ';
          if (i == 0) {
            if (node.SubtreeCount > 1) {
              connector = RenderChars.JunctionDown;
              extender = RenderChars.VerticalLine;
            } else {
              connector = RenderChars.HorizontalLine;
              extender = ' ';
            }
          } else {
            writer.Write(padding);
            if (i == node.SubtreeCount - 1) {
              connector = RenderChars.CornerRight;
              extender = ' ';
            } else {
              connector = RenderChars.JunctionRight;
              extender = RenderChars.VerticalLine;
            }
          }
          writer.Write(string.Concat(connector, RenderChars.HorizontalLine));
          var newPrefix = string.Concat(padding, extender, ' ');
          RenderNode(writer, node.GetSubtree(i), newPrefix);
        }
      } else
        writer.WriteLine();
    }

    // helper class providing characters for displaying a tree in the console
    public static class RenderChars {
      public const char JunctionDown = '┬';
      public const char HorizontalLine = '─';
      public const char VerticalLine = '│';
      public const char JunctionRight = '├';
      public const char CornerRight = '└';
    }
  }
}