using System;
using System.Threading.Tasks;

namespace HeuristicLab.Algorithms.PushGP.Cli {
  using System.Collections.Generic;
  using System.Linq;

  using HeuristicLab.Problems.ProgramSynthesis.Push.Configuration;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Constants;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Interpreter;

  class Program {
    static void Main(string[] args) {
      string code = null;

      if (args.Length == 0) {
        var lines = new List<string>();

        Console.WriteLine(@"Program: ( must start with '(' and end with ')' )");

        var bracesCount = 0;
        var linesRead = 0;

        while (bracesCount > 0 || lines.Count == 0 || linesRead == 0) {
          var line = Console.ReadLine();
          linesRead++;

          if (string.IsNullOrWhiteSpace(line))
            continue;

          line = line.Trim();
          lines.Add(line);

          var openBraces = line.Count(c => c == PushEnvironment.ProgramStartSymbol);
          var closeBraces = line.Count(c => c == PushEnvironment.ProgramEndSymbol);
          bracesCount += openBraces - closeBraces;
        }

        code = string.Join(" ", lines);
      } else {
        code = args[0];
      }

      EvaluateStepwise(code).Wait();

      Console.WriteLine(@"Press any key to terminate...");
    }

    static async Task EvaluateStepwise(string code) {
      var interpreter = new PushInterpreter(new PushConfiguration {
        TopLevelPushCode = false
      });

      Console.WriteLine(@"Press ESC to cancel, SPACE to resume, Any other key to step...");
      interpreter.Run(code, true);

      while (!interpreter.IsCompleted) {
        Console.Clear();
        interpreter.PrintStacks();
        interpreter.Step();

        var input = Console.ReadKey();
        if (input.Key == ConsoleKey.Escape) {
          break;
        }

        if (input.Key == ConsoleKey.Spacebar) {
          await interpreter.ResumeAsync();
        }
      }

      Console.Clear();
      interpreter.PrintStacks();
    }
  }
}