namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
  using System;
  using System.Linq;

  using Attributes;
  using Interpreter;
  using Stack;

  [PushExpression(StackTypes.String, "STRING.FROMINTEGER", StackTypes.Integer)]
  public class StringFromIntegerExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.IntegerStack.IsEmpty)
        return false;

      var value = interpreter.IntegerStack.Pop();
      interpreter.StringStack.Push(value.ToString());
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.FROMFLOAT", StackTypes.Float)]
  public class StringFromFloatExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.FloatStack.IsEmpty)
        return false;

      var value = interpreter.FloatStack.Pop();
      interpreter.StringStack.Push(value.ToString());
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.FROMBOOLEAN", StackTypes.Boolean)]
  public class StringFromBooleanExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.BooleanStack.IsEmpty)
        return false;

      var value = interpreter.BooleanStack.Pop();
      interpreter.StringStack.Push(value.ToString());
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.FROMCHAR", StackTypes.Char)]
  public class StringFromCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.CharStack.IsEmpty)
        return false;

      var value = interpreter.CharStack.Pop();
      interpreter.StringStack.Push(value.ToString());
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.CONCAT")]
  public class StringConcatExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.Count < 2 ||
        interpreter.StringStack.Top.Length + interpreter.StringStack.ReverseElementAt(1).Length >= interpreter.Configuration.MaxStringLength)
        return false;

      var str = interpreter.StringStack.Pop();
      interpreter.StringStack.SetTop(str + interpreter.StringStack.Top);
      return true;
    }
  }

  /// <summary>
  /// Conj char onto string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.CONJCHAR", StackTypes.Char)]
  public class StringConjCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty ||
          interpreter.StringStack.Top.Length + 1 >= interpreter.Configuration.MaxStringLength)
        return false;

      var c = interpreter.CharStack.Pop();
      interpreter.StringStack.SetTop(interpreter.StringStack.Top + c);
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.TAKE", StackTypes.Integer)]
  public class StringTakeExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.IntegerStack.IsEmpty)
        return false;

      var value = interpreter.IntegerStack.Pop();

      if (value < 0) {
        return true;
      }

      var str = interpreter.StringStack.Top;

      if (str.Length > 0) {
        value = Math.Min(str.Length - 1, value);
        interpreter.StringStack.SetTop(str.Substring(0, (int)value));
      }

      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.SUBSTRING", StackTypes.Integer)]
  public class StringSubstringExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.IntegerStack.Count < 2)
        return false;

      var str = interpreter.StringStack.Top;
      var values = interpreter.IntegerStack.Pop(2);
      var first = Math.Min(str.Length - 1, Math.Max(values[0], 0));
      var second = Math.Min(str.Length - 1, Math.Max(values[1], first));
      var length = second - first;

      if (length > 0)
        interpreter.StringStack.SetTop(str.Substring((int)first, (int)length));

      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.FIRST")]
  public class StringFirstExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.StringStack.Top.Length == 0)
        return false;

      interpreter.StringStack.SetTop(interpreter.StringStack.Top[0].ToString());
      return true;
    }
  }


  [PushExpression(StackTypes.String, "STRING.LAST")]
  public class StringLastExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.StringStack.Top.Length == 0)
        return false;

      var str = interpreter.StringStack.Top;
      var c = str[str.Length - 1].ToString();
      interpreter.StringStack.SetTop(c);
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.NTH", StackTypes.Integer)]
  public class StringNthExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.IntegerStack.IsEmpty ||
          interpreter.StringStack.Top.Length == 0)
        return false;

      var str = interpreter.StringStack.Top;
      var index = str.Length == 1 ? 0 : (int)Math.Abs(interpreter.IntegerStack.Pop() % (str.Length - 1));
      var c = str[index].ToString();
      interpreter.StringStack.SetTop(c);
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.REST")]
  public class StringRestExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.StringStack.Top.Length == 0)
        return false;

      var str = interpreter.StringStack.Top;
      interpreter.StringStack.SetTop(str.Length == 1 ? string.Empty : str.Substring(1, str.Length - 1));
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.BUTLAST")]
  public class StringButLastExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.StringStack.Top.Length == 0)
        return false;

      var str = interpreter.StringStack.Top;
      interpreter.StringStack.SetTop(str.Length == 1 ? string.Empty : str.Substring(0, str.Length - 1));
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.LENGTH", StackTypes.Integer)]
  public class StringLengthExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Pop();
      interpreter.IntegerStack.Push(str.Length);
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.REVERSE")]
  public class StringReverseExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty)
        return false;

      interpreter.StringStack.SetTop(interpreter.StringStack.Top.Reverse().ToString());
      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.PARSETOCHARS")]
  public class StringParseToCharsExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty)
        return false;

      if (interpreter.StringStack.Top.Length == 0) {
        interpreter.StringStack.Pop();
        return true;
      }

      var str = interpreter.StringStack.Top;
      interpreter.StringStack.SetTop(str[0].ToString());

      if (str.Length > 1) {
        var chars = new string[str.Length - 1];
        for (var i = 0; i < str.Length - 1; i++) {
          chars[i] = str[i + 1].ToString();
        }

        interpreter.StringStack.Push(chars);
      }

      return true;
    }
  }

  [PushExpression(StackTypes.String, "STRING.SPLIT")]
  public class StringSplitExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty)
        return false;

      var words = interpreter.StringStack.Top.Trim().Split();

      if (words.Length == 0)
        return false;

      interpreter.StringStack.SetTop(words[0]);

      if (words.Length > 1)
        interpreter.StringStack.Push(words, 1);

      return true;
    }
  }

  /// <summary>
  /// True if top string is empty
  /// </summary>

  [PushExpression(StackTypes.String, "STRING.EMPTYSTRING", StackTypes.Boolean)]
  public class StringEmptyStringExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Pop();
      interpreter.BooleanStack.Push(str.Length == 0);
      return true;
    }
  }

  /// <summary>
  /// True if top string is a substring of second string; false otherwise
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.CONTAINS", StackTypes.Boolean)]
  public class StringContainsExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.Count < 2)
        return false;

      var strings = interpreter.StringStack.Pop(2);
      interpreter.BooleanStack.Push(strings[0].IndexOf(strings[1], StringComparison.Ordinal) >= 0);
      return true;
    }
  }

  /// <summary>
  /// True if the top char is in the top string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.CONTAINSCHAR", StackTypes.Boolean | StackTypes.Char)]
  public class StringContainsCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Pop();
      var c = interpreter.CharStack.Pop();

      interpreter.BooleanStack.Push(str.IndexOf(c) >= 0);
      return true;
    }
  }

  /// <summary>
  /// Puts on the integer stack the index of the top char in the top string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.INDEXOFCHAR", StackTypes.Integer | StackTypes.Char)]
  public class StringIndexOfCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Pop();
      var c = interpreter.CharStack.Pop();

      interpreter.IntegerStack.Push(str.IndexOf(c));
      return true;
    }
  }

  /// <summary>
  /// The number of times the top char is in the top string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.OCCURENCESOFCHAR", StackTypes.Integer | StackTypes.Char)]
  public class StringOccurrencesOfCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Pop();
      var c = interpreter.CharStack.Pop();

      var count = 0;
      for (var i = 0; i < str.Length; i++)
        if (str[i] == c) count++;

      interpreter.IntegerStack.Push(count);
      return true;
    }
  }

  /// <summary>
  /// In third string on stack, replaces second string with first string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.REPLACE")]
  public class StringReplaceExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.Count < 3)
        return false;

      var strings = interpreter.StringStack.Pop(2);

      if (strings[0].Length == 0 || strings[1].Length == 0)
        interpreter.StringStack.SetTop(strings[0]);
      else {
        var result = strings[0].Replace(strings[1], interpreter.StringStack.Top);
        interpreter.StringStack.SetTop(result);
      }

      return true;
    }
  }

  /// <summary>
  /// In third string on stack, replaces first occurence of second string with first string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.REPLACEFIRST")]
  public class StringReplaceLastExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.Count < 3)
        return false;

      var strings = interpreter.StringStack.Pop(2);

      var pos = strings[0].IndexOf(strings[1], StringComparison.Ordinal);

      if (pos < 0)
        return true;

      var result = strings[0].Substring(0, pos) +
                   interpreter.StringStack.Top +
                   strings[0].Substring(pos + strings[1].Length);

      interpreter.StringStack.SetTop(result);
      return true;
    }
  }

  /// <summary>
  /// In top string on stack, replaces all occurences of second char with first char
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.REPLACECHAR", StackTypes.Char)]
  public class StringReplaceCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.Count < 2)
        return false;

      var chars = interpreter.CharStack.Pop(2);
      var result = interpreter.StringStack.Top.Replace(chars[0], chars[1]);
      interpreter.StringStack.SetTop(result);
      return true;
    }
  }

  /// <summary>
  /// In top string on stack, replaces first occurence of second char with first char
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.REPLACEFIRSTCHAR", StackTypes.Char)]
  public class StringReplaceLastCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.Count < 2)
        return false;

      var str = interpreter.StringStack.Top;
      var chars = interpreter.CharStack.Pop(2);
      var pos = interpreter.StringStack.Top.IndexOf(chars[0]);

      if (pos < 0)
        return true;

      var result = str.Substring(0, pos) +
                   chars[1] +
                   str.Substring(Math.Min(pos + 2, str.Length - 1));
      interpreter.StringStack.SetTop(result);
      return true;
    }
  }

  /// <summary>
  /// In top string on stack, remove all occurences of char
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.REMOVECHAR", StackTypes.Char)]
  public class StringRemoveCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty)
        return false;

      var c = interpreter.CharStack.Pop();
      var result = interpreter.StringStack.Top.Trim(c);
      interpreter.StringStack.SetTop(result);
      return true;
    }
  }

  /// <summary>
  /// Returns a function that sets char at index in string
  /// </summary>
  [PushExpression(StackTypes.String, "STRING.SETCHAR", StackTypes.Char | StackTypes.Integer)]
  public class StringSetCharExpression : StatelessExpression {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      if (interpreter.StringStack.IsEmpty ||
          interpreter.CharStack.IsEmpty ||
          interpreter.IntegerStack.IsEmpty)
        return false;

      var str = interpreter.StringStack.Top;
      var i = (int)interpreter.IntegerStack.Pop();
      var c = interpreter.CharStack.Pop();

      if (str.Length == 0) {
        interpreter.StringStack.Pop();
        return true;
      }

      var pos = str.Length == 1 ? 0 : Math.Abs(i) % (str.Length - 1);
      var result = str.Substring(0, pos) + c + str.Substring(Math.Min(pos + 2, str.Length - 1));

      interpreter.StringStack.SetTop(result);
      return true;
    }
  }
}