namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
  using System.Collections.Generic;

  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Attributes;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Interpreter;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Stack;

  /// <summary>
  /// Takes the length of the top item on the type stack
  /// </summary>
  /// <typeparam name="T"></typeparam>
  [StorableClass]
  public abstract class VectorLengthExpression<T> : StatelessExpression {
    protected VectorLengthExpression() { }
    [StorableConstructor]
    protected VectorLengthExpression(bool deserializing) : base(deserializing) { }

    protected bool IsNoop(IPushStack<IReadOnlyList<T>> vectorStack) {
      return vectorStack.IsEmpty;
    }

    protected void Eval(IInternalPushInterpreter interpreter, IPushStack<IReadOnlyList<T>> vectorStack) {
      var length = vectorStack.Pop().Count;
      interpreter.IntegerStack.Push(length);
    }
  }

  [StorableClass]
  [PushExpression(
    StackTypes.IntegerVector,
    "INTEGER[].LENGTH",
    "Pushes the length of the top INTEGER[] on the INTEGER stack",
    StackTypes.Integer)]
  public class IntegerVectorLengthExpression : VectorLengthExpression<long> {
    public IntegerVectorLengthExpression() { }
    [StorableConstructor]
    protected IntegerVectorLengthExpression(bool deserializing) : base(deserializing) { }

    public override bool IsNoop(IInternalPushInterpreter interpreter) {
      return IsNoop(interpreter.IntegerVectorStack);
    }

    public override void Eval(IInternalPushInterpreter interpreter) {
      Eval(interpreter, interpreter.IntegerVectorStack);
    }
  }

  [StorableClass]
  [PushExpression(
    StackTypes.FloatVector,
    "FLOAT[].LENGTH",
    "Pushes the length of the top FLOAT[] on the INTEGER stack",
    StackTypes.Integer)]
  public class FloatVectorLengthExpression : VectorLengthExpression<double> {
    public FloatVectorLengthExpression() { }
    [StorableConstructor]
    protected FloatVectorLengthExpression(bool deserializing) : base(deserializing) { }

    public override bool IsNoop(IInternalPushInterpreter interpreter) {
      return IsNoop(interpreter.FloatVectorStack);
    }

    public override void Eval(IInternalPushInterpreter interpreter) {
      Eval(interpreter, interpreter.FloatVectorStack);
    }
  }

  [StorableClass]
  [PushExpression(
    StackTypes.BooleanVector,
    "BOOLEAN[].LENGTH",
    "Pushes the length of the top BOOLEAN[] on the INTEGER stack",
    StackTypes.Integer)]
  public class BooleanVectorLengthExpression : VectorLengthExpression<bool> {
    public BooleanVectorLengthExpression() { }
    [StorableConstructor]
    protected BooleanVectorLengthExpression(bool deserializing) : base(deserializing) { }

    public override bool IsNoop(IInternalPushInterpreter interpreter) {
      return IsNoop(interpreter.BooleanVectorStack);
    }

    public override void Eval(IInternalPushInterpreter interpreter) {
      Eval(interpreter, interpreter.BooleanVectorStack);
    }
  }

  [StorableClass]
  [PushExpression(
    StackTypes.StringVector,
    "STRING[].LENGTH",
    "Pushes the length of the top STRING[] on the INTEGER stack",
    StackTypes.Integer)]
  public class StringVectorLengthExpression : VectorLengthExpression<string> {
    public StringVectorLengthExpression() { }
    [StorableConstructor]
    protected StringVectorLengthExpression(bool deserializing) : base(deserializing) { }

    public override bool IsNoop(IInternalPushInterpreter interpreter) {
      return IsNoop(interpreter.StringVectorStack);
    }

    public override void Eval(IInternalPushInterpreter interpreter) {
      Eval(interpreter, interpreter.StringVectorStack);
    }
  }
}