using System.Collections.Generic;

namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
  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>
  /// Replace first occurrence of the second lit-type item with the first lit-type item in the top type vector.
  /// </summary>
  /// <typeparam name="T"></typeparam>
  [StorableClass]
  public abstract class VectorReplaceFirstExpression<T> : StatelessExpression {
    protected VectorReplaceFirstExpression() { }
    [StorableConstructor]
    protected VectorReplaceFirstExpression(bool deserializing) : base(deserializing) { }

    protected bool IsNoop(IPushStack<IReadOnlyList<T>> vectorStack, IPushStack<T> literalStack) {
      return vectorStack.IsEmpty || literalStack.Count < 2;
    }

    protected void Eval(IPushStack<IReadOnlyList<T>> vectorStack, IPushStack<T> literalStack) {
      var vector = vectorStack.Top;
      var first = literalStack.Top;
      var second = literalStack[1];
      literalStack.Remove(2);

      var index = -1;
      for (var i = 0; i < vector.Count && index < 0; i++) {
        if (vector[i].Equals(second)) {
          index = i;
          break;
        }
      }

      if (index >= 0) {
        var result = new List<T>(vector);
        result[index] = first;
        vectorStack.Top = result;
      }
    }
  }

  [StorableClass]
  [PushExpression(
    StackTypes.IntegerVector,
    "INTEGER[].REPLACEFIRST",
    "Replace first occurrence of the second INTEGER with the INTEGER in the top INTEGER[].",
    StackTypes.Integer)]
  public class IntegerVectorReplaceFirstExpression : VectorReplaceFirstExpression<long> {
    public IntegerVectorReplaceFirstExpression() { }
    [StorableConstructor]
    protected IntegerVectorReplaceFirstExpression(bool deserializing) : base(deserializing) { }

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

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

  [StorableClass]
  [PushExpression(
    StackTypes.FloatVector,
    "FLOAT[].REPLACEFIRST",
    "Replace first occurrence of the second FLOAT with the FLOAT in the top FLOAT[].",
    StackTypes.Float)]
  public class FloatVectorReplaceFirstExpression : VectorReplaceFirstExpression<double> {
    public FloatVectorReplaceFirstExpression() { }
    [StorableConstructor]
    protected FloatVectorReplaceFirstExpression(bool deserializing) : base(deserializing) { }

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

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

  [StorableClass]
  [PushExpression(
    StackTypes.BooleanVector,
    "BOOLEAN[].REPLACEFIRST",
    "Replace first occurrence of the second BOOLEAN with the BOOLEAN in the top BOOLEAN[].",
    StackTypes.Boolean)]
  public class BooleanVectorReplaceFirstExpression : VectorReplaceFirstExpression<bool> {
    public BooleanVectorReplaceFirstExpression() { }
    [StorableConstructor]
    protected BooleanVectorReplaceFirstExpression(bool deserializing) : base(deserializing) { }

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

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

  [StorableClass]
  [PushExpression(
    StackTypes.StringVector,
    "STRING[].REPLACEFIRST",
    "Replace first occurrence of the second STRING with the STRING in the top STRING[].",
    StackTypes.String)]
  public class StringVectorReplaceFirstExpression : VectorReplaceFirstExpression<string> {
    public StringVectorReplaceFirstExpression() { }
    [StorableConstructor]
    protected StringVectorReplaceFirstExpression(bool deserializing) : base(deserializing) { }

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

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