using HeuristicLab.Algorithms.PushGP.Interpreter;
using HeuristicLab.Algorithms.PushGP.Stack;

namespace HeuristicLab.Algorithms.PushGP.Expressions
{
    /// <summary>
    /// Pushes TRUE onto the BOOLEAN stack if the top two items are equal, or FALSE otherwise
    /// </summary>
    /// <typeparam name="T">Stacktype</typeparam>
    public abstract class EqualsExpression<T> : Expression
    {
        public EqualsExpression(string stringRepresentation) : base(stringRepresentation)
        { }

        public void Eval(IStack<T> stack, IStack<bool> booleanStack)
        {
            if (stack.Count < 2)
                return;

            var items = stack.Pop(2);

            booleanStack.Push(items[0].Equals(items[1]));
        }
    }

    public class IntegerEqualsExpression : EqualsExpression<long>
    {
        public IntegerEqualsExpression() : base("INTEGER.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.IntegerStack, interpreter.BooleanStack);
        }
    }

    public class FloatEqualsExpression : EqualsExpression<double>
    {
        public FloatEqualsExpression() : base("FLOAT.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.FloatStack, interpreter.BooleanStack);
        }
    }

    public class BooleanEqualsExpression : EqualsExpression<bool>
    {
        public BooleanEqualsExpression() : base("BOOLEAN.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.BooleanStack, interpreter.BooleanStack);
        }
    }

    public class NameEqualsExpression : EqualsExpression<string>
    {
        public NameEqualsExpression() : base("NAME.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.NameStack, interpreter.BooleanStack);
        }
    }

    public class ExecEqualsExpression : EqualsExpression<Expression>
    {
        public ExecEqualsExpression() : base("EXEC.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.ExecStack, interpreter.BooleanStack);
        }
    }

    public class CodeEqualsExpression : EqualsExpression<Expression>
    {
        public CodeEqualsExpression() : base("CODE.=")
        { }

        public override void Eval(IInterpreter interpreter)
        {
            this.Eval(interpreter.CodeStack, interpreter.BooleanStack);
        }
    }
}