using System;
using System.Collections.Generic;
using System.Reflection.Emit;
using System.Text;
using Sunweaver.DataPrototypes;

namespace Sunweaver.Commands.Abstracts
{
    abstract public class UnaryBooleanLogic : BasePair
    {
        protected VirtualMachine VM;
        public override void Implementation(VirtualMachine VM)
        {
            //fizzle
            if (VM.BoolStack.Count() < 1)
                return;

            this.VM = VM;

            Operation(VM.BoolStack.Pop());
        }

        internal override void Compile(ILGenerator il, Locals locals)
        {
            var cont = il.DefineLabel();

            il.Emit(OpCodes.Ldloc, locals[typeof(VirtualMachine)]);
            il.Emit(OpCodes.Ldfld, typeof(VirtualMachine).GetField("BoolStack"));
            il.Emit(OpCodes.Call, typeof(BoolStack).GetMethod("Count"));
            il.Emit(OpCodes.Ldc_I4_1);
            il.Emit(OpCodes.Conv_I8);
            il.Emit(OpCodes.Blt_S, cont); // We dont return, just go the end of this method

            il.Emit(OpCodes.Ldloc, locals[typeof(VirtualMachine)]);
            il.Emit(OpCodes.Ldfld, typeof(VirtualMachine).GetField("BoolStack"));
            il.Emit(OpCodes.Call, typeof(BoolStack).GetMethod("Pop"));
            il.Emit(OpCodes.Stloc, locals[typeof(bool), 0]);

            CompileOperation(il, locals);

            il.MarkLabel(cont); 
        }

        /// <summary>
        /// An abstract method child classes implement with the specific implementation
        /// </summary>
        /// <param name="a">Top bool value</param>
        abstract public void Operation(bool a);

        /// <summary>
        /// Abstract interface that child classes implement
        /// </summary>
        /// <remarks>
        /// The boolean variable is in the locals as bool0.
        /// </remarks>
        public abstract void CompileOperation(ILGenerator il, Locals locals);
    }
}