/**
 *
 * @author    seagle
 * @date      2024-7-22
 * @Description if语句处理
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MECF.Framework.UI.Core.DxfScript
{
    public class IfSentence:Sentence
    {
        
        private Express ifExpr = null;
        BlockSentence ifBlock = null;
        BlockSentence elseBlock = null;
        public override void Create(StringReader reader)
        {
            KeywordType kw = reader.Next();
            if (kw != KeywordType.KW_IF)
            {
                throw new Exception("SetSentence: if expected");
            }
            kw = reader.Next();
            if (kw != KeywordType.KW_ROUND_LEFT)
            {
                throw new Exception("Round left expected in if sentence");
            }
            ifExpr = new Express();
            ifExpr.Create(reader);
            kw = reader.Next();
            if (kw != KeywordType.KW_ROUND_RIGHT)
            {
                throw new Exception("Round right expected in if sentence");
            }
            kw = reader.Next();
            if (kw != KeywordType.KW_BRACE_LEFT)
            {
                throw new Exception("Brace left expected in if sentence");
            }
            ifBlock = new BlockSentence();
            ifBlock.Create(reader);
            

            kw = reader.Next();
            if(kw== KeywordType.KW_ELSE)
            {
                kw = reader.Next();
                if (kw != KeywordType.KW_BRACE_LEFT)
                {
                    throw new Exception("Brace left expected in if-else sentence");
                }
                elseBlock = new BlockSentence();
                elseBlock.Create(reader);
            }
            else
            {
                if(kw!= KeywordType.KW_EOF)
                {
                    reader.rollback(kw);
                }
            }
             
        }
        public override void Execute()
        {
            ifExpr.Compute();
            if (ifExpr.Root.Var.BoolValue)
            {
                if(ifBlock != null)
                {
                    ifBlock.Execute();
                    if (ifBlock.ShouldReturn)
                    {
                        ShouldReturn = true;
                        ReturnVar = ifBlock.ReturnVar;
                        return;
                    }
                }
            }
            else
            {
                if (elseBlock != null)
                {
                    elseBlock.Execute();
                    if (elseBlock.ShouldReturn)
                    {
                        ShouldReturn = true;
                        ReturnVar = elseBlock.ReturnVar;
                        return;
                    }
                }
            }
            
        }
    }
}