//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="ExpSyntaxAnalyzer.If"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;

using ExpKeyword = StgSharp.Script.Express.ExpressCompile.Keyword;

namespace StgSharp.Script.Express
{
    public partial class ExpSyntaxAnalyzer
    {

        private bool AppendToken_IfBranch(Token t)
        {
            switch (t.Value)
            {
                case ExpKeyword.If:
                    IfBranchStateCache state = new IfBranchStateCache();
                    _cache.CurrentDepthMark.StateCache = state;
                    state.CurrentState = t.Value;
                    return true;
                case ExpKeyword.Then:
                    state = _cache.StateOfCurrentDepth<IfBranchStateCache>();
                    if (state.CurrentState == ExpKeyword.If)
                    {
                        while (_cache.TryPopOperator(out Token op)) {
                            ConvertAndPushOneOperator(op);
                        }
                        _cache.PopOperand(out _, out ExpSyntaxNode? node);
                        state.CurrentState = t.Value;
                        state.BoolExpression = node;
                    } else
                    {
                        throw new ExpCompileException(
                            t, $"Keyword {t.Value} should be after keyword {ExpKeyword.Then}");
                    }
                    return true;
                case ExpKeyword.Else:
                    state = _cache.StateOfCurrentDepth<IfBranchStateCache>();
                    if (state.CurrentState == ExpKeyword.Then)
                    {
                        ExpSyntaxNode node = _cache.PackAllStatements();
                        state.CurrentState = t.Value;
                        state.ExpressionIfTrue = node;
                    } else
                    {
                        throw new ExpCompileException(
                            t, $"Keyword {t.Value} should be after keyword {ExpKeyword.Then}");
                    }
                    return true;

                case ExpKeyword.EndIf:
                    state = _cache.StateOfCurrentDepth<IfBranchStateCache>();
                    if (state.CurrentState == ExpKeyword.Then)
                    {
                        ExpSyntaxNode trueNode = _cache.PackAllStatements();
                        state.CurrentState = t.Value;
                        state.ExpressionIfTrue = trueNode;
                        state.ExpressionIfFalse = ExpSyntaxNode.Empty;
                    } else if (state.CurrentState == ExpKeyword.Else)
                    {
                        ExpSyntaxNode falseNode = _cache.PackAllStatements();
                        state.CurrentState = t.Value;
                        state.ExpressionIfFalse = falseNode;
                    } else
                    {
                        throw new ExpCompileException(
                            t,
                            $"Keyword {t.Value} should be after keyword {ExpKeyword.Then} or {ExpKeyword.Else}");
                    }
                    ExpIfNode ifNode = new ExpIfNode(
                        state.Begin, state.BoolExpression, state.ExpressionIfTrue,
                        state.ExpressionIfFalse);
                    _cache.DecreaseDepth();
                    _cache.StatementsInDepth.Push(ifNode);
                    return true;
                default:
                    AppendToken_Common(t);
                    return true;
            }
        }

        private class IfBranchStateCache : ICompileDepthState
        {

            public ExpSyntaxNode BoolExpression { get; set; }

            public ExpSyntaxNode ExpressionIfTrue { get; set; }

            public ExpSyntaxNode ExpressionIfFalse { get; set; }

            public string CurrentState { get; set; }

            public Token Begin { get; set; }

        }

    }
}