luticate2-api/Luticate2.Auth/Business/Fields/LuExpressionConverterVisito...

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using Luticate2.Auth.Business.Fields.DMEC;
using Luticate2.Auth.Dbo;
using Luticate2.Auth.Dbo.Result;
using Luticate2.Auth.Exceptions;
using Luticate2.Auth.Interfaces;

namespace Luticate2.Auth.Business.Fields
{
    public class LuExpressionConverterVisitor : ExpressionVisitor
    {
        public LuExpressionConverterOptions Options { get; }

        protected IServiceProvider ServiceProvider { get; }

        public LuExpressionConverterVisitor(LuExpressionConverterOptions options, IServiceProvider serviceProvider)
        {
            Options = options;
            ServiceProvider = serviceProvider;
        }

        protected LuResult<Stack<Expression>> StackSimpleExpression(Expression expression, Stack<Expression> stack)
        {
            if (expression is ParameterExpression parameterExpression)
            {
                stack.Push(parameterExpression);
                return LuResult<Stack<Expression>>.Ok(stack);
            }
            else if (expression is MemberExpression memberExpression)
            {
                stack.Push(memberExpression);
                var result = StackSimpleExpression(memberExpression.Expression, stack);
                return result;
            }
            else if (expression is MethodCallExpression methodCallExpression)
            {
                if (methodCallExpression.Object != null)
                {
                    stack.Push(methodCallExpression);
                    var result = StackSimpleExpression(methodCallExpression.Object, stack);
                    return result;
                }
                else
                {
                    stack.Push(methodCallExpression);
                    var param = Expression.Parameter(typeof(LuExpressionConverterStaticMethods));
                    stack.Push(param);
                    return LuResult<Stack<Expression>>.Ok(stack);
                }
            }

            return LuResult<Stack<Expression>>.Error(LuStatus.InternalError.ToInt(), "Invalid Simple Expression Member");
        }

        protected Expression ReplaceExpression(Expression expression)
        {
            var stackResult = StackSimpleExpression(expression, new Stack<Expression>()).ThrowIfNotSuccess();

            var firstResult = stackResult.Data.Peek();

            var type = typeof(ILuExpressionConverter<>);
            var gtype = type.MakeGenericType(firstResult.Type);
            var converter = (ILuExpressionConverter) ServiceProvider.GetService(gtype);
            if (converter == null)
            {
                LuResult<Expression>.Error(LuStatus.InternalError.ToInt(), $"Could not get service: ILuExpressionConverter<{firstResult.Type.Name}>").Throw();
            }

            var exp = converter.ConvertExpression(stackResult.Data, null, Options).ThrowIfNotSuccess();

            return exp.Data;
        }

        protected override Expression VisitMember(MemberExpression node)
        {
            return ReplaceExpression(node);
        }

        protected override Expression VisitMethodCall(MethodCallExpression node)
        {
            return ReplaceExpression(node);
        }


    }
}