using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Linq.Expressions;



namespace Atlassian.Jira.Linq

{

    internal class ExpressionTreeModifier: ExpressionVisitor

    {

        private readonly IQueryable<Issue> _queryableIssues;



        public ExpressionTreeModifier(IQueryable<Issue> queryableIssues)

        {

            _queryableIssues = queryableIssues;

        }



        protected override Expression VisitConstant(ConstantExpression node)

        {

            if (node.Type == typeof(JiraQueryable<Issue>))

            {

                return Expression.Constant(_queryableIssues);

            }

            else

            {

                return node;

            }

        }



        protected override Expression VisitMethodCall(MethodCallExpression node)

        {

            if (node.Method.Name == "Where"

                || node.Method.Name == "Take"

                || node.Method.Name == "OrderBy" 

                || node.Method.Name == "OrderByDescending"

                || node.Method.Name == "ThenBy"

                || node.Method.Name == "ThenByDescending")

            {

                return Expression.Constant(_queryableIssues);

            }



            return base.VisitMethodCall(node);

        }



    }

}