using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Linq.Expressions;



namespace Atlassian.Jira.Linq

{

    public class JiraQueryProvider: IQueryProvider

    {

        private readonly IJqlExpressionVisitor _translator;

        private readonly Jira _jiraServer;



        public JiraQueryProvider(IJqlExpressionVisitor translator, Jira jiraInstance)

        {

            _translator = translator;

            _jiraServer = jiraInstance;

        }



        public IQueryable<T> CreateQuery<T>(Expression expression)

        {

            return new JiraQueryable<T>(this, expression);

        }



        public IQueryable CreateQuery(Expression expression)

        {

            throw new NotImplementedException();

        }



        public T Execute<T>(Expression expression)

        {

            bool isEnumerable = (typeof(T).Name == "IEnumerable`1");



            return (T)this.Execute(expression, isEnumerable);

        }



        public object Execute(Expression expression)

        {

            return Execute(expression, true);

        }



        private object Execute(Expression expression, bool isEnumerable)

        {

            var jql = _translator.Process(expression);



            if (jql.ProcessCount && _jiraServer.UseRestApi)

            {

                return _jiraServer.WithToken<int>((token, client) =>

                    {

                        return _jiraServer.RemoteService.GetIssueCountFromJqlSearch(jql.Expression);

                    });

            }



            IQueryable<Issue> issues = _jiraServer.GetIssuesFromJql(jql.Expression, jql.StartAt, jql.MaxResults ?? _jiraServer.MaxIssuesPerRequest).AsQueryable();



            if (isEnumerable)

            {

                return issues;

            }

            else

            {

                var treeCopier = new ExpressionTreeModifier(issues);

                Expression newExpressionTree = treeCopier.Visit(expression);

            

                return issues.Provider.Execute(newExpressionTree);

            }

        }

    }

}