// OrderedEnumerable.cs
//
// Authors:
//    Marek Safar  <marek.safar@gmail.com>
//    Jb Evain  <jbevain@novell.com>
//
// Copyright (C) 2007 - 2008 Novell, Inc (http://www.novell.com)
//
// 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.

// Needed for NET30

#if !NET_4_6
using System.Collections;
using System.Collections.Generic;

namespace System.Linq.Reimplement
{
    internal abstract class OrderedEnumerable<TElement> : IOrderedEnumerable<TElement>
    {
        private readonly IEnumerable<TElement> _source;

        protected OrderedEnumerable(IEnumerable<TElement> source)
        {
            _source = source;
        }

        public abstract SortContext<TElement> CreateContext(SortContext<TElement> current);

        public IOrderedEnumerable<TElement> CreateOrderedEnumerable<TKey>(
            Func<TElement, TKey> selector, IComparer<TKey> comparer, bool descending)
        {
            return new OrderedSequence<TElement, TKey>
            (
                this,
                _source,
                selector,
                comparer,
                descending ? SortDirection.Descending : SortDirection.Ascending
            );
        }

        public IEnumerator<TElement> GetEnumerator()
        {
            return Sort(_source).GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        protected abstract IEnumerable<TElement> Sort(IEnumerable<TElement> source);
    }
}
#endif