// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using Microsoft.VisualStudio.Shell.Interop;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 
internal class TaskItemsEnum<T> : IVsEnumTaskItems where T : IVsTaskItem
{
    private readonly T[] _items;
    private int _next;
 
    public TaskItemsEnum(T[] immutableItems)
    {
        _items = immutableItems;
        _next = 0;
    }
 
    int IVsEnumTaskItems.Next(uint celt, IVsTaskItem[] rgelt, uint[] pceltFetched)
    {
        checked
        {
            int i;
            for (i = 0; i < celt && _next + i < _items.Length; i++)
            {
                rgelt[i] = _items[_next + i];
            }
 
            _next += i;
 
            if (pceltFetched != null)
            {
                pceltFetched[0] = (uint)i;
            }
 
            return (i == celt) ? VSConstants.S_OK : VSConstants.S_FALSE;
        }
    }
 
    int IVsEnumTaskItems.Skip(uint celt)
    {
        checked
        {
            _next += (int)celt;
        }
 
        return VSConstants.S_OK;
    }
 
    int IVsEnumTaskItems.Reset()
    {
        _next = 0;
        return VSConstants.S_OK;
    }
 
    int IVsEnumTaskItems.Clone(out IVsEnumTaskItems taskItemsEnum)
    {
        taskItemsEnum = new TaskItemsEnum<T>(_items);
        return VSConstants.S_OK;
    }
}