// 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 System;
using System.Diagnostics;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel
{
    [Flags]
    internal enum CodeModelEventType
    {
        Add = 1 << 0,
        Remove = 1 << 1,
        Rename = 1 << 2,
        Unknown = 1 << 3,
        BaseChange = 1 << 4,
        SigChange = 1 << 5,
        TypeRefChange = 1 << 6,
        ArgChange = 1 << 7
    }
 
    internal static class CodeModelEventTypeExtensions
    {
        public static bool IsChange(this CodeModelEventType eventType)
        {
            if (eventType is CodeModelEventType.Add or CodeModelEventType.Remove)
            {
                return false;
            }
 
            // Check that Add and Remove are not set
            if ((eventType & CodeModelEventType.Add) == 0 &&
                (eventType & CodeModelEventType.Remove) == 0)
            {
                // Check that one or more of the change flags are set
                var allChanges =
                    CodeModelEventType.Rename |
                    CodeModelEventType.Unknown |
                    CodeModelEventType.BaseChange |
                    CodeModelEventType.SigChange |
                    CodeModelEventType.TypeRefChange |
                    CodeModelEventType.ArgChange;
 
                if ((eventType & allChanges) != 0)
                {
                    return true;
                }
            }
 
            Debug.Fail("Invalid combination of change type flags!");
            return false;
        }
    }
}