// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Microsoft.Cci.Extensions;
using Microsoft.Cci.Extensions.CSharp;
 
namespace Microsoft.Cci.Differs.Rules
{
    [ExportDifferenceRule]
    internal class CannotMakeAbstract : CompatDifferenceRule
    {
        public override DifferenceType Diff(IDifferences differences, ITypeDefinitionMember impl, ITypeDefinitionMember contract)
        {
            if (impl == null || contract == null)
                return DifferenceType.Unknown;
 
            if (impl.IsAbstract() && !contract.IsAbstract())
            {
                differences.AddIncompatibleDifference("CannotMakeMemberAbstract", impl.GetMemberViolationMessage("Member", $"is abstract in the {Implementation}", $"is not abstract in the {Contract}"));
                return DifferenceType.Changed;
            }
 
            return DifferenceType.Unknown;
        }
 
        public override DifferenceType Diff(IDifferences differences, ITypeDefinition impl, ITypeDefinition contract)
        {
            if (impl == null || contract == null)
                return DifferenceType.Unknown;
 
            if (impl.IsAbstract && !contract.IsAbstract)
            {
                differences.AddIncompatibleDifference("CannotMakeTypeAbstract",
                    $"Type '{impl.FullName()}' is abstract in the {Implementation} but is not abstract in the {Contract}.");
 
                return DifferenceType.Changed;
            }
 
            return DifferenceType.Unknown;
        }
    }
}