﻿// 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.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics.CodeAnalysis;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Collections;
using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;

namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.ExternalElements
{
    public abstract class AbstractExternalCodeType : AbstractExternalCodeElement, EnvDTE.CodeType
    {
        internal AbstractExternalCodeType(CodeModelState state, ProjectId projectId, ITypeSymbol symbol)
            : base(state, projectId, symbol)
        {
        }

        protected internal ITypeSymbol TypeSymbol
        {
            get { return (ITypeSymbol)LookupSymbol(); }
        }

        protected override object GetExtenderNames()
            => CodeModelService.GetExternalTypeExtenderNames();

        protected override object GetExtender(string name)
        {
            var type = TypeSymbol;
            if (type == null)
            {
                throw Exceptions.ThrowEUnexpected();
            }

            var assembly = type.ContainingAssembly;
            if (assembly == null)
            {
                return string.Empty;
            }

            var compilation = GetCompilation();
            if (compilation.GetMetadataReference(assembly) is not PortableExecutableReference metadataReference)
            {
                return string.Empty;
            }

            return CodeModelService.GetExternalTypeExtender(name, metadataReference.FilePath);
        }

        public EnvDTE.CodeElements Bases
        {
            get
            {
                var builder = ArrayBuilder<INamedTypeSymbol>.GetInstance();

                var typeSymbol = TypeSymbol;
                if (typeSymbol.TypeKind == TypeKind.Interface)
                {
                    builder.AddRange(typeSymbol.AllInterfaces);
                }
                else if (typeSymbol.BaseType != null)
                {
                    builder.Add(typeSymbol.BaseType);
                }

                return ExternalTypeCollection.Create(this.State, this, this.ProjectId,
                    builder.ToImmutableAndFree());
            }
        }

        public virtual EnvDTE.CodeElements ImplementedInterfaces
        {
            get { throw Exceptions.ThrowENotImpl(); }
        }

        public EnvDTE.CodeElements DerivedTypes
        {
            get { throw Exceptions.ThrowENotImpl(); }
        }

        public bool IsAbstract
        {
            get { return TypeSymbol.IsAbstract; }
        }

        public override bool IsCodeType
        {
            get { return true; }
        }

        public bool IsSealed
        {
            get { return TypeSymbol.IsSealed; }
        }

        public EnvDTE.CodeElements Members
        {
            get { return ExternalMemberCollection.Create(this.State, this, this.ProjectId, this.TypeSymbol); }
        }

        public EnvDTE.CodeNamespace Namespace
        {
            get { return ExternalCodeNamespace.Create(this.State, this.ProjectId, this.TypeSymbol.ContainingNamespace); }
        }

        public bool get_IsDerivedFrom(string fullName)
        {
            var currentType = TypeSymbol;
            if (currentType == null)
            {
                return false;
            }

            var baseType = GetCompilation().GetTypeByMetadataName(fullName);
            if (baseType == null)
            {
                return false;
            }

            return currentType.InheritsFromOrEquals(baseType);
        }

        public EnvDTE.CodeElement AddBase(object @base, object position)
            => throw Exceptions.ThrowEFail();

        public void RemoveBase(object element)
            => throw Exceptions.ThrowEFail();

        public void RemoveMember(object element)
            => throw Exceptions.ThrowEFail();
    }
}
