// 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.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
using Roslyn.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Collections;
 
[ComVisible(true)]
[ComDefaultInterface(typeof(ICodeElements))]
public sealed class BasesCollection : AbstractCodeElementCollection
{
    private readonly bool _interfaces;
 
    internal static EnvDTE.CodeElements Create(
        CodeModelState state,
        object parent,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        bool interfaces)
    {
        var collection = new BasesCollection(state, parent, fileCodeModel, nodeKey, interfaces);
        return (EnvDTE.CodeElements)ComAggregate.CreateAggregatedObject(collection);
    }
 
    private readonly ComHandle<EnvDTE.FileCodeModel, FileCodeModel> _fileCodeModel;
    private readonly SyntaxNodeKey _nodeKey;
 
    private BasesCollection(
        CodeModelState state,
        object parent,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey,
        bool interfaces)
        : base(state, parent)
    {
        Debug.Assert(fileCodeModel != null);
 
        _fileCodeModel = new ComHandle<EnvDTE.FileCodeModel, FileCodeModel>(fileCodeModel);
        _nodeKey = nodeKey;
        _interfaces = interfaces;
    }
 
    private FileCodeModel FileCodeModel
    {
        get { return _fileCodeModel.Object; }
    }
 
    private SyntaxNode LookupNode()
        => FileCodeModel.LookupNode(_nodeKey);
 
    private ITypeSymbol LookupSymbol()
    {
        var node = LookupNode();
        var semanticModel = FileCodeModel.GetSemanticModel();
        return semanticModel.GetDeclaredSymbol(node) as ITypeSymbol;
    }
 
    private IEnumerable<ITypeSymbol> GetBaseTypes()
    {
        var symbol = LookupSymbol();
        if (symbol == null)
        {
            throw Exceptions.ThrowEFail();
        }
 
        if (symbol.TypeKind == TypeKind.Interface || _interfaces)
        {
            return symbol.Interfaces;
        }
        else
        {
            return [symbol.BaseType];
        }
    }
 
    protected override bool TryGetItemByIndex(int index, out EnvDTE.CodeElement element)
    {
        var baseTypes = GetBaseTypes();
        if (index < baseTypes.Count())
        {
            var child = baseTypes.ElementAt(index);
            var projectId = FileCodeModel.GetProjectId();
            element = CodeModelService.CreateCodeType(this.State, projectId, child);
            return true;
        }
 
        element = null;
        return false;
    }
 
    protected override bool TryGetItemByName(string name, out EnvDTE.CodeElement element)
    {
        if (name != null)
        {
            // When searching by name it may or may not be the fully qualified named,
            // but we need the fully qualified name for comparison.
            var node = LookupNode();
            var semanticModel = FileCodeModel.GetSemanticModel();
 
            name = CodeModelService.GetFullyQualifiedName(name, node.SpanStart, semanticModel);
        }
 
        foreach (var child in GetBaseTypes())
        {
            var childName = child.GetEscapedFullName();
            if (childName == name)
            {
                var projectId = FileCodeModel.GetProjectId();
                element = CodeModelService.CreateCodeType(this.State, projectId, child);
                return true;
            }
        }
 
        element = null;
        return false;
    }
 
    public override int Count
    {
        get
        {
            var symbol = LookupSymbol();
            if (symbol == null)
            {
                throw Exceptions.ThrowEFail();
            }
 
            if (symbol.TypeKind == TypeKind.Interface || _interfaces)
            {
                return symbol.Interfaces.Length;
            }
            else
            {
                return 1;
            }
        }
    }
}