// 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.Immutable;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.InternalElements;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Interop;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Collections;
 
[ComVisible(true)]
[ComDefaultInterface(typeof(ICodeElements))]
public sealed class InheritsImplementsCollection : AbstractCodeElementCollection
{
    internal static EnvDTE.CodeElements Create(
        CodeModelState state,
        object parent,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey)
    {
        var collection = new InheritsImplementsCollection(state, parent, fileCodeModel, nodeKey);
        return (EnvDTE.CodeElements)ComAggregate.CreateAggregatedObject(collection);
    }
 
    private readonly ComHandle<EnvDTE.FileCodeModel, FileCodeModel> _fileCodeModel;
    private readonly SyntaxNodeKey _nodeKey;
 
    private InheritsImplementsCollection(
        CodeModelState state,
        object parent,
        FileCodeModel fileCodeModel,
        SyntaxNodeKey nodeKey)
        : base(state, parent)
    {
        Debug.Assert(fileCodeModel != null);
 
        _fileCodeModel = new ComHandle<EnvDTE.FileCodeModel, FileCodeModel>(fileCodeModel);
        _nodeKey = nodeKey;
    }
 
    private FileCodeModel FileCodeModel
    {
        get { return _fileCodeModel.Object; }
    }
 
    private SyntaxNode LookupNode()
        => FileCodeModel.LookupNode(_nodeKey);
 
    internal override Snapshot CreateSnapshot()
    {
        var node = LookupNode();
        var parentElement = (AbstractCodeElement)this.Parent;
        return new NodeSnapshot(this.State, _fileCodeModel, node, parentElement,
            [
                .. CodeModelService.GetInheritsNodes(node),
                .. CodeModelService.GetImplementsNodes(node),
            ]);
    }
 
    protected override bool TryGetItemByIndex(int index, out EnvDTE.CodeElement element)
    {
        var node = LookupNode();
 
        var currentIndex = 0;
 
        // Inherits statements
        var inheritsNodes = CodeModelService.GetInheritsNodes(node);
        var inheritsNodeCount = inheritsNodes.Count();
        if (index < currentIndex + inheritsNodeCount)
        {
            var child = inheritsNodes.ElementAt(index - currentIndex);
            element = FileCodeModel.GetOrCreateCodeElement<EnvDTE.CodeElement>(child);
            return true;
        }
 
        currentIndex += inheritsNodeCount;
 
        // Implements statements
        var implementsNodes = CodeModelService.GetImplementsNodes(node);
        var implementsNodeCount = implementsNodes.Count();
        if (index < currentIndex + implementsNodeCount)
        {
            var child = implementsNodes.ElementAt(index - currentIndex);
            element = FileCodeModel.GetOrCreateCodeElement<EnvDTE.CodeElement>(child);
            return true;
        }
 
        element = null;
        return false;
    }
 
    protected override bool TryGetItemByName(string name, out EnvDTE.CodeElement element)
    {
        var node = LookupNode();
 
        // Inherits statements
        foreach (var child in CodeModelService.GetInheritsNodes(node))
        {
            CodeModelService.GetInheritsNamespaceAndOrdinal(node, child, out var childName, out var ordinal);
            if (childName == name)
            {
                element = FileCodeModel.GetOrCreateCodeElement<EnvDTE.CodeElement>(child);
                return true;
            }
        }
 
        // Implements statements
        foreach (var child in CodeModelService.GetImplementsNodes(node))
        {
            CodeModelService.GetImplementsNamespaceAndOrdinal(node, child, out var childName, out var ordinal);
            if (childName == name)
            {
                element = FileCodeModel.GetOrCreateCodeElement<EnvDTE.CodeElement>(child);
                return true;
            }
        }
 
        element = null;
        return false;
    }
 
    public override int Count
    {
        get
        {
            var node = LookupNode();
            return
                CodeModelService.GetInheritsNodes(node).Count() +
                CodeModelService.GetImplementsNodes(node).Count();
        }
    }
}