// 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.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.ExternalElements;
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 ExternalParameterCollection : AbstractCodeElementCollection
{
    internal static EnvDTE.CodeElements Create(
        CodeModelState state,
        AbstractExternalCodeMember parent,
        ProjectId projectId)
    {
        var collection = new ExternalParameterCollection(state, parent, projectId);
        return (EnvDTE.CodeElements)ComAggregate.CreateAggregatedObject(collection);
    }
 
    private readonly ProjectId _projectId;
 
    private ExternalParameterCollection(
        CodeModelState state,
        AbstractExternalCodeMember parent,
        ProjectId projectId)
        : base(state, parent)
    {
        _projectId = projectId;
    }
 
    private AbstractExternalCodeMember ParentElement
    {
        get { return (AbstractExternalCodeMember)this.Parent; }
    }
 
    private ImmutableArray<IParameterSymbol> GetParameters()
    {
        var symbol = this.ParentElement.LookupSymbol();
        return symbol.GetParameters();
    }
 
    protected override bool TryGetItemByIndex(int index, out EnvDTE.CodeElement element)
    {
        var parameters = GetParameters();
 
        if (index < parameters.Length)
        {
            element = (EnvDTE.CodeElement)ExternalCodeParameter.Create(this.State, _projectId, parameters[index], this.ParentElement);
            return true;
        }
 
        element = null;
        return false;
    }
 
    protected override bool TryGetItemByName(string name, out EnvDTE.CodeElement element)
    {
        var parameters = GetParameters();
        var index = parameters.IndexOf(p => p.Name == name);
 
        if (index >= 0 && index < parameters.Length)
        {
            element = (EnvDTE.CodeElement)ExternalCodeParameter.Create(this.State, _projectId, parameters[index], this.ParentElement);
            return true;
        }
 
        element = null;
        return false;
    }
 
    public override int Count
    {
        get
        {
            var parameters = GetParameters();
            return parameters.Length;
        }
    }
}