// 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.Linq;
using System.Threading;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.PullMemberUp;
using Microsoft.VisualStudio.Language.Intellisense;
using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.PullMemberUp.MainDialog;
 
/// <summary>
/// View model used to represent and display the inheritance graph as a tree. This tree is constructed by breadth first searching.
/// If one type is the common base type of several other types, it will be showed multiple time.
/// </summary>
internal class BaseTypeTreeNodeViewModel : SymbolViewModel<INamedTypeSymbol>
{
    /// <summary>
    /// Base types of this tree node
    /// </summary>
    public ImmutableArray<BaseTypeTreeNodeViewModel> BaseTypeNodes { get; private set; }
 
    public bool IsExpanded { get; set; }
 
    /// <summary>
    /// Content of the tooltip.
    /// </summary>
    public string Namespace => string.Format(ServicesVSResources.Namespace_0, Symbol.ContainingNamespace?.ToDisplayString() ?? "global");
 
    private BaseTypeTreeNodeViewModel(INamedTypeSymbol node, IGlyphService glyphService) : base(node, glyphService)
    {
    }
 
    /// <summary>
    /// Use breadth first search to create the inheritance tree. Only non-generated types in the solution will be included in the tree.
    /// </summary>
    public static BaseTypeTreeNodeViewModel CreateBaseTypeTree(
        IGlyphService glyphService,
        Solution solution,
        INamedTypeSymbol root,
        CancellationToken cancellationToken)
    {
        var rootTreeNode = new BaseTypeTreeNodeViewModel(root, glyphService) { IsChecked = false, IsExpanded = true };
        var queue = new Queue<BaseTypeTreeNodeViewModel>();
        queue.Enqueue(rootTreeNode);
        while (queue.Any())
        {
            var currentTreeNode = queue.Dequeue();
            var currentTypeSymbol = currentTreeNode.Symbol;
 
            currentTreeNode.BaseTypeNodes = currentTypeSymbol.Interfaces
                .Concat(currentTypeSymbol.BaseType)
                .Where(baseType => baseType != null && MemberAndDestinationValidator.IsDestinationValid(solution, baseType, cancellationToken))
                .OrderBy(baseType => baseType.ToDisplayString())
                .Select(baseType => new BaseTypeTreeNodeViewModel(baseType, glyphService) { IsChecked = false, IsExpanded = true })
                .ToImmutableArray();
 
            foreach (var node in currentTreeNode.BaseTypeNodes)
            {
                queue.Enqueue(node);
            }
        }
 
        return rootTreeNode;
    }
}