// 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.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.Progression;
 
internal static class SymbolContainment
{
    public static async Task<IEnumerable<SyntaxNode>> GetContainedSyntaxNodesAsync(Document document, CancellationToken cancellationToken)
    {
        var progressionLanguageService = document.GetLanguageService<IProgressionLanguageService>();
        if (progressionLanguageService == null)
            return [];
 
        var syntaxTree = await document.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);
        var root = await syntaxTree.GetRootAsync(cancellationToken).ConfigureAwait(false);
        return progressionLanguageService.GetTopLevelNodesFromDocument(root, cancellationToken);
    }
 
    public static async Task<ImmutableArray<ISymbol>> GetContainedSymbolsAsync(Document document, CancellationToken cancellationToken)
    {
        var syntaxNodes = await GetContainedSyntaxNodesAsync(document, cancellationToken).ConfigureAwait(false);
        var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
        using var _ = ArrayBuilder<ISymbol>.GetInstance(out var symbols);
 
        foreach (var syntaxNode in syntaxNodes)
        {
            cancellationToken.ThrowIfCancellationRequested();
 
            var symbol = semanticModel.GetDeclaredSymbol(syntaxNode, cancellationToken);
            if (symbol != null &&
                !string.IsNullOrEmpty(symbol.Name) &&
                IsTopLevelSymbol(symbol))
            {
                symbols.Add(symbol);
            }
        }
 
        return symbols.ToImmutableAndClear();
    }
 
    private static bool IsTopLevelSymbol(ISymbol symbol)
    {
        switch (symbol.Kind)
        {
            case SymbolKind.NamedType:
            case SymbolKind.Method:
            case SymbolKind.Field:
            case SymbolKind.Property:
            case SymbolKind.Event:
                return true;
 
            default:
                return false;
        }
    }
 
    public static IEnumerable<ISymbol> GetContainedSymbols(ISymbol symbol)
    {
        if (symbol is INamedTypeSymbol namedType)
        {
            foreach (var member in namedType.GetMembers())
            {
                if (member.IsImplicitlyDeclared)
                {
                    continue;
                }
 
                if (member is IMethodSymbol method && method.AssociatedSymbol != null)
                {
                    continue;
                }
 
                if (!string.IsNullOrEmpty(member.Name))
                {
                    yield return member;
                }
            }
        }
    }
}