// 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.

using System.Collections.Generic;
using System.Linq;

namespace Microsoft.CodeAnalysis.ExtractMethod;

internal static class Extensions
{
    public static ITypeSymbol? GetLambdaOrAnonymousMethodReturnType(this SemanticModel binding, SyntaxNode node)
    {
        var info = binding.GetSymbolInfo(node);
        if (info.Symbol == null)
        {
            return null;
        }

        var methodSymbol = info.Symbol as IMethodSymbol;
        if (methodSymbol?.MethodKind != MethodKind.AnonymousFunction)
        {
            return null;
        }

        return methodSymbol.ReturnType;
    }

    /// <summary>
    /// get tokens with given annotation in current document
    /// </summary>
    public static SyntaxToken GetTokenWithAnnotation(this SemanticDocument document, SyntaxAnnotation annotation)
        => document.Root.GetAnnotatedNodesAndTokens(annotation).Single().AsToken();

    /// <summary>
    /// resolve the given symbol against compilation this snapshot has
    /// </summary>
    public static T ResolveType<T>(this SemanticModel semanticModel, T symbol) where T : class, ITypeSymbol
    {
        // Can be cleaned up when https://github.com/dotnet/roslyn/issues/38061 is resolved
        var typeSymbol = (T?)symbol.GetSymbolKey().Resolve(semanticModel.Compilation).GetAnySymbol();
        Contract.ThrowIfNull(typeSymbol);
        return (T)typeSymbol.WithNullableAnnotation(symbol.NullableAnnotation);
    }

    /// <summary>
    /// check whether node contains error for itself but not from its child node
    /// </summary>
    public static bool HasDiagnostics(this SyntaxNode node)
    {
        var set = new HashSet<Diagnostic>(node.GetDiagnostics());

        foreach (var child in node.ChildNodes())
        {
            set.ExceptWith(child.GetDiagnostics());
        }

        return set.Count > 0;
    }

    public static bool FromScript(this SyntaxNode node)
    {
        if (node.SyntaxTree == null)
        {
            return false;
        }

        return node.SyntaxTree.Options.Kind != SourceCodeKind.Regular;
    }
}