// 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 Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis;
 
internal partial struct SymbolKey
{
    private sealed class TypeParameterSymbolKey : AbstractSymbolKey<ITypeParameterSymbol>
    {
        public static readonly TypeParameterSymbolKey Instance = new();
 
        public sealed override void Create(ITypeParameterSymbol symbol, SymbolKeyWriter visitor)
        {
            if (symbol.TypeParameterKind == TypeParameterKind.Cref)
            {
                visitor.WriteBoolean(true);
                visitor.WriteLocation(symbol.Locations[0]);
            }
            else
            {
                visitor.WriteBoolean(false);
                visitor.WriteString(symbol.MetadataName);
                visitor.WriteSymbolKey(symbol.ContainingSymbol);
            }
        }
 
        protected sealed override SymbolKeyResolution Resolve(
            SymbolKeyReader reader, ITypeParameterSymbol? contextualSymbol, out string? failureReason)
        {
            var isCref = reader.ReadBoolean();
 
            if (isCref)
            {
                var location = reader.ReadLocation(out var locationFailureReason)!;
                if (locationFailureReason != null)
                {
                    failureReason = $"({nameof(TypeParameterSymbolKey)} {nameof(location)} failed -> {locationFailureReason})";
                    return default;
                }
 
                var resolution = reader.ResolveLocation(location);
 
                failureReason = null;
                return resolution.GetValueOrDefault();
            }
            else
            {
                var metadataName = reader.ReadString();
                var containingSymbolResolution = reader.ReadSymbolKey(contextualSymbol?.ContainingSymbol, out var containingSymbolFailureReason);
 
                if (containingSymbolFailureReason != null)
                {
                    failureReason = $"({nameof(TypeParameterSymbolKey)} {nameof(containingSymbolResolution)} failed -> {containingSymbolFailureReason})";
                    return default;
                }
 
                using var result = PooledArrayBuilder<ITypeParameterSymbol>.GetInstance();
                foreach (var containingSymbol in containingSymbolResolution)
                {
                    foreach (var typeParam in containingSymbol.GetTypeParameters())
                    {
                        if (typeParam.MetadataName == metadataName)
                        {
                            result.AddIfNotNull(typeParam);
                        }
                    }
                }
 
                return CreateResolution(result, $"({nameof(TypeParameterSymbolKey)} '{metadataName}' not found)", out failureReason);
            }
        }
    }
}