// 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.Immutable;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Remote;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.FindSymbols;

internal static partial class DependentTypeFinder
{
    public static async Task<ImmutableArray<INamedTypeSymbol>> FindTypesAsync(
        INamedTypeSymbol type,
        Solution solution,
        IImmutableSet<Project>? projects,
        bool transitive,
        DependentTypesKind kind,
        CancellationToken cancellationToken)
    {
        if (SerializableSymbolAndProjectId.TryCreate(type, solution, cancellationToken, out var serializedType))
        {
            var client = await RemoteHostClient.TryGetClientAsync(solution.Services, cancellationToken).ConfigureAwait(false);
            if (client != null)
            {
                var projectIds = projects?.Where(p => RemoteSupportedLanguages.IsSupported(p.Language)).SelectAsArray(p => p.Id) ?? default;

                var result = await client.TryInvokeAsync<IRemoteDependentTypeFinderService, ImmutableArray<SerializableSymbolAndProjectId>>(
                    solution,
                    (service, solutionInfo, cancellationToken) => service.FindTypesAsync(solutionInfo, serializedType, projectIds, transitive, kind, cancellationToken),
                    cancellationToken).ConfigureAwait(false);

                if (!result.HasValue)
                {
                    return [];
                }

                return await RehydrateAsync(solution, result.Value, cancellationToken).ConfigureAwait(false);
            }

            // TODO: Do not fall back to in-proc https://github.com/dotnet/roslyn/issues/47557
        }

        return await FindTypesInCurrentProcessAsync(type, solution, projects, transitive, kind, cancellationToken).ConfigureAwait(false);
    }

    public static async Task<ImmutableArray<INamedTypeSymbol>> FindTypesInCurrentProcessAsync(
        INamedTypeSymbol type,
        Solution solution,
        IImmutableSet<Project>? projects,
        bool transitive,
        DependentTypesKind kind,
        CancellationToken cancellationToken)
    {
        var functionId = kind switch
        {
            DependentTypesKind.DerivedClasses => FunctionId.DependentTypeFinder_FindAndCacheDerivedClassesAsync,
            DependentTypesKind.DerivedInterfaces => FunctionId.DependentTypeFinder_FindAndCacheDerivedInterfacesAsync,
            DependentTypesKind.ImplementingTypes => FunctionId.DependentTypeFinder_FindAndCacheImplementingTypesAsync,
            _ => throw ExceptionUtilities.UnexpectedValue(kind)
        };

        using (Logger.LogBlock(functionId, cancellationToken))
        {
            var task = kind switch
            {
                DependentTypesKind.DerivedClasses => FindDerivedClassesInCurrentProcessAsync(type, solution, projects, transitive, cancellationToken),
                DependentTypesKind.DerivedInterfaces => FindDerivedInterfacesInCurrentProcessAsync(type, solution, projects, transitive, cancellationToken),
                DependentTypesKind.ImplementingTypes => FindImplementingTypesInCurrentProcessAsync(type, solution, projects, transitive, cancellationToken),
                _ => throw ExceptionUtilities.UnexpectedValue(kind)
            };

            return await task.ConfigureAwait(false);
        }
    }

    private static async Task<ImmutableArray<INamedTypeSymbol>> RehydrateAsync(Solution solution, ImmutableArray<SerializableSymbolAndProjectId> values, CancellationToken cancellationToken)
    {
        using var _ = ArrayBuilder<INamedTypeSymbol>.GetInstance(out var builder);

        foreach (var item in values)
        {
            var rehydrated = await item.TryRehydrateAsync(solution, cancellationToken).ConfigureAwait(false);
            if (rehydrated is INamedTypeSymbol namedType)
                builder.AddIfNotNull(namedType);
        }

        return builder.ToImmutableAndClear();
    }
}