// 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.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Remote;
 
namespace Microsoft.CodeAnalysis.SymbolSearch;
 
/// <summary>
/// Factory that will produce the <see cref="ISymbolSearchUpdateEngine"/>.  The default
/// implementation produces an engine that will run in-process.  Implementations at
/// other layers can behave differently (for example, running the engine out-of-process).
/// </summary>
/// <remarks>
/// This returns an No-op engine on non-Windows OS, because the backing storage depends on Windows APIs.
/// </remarks>
internal static class SymbolSearchUpdateEngineFactory
{
    public static async ValueTask<ISymbolSearchUpdateEngine> CreateEngineAsync(
        Workspace workspace,
        IFileDownloaderFactory fileDownloaderFactory,
        CancellationToken cancellationToken)
    {
        var client = await RemoteHostClient.TryGetClientAsync(workspace, cancellationToken).ConfigureAwait(false);
        return client != null
            ? new SymbolSearchUpdateEngineProxy(client)
            // Couldn't go out of proc.  Just do everything inside the current process.
            : CreateEngineInProcess(fileDownloaderFactory);
    }
 
    /// <summary>
    /// This returns a No-op engine if called on non-Windows OS, because the backing storage depends on Windows APIs.
    /// </summary>
    public static ISymbolSearchUpdateEngine CreateEngineInProcess(IFileDownloaderFactory fileDownloaderFactory)
    {
        return RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
            ? new SymbolSearchUpdateEngine(fileDownloaderFactory)
            : SymbolSearchUpdateNoOpEngine.Instance;
    }
}