// 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.Composition;
using System.Text.Json.Serialization;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.LanguageServer.LanguageServer;
using Microsoft.CodeAnalysis.Text;
using Roslyn.LanguageServer.Protocol;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.LanguageServer.HostWorkspace;
 
[Export(typeof(IDynamicFileInfoProvider)), Shared]
[ExportMetadata("Extensions", new string[] { "cshtml", "razor", })]
internal class RazorDynamicFileInfoProvider : IDynamicFileInfoProvider
{
    private const string ProvideRazorDynamicFileInfoMethodName = "razor/provideDynamicFileInfo";
 
    private class ProvideDynamicFileParams
    {
        [JsonPropertyName("razorDocument")]
        public required TextDocumentIdentifier RazorDocument { get; set; }
    }
 
    private class ProvideDynamicFileResponse
    {
        [JsonPropertyName("csharpDocument")]
        public required TextDocumentIdentifier CSharpDocument { get; set; }
    }
 
    private const string RemoveRazorDynamicFileInfoMethodName = "razor/removeDynamicFileInfo";
 
    private class RemoveDynamicFileParams
    {
        [JsonPropertyName("csharpDocument")]
        public required TextDocumentIdentifier CSharpDocument { get; set; }
    }
 
#pragma warning disable CS0067 // We won't fire the Updated event -- we expect Razor to send us textual changes via didChange instead
    public event EventHandler<string>? Updated;
#pragma warning restore CS0067
 
    private readonly Lazy<RazorWorkspaceListenerInitializer> _razorWorkspaceListenerInitializer;
 
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public RazorDynamicFileInfoProvider(Lazy<RazorWorkspaceListenerInitializer> razorWorkspaceListenerInitializer)
    {
        _razorWorkspaceListenerInitializer = razorWorkspaceListenerInitializer;
    }
 
    public async Task<DynamicFileInfo?> GetDynamicFileInfoAsync(ProjectId projectId, string? projectFilePath, string filePath, CancellationToken cancellationToken)
    {
        _razorWorkspaceListenerInitializer.Value.NotifyDynamicFile(projectId);
 
        var requestParams = new ProvideDynamicFileParams
        {
            RazorDocument = new()
            {
                Uri = ProtocolConversions.CreateAbsoluteUri(filePath)
            }
        };
 
        Contract.ThrowIfNull(LanguageServerHost.Instance, "We don't have an LSP channel yet to send this request through.");
        var clientLanguageServerManager = LanguageServerHost.Instance.GetRequiredLspService<IClientLanguageServerManager>();
 
        var response = await clientLanguageServerManager.SendRequestAsync<ProvideDynamicFileParams, ProvideDynamicFileResponse>(
            ProvideRazorDynamicFileInfoMethodName, requestParams, cancellationToken);
 
        // Since we only sent one file over, we should get either zero or one URI back
        var responseUri = response.CSharpDocument?.Uri;
 
        if (responseUri == null)
        {
            return null;
        }
        else
        {
            var dynamicFileInfoFilePath = ProtocolConversions.GetDocumentFilePathFromUri(responseUri);
            return new DynamicFileInfo(dynamicFileInfoFilePath, SourceCodeKind.Regular, EmptyStringTextLoader.Instance, designTimeOnly: true, documentServiceProvider: null);
        }
    }
 
    public Task RemoveDynamicFileInfoAsync(ProjectId projectId, string? projectFilePath, string filePath, CancellationToken cancellationToken)
    {
        var notificationParams = new RemoveDynamicFileParams
        {
            CSharpDocument = new()
            {
                Uri = ProtocolConversions.CreateAbsoluteUri(filePath)
            }
        };
 
        Contract.ThrowIfNull(LanguageServerHost.Instance, "We don't have an LSP channel yet to send this request through.");
        var clientLanguageServerManager = LanguageServerHost.Instance.GetRequiredLspService<IClientLanguageServerManager>();
 
        return clientLanguageServerManager.SendNotificationAsync(
            RemoveRazorDynamicFileInfoMethodName, notificationParams, cancellationToken).AsTask();
    }
 
    private sealed class EmptyStringTextLoader : TextLoader
    {
        public static readonly TextLoader Instance = new EmptyStringTextLoader();
 
        private EmptyStringTextLoader() { }
 
        public override Task<TextAndVersion> LoadTextAndVersionAsync(LoadTextOptions options, CancellationToken cancellationToken)
        {
            return Task.FromResult(TextAndVersion.Create(SourceText.From(""), VersionStamp.Default));
        }
    }
}