// 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;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeLens;
using Newtonsoft.Json.Linq;
using Roslyn.Utilities;
using StreamJsonRpc;
using LSP = Microsoft.VisualStudio.LanguageServer.Protocol;
 
namespace Microsoft.CodeAnalysis.LanguageServer.Handler.CodeLens;
 
[Method(LSP.Methods.CodeLensResolveName)]
internal sealed class CodeLensResolveHandler : ILspServiceDocumentRequestHandler<LSP.CodeLens, LSP.CodeLens>
{
    /// <summary>
    /// Command name implemented by the client and invoked when the references code lens is selected.
    /// </summary>
    private const string ClientReferencesCommand = "roslyn.client.peekReferences";
 
    private readonly CodeLensCache _codeLensCache;
 
    public CodeLensResolveHandler(CodeLensCache codeLensCache)
    {
        _codeLensCache = codeLensCache;
    }
 
    public bool MutatesSolutionState => false;
 
    public bool RequiresLSPSolution => true;
 
    public LSP.TextDocumentIdentifier GetTextDocumentIdentifier(LSP.CodeLens request)
        => GetCacheEntry(request).CacheEntry.TextDocumentIdentifier;
 
    public async Task<LSP.CodeLens> HandleRequestAsync(LSP.CodeLens request, RequestContext context, CancellationToken cancellationToken)
    {
        var document = context.GetRequiredDocument();
        var (cacheEntry, memberToResolve) = GetCacheEntry(request);
 
        var currentSyntaxVersion = await document.GetSyntaxVersionAsync(cancellationToken).ConfigureAwait(false);
        var cachedSyntaxVersion = cacheEntry.SyntaxVersion;
 
        if (currentSyntaxVersion != cachedSyntaxVersion)
        {
            throw new LocalRpcException($"Cached resolve version {cachedSyntaxVersion} does not match current version {currentSyntaxVersion}")
            {
                ErrorCode = LspErrorCodes.ContentModified
            };
        }
 
        var codeLensReferencesService = document.Project.Solution.Services.GetRequiredService<ICodeLensReferencesService>();
        var referenceCount = await codeLensReferencesService.GetReferenceCountAsync(document.Project.Solution, document.Id, memberToResolve.Node, maxSearchResults: 99, cancellationToken).ConfigureAwait(false);
        if (referenceCount != null)
        {
            request.Command = new LSP.Command
            {
                Title = referenceCount.Value.GetDescription(),
                CommandIdentifier = ClientReferencesCommand,
                Arguments = new object[]
                {
                        cacheEntry.TextDocumentIdentifier.Uri,
                        request.Range.Start
                }
            };
 
        }
 
        return request;
    }
 
    private (CodeLensCache.CodeLensCacheEntry CacheEntry, CodeLensMember MemberToResolve) GetCacheEntry(LSP.CodeLens request)
    {
        var resolveData = (request.Data as JToken)?.ToObject<CodeLensResolveData>();
        Contract.ThrowIfNull(resolveData, "Missing data for code lens resolve request");
 
        var cacheEntry = _codeLensCache.GetCachedEntry(resolveData.ResultId);
        Contract.ThrowIfNull(cacheEntry, "Missing cache entry for code lens resolve request");
        return (cacheEntry, cacheEntry.CodeLensMembers[resolveData.ListIndex]);
    }
}