// 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.Collections.Immutable;
using System.Composition;
using System.Threading;
using Microsoft.CodeAnalysis.DocumentHighlighting;
using Microsoft.CodeAnalysis.ExternalAccess.AspNetCore.EmbeddedLanguages;
using Microsoft.CodeAnalysis.Host.Mef;

namespace Microsoft.CodeAnalysis.ExternalAccess.AspNetCore.Internal.EmbeddedLanguages;

[ExportEmbeddedLanguageDocumentHighlighter(
    nameof(AspNetCoreEmbeddedLanguageDocumentHighlighter),
    [LanguageNames.CSharp],
    supportsUnannotatedAPIs: false,
    // Add more syntax names here in the future if there are additional cases ASP.Net would like to light up on.
    identifiers: ["Route"]), Shared]
internal class AspNetCoreEmbeddedLanguageDocumentHighlighter : IEmbeddedLanguageDocumentHighlighter
{
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public AspNetCoreEmbeddedLanguageDocumentHighlighter()
    {
    }

    public ImmutableArray<DocumentHighlights> GetDocumentHighlights(
        Document document,
        SemanticModel semanticModel,
        SyntaxToken token,
        int position,
        HighlightingOptions options,
        CancellationToken cancellationToken)
    {
        var highlighters = AspNetCoreDocumentHighlighterExtensionProvider.GetExtensions(document.Project);
        foreach (var highlighter in highlighters)
        {
            var highlights = highlighter.GetDocumentHighlights(semanticModel, token, position, cancellationToken);
            if (!highlights.IsDefaultOrEmpty)
            {
                return highlights.SelectAsArray(h => new DocumentHighlights(document,
                    h.HighlightSpans.SelectAsArray(hs => new HighlightSpan(hs.TextSpan, ConvertKind(hs.Kind)))));
            }
        }

        return [];

        static HighlightSpanKind ConvertKind(AspNetCoreHighlightSpanKind kind)
        {
            return kind switch
            {
                AspNetCoreHighlightSpanKind.None => HighlightSpanKind.None,
                AspNetCoreHighlightSpanKind.Definition => HighlightSpanKind.Definition,
                AspNetCoreHighlightSpanKind.Reference => HighlightSpanKind.Reference,
                AspNetCoreHighlightSpanKind.WrittenReference => HighlightSpanKind.WrittenReference,
                _ => throw new NotImplementedException(),
            };
        }
    }
}