// 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.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.InlineHints;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis.ExternalAccess.OmniSharp.InlineHints;

internal static class OmniSharpInlineHintsService
{
    public static async Task<ImmutableArray<OmniSharpInlineHint>> GetInlineHintsAsync(Document document, TextSpan textSpan, OmniSharpInlineHintsOptions options, CancellationToken cancellationToken)
    {
        var service = document.GetRequiredLanguageService<IInlineHintsService>();
        var roslynOptions = options.ToInlineHintsOptions();

        var hints = await service.GetInlineHintsAsync(document, textSpan, roslynOptions, displayAllOverride: false, cancellationToken).ConfigureAwait(false);
        return hints.SelectAsArray(static h => new OmniSharpInlineHint(
            h.Span,
            h.Ranking,
            h.DisplayParts,
            h.ReplacementTextChange,
            h.GetDescriptionAsync));
    }
}

internal readonly struct OmniSharpInlineHint
{
    private readonly Func<Document, CancellationToken, Task<ImmutableArray<TaggedText>>> _getDescriptionAsync;

    public OmniSharpInlineHint(
        TextSpan span,
        double ranking,
        ImmutableArray<TaggedText> displayParts,
        TextChange? replacementTextChange,
        Func<Document, CancellationToken, Task<ImmutableArray<TaggedText>>> getDescriptionAsync)
    {
        Span = span;
        Ranking = ranking;
        DisplayParts = displayParts;
        ReplacementTextChange = replacementTextChange;
        _getDescriptionAsync = getDescriptionAsync;
    }

    public readonly TextSpan Span { get; }
    public readonly double Ranking { get; }
    public readonly ImmutableArray<TaggedText> DisplayParts { get; }
    public readonly TextChange? ReplacementTextChange { get; }

    public Task<ImmutableArray<TaggedText>> GetDescriptionAsync(Document document, CancellationToken cancellationToken)
        => _getDescriptionAsync.Invoke(document, cancellationToken);
}