// 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 System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.TaskList;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.TaskList;
 
[Shared]
[ExportLanguageService(typeof(ITaskListService), LanguageNames.FSharp)]
internal sealed class FSharpTaskListService : ITaskListService
{
    private readonly IFSharpTaskListService? _impl;
 
    [ImportingConstructor]
    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
    public FSharpTaskListService([Import(AllowDefault = true)] IFSharpTaskListService impl)
    {
        _impl = impl;
    }
 
    public async Task<ImmutableArray<TaskListItem>> GetTaskListItemsAsync(Document document, ImmutableArray<TaskListItemDescriptor> descriptors, CancellationToken cancellationToken)
    {
        if (_impl == null)
            return [];
 
        var result = await _impl.GetTaskListItemsAsync(
            document,
            descriptors.SelectAsArray(d => new FSharpTaskListDescriptor(d)),
            cancellationToken).ConfigureAwait(false);
 
        if (result.Length == 0)
            return [];
 
        var text = await document.GetValueTextAsync(cancellationToken).ConfigureAwait(false);
 
        return result.SelectAsArray(d =>
        {
            var priority = d.TaskDescriptor.Descriptor.Priority;
            var span = new FileLinePositionSpan(document.FilePath!, text.Lines.GetLinePositionSpan(d.Span));
 
            return new TaskListItem(priority, d.Message, document.Id, span, span);
        });
    }
}