// 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.
 
#nullable disable
 
using System;
using System.Linq;
using System.Composition;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.ExternalAccess.FSharp.SignatureHelp;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.SignatureHelp;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Internal.SignatureHelp
{
    [Shared]
    [ExportSignatureHelpProvider(nameof(FSharpSignatureHelpProvider), LanguageNames.FSharp)]
    internal class FSharpSignatureHelpProvider : ISignatureHelpProvider
    {
        private readonly IFSharpSignatureHelpProvider _provider;
 
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public FSharpSignatureHelpProvider(IFSharpSignatureHelpProvider provider)
        {
            _provider = provider;
        }
 
        public async Task<SignatureHelpItems> GetItemsAsync(Document document, int position, SignatureHelpTriggerInfo triggerInfo, MemberDisplayOptions options, CancellationToken cancellationToken)
        {
            var mappedTriggerReason = FSharpSignatureHelpTriggerReasonHelpers.ConvertFrom(triggerInfo.TriggerReason);
            var mappedTriggerInfo = new FSharpSignatureHelpTriggerInfo(mappedTriggerReason, triggerInfo.TriggerCharacter);
            var mappedSignatureHelpItems = await _provider.GetItemsAsync(document, position, mappedTriggerInfo, cancellationToken).ConfigureAwait(false);
 
            if (mappedSignatureHelpItems != null)
            {
                return new SignatureHelpItems(
                    mappedSignatureHelpItems.Items?.Select(x =>
                        new SignatureHelpItem(
                            x.IsVariadic,
                            x.DocumentationFactory,
                            x.PrefixDisplayParts,
                            x.SeparatorDisplayParts,
                            x.SuffixDisplayParts,
                            x.Parameters.Select(y =>
                                new SignatureHelpParameter(
                                    y.Name,
                                    y.IsOptional,
                                    y.DocumentationFactory,
                                    y.DisplayParts,
                                    y.PrefixDisplayParts,
                                    y.SuffixDisplayParts,
                                    y.SelectedDisplayParts)).ToList(),
                            x.DescriptionParts)).ToList(),
                    mappedSignatureHelpItems.ApplicableSpan,
                    mappedSignatureHelpItems.ArgumentIndex,
                    mappedSignatureHelpItems.ArgumentCount,
                    mappedSignatureHelpItems.ArgumentName,
                    mappedSignatureHelpItems.SelectedItemIndex);
            }
            else
            {
                return null;
            }
        }
 
        public bool IsRetriggerCharacter(char ch)
        {
            return _provider.IsRetriggerCharacter(ch);
        }
 
        public bool IsTriggerCharacter(char ch)
        {
            return _provider.IsTriggerCharacter(ch);
        }
    }
}