// 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.Collections.Generic;
using System.Collections.Immutable;
using System.Composition;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host.Mef;
 
namespace Microsoft.CodeAnalysis.BraceMatching
{
    [Export(typeof(IBraceMatchingService)), Shared]
    internal class BraceMatchingService : IBraceMatchingService
    {
        private readonly ImmutableArray<Lazy<IBraceMatcher, LanguageMetadata>> _braceMatchers;
 
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public BraceMatchingService(
            [ImportMany] IEnumerable<Lazy<IBraceMatcher, LanguageMetadata>> braceMatchers)
        {
            _braceMatchers = braceMatchers.ToImmutableArray();
        }
 
        public async Task<BraceMatchingResult?> GetMatchingBracesAsync(Document document, int position, BraceMatchingOptions options, CancellationToken cancellationToken)
        {
            var text = await document.GetTextAsync(cancellationToken).ConfigureAwait(false);
            if (position < 0 || position > text.Length)
            {
                throw new ArgumentException(nameof(position));
            }
 
            var matchers = _braceMatchers.Where(b => b.Metadata.Language == document.Project.Language);
            foreach (var matcher in matchers)
            {
                cancellationToken.ThrowIfCancellationRequested();
                var braces = await matcher.Value.FindBracesAsync(document, position, options, cancellationToken).ConfigureAwait(false);
                if (braces.HasValue)
                {
                    return braces;
                }
            }
 
            return null;
        }
    }
}