// 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.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Text;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.Razor
{
    internal sealed class RazorMappingServiceWrapper(IRazorMappingService razorMappingService) : ISpanMappingService
    {
        private readonly IRazorMappingService _razorMappingService = razorMappingService;
 
        public bool SupportsMappingImportDirectives => true;
 
        public async Task<ImmutableArray<(string mappedFilePath, TextChange mappedTextChange)>> GetMappedTextChangesAsync(
            Document oldDocument,
            Document newDocument,
            CancellationToken cancellationToken)
        {
            var mappedEdits = await _razorMappingService.MapTextChangesAsync(oldDocument, newDocument, cancellationToken).ConfigureAwait(false);
 
            var changesCount = mappedEdits.Select(e => e.IsDefault ? 0 : e.TextChanges.Length).Sum();
            var changes = new (string mappedFilePath, TextChange mappedTextChange)[changesCount];
 
            var i = 0;
            foreach (var mappedEdit in mappedEdits)
            {
                if (mappedEdit.IsDefault)
                {
                    continue;
                }
 
                foreach (var textChange in mappedEdit.TextChanges)
                {
                    changes[i++] = (mappedEdit.FilePath, textChange);
                }
            }
 
            Debug.Assert(i == changesCount);
            return changes.ToImmutableArray();
        }
 
        public async Task<ImmutableArray<MappedSpanResult>> MapSpansAsync(
            Document document,
            IEnumerable<TextSpan> spans,
            CancellationToken cancellationToken)
        {
            var razorSpans = await _razorMappingService.MapSpansAsync(document, spans, cancellationToken).ConfigureAwait(false);
            var roslynSpans = new MappedSpanResult[razorSpans.Length];
            for (var i = 0; i < razorSpans.Length; i++)
            {
                var razorSpan = razorSpans[i];
                if (razorSpan.IsDefault)
                {
                    // Unmapped location
                    roslynSpans[i] = default;
                }
                else
                {
                    roslynSpans[i] = new MappedSpanResult(razorSpan.FilePath, razorSpan.LinePositionSpan, razorSpan.Span);
                }
            }
 
            return roslynSpans.ToImmutableArray();
        }
    }
}