// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Razor.PooledObjects;
using Microsoft.AspNetCore.Razor.Threading;
using Microsoft.CodeAnalysis.Razor.Logging;
using Microsoft.CodeAnalysis.Text;
 
namespace Microsoft.CodeAnalysis.Razor.Formatting;
 
internal sealed class FormattingContentValidationPass(ILoggerFactory loggerFactory) : IFormattingValidationPass
{
    private readonly ILogger _logger = loggerFactory.GetOrCreateLogger<FormattingContentValidationPass>();
 
    // Internal for testing.
    internal bool DebugAssertsEnabled { get; set; } = true;
 
    public Task<bool> IsValidAsync(FormattingContext context, ImmutableArray<TextChange> changes, CancellationToken cancellationToken)
    {
        var text = context.SourceText;
 
        if (!text.NonWhitespaceContentEquals(changes))
        {
            // Looks like we removed some non-whitespace content as part of formatting. Oops.
            // Discard this formatting result.
 
            var message = GetLogMessage(changes, text);
            _logger.LogError(message);
 
            if (DebugAssertsEnabled)
            {
                Debug.Fail(message);
            }
 
            return SpecializedTasks.False;
        }
 
        return SpecializedTasks.True;
    }
 
    private static string GetLogMessage(ImmutableArray<TextChange> changes, SourceText text)
    {
        using var _1 = StringBuilderPool.GetPooledObject(out var builder);
        builder.AppendLine(SR.Format_operation_changed_nonwhitespace);
 
        foreach (var change in changes)
        {
            if (change.NewText?.Any(c => !char.IsWhiteSpace(c)) ?? false)
            {
                builder.AppendLine(SR.FormatEdit_at_adds(text.GetLinePositionSpan(change.Span), change.NewText));
            }
            else if (text.TryGetFirstNonWhitespaceOffset(change.Span, out _))
            {
                builder.AppendLine(SR.FormatEdit_at_deletes(text.GetLinePositionSpan(change.Span), text.ToString(change.Span)));
            }
        }
 
        return builder.ToString();
    }
}