﻿// 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.Linq;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CodeGeneration;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis.GenerateDefaultConstructors
{
    internal abstract class AbstractGenerateDefaultConstructorCodeFixProvider : CodeFixProvider
    {
        public override FixAllProvider? GetFixAllProvider() => null;

        protected abstract SyntaxToken? TryGetTypeName(SyntaxNode typeDeclaration);

        public override async Task RegisterCodeFixesAsync(CodeFixContext context)
        {
            var cancellationToken = context.CancellationToken;
            var document = context.Document;
            var diagnostic = context.Diagnostics.FirstOrDefault();
            if (diagnostic == null)
                return;

            var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var headerFacts = document.GetRequiredLanguageService<IHeaderFactsService>();
            if (!headerFacts.IsOnTypeHeader(root, diagnostic.Location.SourceSpan.Start, fullHeader: true, out var typeDecl))
                return;

            var typeName = TryGetTypeName(typeDecl);
            if (typeName == null)
                return;

            var service = document.GetRequiredLanguageService<IGenerateDefaultConstructorsService>();
            var actions = await service.GenerateDefaultConstructorsAsync(
                document, new TextSpan(typeName.Value.Span.Start, 0), context.Options, forRefactoring: false, cancellationToken).ConfigureAwait(false);
            context.RegisterFixes(actions, diagnostic);
        }
    }
}
