﻿// 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.Composition;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.AddAccessibilityModifiers;
using Microsoft.CodeAnalysis.CodeCleanup;
using Microsoft.CodeAnalysis.CodeStyle;
using Microsoft.CodeAnalysis.CSharp.LanguageService;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.Formatting
{
    [ExportNewDocumentFormattingProvider(LanguageNames.CSharp), Shared]
    internal class CSharpAccessibilityModifiersNewDocumentFormattingProvider : INewDocumentFormattingProvider
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public CSharpAccessibilityModifiersNewDocumentFormattingProvider()
        {
        }

        public async Task<Document> FormatNewDocumentAsync(Document document, Document? hintDocument, CodeCleanupOptions options, CancellationToken cancellationToken)
        {
            var accessibilityPreferences = options.FormattingOptions.AccessibilityModifiersRequired;
            if (accessibilityPreferences == AccessibilityModifiersRequired.Never)
            {
                return document;
            }

            var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            var syntaxFacts = document.GetRequiredLanguageService<ISyntaxFactsService>();
            var typeDeclarations = root.DescendantNodes().Where(node => syntaxFacts.IsTypeDeclaration(node));
            var editor = new SyntaxEditor(root, document.Project.Solution.Services);

            var service = document.GetRequiredLanguageService<IAddAccessibilityModifiersService>();

            foreach (var declaration in typeDeclarations)
            {
                if (!service.ShouldUpdateAccessibilityModifier(CSharpAccessibilityFacts.Instance, declaration, accessibilityPreferences, out _, out _))
                    continue;

                // Since we format each document as they are added to a project we can't assume we know about all
                // of the files that are coming, so we have to opt out of changing partial classes. This especially
                // manifests when creating new projects as we format before we have a project at all, so we could get a
                // situation like this:
                //
                // File1.cs:
                //    partial class C { }
                // File2.cs:
                //    public partial class C { }
                //
                // When we see File1, we don't know about File2, so would add an internal modifier, which would result in a compile
                // error.
                var modifiers = syntaxFacts.GetModifiers(declaration);
                CSharpAccessibilityFacts.GetAccessibilityAndModifiers(modifiers, out _, out var declarationModifiers, out _);
                if (declarationModifiers.IsPartial)
                    continue;

                var type = semanticModel.GetDeclaredSymbol(declaration, cancellationToken);
                if (type == null)
                    continue;

                AddAccessibilityModifiersHelpers.UpdateDeclaration(editor, type, declaration);
            }

            return document.WithSyntaxRoot(editor.GetChangedRoot());
        }
    }
}
