// 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.Immutable;
using System.Composition;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis.NewLines.ConsecutiveStatementPlacement
{
    [ExportCodeFixProvider(LanguageNames.CSharp, LanguageNames.VisualBasic, Name = PredefinedCodeFixProviderNames.ConsecutiveStatementPlacement), Shared]
    internal sealed class ConsecutiveStatementPlacementCodeFixProvider : CodeFixProvider
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public ConsecutiveStatementPlacementCodeFixProvider()
        {
        }
 
        public override ImmutableArray<string> FixableDiagnosticIds
            => ImmutableArray.Create(IDEDiagnosticIds.ConsecutiveStatementPlacementDiagnosticId);
 
        public override Task RegisterCodeFixesAsync(CodeFixContext context)
        {
            var document = context.Document;
            var diagnostic = context.Diagnostics.First();
            context.RegisterCodeFix(CodeAction.Create(
                CodeFixesResources.Add_blank_line_after_block,
                c => UpdateDocumentAsync(document, diagnostic, context.GetOptionsProvider(), c),
                nameof(CodeFixesResources.Add_blank_line_after_block)),
                context.Diagnostics);
            return Task.CompletedTask;
        }
 
        private static Task<Document> UpdateDocumentAsync(Document document, Diagnostic diagnostic, CodeActionOptionsProvider fallbackOptions, CancellationToken cancellationToken)
            => FixAllAsync(document, ImmutableArray.Create(diagnostic), fallbackOptions, cancellationToken);
 
        public static async Task<Document> FixAllAsync(Document document, ImmutableArray<Diagnostic> diagnostics, CodeActionOptionsProvider fallbackOptions, CancellationToken cancellationToken)
        {
            var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var options = await document.GetCodeFixOptionsAsync(fallbackOptions, cancellationToken).ConfigureAwait(false);
 
            var generator = document.GetRequiredLanguageService<SyntaxGeneratorInternal>();
            var endOfLineTrivia = generator.EndOfLine(options.NewLine);
 
            var nextTokens = diagnostics.Select(d => d.AdditionalLocations[0].FindToken(cancellationToken));
            var newRoot = root.ReplaceTokens(
                nextTokens,
                (original, current) => current.WithLeadingTrivia(current.LeadingTrivia.Insert(0, endOfLineTrivia)));
 
            return document.WithSyntaxRoot(newRoot);
        }
 
        public override FixAllProvider GetFixAllProvider()
            => FixAllProvider.Create(async (context, document, diagnostics) => await FixAllAsync(document, diagnostics, context.GetOptionsProvider(), context.CancellationToken).ConfigureAwait(false));
    }
}