// 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.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp.CodeGeneration;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.CSharp.UsePatternMatching
{
    [ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.UseNotPattern), Shared]
    internal sealed class CSharpUseNotPatternCodeFixProvider : SyntaxEditorBasedCodeFixProvider
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public CSharpUseNotPatternCodeFixProvider()
        {
        }

        public override ImmutableArray<string> FixableDiagnosticIds
            => ImmutableArray.Create(IDEDiagnosticIds.UseNotPatternDiagnosticId);

        public override Task RegisterCodeFixesAsync(CodeFixContext context)
        {
            RegisterCodeFix(context, CSharpAnalyzersResources.Use_pattern_matching, nameof(CSharpAnalyzersResources.Use_pattern_matching));
            return Task.CompletedTask;
        }

        protected override async Task FixAllAsync(
            Document document, ImmutableArray<Diagnostic> diagnostics,
            SyntaxEditor editor, CodeActionOptionsProvider fallbackOptions, CancellationToken cancellationToken)
        {
            var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
            foreach (var diagnostic in diagnostics)
            {
                cancellationToken.ThrowIfCancellationRequested();
                ProcessDiagnostic(semanticModel, editor, diagnostic, cancellationToken);
            }
        }

        private static void ProcessDiagnostic(
            SemanticModel semanticModel,
            SyntaxEditor editor,
            Diagnostic diagnostic,
            CancellationToken cancellationToken)
        {
            var notExpressionLocation = diagnostic.AdditionalLocations[0];

            var notExpression = (PrefixUnaryExpressionSyntax)notExpressionLocation.FindNode(getInnermostNodeForTie: true, cancellationToken);
            var parenthesizedExpression = (ParenthesizedExpressionSyntax)notExpression.Operand;

            var negated = editor.Generator.Negate(
                CSharpSyntaxGeneratorInternal.Instance,
                parenthesizedExpression.Expression,
                semanticModel,
                cancellationToken);

            editor.ReplaceNode(
                notExpression,
                negated.WithPrependedLeadingTrivia(notExpression.GetLeadingTrivia())
                       .WithAppendedTrailingTrivia(notExpression.GetTrailingTrivia()));
        }
    }
}
